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1
., Nagaraja, Raviraja Adhikari e T. Yasir. "An investigation into tapping of Al6061/SiC metal matrix composite with straight flute HSS machine tap". Journal of Mechanical Engineering and Sciences 13, n. 1 (29 marzo 2019): 4575–95. http://dx.doi.org/10.15282/jmes.13.1.2019.16.0386.
Testo completoAbstract (sommario):
The present study deals with tapping of Al6061/SiC metal matrix composite. Stir casting technique was used for the fabrication of composite. Castings were produced by varying weight percentages of SiC (5%, 7.5% and 10%) of 23μm size in Al6061. The tapping experiments were conducted for the machinability study of Al6061/SiC metal matrix composite using M8 x 1.25 HSS machine taps. The tapping operation was performed under dry condition with different cutting speeds. Torque required for tapping was measured using piezoelectric based 4-component drill tool dynamometer. Surface morphology and profile of thread surfaces were analysed using Scanning Electron Microscope (SEM) and metallurgical microscope. Estimation of progressive flank wear of machine taps was undertaken using profile projector. The performance of HSS machine tap was evaluated in terms of tapping torque, tool flank wear, and surface characteristics of thread surfaces. The flank wear of uncoated HSS machine tap increased with the increase in weight percentage of SiC in Al/SiC composite for a particular cutting speed. Further, when the matrix materials were reinforced by the same kind and the same weight percentage of SiC particles, the flank wear of the tool was found to increase with cutting speed. In addition, the damage caused to thread profiles increased with the increase in cutting speed and weight percentage of SiC.
2
Pang, Minghua, Xiaojun Liu e Kun Liu. "Effect of conical micro-grooved texture on tool–chip friction property and cutting performance of WC-TiC/Co cemented carbide tools". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 233, n. 5 (4 ottobre 2018): 791–804. http://dx.doi.org/10.1177/1350650118804907.
Testo completoAbstract (sommario):
Purpose This study aimed to clarify the influence mechanism of conical micro-grooved texture on the tool–chip friction property and cutting performance of WC-TiC/Co cemented carbide tools under flood lubrication conditions. Design/methodology/approach Conical micro-grooved texture was fabricated on the tool rake face using laser texture technology. Metal cutting tests were conducted on AISI 1045 steel with conventional and developed tools for various cutting speeds (80 m/min to 160 m/min) and conical angles of micro-grooved texture (2 ° to 5 °) under flood lubrication condition. The effect of conical micro-grooved texture on the tool cutting force, tool–chip friction coefficient, surface roughness of the machined workpiece, and wear of the tool rake face was determined. Findings Unlike the conventional tools, the conical micro-grooved tools successfully resulted in reductions in metal cutting force, tool–chip frictional coefficient, surface roughness of the machined workpiece, and wear of the tool rake face. These reductions were more noticeable than those of conventional tools with increases in the cutting speed and conical angle of the micro-grooved texture. Detailed research indicated that conical micro-grooved channel exhibits a directional motion characteristic of liquid, which accelerated the infiltration of cutting fluid at the tool–chip interface. Substantial cutting fluid was supplied and stored at the tool–chip interface for the conical micro-grooved tools. Therefore, the conical micro-grooved texture on the tool rake face showed evident advantages in improving tool–chip friction and tool cutting performance. Originality/value The main contribution of this study is proposing a new conical micro-grooved texture on the tool rake face, which improved tool–chip friction and tool cutting performance.
3
Astarita, Antonello, Silvio Genna, Claudio Leone, Fabrizio Memola Capece Minutolo, Valentino Paradiso e Antonino Squillace. "Laser Cutting of Aluminium Sheets with a Superficial Cold Spray Titanium Coating". Key Engineering Materials 611-612 (maggio 2014): 794–803. http://dx.doi.org/10.4028/www.scientific.net/kem.611-612.794.
Testo completoAbstract (sommario):
In the manufacturing of metal components both wear and corrosion have to be considered. In particular, corrosion is a primary problem in the aeronautic field, where the aluminium alloys are affected by several corrosion typologies. Furthermore, nowadays carbon fibre reinforced plastics (CFRP) are finding an increasing use, but they can induce galvanic corrosion phenomena when coupled with aluminium alloys. To overcome this problem, corrosion resistant coatings are used on aluminium components. On these premises, the realization of a titanium coating on aluminium components could allow the coupling of CFRP and aluminium alloys, improving the corrosion resistance. Cold Spray Deposition is a recent technology to realize these coatings. This technology allows the production of near fully dense coatings on metallic surfaces. In many applications the coated aluminium sheets have to be machined (cut or drilled). Machining with conventional cutting methods leads to both tool wear and damages in the coating. Laser cutting represents a promising alternative: it does not involve any mechanical cutting force or tool wear and, thanks to the small laser beam spot, it allows to realize complex shapes. In this paper, laser cutting of an Al alloy sheet (0.6 mm thick) coated with Ti Alloy, was studied. The adopted laser source was a 150 W, lamp pumped Nd:YAG, specifically developed for micro-machining operations on metals. During the tests, the process parameters (cutting speed, pulse duration and entrance side) were changed and the kerf geometry was analysed as a function of the process parameters.
4
Tian, Xinli, Long Wang, Wanglong Wang, Yongdong Li e Kaiwen Ji. "Tool wear characteristics of cutting and extrusion processing technology based on the edge-chipping effect". Industrial Lubrication and Tribology 68, n. 2 (14 marzo 2016): 191–96. http://dx.doi.org/10.1108/ilt-04-2015-0051.
Testo completoAbstract (sommario):
Purpose – The cutting and extruding processing technology for ceramics based on the edge-chipping effect is a new contact removal machining method for hard, brittle materials such as engineering ceramics. This paper aims to provide an important reference to understand the tool wear mechanism and the wear law of this new processing technology. Design/methodology/approach – The real-time temperature monitoring and the observation of micro-morphology are used to analyse the wear characteristics of the tool face. In addition, the research focuses on the influence of three processing parameters (axial feed rate, thickness of flange and depth of groove) on characteristics including tool wear. Findings – The temperature variation shows that the new processing technology improves the tool temperatures condition. The tool is worn mainly by mechanical friction including abrasive wear, and the flank face also suffers the sustained scratching of residual materials on the rough machining surface. With increased feed rate, the wear of the rear face of the major flank initially decreased and then increased. As the depth of the retained flange increases, the wear became worse. The wear initially decreased and then increased with increasing depth of groove. Research limitations/implications – Study on the new processing technology is still in its early stages. Therefore, researchers are encouraged to test the proposed propositions further. Practical implications – The machining process itself destroys materials, albeit a controllable manner: based on this principle, the authors proposed a new machining technology based on cracks driven by edge chipping. In this way, the surface of such ceramics is removed. Therefore, the research provides a new method for reducing processing costs and promoting the extensive application of engineering ceramic materials. Originality/value – The cutting and extruding processing technology based on cracks driven by edge-chipping effect makes full use of the stress concentration effect caused by prefabricated defects, and the edge-chipping effect which occurs during machining-induced crack propagation. The wear mechanism and law of its tool is unique than other machining ways. This paper provides an important reference to understand the tool wear mechanism and the machining mechanism of this new processing technology. With the application of this study, the ceramics could be removed with less energy consumption and the tools with the hardness of lower than its own one. Therefore, it could not only reduce the processing costs but also promote the extensive applications of engineering ceramic materials.
5
Zhang, Hui, Jian Xin Deng, Gui Yu Li, Xing Ai e Jun Zhao. "Effect of Ambient Temperature on Wear of Cemented Carbide Tool Material". Advanced Materials Research 148-149 (ottobre 2010): 276–79. http://dx.doi.org/10.4028/www.scientific.net/amr.148-149.276.
Testo completoAbstract (sommario):
Cemented carbide has relatively good mechanical properties, so it is widely used as cutting tools. In this paper, a sliding wear test at high ambient temperature between cemented carbide tool material and ceramic was carried out using a ball-on-disc wear-test machine. The characteristics as to wear rate and friction coefficient were investigated. The special wear rate increased with an increase in operating temperature. The cemented carbide material with addition of TiC phase gave better wear resistance than cemented tungsten carbides at elevated temperature. SEM technology was adopted to observe the worn surfaces of specimens and wear mechanism were simultaneously discussed.
6
Li, Kuan Ming. "Experimental Study on Minimum Quantity Lubrication in Mechanical Micromachining". Advanced Materials Research 579 (ottobre 2012): 193–200. http://dx.doi.org/10.4028/www.scientific.net/amr.579.193.
Testo completoAbstract (sommario):
Mechanical micromachining is a promising technique for making complex microstructures. It is challenging to apply mechanical micromachining in the industry due to the low strength of micro tools. Therefore, it is not easy to accurately control the product dimension error and to raise the production rate. In this paper, the applications of minimum quantity lubrication (MQL) in micro-milling and micro-grinding are presented. MQL is considered as a green manufacturing technology in metal cutting due to its low impact on the environment and human health. This study compares the tool wear and surface roughness in MQL micromachining to completely dry condition based on experimental investigations. The supply of MQL in vibration-assisted grinding is also studied. It is found that the use of MQL results in longer tool life and better surface roughness in mechanical micromachining.
7
Weiser, Ingo Felix, Andreas Feuerhack e Thomas Bergs. "Investigation of the Micro Hardness at the Cut Surface of Fine Blanked Parts with Variation of Sheet Material and Cutting Temperature". Key Engineering Materials 883 (aprile 2021): 269–76. http://dx.doi.org/10.4028/www.scientific.net/kem.883.269.
Testo completoAbstract (sommario):
Fine blanking is a production technology of high importance especially for the automotive industry. As a procedure of sheet metal separation, it is possible to produce complex parts in a single stroke. As a difference to conventional punching, the cutting surface of fine blanked parts can often be used as a functional surface without further process steps. However, fine blanking as a forming process changes the microstructure of the metal sheet to a higher extend than cutting or machining processes. Due to this, it is of utmost importance to investigate the cause-effect-relations between the fine blanking process parameters and the resulting properties of the fine blanked part. Especially the condition of the cut surface as an important quality criterion has to be investigated. The quality characteristics of the cut surface of fine blanked parts are often subject of investigations. In addition, it would be of importance to investigate how the material properties in the shear zone are changed by the fine blanking process. This on one hand in turn can enable conclusions to be drawn about possible punch wear. If, on the other hand, hardening of the cut surface takes place as a result of fine blanking, then this could have a positive influence on the application properties of fine blanked components. Thus, an experimental fine blanking investigation of the micro hardness of the cutting surface has been made with variation of steel material and cutting temperature. It could be demonstrated that the micro hardness increases in direction towards the burr. This is independent on material and cutting temperature.
8
Umanath, K., S. T. Selvamani, K. Palanikumar e Ram G. Dinesh. "Worn Surface Analysis of Hybrid Metal Matrix Composite". Advanced Materials Research 984-985 (luglio 2014): 546–50. http://dx.doi.org/10.4028/www.scientific.net/amr.984-985.546.
Testo completoAbstract (sommario):
Metal to the metal wear analysis of Aluminium (Al6061grade) alloy, dis-continuously reinforced with ceramic particles of SiC and Al2O3deliver this paper. The Al matrix with 5 to 25% of vol. Fractions of SiC and Al2O3particulate reinforcements were formed in Hybrid Metal Matrix Composite (HMMC) by stirring casting technology. They are finding applications in automotive, aeronautical and sport goods. For the proper use of these composites, its mechanical properties and wear properties are to be evaluated. The dry sliding behavior of these SiC and Al2O3particulates HMMCs and that of Al alloy at atmosphere was analyzed with a pin on disc type wear testing machine. The result indicates that, the scanning electron micrographs of the worn surfaces of the hybrid composites show the worn surface of the composite alloy is rougher than the unreinforced Al6061alloy.
9
BELASHOVA, I. S., L. N. RABINSKI e O. V. TURSHAVINA. "EVALUATION OF HARDENING EFFICIENCY WITH CONVECTIVE HEAT AND MASS TRANSFER MECHANISM DURING LASER SURFACE ALLOYING IN REFLOW MODE". Periódico Tchê Química 16, n. 33 (20 marzo 2019): 498–504. http://dx.doi.org/10.52571/ptq.v16.n33.2019.513_periodico33_pgs_498_504.pdf.
Testo completoAbstract (sommario):
The modern stage of equipment development imposes increased requirements for the performance characteristics of parts. Different components and parts of machines, metal-cutting tools and metal structural elements work in the conditions of high friction, high specific loads, high temperatures, a wide range of speeds and impact of aggressive media, for instance. Therefore, improvement the quality, reliability, economical efficiency and productivity of machines, tools, equipment and other engineering products as well as reduction of their specific material consumption and energy consumption is achieved primarily by the use of materials and progressive strengthening technology that improve the hardening, wear resistance, corrosion resistance and other physical and mechanical properties of machine parts and tool. Therefore, the main objective of the paper was to evaluate the mass-transfer during laser surface alloying in the reflow mode. To evaluate the effectiveness of surface hardening technology, it was proposed to use two new parameters – reduced wear and reduced integrated micro hardness of the modified surface layer. Based on an analysis of the experimental data on the wear of a cutter made of HVG and U10 steel, processed by a laser with smears in the reflow mode, the existence of a correlation between the entered parameters is demonstrate and the regression equation is obtained. The proposed approach to evaluating the effectiveness of surface hardening can be used not only in the special case of laser modification but also for any other technology for creating gradient and functional coatings.
10
Seong, Yeonuk, Donghyeon Lee, Jihye Yeom e Junhong Park. "The Feature Extraction through Wavelet Coefficients of Metal Friction Noise for Adhesive and Abrasive Wear Monitoring". Applied Sciences 11, n. 9 (21 aprile 2021): 3755. http://dx.doi.org/10.3390/app11093755.
Testo completoAbstract (sommario):
Friction between metals is a physical phenomenon that occurs in manufacturing machine tools. This annoying noise implies unnecessary metal contact and deterioration of a mechanical system. In this study, for the monitoring of the friction between two metal surfaces, the acoustic signature was extracted by applying the wavelet transform method to the noise measured from the change in contact force for each state of adhesive and abrasive wear. Experiments were conducted with a constant relative speed between the contacting metal surfaces. For the adhesive wear, the peak signal-to-noise ratio (PSNR) calculated by the wavelet transformation increases with the increasing contact pressure. Opposite trends were observed for the abrasive wear. The proposed index formed a group within a specific range. This ratio exhibited a strong relationship with the wear characteristics and the surface condition. From the proposed index calculated by the wavelet coefficients, the continuous monitoring of the wear influence on the failure of the machine movement operations is achieved by the sound radiation from the contacting surfaces.
11
Thornton, H. R., E. I. Bailey e J. S. Williamson. "Friction and Wear in Threaded Surfaces of Rotary Drill Collars". Journal of Energy Resources Technology 115, n. 1 (1 marzo 1993): 23–31. http://dx.doi.org/10.1115/1.2905966.
Testo completoAbstract (sommario):
Two surfaces, under high normal stress, in sliding contact provide the basis for friction and wear studies within rotary drill collars. Flat and ring specimens, considering three (3) different contact areas, were rotated to determine the effect of surface finish, coatings, lubricants and normal stress on friction and wear. The 4145 steel specimens were heat-treated to a yield strength of 124,000 lb/in2 (855 MPa) and a Rc hardness of 28. The torque required to rotate the ring specimen was measured as a function of the rotation angle. The friction coefficient was calculated. Seizure and galling were common for metal-to-metal contact. Rust and phosphate coatings break down under the high normal stress. Metal-filled lubricants produce static coefficients of friction (μs) between 0.03 and 0.25 and dynamic coefficients between 0.04 and 0.26. Seizure and galling were not observed.
12
Yang, Yinfei, Jinjin Han, Xiuqing Hao, Liang Li e Ning He. "Investigation on micro-milling of micro-grooves with high aspect ratio and laser deburring". Proceedings of the Institution of Mechanical Engineers, Part B: Journal of Engineering Manufacture 234, n. 5 (24 dicembre 2019): 871–80. http://dx.doi.org/10.1177/0954405419893491.
Testo completoAbstract (sommario):
High aspect ratio micro-grooves are critical structures in the micro-electromechanical system. However, problems like rapid tool wear, low processing efficiency, and inferior machined quality in micro-milling of high aspect ratio micro-grooves by length–diameter ratio tools are particularly significant. In this work, a combined micro-milling method based on water-free alcohol as the cutting fluid and laser deburring is proposed to investigate the high aspect ratio micro-groove generation of oxygen-free high-conductivity copper TU1. Parametric experiments and high aspect ratio micro-groove experiments were conducted to investigate the surface quality, cutting forces, and tool wear. The water-free alcohol was employed to improve the tool life and machined surface quality. In the case of the oxygen-free high-conductivity copper TU1 material, a satisfactory high aspect ratio micro-groove (groove-width = 0.2 μm and aspect ratio = 2.5) with a nanoscale surface roughness ( Ra = 68 nm) was obtained under the preferred machining conditions. Furthermore, the deburring process of the high aspect ratio micro-groove by the laser technology was conducted to achieve ideal machined quality of the top surfaces.
13
Monetti, C., S. Ilo e T. Lebersorger. "Characterization of lubricants for metal forming by means of an oscillating tribo-test-rig". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 223, n. 5 (30 aprile 2009): 817–26. http://dx.doi.org/10.1243/13506501jet541.
Testo completoAbstract (sommario):
Cold metal forming is a versatile and very efficient technology in the manufacture of metal components. In cold metal forming processes high pressure is generated at the tool-workpiece interface, so that good lubrication is required to reduce wear. This improves tool life and the quality of products. The lubricants used in the forming processes usually contain appropriate basis oils with anti-wear (AW) and extreme pressure (EP) additives. In order to examine how wear occurs during cold metal forming, the SRV (Schwingung Reibung Verschleiss) reciprocating-sliding tribometer equipped with a cylinder-on-disc line- contact testing system was adapted and used to characterize lubricant behaviour. Friction coefficient and wear rate were determined under progressively increasing load conditions. The final worn volumes of the flat and the cylinder were evaluated by using optical microscopy methods. The measurement system was validated by replicate tests using some commercially available forming lubricants as reference in a load range of 100-1000 N. The oscillating tribo-test-rig can be used to characterize lubricants for cold metal forming processes by testing the combined effects of different additive systems and their interaction with contacting materials.
14
Ciofu, Florin, e Marius Bibu. "Changes of Structure and Physical-Mechanical Properties in Alloy Steels Thermochemically Treated by Plasma Nitriding". MATEC Web of Conferences 343 (2021): 03010. http://dx.doi.org/10.1051/matecconf/202134303010.
Testo completoAbstract (sommario):
Plasma nitriding is a method of surface modification using a glow discharge technology to introduce nitrogen into the surface of a metal, which subsequently diffuses into the material. The main advantages of plasma nitriding over conventional nitriding processes are: reduced cycle time, controlled growth of the surface layer, elimination of white layer, reduced distortion, no need of finishing, pore-free surfaces and mechanical masks instead of copper plating. The process is especially suitable for complex parts that are intensively solicited by wear, fatigue, contact pressure, shocks, possibly also to corrosion. It is applied in order to bring the metallic products in a state favourable from the point of view of structure, chemical composition and internal stress state. The paper presents an analysis of the structures and characteristics of a widely used structural steel 39 - CrAl6. As a result of plasma nitriding, a surface layer with high wear and fatigue resistance was created on the surface of the material. Also, between the surface layer and the base material was interposed a hard substrate with high wear resistance having a bainitic / martensitic structure.
15
Mahamani, A., N. Muthukrishnan e V. Anandakrishnan. "Determination of Optimum Parameters for Multi-Performance Characteristic in Turning of Al 6061-6% ZrB2 in-situ Metal Matrix Composite Using Grey Relational Analysis". International Journal of Manufacturing, Materials, and Mechanical Engineering 2, n. 1 (gennaio 2012): 11–29. http://dx.doi.org/10.4018/ijmmme.2012010102.
Testo completoAbstract (sommario):
In-situ aluminum matrix composite is the innovation of high performance material technology and it has superior interfacial integrity and thermodynamic stability between the matrix and reinforcement. During synthesis, the ZrB2 particle is formed by exothermic reaction within the aluminum melt. As a result, small, fine and oxide free reinforcements are formed. Excessive temperature released from in-situ chemical reaction will facilitate the homogeneous distribution of particles in entire shape of the composites. Making the engineering components from this composite material require machining operations. Therefore, addressing the machinability issues of the composite is very important. This paper proposes an approach to optimize the machining parameters in turning of Al 6061-6% ZrB2 in-situ Metal Matrix Composite (MMC) with multiple performance characteristics by using grey relational analysis. The effect of in-situ ZrB2 reinforcement particles on machinability behavior need to be studied. The machining parameters, namely cutting speed, feed rate and depth of cut are optimized with considerations of multiple performance characteristics including surface roughness, tool wear and cutting force. It is concluded that the feed rate has the strongest effect. The confirmation experiment indicates that there is a good agreement between the estimated value and experimental value of the Grey relational grade.
16
Pasovets, V. N., V. A. Kovtun e Yu M. Pleskachevsky. "Wear resistance of nanostructured metal-polymer self-lubricating powder composites". Proceedings of the National Academy of Sciences of Belarus, Physical-Technical Series 66, n. 2 (16 luglio 2021): 154–60. http://dx.doi.org/10.29235/1561-8358-2021-66-2-154-160.
Testo completoAbstract (sommario):
Tribotechnical tests and microstructural studies were carried out. Wear mechanism of nanostructured metalpolymer self-lubricating composite materials has been established. This mechanism involves in the formation of separating polymer layers on the friction surface, which reduces the coefficient of friction and running-in period of parts of friction units. Carbon nanoparticles move along the friction surface, hinder the development of seizure processes during the interaction of microroughnesses of the contacting surfaces of the material and the counterbody during the destruction of the separating polymer layers. It was found that the polymer filler is displaced from the friction zone, carbon nanoparticles are pressed into the open areas of the surface of the copper matrix of the composite when the pressure in the tribocontact is higher than 1.5 MPa. The temperature in the tribocontact increases, the polymer filler degrades, the carbon nanoparticles are removed from the friction zone, the strength properties of the composite decrease, the friction coefficient and the wear rate increase at a sliding speed above 1.5 m/s. The obtained research results can be used in mechanical engineering, transportation industry and power engineering.
17
He, Long, Ye Fa Tan, Bin Cai, Hua Tan, Li Gao e Zhong Wei Zhang. "Research on Friction and Wear Properties of Plasma Spraying Ni-Base Alloy Coatings on Aluminum Alloy Surfaces". Advanced Materials Research 538-541 (giugno 2012): 207–13. http://dx.doi.org/10.4028/www.scientific.net/amr.538-541.207.
Testo completoAbstract (sommario):
In order to improve the wear resistance and extend service life of aluminum alloy parts, the Ni-base alloy anti-wear coatings were prepared on the surfaces of 7A05 aluminum alloy by plasma spraying technology. The microstructure and interface of the coatings were analyzed, and the friction and wear properties of Ni-base alloy coatings and aluminum alloy substrates were investigated under dry friction condition at room temperature. The research results show that the main phases of Ni-base alloy coating are γ-Ni, CrB and Cr23C6. The thicknesses of diffusion layers existing between intermediate layer and coating, intermediate layer and substrate are respectively 15μm and 20μm. The bonding types of the coating and the substrate are mechanical combination accompanied with partially metallurgical combination. When wore against GCr15 steel balls, the average friction coefficient of the Ni-base alloy coatings is 11.6% lower than that of the aluminum alloy substrates, and the average wear loss of the former is 9.3mg, which is only 1/3 of that of the latter. With the increase of loads, the wear mechanisms of the Ni-base alloy coatings change from slightly micro-cutting wear and fatigue wear to abrasive wear and micro-fracture wear, while those of the aluminum alloy substrates are mainly adhesive wear and abrasive wear as well as slight oxidation wear.
18
XU, JIANG, FENG WANG e ZILI LIU. "INVESTIGATION OF THE TRIBOLOGY BEHAVIORS OF AUTO-RESTORATION ADDITIVE UNDER HEAVY LOADING CONDITIONS". Surface Review and Letters 14, n. 02 (aprile 2007): 329–34. http://dx.doi.org/10.1142/s0218625x07008998.
Testo completoAbstract (sommario):
Lubricant additives are crucial in minimizing friction and wear, and protecting surfaces under severe contact condition. The traditional additive can only diminish the wear rate of materials by increasing the sliding distance. As a wear-self-compensation lubricating additive, the auto-restoration technology (ART) of worn surface of metals is a novel technique for the repair of mechanical equipment and breakthrough of tribology theory that cannot obey the traditional law. The previous experiments have measured the friction and wear behaviors of ART additives under low load conditions. This paper presents the tribology behaviors of auto-restoration lubricating additive under heavily loaded condition. The results show that the auto-restoration lubricating additive can reduce pronouncedly the frictional coefficient and wear weight; after 6 h wear examination the friction coefficient is only 0.027. The morphology of the worn surface and the chemical composition of tribofilm have been observed by SEM. It proved that the worn surface is very smooth and there exists a tribochemical reaction between the metal and the auto-restoration lubricating additive.
19
Dong, Shuhan, Huiyong Yuan, Xiaochao Cheng, Xue Zhao, Mingxu Yang, Yongzhe Fan e Xiaoming Cao. "Improved Friction and Wear Properties of Al6061-Matrix Composites Reinforced by Cu-Ni Double-Layer-Coated Carbon Fibers". Metals 10, n. 11 (19 novembre 2020): 1542. http://dx.doi.org/10.3390/met10111542.
Testo completoAbstract (sommario):
The friction and wear properties of an Al6061 alloy reinforced with carbon fibers (CF) modified with Cu-Ni bimetallic layers were researched. Cu-Ni double layers were applied to the CF by electroless plating and Al6061-matrix composites were prepared by powder metallurgy technology. The metal-CF/Al interfaces and post-dry-wear-testing wear loss weights, friction coefficients, worn surfaces, and wear debris were characterized. After T6 heat treatment, the interfacial bonding mechanism of Cu-Ni-CF changed from mechanical bonding to diffusion bonding and showed improved interfacial bonding strength because the Cu transition layer reduced the fiber damage caused by Ni diffusion. The metal–CF interfacial bonding strongly influenced the composite’s tribological properties. Compared to the Ni-CF/Al and Cu-CF/Al composites, the Cu-Ni-CF/Al composite showed the highest hardness, the lowest friction coefficient and wear rate, and the best load-carrying capacity. The wear mechanisms of Cu-Ni-CF/Al composite are mainly slight abrasive wear and adhesive wear.
20
Grigoriev, Sergey N., Alexey B. Nadykto, Marina A. Volosova, Alexander A. Zelensky e Petr M. Pivkin. "WEDM as a Replacement for Grinding in Machining Ceramic Al2O3-TiC Cutting Inserts". Metals 11, n. 6 (28 maggio 2021): 882. http://dx.doi.org/10.3390/met11060882.
Testo completoAbstract (sommario):
Small-size cutting inserts for assembly cutters are widely used to manufacture a variety of parts for the aerospace, automotive and mechanical engineering industries. Due to their high hardness and chemical stability, cutting Al2O3-TiC ceramics significantly outperform hard alloys in machining heat-resistant and difficult-to-machine materials. However, grinding on CNC machines, the most common technology for manufacturing ceramic inserts, is associated with numerous issues when it comes to manufacturing small-size cutting inserts. For example, high cutting forces and high grinding wheel wear rates cause a rapid loss of dimensional accuracy and deterioration of the quality of the surface being machined, while the interference of the grinding wheel with the surface being treated imposes serious limitations on the geometry of the small-size ceramic inserts to be grinded. Here we show that Wire Electrical Discharge Machining (WEDM), which is a contactless and, thus, a more flexible method in terms of the size and geometrical properties of a workpiece to be machined, can be used as a replacement for grinding operations in machining small ceramic inserts. A composite of 70% aluminum oxide and 30% titanium carbide was chosen as a ceramic material because a further increase in the TiC fraction causes a marked decrease in wear resistance, while its decrease results in an undesirable loss of electrical conductivity. While in order to replace grinding with WEDM, WEDM has to be stable in the sense of occurring without frequent wire breakages, achieving WEDM stability is not an easy task due to the low electrical conductivity of Al2O3-TiC ceramics and high operational temperatures, which promote the diffusion of dielectric and electrode products in the surface layer of the cutting inserts being machined. These factors may lower the quality of the final product due to damage to the insert surface, marked increases in the roughness RA and in diffusion in the surface layer, which increases the friction coefficient and, hence, reduces the life of the manufactured cutting inserts. We have increased stability of the WEDM process by identifying and applying rational process conditions that lead to a reduced, by a factor of 2.63, roughness Ra and also a reduced, by a factor of 1.3, depth of craters. Performing a chemical and structural analysis, we found that the application of high energies combined with an increasing interelectrode gap (IG) (technological parameter SSol, a complex indicator that determines the speed of the wire electrode depending on the number of pulses per unit of time and the IG size, is set at 80, EDM3 technology) causes increased surface damage and contamination, while a small IG (SSol = 45, EDM1 technology) reduces the material removal rate due to contamination of the working zone between the surface being machined and the electrodes. After reducing the IG by lowering SSol from 80 to 45, the roughness Ra of 0.344 µm was achieved, which allows for replacing grinding operations with WEDM in machining hardening chamfers, front surfaces and, to a lesser degree, the rear and support surfaces of cutting inserts. In this case, when the IG is reduced to SSol = 45, the electroerosion products in the dielectric promote local breakdowns, which in turn produce a large number of deep craters which adversely affect the performance of cutting inserts. However, we found that a slight increase in SSol from 45 to 55 (EDM3 technology) significantly reduces the number of craters and lowers their depth from 50 μm to 37 μm. Although in this case the roughness grows to 0.534 μm due to increased discharge energy, the improved flushing of the IG and the reduced occurrence of local high-temperature breakdowns—evidenced by a decrease in the depth and number of deep craters formed due to current localization during short circuits—significantly reduced contamination of the surface layer and the crater formation rate. Therefore, WEDM can be recommended for use in machining reinforcing chamfers and, to a lesser degree, front surfaces. These considerations lead us to conclude that WEDM is a viable alternative to grinding in machining Al2O3-TiC ceramic cutting inserts of a small size and a complex shape, and that its application to manufacturing cutting inserts from poorly conductive cutting ceramics should be studied further.
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Dehbi, Said, e Khaled Hamouda. "Improved Surface Quality by the Process of Vibratory Grinding". Defect and Diffusion Forum 365 (luglio 2015): 183–87. http://dx.doi.org/10.4028/www.scientific.net/ddf.365.183.
Testo completoAbstract (sommario):
The main purpose of this work is the energy saving by reducing friction and minimizing wear to avoid losses by raising the properties of nanomaterials on the surface layer. Therefore, we develop approaches for studying the tribological behavior phenomena concerning materials on surfaces of the layers to define the mechanical and tribological properties of materials to improve the surface layer materials of the treated parts. It was used for the vibratory grinding method of chemical mechanical processing surface using the technology of low-frequency vibration in the treatment of metal parts in the presence of chemical additives, which have a great influence on the improvement of mechanical and geometrical parameters (roughness, fatigue resistance, corrosion resistance, micro and macro hardness, structure) of mechanical parts. This method of vibratory grinding has great advantages such as the treatment of complex mechanical parts, the ability to process parts of different types and shapes at the same time. It is also known to be an environmentally friendly process. Thus this work consisted of a surface treatment by vibratory grinding of samples of different materials.
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ZASIŃSKA, Katarzyna, Tomasz SERAMAK, Jacek ŁUBIŃSKI e Grzegorz ROTTA. "THE ANALYSIS OF THE INFLUENCE OF STRESS DISTRIBUTION ON WEAR PROFILE IN LUBRICATED SLIDING CONTACT OF UHMW-PE VS TITANIUM Ti-13Nb-13Zr ALLOY". Tribologia 271, n. 1 (28 febbraio 2018): 113–16. http://dx.doi.org/10.5604/01.3001.0010.6371.
Testo completoAbstract (sommario):
Metal – polymer sliding contacts are a typical combination in industry and medicine. For decades such a set of materials has been the primary choice in human joints endoprosthetic technology. In this paper tribological issues of are presented from a research on the potential for practical use of Ti-13Nb-13Zr/UHMW-PE couple for orthopedic endoprosthesis. In tests on simplified models it is critically important to carefully select geometry of contact, load and velocity magnitudes and profiles to the later interpretation of results. In case of organic polymers interacting with metallic components the problem is even more prominent, than in the case of all metal systems because of great differences in the modulus of elasticity between the specimens in contact. High local loading can cause excessive heat generation and accelerated loss in polymer’s strength induced by thermal plastification. The process may not be manifested in the course of the experiment in any way detectable and might compromise the accuracy of wear measurement. In the case of the presented research an analysis has been performed to evaluate the observed wear profile of UHMW-PE with respect to non-uniform distribution of contact stress. A simulation was run with the use of FEM to evaluate the contact conditions between the titanium alloy and UHMW-PE specimens and the results were confronted with the wear profiles. Interesting similarities were discovered yielding useful information on the fundamentals of the wear in and for future research on similar systems.
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Hlushkova, D., O. Voronkov, I. Кirichenko e O. Nikonov. "INCREASING OF WEAR RESISTANCE OF RESPONSIBLE PARTS OF THE HYDRAULIC BREAKER BY ION-PLASMA TREATMENT". Odes’kyi Politechnichnyi Universytet Pratsi 2, n. 61 (2020): 12–18. http://dx.doi.org/10.15276/opu.2.61.2020.02.
Testo completoAbstract (sommario):
During operation, parts of the hydraulic hammer are subjected to intense abrasive wear, which leads to a decrease in the duration of their work. The issue of increasing wear resistance occupies a special place in solving the problem of ensuring the necessary resource of these parts. In accordance with the literature data, as well as on the basis of analysis of many years of experience in operating hydraulic hammers, many methods of volumetric and surface hardening of parts are used that do not give a significant effect. Therefore, it became relevant to attract new methods of surface hardening. These methods include ion-plasma chromium plating. As the tasks of the work, a detailed analysis of the damaged working surfaces of the hydraulic hammer parts was provided; the study of changes in the structure and properties of hardened surface areas during operation; development of the hardening process, providing increased wear resistance of parts as a result of ion-plasma chromium plating. We investigated the condition of the working surface of the critical parts of the hydraulic hammer - the hammer and peaks - after hardening and operation. Data were obtained on the nature and intensity of wear in the zones and sections of each part. High-quality chromium coatings were obtained at substrate temperatures not lower than 80–100 ° С. Based on experimental studies, the effect of ion-plasma chromium plating on the wear resistance and mechanical properties of hydraulic hammer parts is proved, and structural changes in the material are analyzed. After operation, the surface of the part may have defects such as scuffing, cracks along the axis of the part, loss of metal mass (decrease in coating thickness), as well as local hardening and deformation of the metal. Ion-plasma chrome plating of parts according to the proposed technology increased their wear resistance by 1.75 times compared with unstressed. The technology of ion-plasma chromium plating ensures the operation of hardened parts without chips and without chipping. In areas of damage to parts, zones of structural transformations characteristic of secondary hardening phenomena are noted.
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Ipatov, Aleksey G., e Sergey N. Shmykov. "Performance characteristics of modified antifriction coatings based on the metal composition". Tekhnicheskiy servis mashin, n. 1 (1 marzo 2020): 186–94. http://dx.doi.org/10.22314/2618-8287-2020-58-1-186-194.
Testo completoAbstract (sommario):
This paper proposes the technology for obtaining antifriction coatings by short-pulse laser treatment of powder compositions. (Research purpose) The research purpose is in synthesizing thin anti-friction coatings on the surface of steel substrates by short-pulse laser treatment of metal powder compositions and analyze their physical and mechanical properties. (Materials and methods) A solid-state pulsed laser generator was used to synthesize antifriction coatings. B83 babbit powder has been used as an additive material. The powder composition was additionally doped with PMS-1 copper and molybdenum disulfide in order to increase the friction properties and load-bearing capacity of the coatings. Laboratory samples were subjected to wear tests under boundary friction conditions using the SMT-2070 friction machine in comparison with standard surfaces of B83 babbite coating, steel surface, and Molykote d-321R clad surface. X-ray diffractometer DRON-6 was used for x-ray diffractometry. (Results and discussion) It was found that the porosity of the modified coating does not exceed 5 percent, and there are no traces of detachment and destruction in the experimental samples. It was found that the coefficient of friction of the analyzed coating under conditions of boundary friction was 0.12-0.13, which corresponds to the coefficient of friction of a standard babbit alloy. The modified coating have a more efficient workability and a stable coefficient of friction over a large range of loads. It was found that the wear intensity of the analyzed coating is significantly lower than one of the compared surfaces. The increase in friction characteristics is due to the features of the coating structure, which is characterized by a large number of solid intermetallic compounds Cu3Sn having a hexagonal structure, which determines the low friction coefficient. (Conclusions) The results shows the high practical potential of modified antifriction coatings that can be used in mechanical engineering and repair production in the design and restoration of bearing assemblies.
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TRCKA, TOMAS, e ALES POLZER. "ANALYZING THE PERFORMANCE OF CIRCLE SEGMENT END MILL WITH PCD INSERTS WITH LASER-MACHINED INTEGRAL CHIPBREAKER WHEN DRY MILLING OF ADDITIVE MANUFACTURED TI-6AL-4V TITANIUM ALLOY". MM Science Journal 2021, n. 2 (2 giugno 2021): 4434–43. http://dx.doi.org/10.17973/mmsj.2021_6_2021006.
Testo completoAbstract (sommario):
Components with generally shaped surfaces requiring higher surface quality and dimensional accuracy are, in most cases, machined. Specifically, milling technology is involved very often, which can be supplemented by finishing operations. Besides standard ball-nose end mills, circle segment end mills are modern type of cutter that has begun to be used with the development of advanced computer aided machining software, that allows to work with these shaped tools. In this research, comparing the performance of these two modern shaped end mills was investigated. One tool was a commercially available coated solid carbide circle segment end mill. A second prototype end mill with the same profile but different geometry was made with a PCD insert, that additionally had a chipbreaker produced by laser technology. Machining was carried out on the workpiece material the Ti-6Al-4V that was manufactured by additive manufacturing (AM) technology – selective laser melting (SLM). The titanium complex parts are generally used in the transport industries and medicine. Milling tests were performed under dry cutting conditions. The evaluation was based on the force load, the roughness of the machined surface and tool wear. The higher total forces were measured by the tool with a PCD insert, because a different tool geometry was used, despite the use of integral chipbreaker, which allows a partial change of the cutting geometry of the insert. The geometry of end mills with brazed insert is limited by the production process.
26
Белинский, Aleksandr Belinskiy, Семушкин, Nikolay Semushkin, Зиганшин, Bulat Ziganshin, Яхин e Sergey Yakhin. "Energy index of working units abrasion of agricultural machinery in contact with abrasives". Vestnik of Kazan State Agrarian University 8, n. 4 (13 gennaio 2014): 55–60. http://dx.doi.org/10.12737/2434.
Testo completoAbstract (sommario):
One of the priority directions of science and technology development in the Russian Federation are: energy efficiency, energy saving, technology of energy-efficient production. In the agriculture the most energy-intensive processes are in tillage, shredded stems by fodder chopper machines and etc. The working units of agricultural machinery exposed to abrasion, which leads to mechanical wear of the material, that occurs as a result of cutting and scratching action on him solids in free or clamped. The obtained formula for determining the energy index of the sample is a rational, because it is derived from the laws of mechanics. The proposed methodology and the resulting energy abrasion index is recommended for the calculation of required energy for wear, when determining the reliability and life of the working units of the various machines, interacting with an abrasive material. The numerical values of the energy index of the sample of working unit abrasion some agricultural machines are in a wide range from 0.416 kJ per kilogram in the spiral of equalizer roller of tillage machines to 1.716 to kJ per kilogram in the tooth of harrows BZS-1.0. The device is suitable for the determination by express - method (the duration of control time on sample attrition is 10 times smaller than a standard device) power indicator abrasion of tested materials in their selection for the production of cheaper and more wear-resistant working units of agricultural machinery, as well as after heat treatment, sputtering work surfaces by wearproof materials.
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Sherov, K. T., T. M. Buzauova, B. T. Mardonov, A. Zhauyt, S. B. Abdreshova, K. Imasheva e B. K. Smaylova. "INVESTIGATION METHOD OF THERMAL FRICTION PROCESSING OF THE ECCENTRIC CONE CRUSHER PART". NEWS of National Academy of Sciences of the Republic of Kazakhstan 6, n. 444 (15 dicembre 2020): 245–53. http://dx.doi.org/10.32014/2020.2518-170x.153.
Testo completoAbstract (sommario):
The article presents the results of the study performance of cone crushers and the existing technology restoration of their parts. The main reasons for the failure of cone crushers are the following: failure armor of the cone and the middle part, the protective cap, parts of the upper suspension, dust seal rings, bearing rings, the eccentric of the crusher. The most time-consuming is to restore the details of the eccentric crusher. A new technology restoration worn surfaces of the eccentric part and the results of an experimental study of thermal friction treatment (TFТ) after surfacing are proposed. It is revealed that despite the high level of temperature corresponding to intensive treatment modes it is possible to achieve effective hardening. Implementation of the proposed technology allows: eliminate the undesirable effects of softening due to re-riveting and reduce the oxidized layer; increase productivity relative to mechanical cutting methods in 23 times and tool life of more than 10 times; the use of affordable cheap material steel 45, 50, 60G for the manufacture of tools and perform processing at more intensive modes S =0,2-1mm / Rev; n=2000-3000 rpm. It is established that the TFO of the deposited surface part eccentric, provides wear resistance of the treated surfaces parts in 2….8 times more than the factory processing technology, while the depth of the hardened layer can be 1.5…. 2 mm.
28
Kuru, E., e A. K. Wojtanowicz. "A Compound Effect of Cutting Depth and Bit Dull on Cutters’ Temperature for Polycrystalline Diamond Compact Bits". Journal of Energy Resources Technology 115, n. 2 (1 giugno 1993): 124–32. http://dx.doi.org/10.1115/1.2905979.
Testo completoAbstract (sommario):
This paper presents a simulation study to evaluate the combined effect of cutting depth (drilling rate) and wear (bit dull) on the thermal response of polycrystalline diamond compact (PDC) cutters under downhole drilling conditions. A new understanding of frictionally generated heat between rock and PDC cutter is introduced from the analysis of forces active on the wearflat and the cutting (leading) surfaces of a cutter. Then this new concept is used to predict PDC bit performance with the controlled temperature of its cutters. Previous concepts, largely based on the laboratory drilling tests (with low drilling rate and under atmospheric conditions), recognize only one source of heat—the wearflat surface. However, this study, using field data, shows that the heat generated at the cutting surface may significantly contribute to the total heat flux in the cutter. As a result, the distribution of temperature within the cutter is changed, which particularly affects the maximum value of temperature at the cutting edge. A simplified 2-D finite difference numerical code is used to quantify the difference in cutter wearflat temperatures calculated with and without the additional heat flux generated at the cutting surface. The numerical analysis reveals that neglecting the cutting surface effect results in underestimation of the actual wearflat temperature by 10 to 530 percent, depending upon bit dull and downhole hydraulics. Also demonstrated is the actual impact of these findings on field drilling practices. The example comparison is made by calculating the optimal-control procedures for PDC bit with and without the effect of cutting surface. In these procedures, wearflat temperature becomes a mathematical constraint which limits weight on bit and rotational speed. The comparison includes calculation of the maximum bit performance curves which represent maximum drilling rate attainable for a bit to drill a predetermined length of a borehole (footage). The curves show an up to 18 percent reduction of drilling rate when the new and more rigorous temperature limitation is used. In addition, the example calculations show that the actual temperature of the bit cutters can be 460°C (860°F), and exceeds by almost 30 percent its maximum acceptable value of 350°C (660°F). For practical applications, the study reveals that many field failures of PDC bits may have been caused by lack of understanding of operational limits imposed by heat considerations.
29
Holovenko, Y., M. Antonov, L. Kollo e I. Hussainova. "Friction studies of metal surfaces with various 3D printed patterns tested in dry sliding conditions". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 232, n. 1 (30 ottobre 2017): 43–53. http://dx.doi.org/10.1177/1350650117738920.
Testo completoAbstract (sommario):
In recent years, 3D scanning and printing of plastics has rapidly matured while printing of metallic parts is only gaining popularity due to required refinements of technology combined with cost- and resources effectiveness for the main components of printers and consumables. The 3D printing allows producing complicated shapes that can be hardly produced by conventional mechanical tools and can provide the functionalization of surfaces. In this work, several different stainless steel (AISI 316 L) surface patterns (flat, gecko’s fibrils, dimples, pyramids, mushrooms, mesh, brush, inclined brush) intended for controlling the coefficient of friction were printed with the help of a 3D metal printer by selective laser melting technique. Unidirectional sliding tests were performed with pin-on-disc configuration. Sliding velocity of 5 × 10−3 m/s and continuously increasing load ranged from 5 to 103 N has been applied in the course of “scanning” mode and accompanied by simultaneous recording of the coefficient of friction. A stainless steel (AISI 316) disc counterbody was used in this series of the tests. It was found that the 3D printed structures allow to control the value and stability of the coefficient of friction in a wide range of loads. Microstructural analysis of the worn samples was performed to support the conclusions regarding wear mechanism.
30
Knyazeva, Zh V., P. E. Yudin, S. S. Petrov e A. V. Maksimuk. "Application of metallization coatings for protection of submersible electric motors of pumping equipment from influence of complicating factors in oil wells". Izvestiya vuzov. Poroshkovaya metallurgiya i funktsional’nye pokrytiya, n. 1 (14 marzo 2020): 75–86. http://dx.doi.org/10.17073/1997-308x-2020-75-86.
Testo completoAbstract (sommario):
The paper provides a review of results obtained when using metallization coatings to protect the outer surface of electric centrifugal pump (ECP) equipment against the complicating factors in oil wells. Metallization coating is applied by thermal spraying using the method selected based on the chemical composition, materials used and properties of the finished coating. The most common coatings on the Russian market are Monel and alloys based on austenitic stainless steel applied by methods of electric arc metallization or high-speed spraying. Traditional coatings obtained by thermal spraying feature by insufficiently high level of physical, mechanical and chemical properties. The studies of failed cases of submersible motors show that most critical shortcomings of the coatings used include insufficient resistance to mechanical impact and abrasive wear, higher electrochemical potential in relation to the base metal, application technology violations, and significant coating porosity. One of the main reasons for the observed shortcomings is the limited number of traditionally used methods and materials. In order to solve the problem of using protective coatings for submersible motors, significantly improve their properties, service life and economic efficiency, it is necessary to use modern achievements of science in the development of coatings to protect metal surfaces from wear and corrosion, namely: to expand the number of methods and materials for coating application; to develop a methodology for coating quality assessment; to develop a methodology for assessing the economic efficiency of protective coatings. Solving these tasks will enable a reasonable technical and economic choice of a specific submersible motor coating for specific operating conditions.
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RYNIEWICZ, Wojciech, Anna M. RYNIEWICZ, Łukasz BOJKO, Beata LESZCZYŃSKA-MADEJ e Andrzej RYNIEWICZ. "ANALYSIS OF SURFACE MICROGEOMETRY AND STRUCTURE OF LAYERED BIOMATERIALS USED FOR PROSTHETIC CONSTRUCTIONS IN DIGITAL TECHNOLOGIES". Tribologia 287, n. 5 (31 ottobre 2019): 101–13. http://dx.doi.org/10.5604/01.3001.0013.6567.
Testo completoAbstract (sommario):
Veneering layers of prosthetic substructures are responsible for tribological cooperation with opposite teeth in the stomatognathic system (SS). Investigations of microgeometry and structure of veneering layers are aimed at checking to what extent these layers replicate enamel parameters, which, under complex load conditions, are characterized by the phenomenon of resistance to tribological wear. Ceramic veneering layers are dedicated for substructures made in digital technologies from factory fittings by milling and laser sintering of metal powders. Using a confocal microscope, contactless tests of the surface layer stereometry were performed and surface roughness parameters were determined on samples of ceramics veneering of prosthetic substructures. The analysis was performed in comparison to the natural enamel of premolars and molars. The shaping of the surface of materials veneering the substructures is similar to the regularity determined in the statistical analysis of the enamel roughness. Layers facing samples from milling technology are characterized by lower values of roughness parameters than layers created on substructures made of SLM technology.
32
Tian, Tian, Bo Dang, Feng Ding, Fengkun Li, Kai Yang, Jianzhi Yuan, Dongbo Wei e Pingze Zhang. "Study on the ZrN/Ag2O Micro–Nano Gradient Composite Structure Constructed on Pure Ti for Biomaterials". Coatings 11, n. 6 (3 giugno 2021): 677. http://dx.doi.org/10.3390/coatings11060677.
Testo completoAbstract (sommario):
Titanium and titanium alloys have been extensively utilized in biomedical implants due to their excellent comprehensive mechanical properties and biocompatibility. In this study, a ZrN/Ag2O micro–nano gradient composite structure was prepared on the surface of pure Ti by multi-arc ion plating (MAIP) technique and metal vapor vacuum arc (MEVVA) ion implantation technology. This study indicated that a dramatic improvement in performance in the surface hardness (~1800 HV0.1) was attributed to the presence of the ceramic phase (ZrN) with high hardness included in composite structure. The relatively low wear rate of gradient composite structure confirmed its excellent performance in abrasion resistance and the abrasion mechanism of gradient composite structure was mainly abrasive wear. After the potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) tests, because of the synergy effect of ZrN micron coating and Ag2O nanoparticles, the ZrN/Ag2O gradient coatings indicated the highest free corrosion potential (Ecorr) and lowest corrosion current density (icorr) in Ringer’s solution, and the polarization resistances of multilayer coatings were greater than that of the substrate, exhibiting positive effects on retarding localized corrosion tendency. Additionally, the suitable dose of ZrN/Ag2O gradient composite coating can obtain antibacterial ability, which exerts no significant cytotoxicity and even excellent cytocompatibility over a longer service process. Furthermore, this study is conducive to design and develop for multifunctional coatings of implant materials.
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Agarwal, A. K., J. Bijwe e L. M. Das. "Wear Assessment in a Biodiesel Fueled Compression Ignition Engine". Journal of Engineering for Gas Turbines and Power 125, n. 3 (1 luglio 2003): 820–26. http://dx.doi.org/10.1115/1.1501079.
Testo completoAbstract (sommario):
Biodiesel is prepared using linseed oil and methanol by the process of transesterification. Use of linseed oil methyl ester (LOME) in a compression ignition engine was found to develop a highly compatible engine-fuel system with low emission characteristics. Two similar engines were operated using optimum biodiesel blend and mineral diesel oil, respectively. These were subjected to long-term endurance tests. Lubricating oil samples drawn from both engines after a fixed interval were subjected to elemental analysis. Quantification of various metal debris concentrations was done by atomic absorption spectroscopy (AAS). Wear metals were found to be about 30% lower for a biodiesel-operated engine system. Lubricating oil samples were also subjected to ferrography indicating lower wear debris concentrations for a biodiesel-operated engine. The additional lubricating property of LOME present in the fuel resulted in lower wear and improved life of moving components in a biodiesel-fuelled engine. However, this needed experimental verification and quantification. A series of experiments were thus conducted to compare the lubricity of various concentrations of LOME in biodiesel blends. Long duration tests were conducted using reciprocating motion in an SRV optimol wear tester to evaluate the coefficient of friction, specific wear rates, etc. The extent of damage, coefficient of friction, and specific wear rates decreased with increase in the percentage of LOME in the biodiesel blend. Scanning electron microscopy was conducted on the surfaces exposed to wear. The disk and pin using 20% biodiesel blend as the lubricating oil showed lesser damage compared to the one subjected to diesel oil as the lubricating fluid, confirming additional lubricity of biodiesel.
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Vencl, Aleksandar, Ilija Bobic e Blaza Stojanovic. "Tribological properties of A356 Al-Si alloy composites under dry sliding conditions". Industrial Lubrication and Tribology 66, n. 1 (4 febbraio 2014): 66–74. http://dx.doi.org/10.1108/ilt-06-2011-0047.
Testo completoAbstract (sommario):
Purpose – Aluminium alloys are frequently applied in automotive and other industries, since they provide mass reduction. Besides positive effects, aluminium alloys have their shortcomings reflected, first of all, in inappropriate tribological properties of these materials. The aim of this research was to enable the production of cheap aluminium alloy matrix composite with favourable combination of structural, mechanical and tribological properties, focusing on the tribological behaviour. Design/methodology/approach – The A356 Al-Si alloy was used as a matrix for producing metal matrix composites in compocasting process. Three different materials, in form of particles, were added to the matrix (Al2O3, SiC and graphite). Hardness and tribological properties (wear, friction and wear mechanism) of heat-treated (T6) samples were examined and compared. Tribological tests were carried out on ball-on-block tribometer under dry sliding conditions. Sliding was linear (reciprocating). Counter body was alumina ball. Average velocity was 0.038 m/s (max. 0.06 m/s), sliding distance was 500 m and normal load was 1 N. Findings – The effect of two different ceramic particles and graphite particles on tribological properties of obtained composites was evaluated. Wear resistance of composites reinforced with SiC particles was higher and coefficient of friction was lower compared to the composite reinforced with Al2O3 particles. A dual hybrid composite (with SiC and graphite particles) showed the lowest value of wear rate and friction coefficient. Dominant wear mechanism for all tested material was adhesion. Research limitations/implications – It seems useful to continue the work on developing hybrid composites containing soft graphite particles with A356 Al-Si alloy as matrix. The major task should be to improve particles distribution (especially with higher graphite content) and to explore tribological behaviour in diverse working conditions. Originality/value – Particulate composites with A356 aluminium alloy as a matrix produced in compocasting process using ceramic particles (Al2O3, SiC) were investigated in many researches, but there are only few detailed analyses of dual composites (with the addition of ceramic and graphite particles). In some previous studies, it was shown that compocasting process, as relatively cheap technology, can obtain good structural and mechanical characteristics of composites. In this study, it was shown that even a low graphite content, under specified conditions, can improve tribological properties.
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Trukhanska, Olena. "TECHNOLOGICAL METHODS OF INCREASING WEAR RESISTANCE AND DURABILITY OF DETAILS". ENGINEERING, ENERGY, TRANSPORT AIC, n. 4(111) (18 dicembre 2020): 109–15. http://dx.doi.org/10.37128/2520-6168-2020-4-12.
Testo completoAbstract (sommario):
Improving the reliability and service life of machines, components, units is an important factor in reducing the cost of restoration, downtime of equipment in repair, reducing the number of spare parts. The introduction of the latest technologies of agricultural production, as well as constant modern improvement, the complexity of agricultural machinery is a natural result of its development. Parts restoration technologies are among the most resource-saving, because compared to the manufacture of new parts costs are reduced by up to 70%. The main source of resource savings is the cost of materials. At longtime use of machines wear of details is followed by decrease in operational indicators, causes deterioration of quality of products. The tractor PTO shaft is subjected to significant static and dynamic loads. The high wear rate is due to constant friction with the grafting disc, gear, inner bearing rings. The production of a new power take-off shaft requires significant costs, so the development of new technological processes of repair and restoration is relevant. It is rational at restoration of the previous sizes and return of a detail of normal mechanical properties. The remanufactured part is consuming its life, like a new part, and may exceed the service life of the new part. With the increase in the equipment of agricultural production with more advanced equipment, the conduct of complex mechanization and increasing the efficiency of the use of equipment, repair production is developing and changing. The development of the field of restoration of worn parts is based on close cooperation of repair production with branch and basic science, and achievement of scientific and technical progress. A promising direction of restoration technology in the organizational plan is the deepening of the method of group restoration technology - the creation of a unified group equipment for the restoration of surfaces. It is established that the majority of details of the restored cars are rejected at the expense of insignificant wear of working surfaces, making no more than 1% of initial weight of details. Experiments and practice show that the repair of agricultural machinery is technically impossible to avoid. Most worn parts have a high residual value: their restoration consumes 20-30 times less metal and materials than the manufacture of new ones, which is economically feasible. Problems are considered: the choice of technological process of restoration, the choice of technological equipment, tools.
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Iatecola, Amilton, Guilherme Arthur Longhitano, Luiz Henrique Martinez Antunes, André Luiz Jardini, Emilio de Castro Miguel, Miloslav Béreš, Carlos Salles Lambert et al. "Osseointegration Improvement of Co-Cr-Mo Alloy Produced by Additive Manufacturing". Pharmaceutics 13, n. 5 (14 maggio 2021): 724. http://dx.doi.org/10.3390/pharmaceutics13050724.
Testo completoAbstract (sommario):
Cobalt-base alloys (Co-Cr-Mo) are widely employed in dentistry and orthopedic implants due to their biocompatibility, high mechanical strength and wear resistance. The osseointegration of implants can be improved by surface modification techniques. However, complex geometries obtained by additive manufacturing (AM) limits the efficiency of mechanical-based surface modification techniques. Therefore, plasma immersion ion implantation (PIII) is the best alternative, creating nanotopography even in complex structures. In the present study, we report the osseointegration results in three conditions of the additively manufactured Co-Cr-Mo alloy: (i) as-built, (ii) after PIII, and (iii) coated with titanium (Ti) followed by PIII. The metallic samples were designed with a solid half and a porous half to observe the bone ingrowth in different surfaces. Our results revealed that all conditions presented cortical bone formation. The titanium-coated sample exhibited the best biomechanical results, which was attributed to the higher bone ingrowth percentage with almost all medullary canals filled with neoformed bone and the pores of the implant filled and surrounded by bone ingrowth. It was concluded that the metal alloys produced for AM are biocompatible and stimulate bone neoformation, especially when the Co-28Cr-6Mo alloy with a Ti-coated surface, nanostructured and anodized by PIII is used, whose technology has been shown to increase the osseointegration capacity of this implant.
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Skoblo, T., I. Rybalko, O. Nanka e O. Saychuk. "Evaluation of the wear of the duckfoot sweep cultivator blades and the technology of their hardening". Problems of tribology 100, n. 2 (23 giugno 2021): 6–18. http://dx.doi.org/10.31891/2079-1372-2021-100-2-6-18.
Testo completoAbstract (sommario):
In recent years, research and developments related to the creation of new areas using nanotechnology take a special place in scientific achievements. They are developed and widely used in Physics, Chemistry, Biology, Electronics, Medicine, Food Production and to a much lesser extent in Engineering. This is due to the fact that there are different requirements to parts and products used in mechanical engineering, they have a complex shape, are made of different materials, production methods, heat treatment. While operating, their working layer undergoes degradation with a significant change in structure and their hardening using nanocoatings may turn out to be ineffective in both technical and economic aspects. In this case, only a specific approach, which is determined by comprehensive research with identification of the main factors of parts damageability in specific production and operation conditions, can be expedient. In addition, in some cases for hardening, repair and restoration of parts it is expedient to use surfacing methods with the introduction of modifying agents in a liquid bath during crystallization. These modifying agents are nano-and dispersed diamonds, which make it possible to adjust temperature parameters of crystallization, grain size, and stress level. This approach allows using high-alloyed, high-carbon electrodes even for thin-walled steel and cast iron products. In this case, the diamond inclusions additive plays the role of micro-refrigerators, which significantly change the crystallization temperature range. It is important to determine the optimal dose of the introduction of such a modifier and ensure uniform distribution the components in the coating. The presented work is devoted to the new technology development of hardening of cultivator blades metal with nano-and dispersed diamond additives, which are the part of the detonation charge from the disposal of ammunition. Nowadays, in agriculture, a large number of tillage implements are used for tillage, the working bodies of which are sweep blades. They are operated under conditions of abrasive particles impact, and this is accompanied by their intense wear with a corresponding change in the geometric dimensions of the main working surfaces. The worn sweep blades significantly reduce efficiency and quality of the carried-out work. The analysis of the effective choice of surfacing materials for hardening and improving their performance has been carried out and the nature of wear has been evaluated in order to identify areas of maximum damage and to determine the optimal method. It is known that T-590 and T-620 electrodes are used for the restoration surfacing of tillage implements. It was found the hardfacing of thin-walled parts is accompanied by a smaller heat sink and, in some cases, they are flooded with defect formation. To reduce it, a non-magnetic fraction of detonation charge from ammunition disposalin the form of an electrode modification was introduced, which ensured the uniform distribution the components in the coating. The method of the X-ray electron-probe analysis has been used to evaluate features of structure formation and component distribution along the perimeter of the coating. It was found out that this method of hardening reduces heat input and increases the microhardness and wear resistance of the surfaced coating, reduces the transition zone and thermal impact. The recommended method of metal hardening of new cultivator blades is to apply stripes on the point tip and wings of blades. On the basis of the nature of wear, the expediency of applying stripes on the point tip of the cultivator blade from the front side, and on wings from the rear side, is justified. The optimal geometrical dimensions of hardening stripes and their location on the blade are presented, which allows minimizing the local stresses and increasing wear resistance.
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V. Nekhoroshev, Maxim, Nikolay D. Pronichev e Gennadiy V. Smirnov. "Computer Simulation of High-Speed Anodic Dissolution Processes of Geometrically-Complex Surfaces of GTE Details". Open Mechanical Engineering Journal 8, n. 1 (9 dicembre 2014): 436–40. http://dx.doi.org/10.2174/1874155x01408010436.
Testo completoAbstract (sommario):
Electrochemical machining (ECM) is widely used in modern aircraft engine technology. This method was developed on a step-by-step basis in accordance with development of gas turbine equipment. Introduction of new difficult to machine materials into engines designs and improvement of accuracy of detail geometric parameters required new technological solutions. ECM method has a number of advantages: zero tool wear, the process does not depend on physical-mechanical properties of work piece material, no heat and force action on a work piece; these facts provide high quality of the surface layer and increase engine life. However, electrochemical machining has also disadvantages which essentially limit its applicability. This is primarily a low localization of ECM process. In order to eliminate this disadvantage new ECM schemes were developed, inter-electrode gap was reduced, switched mode power supply units, vibration of electrochemical machining electrode, etc. were used. Electrochemical machines design became more complicated and ECM operations design techniques required new solutions, therefore the scientific inquiry in this area continued intensively. Rapid development of computer technology contributed to the creation of digital models that adequately describe processes in the inter-electrode spacing at ECM. It is necessary to create electronic databases for various electrochemical metal-electrolyte systems, to develop techniques to simulate electric fields in the inter-electrode spacing, and to profile tool electrode automatically. The authors carried out active researches in this area at all stages of ECM development; they have a large number of publications in the field, including 4 monographs.
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Kovaleva, I. A., I. A. Ovchinnikova e S. V. Stefanovitch. "Development of actions on optimization of chemical composition of carburized steel grade 16MnCrS5 to eliminate the causes of the growth of large austenite grains". Litiyo i Metallurgiya (FOUNDRY PRODUCTION AND METALLURGY), n. 1 (10 aprile 2019): 49–56. http://dx.doi.org/10.21122/1683-6065-2019-1-49-56.
Testo completoAbstract (sommario):
The problem of friction, wear of machine parts and cutting tools, the need to increase the life of machines makes the task of creating new high-performance, energy-saving technologies of hardening one of the main in engineering. In mechanical engineering, the problem of improving the physical, mechanical and operational properties in thin surface layers (~10 microns) of such parts as shafts, gears, measuring tools, drills, cylinders of internal combustion engines, etc. is important. Currently, these tasks are often solved by applying reinforcing coatings. Cementation is economical. The technology of cemented steels smelting, which is currently used by metallurgical plants, does not ensure stable production of fine-grained structure in products. At the same time, the capacity of machines and units are growing, and to obtain parts that can withstand higher loads while maintaining their overall dimensions, new steel grades are needed. The complexity of the configuration of gears with a thin tooth and a massive sleeve, and the need for minimal warping make heat treatment as difficult and responsible as a complex tool, such as shaped cutters. Therefore, for the manufacture of gears you want to assign steel with small hereditary grain size. In this article we will focus on the development and production of cemented steel in the conditions of OJSC «BSW – Management Company of Holding «BMC», in particular, the steel brand 16MnCrS5 commissioned by the European manufacturer of gearboxes and motors. To determine the grain size of the metal must be subjected to special types of processing for the manifestation of certain characteristics. These results allow us to draw conclusions about the need to adjust the chemical composition of steel grade 16MnCrS5 by introducing a system of modifying elements, which will reduce the tendency of steel to overheating, therefore, reduce the size of austenitic grains. On the basis of the revealed regularities on the influence of carbide-forming elements, a further system of steel modification is determined, which includes a complex of elements V, Nb, Ti.
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Ojstršek, Alenka, Olivija Plohl, Selestina Gorgieva, Manja Kurečič, Urška Jančič, Silvo Hribernik e Darinka Fakin. "Metallisation of Textiles and Protection of Conductive Layers: An Overview of Application Techniques". Sensors 21, n. 10 (18 maggio 2021): 3508. http://dx.doi.org/10.3390/s21103508.
Testo completoAbstract (sommario):
The rapid growth in wearable technology has recently stimulated the development of conductive textiles for broad application purposes, i.e., wearable electronics, heat generators, sensors, electromagnetic interference (EMI) shielding, optoelectronic and photonics. Textile material, which was always considered just as the interface between the wearer and the environment, now plays a more active role in different sectors, such as sport, healthcare, security, entertainment, military, and technical sectors, etc. This expansion in applied development of e-textiles is governed by a vast amount of research work conducted by increasingly interdisciplinary teams and presented systematic review highlights and assesses, in a comprehensive manner, recent research in the field of conductive textiles and their potential application for wearable electronics (so called e-textiles), as well as development of advanced application techniques to obtain conductivity, with emphasis on metal-containing coatings. Furthermore, an overview of protective compounds was provided, which are suitable for the protection of metallized textile surfaces against corrosion, mechanical forces, abrasion, and other external factors, influencing negatively on the adhesion and durability of the conductive layers during textiles’ lifetime (wear and care). The challenges, drawbacks and further opportunities in these fields are also discussed critically.
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Karakurkchi, Hanna, Mykola Sakhnenko, Irina Yermolenko, Serhii Indykov, Natalia Horokhivska e Vasyl Sarai. "FUNCTIONAL ELECTROCHEMICAL COATINGS IN DUAL-USE TECHNOLOGIES". Bulletin of the National Technical University «KhPI» Series: New solutions in modern technologies, n. 2(8) (15 giugno 2021): 101–12. http://dx.doi.org/10.20998/2413-4295.2021.02.15.
Testo completoAbstract (sommario):
Technological approaches to the application of functional electrochemical coatings in civil and military technologies are analyzed. It is shown that the existing technical solutions are aimed at solving the problems of strengthening and protection of surfaces and detoxification of environments from pollutants of natural and man-made origin. Electrochemical coatings based on the iron triad, doped with refractory metals, increase corrosion resistance, microhardness and wear resistance of surfaces. Doped with transition metals heteroxide coatings, which are synthesized by the method of plasma electrolytic oxidation on aluminum and titanium alloys have catalytic properties to neutralize toxic substances in the gas and liquid phases. Peculiarities of electrochemical formation of functional coatings on construction materials of different types are investigated. It is shown that cathodic deposition by direct and pulsed current on low-carbon steel and gray cast iron forms uniform ternary coatings of Fe-Mo-W and composite systems of Fe-Co-Mo (Fe-Co-W), which have increased corrosion resistance and mechanical properties compared to base metal material. The obtained thin-layer coatings are recommended for the restoration and strengthening of worn surfaces, in particular in the technology of repair of weapons and military equipment. It was found that plasma-electrolyte treatment of piston silumin in alkaline solutions based on diphosphates synthesized heteroxide systems that are active in reducing the number of toxic emissions of internal star engines and reducing hourly fuel consumption. It is shown that nanocomposite coatings on titanium show photocatalytic activity on the destruction of model pollutants. The obtained materials have a set of enhanced functional properties and are promising for use in industrial and repair production, including the security and defense sector.
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Jia, Peng, M. Zhou e S. N. Huang. "Progressive Tool Wear in Diamond Cutting of Glass Soda-Lime". Key Engineering Materials 499 (gennaio 2012): 138–43. http://dx.doi.org/10.4028/www.scientific.net/kem.499.138.
Testo completoAbstract (sommario):
For the technology of diamond cutting of optical glass, the high tool wear rate is a main reason for hindering the practical application of this technology. Minimizing the tool wear is of great significance in order to achieve the satisfactory surface quality and dimensional accuracy. For in depth understanding of the tool wear mechanisms, experiments of diamond turning with cutting distance increased gradually was carried out on soda-lime glass in this work. Experimental results indicate that the flank wear was predominant in diamond cutting glass and the flank wear land was characterized by micro-grooves, some smooth crater on the rake face was also seen. The mainly mechanisms inducing tool wear in diamond cutting of glass are diffusion, mechanical friction, thermo-chemical action and abrasive wear.
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Maekawa, K. "Computational aspects of tribology in metal machining". Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 212, n. 4 (1 aprile 1998): 307–18. http://dx.doi.org/10.1243/1350650981542128.
Testo completoAbstract (sommario):
The present paper reviews tribological phenomena in metal machining from computational aspects. Emphasis is laid on the interaction between the mechanical aspects of tribology and the characteristics of the cutting process. Firstly, the fundamentals of the mechanics and physics of cutting processes are outlined. This is extended to friction and lubrication at the tool-workpiece interface and tool wear. On the basis of this quantitative knowledge, the interaction of tribology with a cutting process is demonstrated by means of computer simulation including machinability of free-cutting steels, cutting fluid action and prediction of tool wear. Finally, concluding remarks are devoted to the interaction of tribology with wider aspects of cutting towards the goal of ‘better machining‘.
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Pasov, Hennadii, Volodymyr Venzhega e Valerii Bakalov. "GRINDING OF SHAPED SURFACES ON THE MACHINE VZ-208-F3". Technical Sciences and Technologies, n. 2(16) (2019): 16–22. http://dx.doi.org/10.25140/2411-5363-2019-2(16)-16-22.
Testo completoAbstract (sommario):
Urgency of the research. Grinding of the shaped surfaces on the equipment with wide technological possibilities enables productive and accurate processing of the complex parts. Its use in mechanical engineering is possible both in the main production and in repair and restoration. Target setting. At present, one of the ways out of a grave crisis is the formation of machine building and metalworking. In the total volume of metal processing, the percentage of parts with complex surfaces continuously increasing, which significantly affect the technical and economic performance of machines. These details include: blades of gas and steam turbines, asterisks of cars differentials, molds, rolling rolls of rolling mills, body parts of ships, missiles, planes, disk, cylindrical, end cam, and others. Actual scientific researches and issues analysis. Special difficulties in the processing of shaped surfaces results in the processing of precision shaped surfaces in the conditions of mass production as well as mass production. The treatment of these surfaces differs from the treatment of simple surfaces with vividly detected non-stationary, the level of which significantly influences the choice of the technological process of processing these surfaces, as well as equipment for their processing. Therefore, before choosing technology and equipment, it is necessary to analyze the patterns that are inherent in the processing of shaped surfaces. Taking into account the change in the range of treated surfaces, as well as to improve the accuracy of processing, it is advisable to use numerically controlled machine tools. Uninvestigated parts of general matters defining. In the process of removing the drop and shaping the required surface, the tool moves not in the normal. On a machine model MA-369-Ф3 the grinding wheel moves only in one direction, that is, will be reciprocating motion. It is necessary to take into account the radius of the grinding wheel. It is necessary to offer such equipment, which will solve this problem. The research objective. The purpose of this work is researchіng the opportunity of shaped surface grinding on the machine VZ-208-F3. The statement of basic materials. On the machine model of the VZ-208-F3 is the ability to handle the grinding wheel, which moves in two coordinates, that is, a plan of processing with plane-translational motion is carried out. With a reciprocating motion, the removal of the abutment will be carried out in parallel curves, while plane-translational - by the equidistance. In the process of processing, the grinding wheel is constantly wearing out and requires periodic editing, which must be taken into account when compiling the control program, ie each working circuit must be programmed separately. On the machine VZ-208-F3 (plane-translational motion) is possible to exclude the influence of the radius of the grinding wheel, and, consequently, its wear, on the accuracy of shaping. In this case, the control program requires periodic additional supplies, the processing contour does not change. At the finishing process there is a constant refinement of the processing profile. Conclusions. It is possible to process details of the type of cam on the machine VZ-208-F3 with CNC 2С42 with the plane-translational processing scheme. The developed method allows to improve the accuracy of processing by removing the admission by the equidistant curves, not taking into account the radius of the grinding wheel. The control program is greatly simplified, since it requires only one cam profile and periodic additional traps that take into account the wear and tear of the grinding wheel and its editing. The proposed treatment method can be used in serial production, where it is often necessary to switch to diverse products, as well as during repair and restoration works.
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Posadowski, Witold, Artur Wiatrowski e Grzegorz Kapka. "Effect of pulsed magnetron sputtering process for the deposition of thin layers of nickel and nickel oxide". Materials Science-Poland 36, n. 1 (18 maggio 2018): 69–74. http://dx.doi.org/10.1515/msp-2017-0092.
Testo completoAbstract (sommario):
Abstract Magnetron sputtered nickel and nickel oxide films have been studied for various applications. We may find, among others, these films in electrochromic display devices, in resistive type gas sensors, as metal electrodes in electronic devices, in solar thermal absorbers. Pure nickel films deposited using PVD technique possess good corrosion and wear resistant properties. Magnetron sputtering has several advantages in film deposition (in comparison to other methods) such as relatively low heating temperature of the deposited substrate during sputtering process, high energy of sputtered atoms (about 10 eV) at the substrate, which influences positively the films adhesion. From application point of view, the most valuable feature of these films is the possibility of scaling target dimensions, which makes feasible the deposition on a several square meter surfaces. The improvement of magnetron sputtering devices design may influence positively the optimization of the deposition technology and its efficiency. The thin nickel and nickel oxide films were prepared by pulsed magnetron sputtering using original type WMK magnetron device. Ni (99.9 %) has been used as a sputtering target of 100 mm in diameter and different thicknesses (3 mm, 5 mm, and 6 mm). The distance between the substrate and target was the same in all experiments and equal to 120 mm. Argon and oxygen gases were introduced during the reactive process through needle gas valves at a total pressure of 0.4 Pa. The sputtering power, sputtering pressure and oxygen partial pressure have been used as technological knobs for deposition processes. The helpful tool for controlling the pulsed magnetron sputtering process was the original parameter of supply (so called circulating power). Results from our experiments showed that the deposition of Ni films is possible even from targets of 6 mm thickness. Deposition rate increased proportionally with the sputtering power. The aim of this work is to use the acquired expertise to develop an efficient technology of thin nickel oxide layers for electrochromic systems.
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Li, Qinghua, Chen Pan, Yuxin Jiao e Kaixing Hu. "Investigation on Cutting Performance of Micro-Textured Cutting Tools". Micromachines 10, n. 6 (28 maggio 2019): 352. http://dx.doi.org/10.3390/mi10060352.
Testo completoAbstract (sommario):
This paper explores the influence of micro textures on cutting performance of polycrystalline cubic boron nitride (PCBN) tools from two aspects, that is, tool wear and machined surface roughness. By designing micro-hole textures with different forms and scales on the rake face of tools when PCBN tools turn hardened steel GCr15, and combining finite element analysis (FEA) technology and cutting experiments, the cutting performance of micro-textured tools is simulated and analyzed. This paper analyses the influence of micro textures on tool wear and machined surface roughness by analyzing cutting force, Mises stress and maximum shear stress of tool surface. Results of finite element analysis (FEA) and cutting experiments show that the reasonable micro-hole textures can significantly alleviate tool wear and improve machined surface quality when compared with the non-textured tools. Besides, the size of micro-hole textures on the rake face play an important role in reducing the cutting force and tool wear. This is mainly because micro-hole textures can reduce cutting force and improve tool surface stress. Finally, by designing reasonable micro-hole textures on the rake face, the problems of bad roughness of machined workpiece and severe tool wear of PCBN tools in cutting GCr15 material are solved. Consequently, the paper shows that micro-hole textures have a positive effect on improving the cutting performance of tool.
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Xia, Zhen Sheng, Ben Sheng Zhang e De Yao Zhao. "Study on Plating Bath Preparation Method of Novel Nano-Composite Plating". Advanced Materials Research 546-547 (luglio 2012): 13–18. http://dx.doi.org/10.4028/www.scientific.net/amr.546-547.13.
Testo completoAbstract (sommario):
This article studies plating bath preparation method of novel nano-composite plating technology to improve properties of coatings when repairing the wear of equipments surface with the application of composite plating technology. The Nanoparticles of plating bath use Al2O3, metal substrates use Fe-based nano-composite plating coatings of Fe. The liquids ingredients of plating bath are prepared with ferric chloride and hydrochloric acid. The experiments of mechanical properties indicate that this plating method is an advanced technology on repairing the surface wear, which can effectively enhance the coatings properties of hardness, strength and wear resistance, which especially is suitable for the restoration to the wear of the high accuracy metal components of important equipments
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Kümmel, Johannes, Katja Poser, Frederik Zanger, Jürgen Michna e Volker Schulze. "Surface Layer States of Worn Uncoated and TiN-Coated WC/Co-Cemented Carbide Cutting Tools after Dry Plain Turning of Carbon Steel". Advances in Tribology 2013 (2013): 1–10. http://dx.doi.org/10.1155/2013/519686.
Testo completoAbstract (sommario):
Analyzing wear mechanisms and developments of surface layers in WC/Co-cemented carbide cutting inserts is of great importance for metal-cutting manufacturing. By knowing relevant processes within the surface layers of cutting tools during machining the choice of machining parameters can be influenced to get less wear and high tool life of the cutting tool. Tool wear obviously influences tool life and surface integrity of the workpiece (residual stresses, surface quality, work hardening, etc.), so the choice of optimised process parameters is of great relevance. Vapour-deposited coatings on WC/Co-cemented carbide cutting inserts are known to improve machining performance and tool life, but the mechanisms behind these improvements are not fully understood. The interaction between commercial TiN-coated and uncoated WC/Co-cemented carbide cutting inserts and a normalised SAE 1045 steel workpiece was investigated during a dry plain turning operation with constant material removal under varied machining parameters. Tool wear was assessed by light-optical microscopy, scanning electron microscopy (SEM), and EDX analysis. The state of surface layer was investigated by metallographic sectioning. Microstructural changes and material transfer due to tribological processes in the cutting zone were examined by SEM and EDX analyses.
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Ambhore, Nitin, Dinesh Kamble e Satish Chinchanikar. "Analysis of tool vibration and surface roughness with tool wear progression in hard turning: An experimental and statistical approach". Journal of Mechanical Engineering and Sciences 14, n. 1 (23 marzo 2020): 6461–72. http://dx.doi.org/10.15282/jmes.14.1.2020.21.0506.
Testo completoAbstract (sommario):
The machined surface quality and dimensional accuracy obtained during hard turning is prominently gets affected due to tool wear and cutting tool vibrations. With this view, the results of tool wear progression on surface quality and acceleration amplitude is presented while machining AISI 52100 hard steel. Central Composite Rotatable Design (CCRD) is employed to develop experimental plan. The results reported that vibration signals sensed in a tangential direction (Vz) are most sensitive and found higher than the vibrations in the feed direction (Vx) and depth of cut direction (Vy). The acceleration signals in all three directions are observed to increase with the advancement of tool wear and good surface finish is observed as tool wear progresses up-to 0.136mm. The vibration amplitude is discovered high in the range 3 kHz – 10 kHz within selected cutting parameter range (cutting speed 60-180mm/min, feed 0.1-0.5mm/rev, depth of cut 0.1-0.5mm). The investigation is extended for the development of multiple regression models with regression coefficients value 0.9. These models found statically significant and give dependable estimates between a tool vibrations and cutting parameters.
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Anasyida, Abu Seman, e Mohd Sharif Nurulakmal. "Wear behaviour of carbon steel cutting wheel thermal flame sprayed with chromium carbide". Industrial Lubrication and Tribology 67, n. 2 (9 marzo 2015): 93–98. http://dx.doi.org/10.1108/ilt-04-2013-0042.
Testo completoAbstract (sommario):
Purpose – This study aims to develop and evaluate an inexpensive and durable metal cutting wheel using thermal spraying and polymer binding to enhance the wheel’s cutting capability by bonding hard particles (abrasives) onto the wheel. Design/methodology/approach – Thermal spraying was used to deposit the coating powder (chromium and silicon carbide) onto high carbon substrate. Wear loss and depth of cut as function of load, time and speed were evaluated on uncoated and coated wheel. Findings – The coated cutting wheel performed better than the uncoated cutting wheel in terms of wear performance. However, the coated cutting wheel experienced coating peel off at higher load and cutting speed, leading to a decrease in wear resistance of the cutting wheel. Thus, optimally cutting should be performed either at low cutting speed and high load or at high cutting speed and low load to prolong the wheel’s lifetime. Originality/value – The outcome of the study will be beneficial for academicians and industrial working on cutting wheel process.