Journal articles: 'Aluminum coating Cementation (Metallurgy)'

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Alshmri, F. "Metallic Coatings: Al-Zn Alloys." Advanced Materials Research 915-916 (April 2014): 608–11. http://dx.doi.org/10.4028/www.scientific.net/amr.915-916.608.

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Steel sheet has one major drawback, it is attacked by moisture at low temperatures and oxygen at high temperatures. Fortunately, coatings can provide protection to steel sheet from corrosion. Aluminum and aluminum zinc coatings can be applied by different methods. These are chemical vapor deposition coating (CVD), slurry coating, vacuum coating, spray coating, cladding, electroplating, electrophoresis, diffusion coatings, cementation, calorizing and hot dipping. This paper aims at providing a survey of these processes.

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Zhou, Feng, Ming Gao, Ying Che Ma, Gan Feng Tu, and Ke Wu Peng. "The Effects of Aluminum Activity on Aluminide Coating Formation of Nickel-Base Superalloy." Applied Mechanics and Materials 198-199 (September 2012): 32–35. http://dx.doi.org/10.4028/www.scientific.net/amm.198-199.32.

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The effects of different pure Al compositon in the pack powder on aluminide coating formation of a new kind of Ni-Cr-W-Al nickel-base superalloy by pack cementation aluminizing was investigated. The content of pure Al powder is 15% and 30% in the aluminizing agent. The microstructure and phase composition of diffusion coating was studied.

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Kianicová, Marta, and Jan Kafrik. "A Study of Hot Corrosion Behaviour of NiAl Coatings in an Aggressive Environment." Solid State Phenomena 226 (January 2015): 177–82. http://dx.doi.org/10.4028/www.scientific.net/ssp.226.177.

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The microstructure and corrosion behaviour was studied for a diffusionβ-NiAl and Si modifiedβ-NiAl coatings formed on the superalloy MAR-M 247. First type,β-NiAl coating was applied with the help of method “out-of-pack”. Second type, Si modifiedβ-NiAl coating was applied by method “pack-cementation”. Diffusion coatings created protective, heat-activated layer which separated superalloy from aggressive environment. Corrosive environment was created by tablets Na2SO4at 900°C. Technique of scanning electron microscopy/energy dispersive X-ray analysis (SEM/EDS) was used to characterize the corrosion products. Experiment confirmed the advantages relating to the application of diffusion coating in aggressive environment which imitated environmental condition during operation of turbine engine. This experiment was made in cooperation with company PBS Velká Bíteš a. s., Velká Bíteš, Czech Republic and The Silesian University of Technology, Faculty of Materials Science and Metallurgy, Katowice, Poland.

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Zhu, Li'an, Shuxin Bai, Hong Zhang, Yicong Ye, and Wei Gao. "Double-layer iridium–aluminum intermetallic coating on iridium/rhenium coated graphite prepared by pack cementation." Surface and Coatings Technology 258 (November 2014): 524–30. http://dx.doi.org/10.1016/j.surfcoat.2014.08.044.

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Park, Joon Sik, J. M. Kim, H. Y. Kim, C. S. Kang, and S. W. Choi. "Surface Protection of Magnesium Alloys via Pack Cementation Coatings with Aluminum Powder and Chlorides." Materials Science Forum 638-642 (January 2010): 793–98. http://dx.doi.org/10.4028/www.scientific.net/msf.638-642.793.

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Magnesium alloys have been received an attention for structural applications due to their low density compared to other alloys, and intensive studies have been focused for enhancing mechanical strength and surface protection as well. Especially, for environmental reasonings, coating processes in a dry condition have been recently received a great attention. In this study, diffusion coatings via Al powders with an aluminum chloride activator have been investigated in order to examine surface protection effect on magnesium alloys. The commercial AZ31 magnesium alloy has been subjected to diffusion coatings in an Al alloy powder for various time frames. An intermediate layer of Mg17Ag12 was successfully synthesized via diffusion annealing. The underlying mechanisms for surface layer formation are discussed together with growth kinetics and microstructural observations

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Behrens, Bernd Arno, Klaus Georg Kosch, Conrad Frischkorn, Najmeh Vahed, and Adis Huskic. "Compound Forging of Hybrid Powder-Solid-Parts Made of Steel and Aluminum." Key Engineering Materials 504-506 (February 2012): 175–80. http://dx.doi.org/10.4028/www.scientific.net/kem.504-506.175.

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Compound forging is a technology to successfully manufacture hybrid parts by applying resource-saving process steps. During compound forging of steel-aluminum parts the formation of intermetallic phases is benefited. The thickness of these intermetallic phases influences the bonding and thus the global part quality. According to literature, specific coating elements reduce the phase seam thickness. In powder-metallurgically manufactured parts it is possible to selectively insert specific elements in the surface area. Therefore, a time intensive coating process can be avoided. The applicability of combining the technologies of powder-metallurgy and compound forging is discussed in this paper. Powder-metallurgically manufactured and solid parts made of steel and aluminum are compound forged and the influences on deformation behavior and the joining zone are investigated.

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Ma, Lu Ping, Jin Song Li, Li Zhang, Jian Chang Li, and Jian Jun Hao. "Study on TiAl(CN) Particle Reinforce Composites Coating Prepared by Reaction Nitrogen Arc Welding Cladding Process." Applied Mechanics and Materials 217-219 (November 2012): 1283–86. http://dx.doi.org/10.4028/www.scientific.net/amm.217-219.1283.

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Particle reinforce composites coating of TiAl(CN) was made on the surface of Q235B steel substrate by reaction nitrogen arc welding cladding process, which take the titanium powder, aluminum powder and the graphite powder as original material. The microstructures, structure and the phase of the coatings were investigated by scanning electronic microscope, X-ray diffract instrument, micro-hardness, reciprocating friction testing machine. The result indicated that the TiAl(CN) coating has a metallurgy union with the substrate, the phase of the coatings are mainly composed of TiAl(C0.51N0.12), AlFe3 and FeC. The microhardness and anti-abrasive performance of the TiAl(CN) coating is better than the Ti(CN) coating processed by tungsten nitrogen arc surfacing welding process.

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Kumar, R., S. Madhu, and M. Balasubramanian. "Analysis of AlSi CNT Composite Coating on Al6061 and SS304L Substrate by Plasma Spray." Applied Mechanics and Materials 591 (July 2014): 112–15. http://dx.doi.org/10.4028/www.scientific.net/amm.591.112.

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Recent trends shows powder metallurgy composites are most familiar due to its wide applications in the areas like defense, aircraft, automobile, sports etc. Powder metal mixtures are prepared for surface coating in the areas where high corrosive and heat resistance are required. Carbon Nanotubes are widely used in the field of engineering with its remarkable mechanical, electrical properties and very good reinforcement in composite preparation. In this research, multi wall Carbon Nanotube along with Aluminum and Silicon powder were mixed thoroughly by ball milling process. The powder mixture (AlSiCNT) reveals that Carbon Nanotube are well dispersed uniformly with Aluminum and Silicon which promotes toughening mechanism with good reinforcement. The AlSiCNT mixture is then coated over the surface of Aluminum alloy 6061 and Stainless steel 304 L by plasma spraying technique. Tensile test, micro hardness tests with micro structural study were carried out over the composite. Coated composite reveal better mechanical properties than the base metals.

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Ahmed, Afzaal. "Deposition and Analysis of Composite Coating on Aluminum Using Ti–B4C Powder Metallurgy Tools in EDM." Materials and Manufacturing Processes 31, no. 4 (March 23, 2015): 467–74. http://dx.doi.org/10.1080/10426914.2015.1025967.

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Deepa, J. P., S. Abhilash, T. P. D. Rajan, C. Pavithran, and B. C. Pai. "Structure and Properties of Electroless Cu and Ni-B Coated B₄C Particle Dispersed Aluminum Composites by Powder Metallurgy Technique." Materials Science Forum 830-831 (September 2015): 480–84. http://dx.doi.org/10.4028/www.scientific.net/msf.830-831.480.

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The widespread demand for light-weight materials in various emerging industrial sectors lead to the fabrication of aluminum- boron carbide composites. In this study, the B4C particles were coated copper and Ni-B through electroless process using formaldehyde and sodium borohydride respectively as reducing agents under optimized condition. The microstructural and hardness behavior were investigated for powder metallurgy processed 20 vol. % of B4C and coated B4C particles in the aluminum matrix. Microscopic observation revealed that coating improved the dispersibility of B4C particles in the matrix. The coated particles showed an increase in hardness and particle compaction with reduced porosity.

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Lee, Byeong Woo. "Effect of diffusion coatings on the high temperature properties of nickel-chromium-superalloys." International Journal of Modern Physics B 32, no. 19 (July 18, 2018): 1840056. http://dx.doi.org/10.1142/s0217979218400568.

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The halide-activated pack cementation method was utilized to deposit aluminide or silicide coatings on Inconel 617 and Hastelloy X superalloys. Aluminide and silicide diffusion coatings were formed at 850[Formula: see text]C for 2 h in nitrogen atmosphere, using a pack mixture containing pure aluminum (Al) or silicon (Si) and aluminum oxide (Al2O3) powders with activators of NH4Cl and AlF3. Aluminide-coated alloys showed homogeneous and uniform microstructures. Al diffused into the alloy inwards and aluminide diffusion coatings of [Formula: see text]17 [Formula: see text]m thick were formed inside the alloy. It was shown that the Al coatings played a key role in blocking off the excessive corrosion products at a high temperature for the alloys. The enhanced thermal stability and improved wear resistance were achieved in the aluminide coatings. In contrast to the aluminide coating, the silicide coating played a negative role, unable to provide the protective layer. The microstructural evolution and thermal stability of the aluminide- and silicide-coated alloys have been elucidated.

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Bianchi, Sergio, and Fabrizio Broggi. "Coil Coating: The Advanced Finishing Technology." Key Engineering Materials 710 (September 2016): 181–85. http://dx.doi.org/10.4028/www.scientific.net/kem.710.181.

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Coil Coating is an advanced finishing technology available for different metal substrates, specifically steel and aluminum, with several millions of square meters processed each year. Born in the 60’s, the coil coating technology has gained interest in the market in the late 80’s and 90’s and it’s now booming due its peculiarities both technical as well as environmental and in terms of energy. The Coil Coated product is used in many different applications’ fields: architecture, with facades, cladding, industrial and residential roofing, shutters: transportation, with caravan, train interiors; industry, with caps, closures. The same application technology is widely used for canstock – body, ends and taps: the process concept, being the same, though with remarkable differentiation in terms of speed, metal gauges, application systems and paint qualities (water based, low gauge and highly diluted). The process and the product are both very complex: the Product consists of a combination merging metal, surface treatment and paints; the Process is thus a combination of different steps, perfectly synchronized unique in terms of speed and contact time. Metallurgy, Chemistry, Mechanics, Fluid Dynamics, Energy management: this all comes together within seconds on the same line. For Aluminum, the product features depends on metal alloy – usually 1xxx, 3xxx and 5xxx, with the most different tempers ranging from fully soft through fully hard; different paint types and qualities, ranging from standard Polyester, through the newly developed HDPE and Polyurethane with / without Polyamide to high quality PVdF and Fluopolymers. The presentation will detail these technical features highlighting the significant differences between traditional finishing and Coil Coating

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Sonoda, Tsutomu, and Kiyotaka Katou. "Coating of Granular Polymeric Spacers with Copper by Sputter-Deposition for Enhancing Cell Wall Structure of Sintered Highly Porous Aluminum Materials." Materials Science Forum 660-661 (October 2010): 432–36. http://dx.doi.org/10.4028/www.scientific.net/msf.660-661.432.

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The deposition of copper onto acrylic resin powder in its self-convective motion by magnetron DC sputtering was examined in order to prepare granular polymeric spacers coated with the metal, aiming at enhancing the cell wall structure of sintered highly porous aluminum materials. The fabrication of sintered highly porous aluminum materials was carried out in an ordinary powder metallurgy processing combined with a space-holder method with the polymer-copper binary spacer granules prepared by powder-coating using the sputter-deposition technique. The effects of the sputter-deposition of copper onto the spherical polymeric spacers on cell structures of the sintered porous compacts were investigated. According to optical observations, it was found that the sputtered copper could be uniformly and adherently deposited onto the surface of the acrylic granules. According to EPMA analysis on the cross-section on a sintered porous compact, it was found that Cu atoms were distributed at the vicinity of its cell walls, concluding that cell wall structures could be enhanced by this processing. Therefore it was expected that the compressive properties of the sintered highly porous aluminum materials were also improved by this powder coating process.

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14

Pei, Ji Bin, Li Wen Zhang, Jing Niu, and Quan Zhong Zhang. "Microstructure and Formation Mechanism of Aluminized Coatings on Nickel-Based Superalloys." Key Engineering Materials 373-374 (March 2008): 204–7. http://dx.doi.org/10.4028/www.scientific.net/kem.373-374.204.

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Aluminized coatings prepared on nickel-based superalloys can provide good protection against high temperature oxidation and hot corrosion. This study investigated the simple aluminized and silicon-aluminized coatings on nickel-based superalloy K4104. The simple aluminized coating was prepared by pack cementation and the Al-Si coating was prepared by slurry aluminizing, respectively. The microstructure of simple aluminized and Al-Si coatings was analyzed by means of scanning electron microscope (SEM), X-ray diffraction (XRD) and electron probe microanalysis (EPMA). And the formation mechanism of simple aluminized and Al-Si coatings was discussed. The results showed that the simple aluminized coating was about 49 um thick and consisted of three layers. The outer layer mainly consisted of Al-rich β-NiAl. The intermediate layer consisted of Ni-rich β-NiAl and Cr-rich. The inner diffusion layer consisted of Cr-rich and γ’-Ni3Al. The microstructure of Al-Si coating showed that the coating was about 70 um thick and consisted of five layers. The Al-Si coating consisted of CrxSiy, Al-rich β-NiAl, Ni-rich β-NiAl, Cr-rich and γ’-Ni3Al. The microstructure of simple aluminized coating was compared with that of Al-Si coating in order to find out the effect of Si. Owing to the effect of Si, there was a Transition layer in Al-Si coating. The Al-Si coating was thicker than simple aluminized coating. The declining trend of the aluminum concentration in the Al-Si coating was smoother than that of the simple aluminized coating.

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Damanik, Ferdinandus Sarjanadi, and Günther Lange. "Influence of MWCNT Coated Nickel on the Foaming Behavior of MWCNT Coated Nickel Reinforced AlMg4Si8 Foam by Powder Metallurgy Process." Metals 10, no. 7 (July 15, 2020): 955. http://dx.doi.org/10.3390/met10070955.

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This research studies the effect of multi-wall carbon nanotube (MWCNT) coated nickel to foaming time on the foam expansion and the distribution of pore sizes MWCNT reinforced AlMg4Si8 foam composite by powder metallurgy process. To control interface reactivity and wettability between MWCNT and the metal matrix, nickel coating is carried out on the MWCNT surface. Significantly, different foaming behavior of the MWCNT coated nickel reinforced AlMg4Si8 was studied with a foaming time variation of 8 and 9 min. Digital images generated by the imaging system are used with the MATLAB R2017a algorithm to determine the porosity of the surface and the pore area of aluminum foam efficiently. The results can have important implications for processing MWCNT coated nickel reinforced aluminum alloy composites.

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Sonoda, Tsutomu, Kiyotaka Katou, and Tadashi Asahina. "Porous Structure and Mechanical Properties of the Cellular Metallic Materials Fabricated by Sintering Al Powder Coated with Sn." Materials Science Forum 591-593 (August 2008): 277–81. http://dx.doi.org/10.4028/www.scientific.net/msf.591-593.277.

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The deposition of pure tin onto pure aluminum powder in its self-convective motion by magnetron DC sputtering was examined in order to prepare Al-Sn composite powder and thereby to improve the sintering of the aluminum particles, aiming at the development of highly structure-controlled porous aluminum materials. The fabrication of porous aluminum materials was carried out by space-holder method using the prepared Al-Sn composite powder in ordinary powder metallurgy processing. The effects of the sputterdeposition of tin on porous structure and mechanical properties of the sintered compact were investigated. It was found that the porous structure of the sintered porous materials with the porosity 80% was better regulated by the sputter-deposition, compared to that without the deposition. Regarding their compressive properties, it was found that the plateau stress of the sintered porous materials reached by the sputter-deposition twice as high as that without the deposition. Therefore it was concluded that coating of aluminum powder with tin deposits enables the porous-structure to be controlled more effectively in fabricating sintered highly porous aluminum materials, as well as improves their mechanical property.

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Vanarotti, Mohan, P. Shrishail, B. R. Sridhar, K. Venkateswarlu, and S. A. Kori. "Surface Modification of SiC Reinforcements & its Effects on Mechanical Properties of Aluminium Based MMC." Applied Mechanics and Materials 446-447 (November 2013): 93–97. http://dx.doi.org/10.4028/www.scientific.net/amm.446-447.93.

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Aluminum (A356)-SiC metal matrix composites were fabricated by using liquid metallurgy route. To improve the interfacial bonding between the Al and SiC, an attempt has been made to coat the SiC particles with Ni and Cu. Electroless process was used for coating the reinforced particle. This surface modification due to electroless coating on SiC particles was confirmed with SEM/ EDS analysis. Processing parameters such as melt temperature, stirring speed, stirring time, and preheating temperature were optimized. SiC content in Al-SiC MMC were taken from 5 to 15% and effect of Ni and Cu coating was studied using hardness measurements. Influence of coated SiC particles in Al-SiC showed significant improvement in hardness values. Moreover, micro structural examination clearly demonstrated that Cu coating on SiC particles resulted in good metallurgical boding as compared to SiC particles with Ni coating. As a result, the hardness values of Al-SiC (Cu) exhibited better hardness values as compared to Al-SiC (Ni) MMCs. As expected, high SiC content in types of Al-SiC MMCs showed high hardness values as compared to low SiC content and base alloy. The present investigation suggests that Cu coating on SiC particles are more suitable as compared to Ni coating on SiC particles to synthesis Al-SiC MMCs.

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Henriques, Vinicius André Rodrigues, T. G. Lemos, Carlos Alberto Alves Cairo, Julia Faria, and Eduardo T. Galvani. "Titanium Nitride Deposition in Titanium Implant Alloys Produced by Powder Metallurgy." Materials Science Forum 660-661 (October 2010): 11–16. http://dx.doi.org/10.4028/www.scientific.net/msf.660-661.11.

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Titanium nitride (TiN) is an extremely hard material, often used as a coating on titanium alloy, steel, carbide, and aluminum components to improve wear resistance. Electron Beam Physical Vapor Deposition (EB-PVD) is a form of deposition in which a target anode is bombarded with an electron beam given off by a charged tungsten filament under high vacuum, producing a thin film in a substrate. In this work are presented results of TiN deposition in targets and substrates of Ti (C.P.) and Ti-13Nb-13Zr obtained by powder metallurgy. Samples were produced by mixing of hydrided metallic powders followed by uniaxial and cold isostatic pressing with subsequent densification by sintering between 900°C up to 1400 °C, in vacuum. The deposition was carried out under nitrogen atmosphere. Sintered samples were characterized for phase composition, microstructure and microhardness by X-ray diffraction, scanning electron microscopy and Vickers indentation, respectively. It was shown that the samples were sintered to high densities and presented homogeneous microstructure, with ideal characteristics for an adequate deposition and adherence. The film layer presented a continuous structure with 15m.

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Hassan, Mohamed Ali, Hossam M. Yehia, Ahmed S. A. Mohamed, Ahmed Essa El-Nikhaily, and Omayma A. Elkady. "Effect of Copper Addition on the AlCoCrFeNi High Entropy Alloys Properties via the Electroless Plating and Powder Metallurgy Technique." Crystals 11, no. 5 (May 12, 2021): 540. http://dx.doi.org/10.3390/cryst11050540.

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To improve the AlCoCrFeNi high entropy alloys’ (HEAs’) toughness, it was coated with different amounts of Cu then fabricated by the powder metallurgy technique. Mechanical alloying of equiatomic AlCoCrFeNi HEAs for 25 h preceded the coating process. The established powder samples were sintered at different temperatures in a vacuum furnace. The HEAs samples sintered at 950 °C exhibit the highest relative density. The AlCoCrFeNi HEAs model sample was not successfully produced by the applied method due to the low melting point of aluminum. The Al element’s problem disappeared due to encapsulating it with a copper layer during the coating process. Because the atomic radius of the copper metal (0.1278 nm) is less than the atomic radius of the aluminum metal (0.1431 nm) and nearly equal to the rest of the other elements (Co, Cr, Fe, and Ni), the crystal size powder and fabricated samples decreased by increasing the content of the Cu wt%. On the other hand, the lattice strain increased. The microstructure revealed that the complete diffusion between the different elements to form high entropy alloy material was not achieved. A dramatic decrease in the produced samples’ hardness was observed where it decreased from 403 HV at 5 wt% Cu to 191 HV at 20 wt% Cu. On the contrary, the compressive strength increased from 400.034 MPa at 5 wt% Cu to 599.527 MPa at 15 wt% Cu with a 49.86% increment. This increment in the compressive strength may be due to precipitating the copper metal on the particles’ surface in the nano-size, reducing the dislocations’ motion, increasing the stiffness of produced materials. The formability and toughness of the fabricated materials improved by increasing the copper’s content. The thermal expansion has increased gradually by increasing the Cu wt%.

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Stopic, Srecko, and Bernd Friedrich. "Advances in Understanding of the Application of Unit Operations in Metallurgy of Rare Earth Elements." Metals 11, no. 6 (June 18, 2021): 978. http://dx.doi.org/10.3390/met11060978.

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Unit operations (UO) are mostly used in non-ferrous extractive metallurgy (NFEM) and usually separated into three categories: (1) hydrometallurgy (leaching under atmospheric and high pressure conditions, mixing of solution with gas and mechanical parts, neutralization of solution, precipitation and cementation of metals from solution aiming purification, and compound productions during crystallization), (2) pyrometallurgy (roasting, smelting, refining), and (3) electrometallurgy (aqueous electrolysis and molten salt electrolysis). The high demand for critical metals, such as rare earth elements (REE), indium, scandium, and gallium raises the need for an advance in understanding of the UO in NFEM. The aimed metal is first transferred from ores and concentrates to a solution using a selective dissolution (leaching or dry digestion) under an atmospheric pressure below 1 bar at 100 °C in an agitating glass reactor and under a high pressure (40–50 bar) at high temperatures (below 270 °C) in an autoclave and tubular reactor. The purification of the obtained solution was performed using neutralization agents such as sodium hydroxide and calcium carbonate or more selective precipitation agents such as sodium carbonate and oxalic acid. The separation of metals is possible using liquid (water solution)/liquid (organic phase) extraction (solvent extraction (SX) in mixer-settler) and solid-liquid filtration in chamber filter-press under pressure until 5 bar. Crystallization is the process by which a metallic compound is converted from a liquid into a crystalline state via a supersaturated solution. The final step is metal production using different methods (aqueous electrolysis for basic metals such as copper, zinc, silver, and molten salt electrolysis for REE and aluminum). Advanced processes, such as ultrasonic spray pyrolysis, microwave assisted leaching, and can be combined with reduction processes in order to produce metallic powders. Some preparation for the leaching process is performed via a roasting process in a rotary furnace, where the sulfidic ore was first oxidized in an oxidic form which is a suitable for the metal transfer to water solution. UO in extractive metallurgy of REE can be successfully used not only for the metal wining from primary materials, but also for its recovery from secondary materials.

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Narita, Toshio, Takeshi Izumi, Takumi Nishimoto, Yoshimitsu Shibata, Kemas Zaini Thosin, and Shigenari Hayashi. "Advanced Coatings on High Temperature Applications." Materials Science Forum 522-523 (August 2006): 1–14. http://dx.doi.org/10.4028/www.scientific.net/msf.522-523.1.

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To suppress interdiffusion between the coating and alloy substrate in addition to ensuring slow oxide growth at very high temperatures advanced coatings were developed, and they were classified into four groups, (1) the diffusion barrier coating with a duplex layer structure, an inner σ−(Re-Cr-Ni) phase as a diffusion barrier and outer Ni aluminides as an aluminum reservoir formed on a Ni based superalloy, Hastelloy X, and Nb-based alloy. (2) the up-hill diffusion coating with a duplex layer structure, an inner TiAl2 + L12 and an outer β-NiAl formed on TiAl intermetallic and Ti-based heat resistant alloys by the Ni-plating followed by high Al-activity pack cementation. (3) the chemical barrier coating with a duplex layer structure, an inner* γ + β + Laves three phases mixture as a chemical diffusion barrier and an outer Al-rich γ-TiAl as an Al reservoir formed by the two step Cr / Al pack process. (4) the self-formed coating with the duplex structure, an inner α-Cr layer as a diffusion barrier and an outer β-NiAl as an Al-reservoir on Ni-(2050)at% Cr alloy changed from the δ-Ni2Al3 coating during oxidation at high temperature. The oxidation properties of the coated alloys were investigated at temperatures between 1173 and 1573K in air for up to 1,000 hrs (10,000 hrs for the up-hill diffusion coating). In the diffusion barrier coating the Re-Cr-Ni alloy layer was stable, existing between the Ni-based superalloy (or Hastelloy X) and Ni aluminides containing 1250at%Al when oxidized at 1423K for up to 1800ks. It was found that the Re-Cr-Ni alloy layer acts as a diffusion barrier for both the inward diffusion of Al and outward diffusion of alloying elements in the alloy substrate. In the chemical barrier coating both the TiAl2 outermost and Al-rich γ-TiAl outer layers maintained high Al contents, forming a protective Al2O3 scale, and it seems that the inner, γ, β, Laves three phase mixture layer suppresses mutual diffusion between the alloy substrate and the outer/outermost layers.

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Fathy, A., M. Abdelhameed, and F. Shehata. "Effect of Some Manfacturing Parameters on Machining of Extruded Al-Al2O3 Composites." ISRN Materials Science 2012 (April 17, 2012): 1–6. http://dx.doi.org/10.5402/2012/748734.

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A wide range of particulate metal matrix composites (PMMCs) of alumina and aluminum powders was formed using powder metallurgy techniques followed by extrusions at various extrusion ratios. The machining characteristics of the extruded PMMC were investigated. Results showed significant effects of weight fractions of reinforcement and extrusion ratios on tool wear and surface integrity of machined surface. The wear rate of cutting tool decreased rapidly with increasing the cutting parameters: cutting speed, feed, and depth of cut, however cutting speed is shown to be more effective. Sudden breakage of tool inserts occurred when the experiment started at high cutting speed. Wear rate has also decreased by decreasing volume fraction of reinforcement particles. Coating carbide tools have significantly improved the tool life. Coated tools showed 5% decrease in flank wear size compared to uncoated tools. This was valid within tested range of weight fractions and extrusion ratios. The surface finish of machined surfaces deteriorated when coated carbide tools were used. However, surface finish did not change significantly when volume fractions or extrusion ratios were altered.

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Park, Ilhwan, Carlito Tabelin, Hiroyuki Inano, Kensuke Seno, Kazuki Higuchi, Mayumi Ito, and Naoki Hiroyoshi. "Formation of surface protective coatings on arsenopyrite using Al-catecholate complex and its mode of inhibition of arsenopyrite oxidation." MATEC Web of Conferences 268 (2019): 06015. http://dx.doi.org/10.1051/matecconf/201926806015.

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Arsenopyrite is the most common arsenic-bearing sulfide mineral in nature. It is readily oxidized and releases toxic arsenic (As) into the environment when exposed to atmospheric conditions via anthropogenic activities like mining, mineral processing, extractive metallurgy, and underground space developments. Carrier-microencapsulation (CME) is a technique that uses metal(loid)-organic complexes to selectively form protective coatings on the surfaces of sulfide minerals. In this study, CME using Al-catecholate complexes (i.e., Al-based CME) was investigated to suppress the oxidation of arsenopyrite. Aluminum(III) and catechol form three complex species depending on the pH and among them, [Al(cat)]+ was the most effective in suppressing arsenopyrite oxidation. Its suppressive effect was improved as [Al(cat)]+ concentration increased due most likely to the formation of a more extensive surface protective coating at higher concentrations. Surface characterization of leaching residues using SEM-EDX and XPS indicates that CME-treated arsenopyrite was covered with bayerite (γ-Al(OH)3). The results of electrochemical studies showed that the surface protective coatings suppressed both anodic and cathodic half-cell reactions of arsenopyrite oxidation.

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Journal articles on the topic 'Aluminum coating Cementation (Metallurgy)'

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