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1
Szparaga, Łukasz, Przemysław Bartosik, Adam Gilewicz, Katarzyna Mydłowska, and Jerzy Ratajski. "Optimisation of Mechanical Properties of Gradient Zr–C Coatings." Materials 14, no. 2 (2021): 296. http://dx.doi.org/10.3390/ma14020296.
Повний текст джерелаАнотація:
One of the key components of the designing procedure of a structure of hard anti-wear coatings deposited via Physical Vapour Deposition (PVD) is the analysis of the stress and strain distributions in the substrate/coating systems, initiated during the deposition process and by external mechanical loads. Knowledge of residual stress development is crucial due to their significant influence on the mechanical and tribological properties of such layer systems. The main goal of the work is to find the optimal functionally graded material (FGM) coating’s structure, composed of three functional layers: (1) adhesive layer, providing high adhesion of the coating to the substrate, (2) gradient load support and crack deflection layer, improving hardness and enhancing fracture toughness, (3) wear-resistant top layer, reducing wear. In the optimisation procedure of the coating’s structure, seven decision criteria basing on the state of residual stresses and strains in the substrate/coating system were proposed. Using finite element simulations and postulated criteria, the thickness and composition gradients of the transition layer in FGM coating were determined. In order to verify the proposed optimisation procedure, Zr-C coatings with different spatial distribution of carbon concentration were produced by the Reactive Magnetron Sputtering PVD (RMS PVD) method and their anti-wear properties were assessed by scratch test and ball-on-disc tribological test.
2
Szparaga, Łukasz, Przemysław Bartosik, Adam Gilewicz, Katarzyna Mydłowska, and Jerzy Ratajski. "Optimisation of Mechanical Properties of Gradient Zr–C Coatings." Materials 14, no. 2 (2021): 296. http://dx.doi.org/10.3390/ma14020296.
Повний текст джерелаАнотація:
One of the key components of the designing procedure of a structure of hard anti-wear coatings deposited via Physical Vapour Deposition (PVD) is the analysis of the stress and strain distributions in the substrate/coating systems, initiated during the deposition process and by external mechanical loads. Knowledge of residual stress development is crucial due to their significant influence on the mechanical and tribological properties of such layer systems. The main goal of the work is to find the optimal functionally graded material (FGM) coating’s structure, composed of three functional layers: (1) adhesive layer, providing high adhesion of the coating to the substrate, (2) gradient load support and crack deflection layer, improving hardness and enhancing fracture toughness, (3) wear-resistant top layer, reducing wear. In the optimisation procedure of the coating’s structure, seven decision criteria basing on the state of residual stresses and strains in the substrate/coating system were proposed. Using finite element simulations and postulated criteria, the thickness and composition gradients of the transition layer in FGM coating were determined. In order to verify the proposed optimisation procedure, Zr-C coatings with different spatial distribution of carbon concentration were produced by the Reactive Magnetron Sputtering PVD (RMS PVD) method and their anti-wear properties were assessed by scratch test and ball-on-disc tribological test.
3
Maulet, M., B. K. Rakhadilov, W. Wieleba, and Zh B. Sagdoldina. "UTILIZING DETONATION SPRAYING IN THE PROCESS OF FORTIFYING COMPONENTS WITHIN POWER PLANT TECHNOLOGY." Bulletin of Shakarim University. Technical Sciences, no. 1(13) (March 29, 2024): 347–52. http://dx.doi.org/10.53360/2788-7995-2024-1(13)-43.
Повний текст джерелаАнотація:
The article addresses challenges related to enhancing the performance characteristics of power plant components. Research conducted by different authors demonstrates that when aiming to enhance the operational qualities of these parts, detonation spraying yields superior outcomes owing to its low porosity, high strength, and strong adhesion of the coatings produced. Also benefits of employing Ni-Cr-Al-based coatings as high oxidation resistant coating. The study involves the acquisition of Ni-Cr-Al-based gradient structured coatings using detonation spraying techniques. Investigated their phase composition and microstructures. By modifying the technological parameters during spraying, we achieved control over the properties of the resulting gradient coatings. Analysis of the elemental composition via the EDS method revealed that the Ni–Cr–Al gradient coatings possess a structured gradient, wherein the aluminum concentration progressively rises from the substrate towards the surface of the coating. The Ni–Cr–Al gradient coating thereby obtained the presence of phases NiCr with a surface of NiAl that has a high hardness and wear resistance.
4
Li, Chenchen, Xuefeng Yang, Shouren Wang, Yanjun Wang, and Jinlong Cao. "Preparation of WC Reinforced Co-Based Alloy Gradient Coatings on a H13 Mold Steel Substrate by Laser Cladding." Coatings 10, no. 2 (2020): 176. http://dx.doi.org/10.3390/coatings10020176.
Повний текст джерелаАнотація:
H13 die steel often fails as a result of physical and chemical effects such as wear, erosion and cyclic stress. Accordingly, the study evaluates Co-based gradient coating on an H13 steel featuring a stress-relieving effect. Scanning electron microscope and X-ray diffraction were used to analyze the microstructure and phase of the coatings. A microhardness tester and friction and wear tester were used to compare the hardness and wear resistance of the coatings and the substrate, and the wear morphology was observed. A pendulum impact test was used to compare the impact resistance of the coatings and the substrate, and the fracture morphology was observed. Finally, a corrosion test was used to compare the corrosion resistance of coatings and substrate. The results show that the Co-based gradient coatings have good combinations with the substrate, the hard phase content gradually increases from the bottom to the top of the coating, and the crystal microstructure generally maintains a distribution trend from coarse to fine. The hardness of the gradient coatings is significantly higher than the substrate, and from the coating surface to the substrate, the hardness decreases slowly. The wear loss of the coatings is much lower than that of the substrate, the main wear mechanism of the substrate is abrasive wear, and the main wear mechanism of the coatings is brittle spalling. While the gradient coatings increase the surface hardness, the brittleness also increases, the impact resistance of the coatings is lower than that of the substrate, the fracture form of the substrate is a ductile fracture, and the fracture form of the coating is a brittle fracture. The gradient coatings effectively improve the corrosion resistance of the substrate surface, and the higher the content of the reinforcing phase, the better the corrosion resistance of the coatings.
5
Su, Ya Yu, Xiao Lei Li, Hui Jie Tang, Zhi Hao Zhao, and Jian He. "Thermal Shock Behavior and Bonding Strength of MoSi2-BaO-Al2O3-SiO2 Gradient Porous Coating with Polymethyl Methacrylate Addition for Porous Fibrous Insulations." Solid State Phenomena 281 (August 2018): 493–98. http://dx.doi.org/10.4028/www.scientific.net/ssp.281.493.
Повний текст джерелаАнотація:
In order to improve the thermal shock behavior of high temperature resistant coating on porous fibrous referactory insulations, the MoSi2-BaO-Al2O3-SiO2(MoSi2-BAS) gradient porous coatings were designed by preparing a dense surface layer and a porous bonding layer with the method of brushing and subsequent sintering at 1773 K. The porous bonding layer was obtained by adding polymethyl methacrylate (PMMA) as pore former. As the content of PMMA increases, the MoSi2-BAS coatings changed from a dense structure into a gradient porous structure. The interface bonding strength and thermal shock resistance of the MoSi2-BAS coatings were investigated. The result shows that the as-prepared coating with gradient porous structure exhibited excellent thermal shock resistance, which remained gradient structure without cracking after thermal cycling 100 times between 1773 K and room temperature. And the interface bonding strength of the gradient porous coating reached 1.5±0.08 Mpa, which was much better than that of the dense coating.
6
M. Maulet, B. Rakhadilov, M. Rutkowska-Gorczyca, Zh. Sagdoldina, and D. Buitkenov. "ASSESSMENT OF NI-CR-AL HIGH-TEMPERATURE DETONATION COATINGS UNDER OPERATIONAL CONDITIONS." Bulletin of Toraighyrov University. Energetics series, no. 4.2024 (December 30, 2024): 231–41. https://doi.org/10.48081/wmcr9023.
Повний текст джерелаАнотація:
This study evaluates the high-temperature durability and oxidation resistance of homogeneous and gradient Ni-Cr-Al detonation coatings applied to 12Kh1MF steel substrates. Samples were exposed to operational conditions in a power plant for two weeks, simulating high-temperature industrial environments. The research utilizes X-ray diffraction (XRD) and scanning electron microscopy (SEM) to analyze phase stability, surface morphology, and structural integrity of the coatings before and after thermal exposure. Findings reveal that gradient coatings outperform homogeneous ones, demonstrating superior oxidation resistance and reduced susceptibility to thermal stress-induced microcracks. The multi-layered oxide structure and compositional gradient of the gradient coatings contribute to their enhanced thermal stability and long-term durability. In contrast, homogeneous coatings exhibited surface roughness and microcracks, which may compromise their longevity under extreme conditions. These insights emphasize the advantages of gradient Ni-Cr-Al coatings for high-temperature applications, highlighting their potential for improved performance and reliability in demanding industrial settings. The study bridges knowledge gaps regarding the long-term behavior of these coatings, aiding their optimization for critical applications. Keywords: High-temperature coating, power plant, Ni-Cr-Al coating, detonation technology, steel 12Kh1MF.
7
WANG, TAO, NING WANG, YANG LI, HAO WANG, JIE TANG, and YUNSHAN WANG. "STUDY ON PREPARATION TECHNOLOGIES OF THERMAL BARRIER COATINGS." Surface Review and Letters 24, no. 04 (2016): 1730004. http://dx.doi.org/10.1142/s0218625x17300040.
Повний текст джерелаАнотація:
Thermal barrier coatings (TBCs) is one of the main key technology for the high-pressure turbine blades which are the main components of the high-performance aerospace engines. It offers protection for underline metallic components from corrosion, oxidation and localized melting by insulating the metal from hot gases in the engine core. The properties and lifetime of TBCs are greatly influenced by the preparation technology, which includes plasma spraying (PS), physical vapor deposition (PVD) and laser re-melting (LM). In this paper, three technologies used to prepare the TBCs are reviewed. Resulting features of coating fabricated by each technology are also discussed such as: the porosity, the thermally grown oxide (TGO), the erosion resistance, the thermal shock and so on. Especially, it is pointed out that the performances of gradient coating and nano-coating are better than the traditional coatings. In addition, it is widely accepted that laser can be applied to re-melt the PS coating and even directly clad the gradient coating. In the future, the traditional preparation technology should be improved continually in order to enhance the coating lifetime, enhance the properties of coating and lower the cost of process. Moreover, the researches on gradient-nano-structured coatings preparation are absent and should be done with emphasis since the nano-structure and gradient structure can both benefit the lifetime and properties of coatings.
8
Rakhadilov, Bauyrzhan, Laila Sulyubayeva, Meruyert Maulet, Zhuldyz Sagdoldina, Dastan Buitkenov, and Ainur Issova. "Investigation of High-Temperature Oxidation of Homogeneous and Gradient Ni-Cr-Al Coatings Obtained by Detonation Spraying." Coatings 14, no. 1 (2023): 11. http://dx.doi.org/10.3390/coatings14010011.
Повний текст джерелаАнотація:
The high-temperature oxidation of homogeneous and gradient coatings based on Ni-Cr-Al obtained by detonation spraying is investigated. To assess the resistance to high-temperature oxidation of Ni-Cr-Al coatings, cyclic tests were carried out at a temperature of 1000 °C for 50 cycles. The assessment of high-temperature oxidizing ability was carried out by measuring the weight gain of samples after each cycle. After high-temperature oxidation tests, the morphology and chemical composition of the coating structure in the cross-section were investigated using SEM/EDS. The phase composition of the samples was studied by X-ray diffraction (XRD) phase analysis. Visual analysis of the sample surface under study after high-temperature oxidation showed that the surface of homogeneous or gradient Ni-Cr-Al coatings remained undamaged. The results of X-ray phase analysis showed the peaks of Al2O3 in Ni-Cr-Al gradient coatings are more expressed and intense compared to homogeneous coatings of Ni-Cr-Al. Gradient coatings also retain an increased chromium content compared to homogeneous Ni-Cr-Al coatings. This increased chromium content can slow down mixing or diffusion between different phases of the material at their boundary, which, in turn, contributes to increasing the resistance of the gradient coating to oxidation.
9
He, Dai Hua, Qian Zhao, Chang Bao Wang, et al. "Sol-Gel Derived Gradient Biocoatings on Titanium Alloy." Applied Mechanics and Materials 80-81 (July 2011): 426–30. http://dx.doi.org/10.4028/www.scientific.net/amm.80-81.426.
Повний текст джерелаАнотація:
The bioceramic hydroxyapaptie (HA) is frequently used as coat in titanium medical implants improving bone fixation and thus increasing a lifetime of the implant. However, its joining to the titanium alloy is not satisfactorily good. The aim of this work is to produce TiO2and HA gradient coatings on Ti6Al4V alloy to improve the interface joining. Compared the microstructures of cross section of Ti6Al4V-HA coating and Ti6Al4V-TiO2/HA gradient coatings. HA coatings were obtained by sol-gel method with sol solutions prepared from calcium nitrate tetrahydrate and triethyl phosphate as the calcium and phosphorous sources. And TiO2 coatings were obtained from Tetra Butyl Titanate and absolute ethyl alcohol as the sources by sol-gel method too. The configuration and structure were investigated with scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. The results demonstrated that the TiO2/HA gradient coatings have a homogeneous microstructure. The TiO2coating made the HA coating adhere to the Ti-6Al-4V substrate well.
10
Sagdoldina, Zh B., D. R. Baizhan, Y. Y. Kambarov, and K. Torebek. "Obtaining functional-gradient Ti-HA coatings by detonation spraying." Bulletin of the Karaganda University. "Physics" Series 107, no. 3 (2022): 43–51. http://dx.doi.org/10.31489/2022ph3/43-51.
Повний текст джерелаАнотація:
Functional-gradient titanium/hydroxyapatite (TiHA) coatings were obtained using detonation spraying technology to improve the structure and mechanical properties. To obtain functional-gradient coatings, pulsed energy sources are best suited, namely, detonation spraying, in which the energy of the explosion of gas mixtures is used as a source of pulsed action. By controlling the modes of detonation spraying, it is possible to vary the temperature and rate of coating deposition; accordingly, it is possible to obtain a certain structuralphase structure of the coatings. The structural-phase state and tribological properties of TiHA detonation coatings were investigated by modern materials science methods: X-ray phase analysis (XRD), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDX-mapping), profilometry and ball-disk wear-resistance test. The results showed that the coatings had a continuously gradient elemental composition across the cross-section of the coatings with no boundary between the elemental layers of the coatings. The amount of Ti gradually decreased and the amount of hydroxyapatite gradually increased in the direction from the substrate to the surface of the coatings, which allows to expand the possibilities of using TiHA-coatings for bone implants. Since the surface layer is composed of HA, the resulting functional-gradient coating demonstrates excellent biocompatibility and the ability to create new bone tissue. The excellent mechanical strength of the functionally graded coatings is ensured by the Ti phase.
11
Ning, Cheng Yun, Ying Jun Wang, Xiao Feng Chen, Jian Dong Ye, Gang Wu, and Na Ru Zhao. "TEM Analysis on Bio-Functional Gradient Hydroxyapatite/ZrO2 Coatings." Key Engineering Materials 336-338 (April 2007): 1676–78. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.1676.
Повний текст джерелаАнотація:
In the present study, bioactive functional gradient coatings were prepared using net-energy controlled plasma spraying technology. The microstructure and phases of the bioactive functional gradient coating were examined by means of transmission electron microscope, scanning electron microscopy and X-ray diffraction. The results revealed that: (1) as-sprayed coatings contained a large amount of amorphous phases and some nano-sized HA crystals formed during rapid solidification, (2) surface of the coating was very rough with different-sized micropores, and the gradient layer was much denser which firmly bonded to the substrate without gaps and obvious interface between the coating and the substrate
12
Ratajski, Jerzy, Adam Gilewicz, Katarzyna Mydłowska, and Łukasz Szparaga. "Inter-Relationship between Coating Micro/Nanostructure and the Tribological Performance of Zr–C Gradient Coatings." Coatings 10, no. 11 (2020): 1121. http://dx.doi.org/10.3390/coatings10111121.
Повний текст джерелаАнотація:
The research presented in this article concerns Zr–C gradient coatings that were deposited on HS6-5-2 steel by reactive magnetron sputtering from the Zr target in appropriately programmed C2H2 mass flow rate, resulting in various profiles of atomic carbon concentrations in the coating and consequently in spatial change of the properties (H, E, …) and behavior (H/E, H3/E2, We). In particular, the characteristic changes in hardness and Young’s modulus in the Zr–C coatings represented approximately by the bell curve, which has a maximum at the content of about 50 at.% C, were an inspiration to study the behavior of gradient coatings with carbon content in the range of 0–50 and 50–85 at.% with the same hardness change profile. The obtained results indicate that, firstly, the gradient of spatial changes in the coating composition increases their resistance to cohesive damage in comparison to non-gradient coatings, and, secondly, the results show that high hardness is a desired property but not sufficient to ensure adequate coating performance. Independently, an appropriate nano/microstructural structure is necessary, which determines their tribological behavior. In particular, in the case of the tested Zr–C coatings, the obtained results indicate that gradient coatings with a carbon content in the range of 50–85 at.% have better properties, characterized by the critical force Lc2, wear, coefficient of friction, H/E and H3/E2 ratios.
13
Maulet, M., Zh B. Sagdoldina, A. Çoruh, and A. B. Alibekova. "INVESTIGATION OF TRIBOLOGICAL PROPERTIES OF DETONATION Ni-Cr-Al COATINGS." Bulletin of Shakarim University. Technical Sciences 1, no. 4(16) (2024): 355–60. https://doi.org/10.53360/2788-7995-2024-4(16)-45.
Повний текст джерелаАнотація:
This study explores the tribological properties of Ni-Cr-Al coatings applied through detonation spraying technology, with a focus on the comparison between gradient coatings and homogeneous coatings. Ni-Cr-Al coatings, widely used in aerospace, automotive, and energy industries like power plants, are valued for their exceptional hardness, wear resistance, and high-temperature stability. Gradient coatings, produced by tailoring the detonation spraying parameters, exhibit a microstructure combining a hard, wear-resistant surface with a softer, ductile subsurface, enhancing their load-bearing capacity and tribological performance. Experimental results reveal that gradient coatings achieve lower and more stable friction coefficients (0.3-0.4) compared to homogeneous coatings (0,4-0,5), attributed to their optimized stress distribution and reduced adhesive interactions. These findings underscore the superior wear resistance and durability of gradient Ni-Cr-Al coatings, making them highly suitable for applications involving prolonged operation under sliding conditions. This research contributes to the development of advanced coating systems optimized for demanding operational environments.
14
Zhu, Yousheng, Biju Zheng, Chen Hua, Hezhong Pei, and Peng Song. "Influence of Gradient Index and Pores on the Properties and Internal Stress of Continuous Transition Ceramic–Metal Coating." Coatings 12, no. 5 (2022): 569. http://dx.doi.org/10.3390/coatings12050569.
Повний текст джерелаАнотація:
Thermal-sprayed ceramic coatings are widely used in industry due to their favorable mechanical properties. However, traditional ceramic coatings are prone to failure due to the differences in physical properties between the bonding coating and the ceramic coating. In order to solve this problem, a continuous transition zone was introduced between the ceramic coating and the bonding coating, then air plasma spraying was used to prepare traditional coatings and continuous transition coatings. The Vickers hardness analysis results show that the existence of the continuous transition zone made the change of hardness between the ceramic coating and the bonding coating more gradual. To understand the stress distribution inside the continuous transition coating, models were established to express the interface between ceramic and metal in the continuous transition zone. Simulation analysis found that the existence of the continuous transition zone can significantly reduce the stress gradient inside the coating, and the gradient index of the continuous transition zone also has a great influence on the stress distribution inside the coating model. SEM (Scanning Electron Microscope) analysis found many pores inside the coating; modeling the pores and simulating the influence of pores on the internal stress of the coating showed that the existence of pores inside the coating can reduce the stress gradient at the interface.
15
Zhang, Dong, Bao Ping Zhang, Zhi Ge Li, Lin Wang, Bin Liu, and Jin Qing Wang. "Biocompatibility of HAP/Ti Gradient Coating by Microarc Oxidation and Biomimetic Process." Advanced Materials Research 177 (December 2010): 325–28. http://dx.doi.org/10.4028/www.scientific.net/amr.177.325.
Повний текст джерелаАнотація:
This study is to evaluate the biocompatibility of HAP/Ti gradient coating by microarc oxidation and biomimetic process. Titanium alloys were activated by microarc oxidation (MAO), and immersed in simulated body fluid to prepare HAP/Ti gradient coating. Scanning electron microscopy (SEM) had been used to investigate the microstructure of the coatings. The biocompatibility of the coatings was evaluated by animal acute and subacute toxicity test, micronucleus test, hemolysis test, and oral mucosa test. The results showed HAP/Ti gradient coating was successfully fabricated on the substrate. The animal experiment showed the coating had not short-term toxicity, oral mucosa irritation, and micronucleus occurrence rate was 3.2 ‰ and hemolysis rate was 2.5%. The HAP/Ti gradient coating made by MAO and biomimetic process showed good bio-security and compatibility, it may be new oral implant materials.
16
Kantay, N., B. K. Rakhadilov, A. Nabioldina, and M. Paszkowski. "Influence of Detonation Spray Parameters on the Formation of Mechanical and Tribological Properties of Gradient Coatings based on Alumina." Bulletin of the Karaganda University. "Physics" Series 105, no. 1 (2022): 6–14. http://dx.doi.org/10.31489/2022ph1/6-14.
Повний текст джерелаАнотація:
Using the detonation method, the shaft was filled with a gas mixture of C2H2 /O2 from 53 to 68 % and an alumina-based gradient coating was obtained on the surface of the substrate. The microstructure of the coatings was studied by scanning electron microscopic analysis. By increasing the proportion of α-Al2O3 phase towards the surface layer of the coating by 10–15 %, a coating layer with increased strength and wear resistance was received. By X-ray structural study, changes in the α-Al2O3 lattice were studied by reducing the amount of gas filling in the barrel and the firing time from 1 s to 0.25 s. By reducing the amount of gas in the shaft from 68 to 53 % and the firing time from 1 s to 0.25 s, a compatible gradient coating with improved mechanical properties was obtained, the maximum value of microhardness of the gradient coating was 23.73 GPa. The tribological properties of the coatings were studied and showed that the value of the coefficient of friction of the gradient coating is about 50 % lower than that of other coatings, i.e. wearresistant
17
Rakhadilov, B. K., M. Maulet, D. N. Kakimzhanov, O. A. Stepanova, and G. B. Botabaeva. "Comparative study of the structure and properties of homogeneous and gradient Ni-Cr-Al coatings." Eurasian Journal of Physics and Functional Materials 6, no. 1 (2022): 47–55. http://dx.doi.org/10.32523/ejpfm.2022060105.
Повний текст джерелаАнотація:
This paper compares the structure and properties of homogeneous and gradient coatings in the Ni-Cr-Al system obtained by detonation spraying. According to X-ray analysis, only the CrNi3 phase appears in the homogeneous coating, and CrNi3 , Al, and NiAl phases appear on the gradient coating. The elements distribution graphs show that a small amount of aluminum is distributed over the depth of the homogeneous coating and in the gradient coating. The distribution of aluminum in the gradient Ni-Cr-Al coating gradually increases from the depth to the surface, and a high amount of aluminum forms in the coating surface. According to EDS analysis, a small amount of aluminium is distributed on the surface of the homogeneous coating and a large amount on the gradient coating. In the gradient coating, aluminium gradually increases from the substrate surface to the coating surface. Also, the gradient coating has a higher hardness than the homogeneous coating.
18
Maulet, M., Zh B. Sagdoldina, B. K. Rakhadilov, D. N. Kakimzhanov, and N. M. Magazov. "Influence of the content of aluminum on the structure of gradient detonation coatings based on NiCr-Al." Bulletin of the Karaganda University. "Physics" Series 107, no. 3 (2022): 18–24. http://dx.doi.org/10.31489/2022ph3/18-24.
Повний текст джерелаАнотація:
This paper studies the effects of aluminium content in the composite powder on the structure of detonation gradient coatings based on NiCr-Al. Gradient coatings were obtained by detonation spraying with a gradual stepwise decrease in the barrel filling volume with an acetylene-oxygen gas mixture from 50% to 25%. The elemental and phase composition, microstructure and surface roughness of coatings based on NiCr-Al with different aluminium content of 15%, 20%, and 30% were investigated. By varying the aluminium content in the powder composition, coatings with a gradient structure were obtained. The study results showed that the phase composition of the gradient coating strongly depends on the mass fraction of Al. In the case of an aluminium content of 30% in the composition of the composite powder, the formation of aluminium oxide was detected. It is established that under the same detonation deposition modes, the formation of the gradient structure of coatings will strongly depend on the aluminium content in the NiCr-Al composition. The study results showed that the optimal composition of the powder is NiCr – 80% and Al – 20% to obtain NiCr-Al coatings with a gradient structure.
19
Szparaga, Łukasz, Przemysław Bartosik, Adam Gilewicz, and Jerzy Ratajski. "Optimization of CrN/CrCN Gradient Coatings." Solid State Phenomena 237 (August 2015): 41–46. http://dx.doi.org/10.4028/www.scientific.net/ssp.237.41.
Повний текст джерелаАнотація:
The paper describes the optimization procedure supporting the designing process of geometry of gradient coatings basing on numerical simulation of internal stress and strain distributions in the coating and substrate. In mathematical model the gradient coating is represented by the so-called transition functions describing the change of physico-chemical parameters such as Young's modulus, Poisson's ratio, thermal expansion coefficient and the density as a function of the spatial variables. The object of optimization is system composed of a CrN/CrCN gradient coating and Cr interlayer between the CrN /CrCN coating and the steel substrate deposited on nitrided 4140 steel substrate. Decision variables are: the parameters of the of curvature of transition function , thickness of gradient coating and the thickness of the Cr interlayer. Optimization was carried out under pre-defined fixed continuous external loads and created decision criteria were the functions of the state of stress and strain in the coating and the substrate. Using the optimization procedure the sets of optimal parameters (Pareto sets) of the PVD gradient coating/nitrided substrate systems, due to the adopted decision criteria were determined. The analysis of the obtained optimal solutions (Pareto-optimal sets) was carried out using the "utopian solution method". It was also examined the technological stability of the Pareto-optimal solutions (nondominated) by analyzing the number of direct neighbors of these solutions in the decision variables space.
20
Maulet, M., M. N. Azlan, S. Bolatov, and A. Alibekova. "DURABILITY AND CORROSION BEHAVIOR OF Ni-Cr-Al DETONATION COATINGS UNDER Na2SO4/NaCl EXPOSURE." Bulletin of Shakarim University. Technical Sciences 1, no. 4(16) (2024): 389–94. https://doi.org/10.53360/2788-7995-2024-4(16)-49.
Повний текст джерелаАнотація:
This study investigates the durability and corrosion resistance of Ni-Cr-Al detonation-sprayed coatings when exposed to high-temperature environments containing molten Na₂SO₄ and NaCl. Such conditions are highly corrosive and frequently encountered in aerospace, energy, and chemical industries. Gradient and homogeneous Ni-Cr-Al coatings were compared to understand their behavior under aggressive exposure. The reveal of results those gradient coatings exhibit superior corrosion resistance due to their ability to retain protective oxides, such as Cr₂O₃, and mitigate stress-induced damage through compositional grading. In contrast, homogeneous coatings displayed significant degradation, including widespread corrosion, delamination, and the formation of sodium-based phases like NaNiO₂. XRD analysis confirmed the presence of oxidation and sulfidation products, with gradient coatings showing enhanced stability against phase transitions. These findings highlight the potential of gradient Ni-Cr-Al coatings to improve component performance in extreme conditions and provide valuable insights for optimizing coating compositions and processes to enhance operational reliability in harsh environments.
21
Makarov, A. M., T. I. Bobkova, A. F. Vasiliev, D. A. Geraschenkov, I. S. Prudnikov, and B. V. Farmakovsky. "Effect of gas phase composition on functional-gradient coatings formation by supersonic cold gas dynamic spraying." Voprosy Materialovedeniya, no. 1(93) (January 6, 2019): 65–69. http://dx.doi.org/10.22349/1994-6716-2018-93-1-65-69.
Повний текст джерелаАнотація:
The paper develops method for manufacturing wear and corrosion-resistant gradient coating. A special feature of the proposed method is the creation of chemical composition gradient due to controlled variation of the gas phase composition when applying supersonic cold gas-dynamic spraying. This ensures high adhesive strength of the composite coatings of the metal-non-metal system in combination with high micro-hardness of the peripheral layers. Such functional gradient coatings have wide practical applications.
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Kolaklieva, Lilyana, Roumen Kakanakov, D. Chaliampalias, et al. "Mechanical, Structural and Thermal Properties of Multilayered Gradient Nanocomposite Coatings." Journal of Nano Research 17 (February 2012): 193–202. http://dx.doi.org/10.4028/www.scientific.net/jnanor.17.193.
Повний текст джерелаАнотація:
Multilayered, Gradient Tialsin-Based Nanocomposite Coatings Have Been Developed and Investigated with Respect to their Applicability in the Machining Industry. the Main Coating Layer Was Composed of 5-8 Nm Tin and Aln Nanograins. the Coating Possessed Hardness as High as 40 GPA, which Allows it to Be Classified as Superhard. during Heating up to 900oC in Air in Steps of 100oC for 6 H at each Temperature, the Coating Showed Good Stability up to 700oC. Thermal Treatment over this Temperature Caused a Decrease in the Hardness to Values Characteristic for Tialn Multilayered Coatings, while the Adhesion to the Substrate Remained Steady.
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Liu, Qi Bin, and Bang Cheng Yang. "The Bioactivity of Gradient Composite Bioceramic Coating with La2O3 Fabricated by Wide Band Laser Cladding." Advanced Materials Research 668 (March 2013): 91–95. http://dx.doi.org/10.4028/www.scientific.net/amr.668.91.
Повний текст джерелаАнотація:
To improve the quality of bioceramic gradient coatings, wide band laser cladding technique was adopted to produce a kind of gradient composite bioceramic coating, which combines the good biocompatibility of HA and β-TCP with good toughness and strength of TC4 alloy. The rare earths oxide La2O3 was added to improve the properties of the bioceramic coating. The results indicate that when the adding of La2O3 is 0.6wt%, the ceramics coating is of the largest amount of HA and β-TCP catalyzed, and the number of cells proliferated and the ALP secreted on coatings is the biggest, which indicates that the biocompatibility and bioactivity of gradient bioceramic coating is the best. The biocompatibility and bioactivity are closely related to the amount of HA and β-TCP catalyzed by La2O3.
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Gou, Li, Ji Lei Zhu, Jun Guo Ran, and Suang Feng Yan. "Diamond Coated on Cobalt-Deficient Gradient Tungsten Carbide." Key Engineering Materials 280-283 (February 2007): 1889–92. http://dx.doi.org/10.4028/www.scientific.net/kem.280-283.1889.
Повний текст джерелаАнотація:
In order to improve the adhesion between diamond coatings and cemented tungsten carbide (WC-Co) substrates, the diamond coatings were deposited on one kind of cobalt-deficient gradient WC-Co by the microwave plasma chemical vapor deposition (MPCVD). Scanning electron microscopy, X-ray diffraction and Raman spectroscopy were used to characterize the diamond coatings. The results showed dense, well facet diamond coatings. The cobalt content at the surface of substrate was measured by electron probe microanalysis. It was found that Co did not largely move to the surface as usual with deposition time increasing compared with the conventional tungsten carbide; The cobalt content at the surface of substrate after deposition (about 1 wt %) was lower than before (3.42wt%), which improved diamond coating’s adhesion against the tungsten carbide substrate.
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Xi, Yuntao, Lin Wan, Jungang Hou, et al. "Improvement of Erosion-Corrosion Behavior of AISI 420 Stainless Steel by Ion-Assisted Deposition ZrN Coatings." Metals 11, no. 11 (2021): 1811. http://dx.doi.org/10.3390/met11111811.
Повний текст джерелаАнотація:
In this paper, a pragmatic technique has been developed to evaluate the erosion-corrosion behavior of three kinds of ZrN coatings (i.e., monolayer, multilayer, and gradient layers) which were deposited on AISI 420 martensitic stainless steel using an ion-assisted deposition technology. Among them, the monolayer coating refers to the coating with no change in composition and structure, the multilayer coating refers to the coating with alternating change of Zr/ZrN, and the gradient coating refers to the ZrN coating by increasing N2 partial pressure gradually. The morphology, composition, and microhardness of these ZrN coatings were examined by means of integrating the scanning electron microscopy (SEM), X-ray diffraction (XRD), and Knoop hardness measurements, while anodic polarization tests and salt fog spray tests in a simulated industrial environment have been performed to evaluate and identify the corrosion mechanisms of these coatings. The surface microhardness and corrosion resistance of the AISI420 martensitic stainless steel is found to be significantly improved by depositing the ion-assisted deposition ZrN coatings. The study indicates that the erosion-corrosion behavior in the slurry is the result of the synergistic effect of small-angle erosion and acid solution corrosion. Three ZrN coatings hinder the slurry erosion-corrosion behavior from two aspects (i.e., erosion resistance of small-angle particles as well as corrosion resistance of the substrate), thereby significantly improving the erosion-corrosion resistance of AISI 420 stainless steel. In addition, the ZrN gradient coatings show a much better erosion-corrosion resistance than that of the monolayer/multilayer ZrN coating because they have excellent crack resistance, bearing capacity, and electrochemical performance.
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Rakhadilov, Bauyrzhan, Meruyert Maulet, Madi Abilev, Zhuldyz Sagdoldina, and Rauan Kozhanova. "Structure and Tribological Properties of Ni–Cr–Al-Based Gradient Coating Prepared by Detonation Spraying." Coatings 11, no. 2 (2021): 218. http://dx.doi.org/10.3390/coatings11020218.
Повний текст джерелаАнотація:
In this paper, Ni–Cr–Al coatings were deposited using the detonation spraying method. The aim was to investigate how technological parameters influence coating structure formation, phase composition and tribological performances. We observed that the degree to which the barrel is filled with an O2/C2H2 gas mixture strongly influences the chemical composition of manufactured coatings. High degrees of barrel filling led to a decrease in aluminum content in the coating. Filling degrees of 40% and 50% produced sprayed coatings in which only Ni–Cr phases could be found. When the filling degree was reduced up to 25%, Ni–Al phases began to form in the sprayed coatings. Gradient Ni–Cr–Al coatings were produced by gradually reducing the filling degree from 50% to 25%. These coatings are characterized by Ni–Cr near the substrate level with Ni–Cr and Ni–Al phases at higher levels. The results obtained confirm that gradient Ni–Cr–Al coatings exhibit high hardness as well as good wear resistance.
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Fang, Ming Hao, Yan Gai Liu, and Zhao Hui Huang. "Microstructure and Corrosion Behaviour of Ni/Al-Al2O3 Gradient Ceramic Coatings on Q235 Steel." Key Engineering Materials 336-338 (April 2007): 2647–48. http://dx.doi.org/10.4028/www.scientific.net/kem.336-338.2647.
Повний текст джерелаАнотація:
Ni/Al-Al2O3 gradient ceramic coating was prepared on Q235 steel by plasma spraying. Microstructure and corrosion behavior in boiling 5%HCl solution of the samples sprayed with this coating were investigated. The results showed that thickness of Al2O3 ceramic coating was increased greatly and almost no connected pores formed in the gradient coating due to the existent of Ni/Al-Al2O3 transition interlayer coatings. The corrosion resistance of Q235 steel with Ni/Al-Al2O3 gradient composite ceramic coating in boiling 5%HCl solution was greatly improved.
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Wang, Yu, Qi Liu, Quansheng Zheng, Tianqing Li, Nanjing Chong, and Yu Bai. "Bonding and Thermal-Mechanical Property of Gradient NiCoCrAlY/YSZ Thermal Barrier Coatings with Millimeter Level Thickness." Coatings 11, no. 5 (2021): 600. http://dx.doi.org/10.3390/coatings11050600.
Повний текст джерелаАнотація:
The thermal insulation properties of thermal barrier coatings (TBCs) can be significantly improved with increasing the coating thickness. However, due to the weak bonding of high-thickness TBCs, the low reliability and short lifetime greatly limits their application under some severe operating conditions. In this study, a novel and high-efficiency synchronous dual powder feeding method is used to deposit a series of gradient NiCoCrAlY/YSZ coatings with millimeter level thickness. The tensile bonding strengths and residual stress state of coatings are evaluated in order to explore the effect of thickness on the bonding strength of coatings. The results suggested that, due to some micro-convex structure at the “GC/TC” interface and inside “GC” layer, the bonding strength of 1000-μm-thickness gradient NiCoCrAlY/YSZ TBCs with the 4:6 and 2:8 hybrid ratios is over 44 MPa compared to the common TBCs. The fracture position gradually shifts from NiCoCrAlY bond coat to NiCoCrAlY/YSZ transition zone and finally to the YSZ top coat owing to the different position of residual stress concentrations. After thermal cycling tests, the 1000-μm-thickness gradient coating exhibits a higher thermal cycling life. Some coarse cracks initiate and propagate at the bottom region of TBCs, which is mainly due to thermal expansion mismatch stress that finally results in the failure of the gradient coating between the “BC” layer and the substrate.
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Rakhadilov, Bauyrzhan, Dauir Kakimzhanov, Merkhat Dautbekov, Zhuldyz Sagdoldina, Meruyert Adylkanova, and Riza Abylkalykova. "Influence of Spraying Parameters on the Structure and Tribological Properties of Cr3C2-NiCr Detonation Coatings." Advances in Tribology 2023 (March 31, 2023): 1–9. http://dx.doi.org/10.1155/2023/6684656.
Повний текст джерелаАнотація:
In this work, the influence of spray parameters on the formation of the microstructure, phase composition, and the tribological properties of detonation flame sprayed coatings was studied. It was determined that the chemical composition of Cr3C2-NiCr coatings during detonation spraying depends on the degree of filling the barrel with an explosive gas mixture. The degree of filling the barrel with an explosive gas mixture at 73% leads to a decrease in the content of carbide phases, and at 57% filling of the barrel, an increase in carbide phases is observed. It is established that the decrease of the filling degree leads to the increase of hardness and wear resistance of the Cr3C2-NiCr coatings since the hardness and wear resistance of the coating material deposited at 57% is higher than at 65% and 73%; this is due to the increase in the carbide phase Cr3C2. Detonation flame sprayed Cr3C2-NiCr gradient coatings have been developed in this study, which is carried out by varying the spray parameters. It was found that in the gradient coating, Cr3C2-NiCr carbide phases gradually increase from the depth to the surface. The obtained gradient coating closer to the substrate consists of the CrNi3 phase, while the coating surface consists of CrNi3 and Cr3C2 phases.
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Zhou, Li Ming, Wei Gong, and En Ze Wang. "Analysis on the Residual Stresses in Functionally Gradient Fe360/Glass-Ceramic Coatings." Advanced Materials Research 717 (July 2013): 215–20. http://dx.doi.org/10.4028/www.scientific.net/amr.717.215.
Повний текст джерелаАнотація:
A novel functionally gradient composite was reported in this article. The composite material are composed of plain low carbon steel Fe360 as a substrate and glass-ceramics containing ZrO2 reinforcing particles as a coating. Based on a mathematical model of the residual stress, the geometric model and finite element analysis models of the Fe360/glass-ceramic gradient coatings were established. The residual stress of the gradient layers was calculated with the commercial software ANSYS 10.0. The results showed that the differences of thermal expansion coefficient and shrinkage rate in each layer resulting from the difference of the volume fraction of ZrO2 in each gradient layer could make the surface layer generate suitable compressive stress. The maximum residual stress presents itself at the interface between the substrate and the gradient coatings. The layer numbers and the thickness of graded coatings have a significant effect on the residual stress.
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Rakhadilov, B. K., A. B. Nugumanova, P. Kowalewski, M. K. Kylyshkanov, L. B. Bayatanova, and D. N. Kakimzhanov. "Obtaining functional gradient coatings based on Al2O3 by detonation spraying." Bulletin of the Karaganda University. "Physics" Series 100, no. 4 (2020): 22–27. http://dx.doi.org/10.31489/2020ph4/22-27.
Повний текст джерелаАнотація:
The article deals with the phase composition and hardness of Al2O3 coatings obtained by detonation spraying. It was found that a decrease in the delay time between shots is leading to an increase in the hardness and elastic module of Al2O3 coatings. It was found based on X-ray diffraction analysis that the main reason for the increase in hardness with a decreasing in the delay time between shots is associated with increases in the volume fraction of α- Al2O3 phase. A high content of the more ductile γ-Al2O3 phase at the substrate-coating interface leads to an increase in adhesion characteristics, and a high content of the α-Al2O3 phase on the coating surface provides high hardness and wear resistance. The studies of X-ray diffraction presented that the highest phase content is achieved when the coatings are formed with a delay time between shots of 0.25 s. It was found that increase in the volume fraction of the α-Al2O3 phase is caused by the secondary recrystallization γ → α, which occurs due to the heating of particles during coating formation, i.e. due to increase in temperature above 1100 ºС in single spots of the coating when they are put each other
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Buitkenov, Dastan, Aiym Nabioldina, and Nurmakhanbet Raisov. "Development of Method for Applying Multilayer Gradient Thermal Protective Coatings Using Detonation Spraying." Coatings 14, no. 7 (2024): 899. http://dx.doi.org/10.3390/coatings14070899.
Повний текст джерелаАнотація:
In this work, multilayer gradient coatings obtained by detonation spraying were studied. To obtain a multilayer gradient coating by detonation spraying, two modes with different numbers of shots of NiCrAlY and YSZ were developed. The presented results demonstrate the effectiveness of creating a gradient structure in coatings, ensuring a smooth transition from metal to ceramic materials. Morphological analysis of the coatings confirmed a layered gradient structure, consisting of a lower metallic (NiCrAlY) layer and an upper ceramic (YSZ) layer. The variation in the contents of elements along the thickness of the coatings indicates the formation of a gradient structure. X-ray analysis shows that all peaks in the X-ray diffraction patterns correspond to a single ZrO2 phase, indicating the formation of a non-transformable tetragonal primary (t′) phase characteristic of the thermal protective coatings. This phase is known for its stability and resistance to phase transformation under changing operating temperature conditions. As the thickness of the coatings increased, an improvement in their mechanical characteristics was found, such as a decrease in the coefficient of friction, an increase in hardness, and an increase in surface roughness. These properties make such coatings more resistant to mechanical wear, especially under sliding conditions, which confirms their prospects for use in a variety of engineering applications, including aerospace and power generation.
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Ren, Yuxin, Zhaolu Zhang, Guangyu He, Yan Chai, Yanli Zhang, and Zilei Zhang. "Erosion Performance of TiN/Ti Coatings under Different Nitrogen Flow Rates." Coatings 14, no. 9 (2024): 1144. http://dx.doi.org/10.3390/coatings14091144.
Повний текст джерелаАнотація:
This study employed magnetic filtered cathodic vacuum arc deposition to fabricate TiN/Ti multilayer coatings, examining the impact of nitrogen flow rates—4, 8, 12, and 16 sccm—on their performance, with an emphasis on gradient flow rates from 4 to 12 sccm. The coatings’ phase composition shifted from TiN0.26 to a Ti2N and TiN composite, optimizing the microstructure and significantly increasing the hardness to 24.37 GPa and the elastic modulus to 219.84 GPa at the 16 sccm rate. The surface roughness reduction further improved erosion resistance. Coatings made under gradient flow exhibited reduced mass loss and an erosion rate of 0.07 mg·g−1, outperforming single flow rates. Erosion failure analysis highlighted that while 12 sccm coatings failed due to extensive crack interconnection, 16 sccm coatings showed spalling from crack expansion. Gradient flow coatings, despite the presence of a crack, demonstrated a more confined damage area and enhanced erosion resistance, indicating the benefits of varied nitrogen flow rates in coating optimization.
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Tu, Rong, Jiao Jiao, Mingquan Jiang, et al. "Effect of Gradient Multilayer Design on Tribological Performance of TiN/TiSiN Coatings Prepared by Cathodic Arc Ion Plating." Coatings 13, no. 5 (2023): 836. http://dx.doi.org/10.3390/coatings13050836.
Повний текст джерелаАнотація:
Hard coatings, such as transition metal nitrides, have been widely applied to improve the mechanical properties and tribological performance of cutting tools. The coatings in various multilayered or gradient structures have been designed to meet the demands of more severe service environments and more precise processing requirements. In this work, TiN/TiSiN coatings in several gradient and multilayered structures were deposited on cemented carbides by cathodic arc ion plating using Ti and TiSi alloy targets. The modulation period (Λ) of the multilayer gradually varies with thickness, ranging from 6 to 46 nm. The gradient multilayer coatings consist of a nanocrystalline-amorphous composite with compact growth. The coating with a modulation period first increasing and then decreasing has the highest hardness of 38 GPa, and the maximum residual compressive stress of −2.71 GPa, as well as the minimum coefficient of friction (COF) and wear rate. Gradient and multilayer structures moderate the brittleness caused by the presence of amorphous SiNx phase and optimize the mechanical properties and tribological performances of the coatings.
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Szparaga, Łukasz, Piotr Myśliński, Adam Gilewicz, and Jerzy Ratajski. "Investigations on the Thermo-Mechanical Properties of CrN/CrCN Gradient Coatings Using a Thermo-Dilatometric Method." Solid State Phenomena 223 (November 2014): 100–109. http://dx.doi.org/10.4028/www.scientific.net/ssp.223.100.
Повний текст джерелаАнотація:
The paper describes issues related to the use of dilatometric methods for the study of thermo-mechanical properties of PVD gradient coatings. Tests were conducted on three types of CrCN / CrN coatings, which differed in the nature of the change of physico-chemical parameters in the gradient transition layer, deposited on a molybdenum substrate with the use of the cathodic arc evaporation method. The scope of the experimental studies included an analysis of the changes of the thermal “extortion” of the substrate – PVD coating system during annealing processes. In parallel, for comparison purposes, a mathematical description was proposed of gradient coatings containing the transition functions of material parameters. These functions describe the changes of such parameters as the Young's modulus, the Poisson's ratio, the thermal expansion coefficient, and the density as a function of spatial variables. Using the mathematical description proposed, numerical calculations of the state of thermal stress and strain for coatings are represented, respectively, by the transition function forms (a stepped, square, and square root) were carried via FEM. Based on the experimental and computational results obtained, the comparison between the elongation of the tested samples, and the state of thermal stress and strain in the substrate-gradient coating systems analysed were all specified.
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Yoo, Sungju, Eunpyo Hong, Youngkue Choi та Heesoo Lee. "Internal Stress of Titanium-Based Nitride with Penetration Depth and Surface Roughness by sin2ψ Method Using HR-XRD". Nanomaterials 15, № 11 (2025): 813. https://doi.org/10.3390/nano15110813.
Повний текст джерелаАнотація:
The test method for internal stress of titanium-based nitride was optimized via penetration depth and surface roughness. Through the test method, the variations in the mechanical properties due to the ratio of the carbon gradient layer were investigated in terms of internal stress. TiN coatings were deposited on SUS 304 using RF/DC magnetron sputtering, and the penetration depth was adjusted by varying the X-ray power of HR-XRD for test specimens with the same coating thickness of 1 μm. The gradient of diagram for internal stress remained constant regardless of the penetration depth, and this was attributed to the analysis of internal stress focusing on the preferred growth orientation of the coating and excluding the influence of the substrate. In addition, we tested different surface roughness values (0.01 Sa, 0.02 Sa, and 0.03 Sa) to observe the effect on internal stress measurement. The results showed negligible difference in internal stress, confirming that this measurement method is valid for coatings with a surface roughness of 0.03 Sa or less. The test method was applied to analyze the carbon-doped TiZrN coating. TiZrN coatings were deposited on SUS 304, and coating thicknesses of 0.5 μm, 1 μm, and 2 μm were used to control the ratio of the carbon gradient layer. After applying the carbon paste for carbon doping, the TiZrN coating was irradiated with a pulsed laser. The compressive internal stress increased from −1263 MPa to −1687 MPa at a coating thickness of 0.5 μm, where the ratio of the carbon gradient layer was the highest. It was confirmed that the increase in internal stress with the ratio of the carbon gradient layer improved the mechanical properties of the carbon-doped TiZrN coating by laser carburization.
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Liu, Qi Bin, and Bang Cheng Yang. "Mechanical Properties on Gradient Bioceramic Composite Coating Produced by Wide-Band Laser Cladding." Key Engineering Materials 342-343 (July 2007): 681–84. http://dx.doi.org/10.4028/www.scientific.net/kem.342-343.681.
Повний текст джерелаАнотація:
To eliminate thermal stress during laser cladding and to raise the bonding strength between substrate and coating, composition gradient coatings are designed and fabricated by using wideband laser cladding technique on a Ti alloy. And mechanical properties on coating is studied. The experimental results indicate that the bonding strength between coating and substrate is fairly high, above 38.8MPa. The highest microhardness is obtained for coating containing 0.6wt.% Y2O3 1062HV0.1 and 1405HV0.1, respectively at bioceramic coating and alloyed transition layer. The average tensile strength, bending strength, and elastic modules of coatings are 767.83MPa, 1671.65MPa, and 13.98GPa, respectively.
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Kunioshi, Clarice Terui, Olandir Vercino Correa, and Lalgudi Venkataraman Ramanathan. "Gradient Nickel – Alumina Composite Coatings." Materials Science Forum 530-531 (November 2006): 261–68. http://dx.doi.org/10.4028/www.scientific.net/msf.530-531.261.
Повний текст джерелаАнотація:
Particle reinforced metal matrix composite (MMC) coatings have been developed due to property combinations such as increased hardness, high creep/fatigue resistance as well as superior wear and oxidation resistance. MMC coatings can be produced by various techniques, which include powder metallurgy (plasma spray and HVOF processes), liquid metal processes and electrodeposition. This paper presents the development of the electrodeposition process to obtain nickel-alumina composites. The process conditions were optimized and based on these gradient nickel-alumina composites were prepared. Microstructural characterization and hardness determinations were carried out. The effect of process parameters on the amount and distribution of alumina particles as well as morphology of the deposits with and without alumina gradients are presented and discussed.
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Liu, Fei, Hejun Li, Qiangang Fu, Xinhai He, and Wei Zhang. "ZrSi2-SiC/SiC Gradient Coating of Micro-Structure and Anti-Oxidation Property on C/C Composites Prepared by SAPS." Coatings 12, no. 10 (2022): 1377. http://dx.doi.org/10.3390/coatings12101377.
Повний текст джерелаАнотація:
A ZrSi2-SiC/SiC gradient coating system was designed to reduce the thermal stress of anti-oxidation coatings for C/C composites and prolong their anti-oxidation time at a high temperature. The SiC transition layer was prepared by pack cementation and the gradient ZrSi2-SiC outer coatings with different ZrSi2 contents added were deposited by supersonic air plasma spraying (SAPS). The micro-morphologies and phase compositions of the coatings were studied by SEM, EDS, XRD, and TG/DSC, and their anti-oxidation performances were tested by a static oxidation experiment. The findings suggested that the gradient coating with 30 wt.% ZrSi2 content displayed the optimum and dense microstructure without obvious pores and microcracks, compared with the other three proportional coatings. During the oxidation test, because of the oxidation reaction of ZrSi2 and SiC phases, a large amount of silica was formed in the coating to fill the pores and microcracks and densify the coating further. Oxidation products ZrO2 and ZrSiO4, having a high melting point and outstanding anti-oxidation property, were embedded in the SiO2 glass layer to reduce the layer volatilization rate and improve the ability to block oxygen. Therefore, the specimen with 30 wt.% ZrSi2 still kept mass gain after 188 h oxidation time at 1500 °C. However, when the oxidation time was increased to 198 h, it had a mass loss of 0.1%, because the coating compactness was destroyed by the escape of the oxidation gases.
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Wang, Jiang Ting, Peter D. Hodgson, Jing De Zhang, and Chun Hui Yang. "Residual Thermal Stresses in a Fe3Al/Al2O3 Gradient Coating System." Advanced Materials Research 32 (February 2008): 71–74. http://dx.doi.org/10.4028/www.scientific.net/amr.32.71.
Повний текст джерелаАнотація:
To combine the merits of both metals and ceramics into one material, many researchers have been studying the deposition of alumina coating using plasma spray on metal substrates. However, as the coatings are deposited at a high temperature, residual thermal stresses develop due to the mismatch of thermal expansion coefficients of the coating and substrate and these are responsible for the initiation and expansion of cracks, which induce the possible failure of the entire material. In this paper, the residual thermal-structural analysis of a Fe3Al/Al2O3 gradient coating on carbon steel substrate is performed using finite element modelling to simulate the plasma spray. The residual thermal stress fields are obtained and analyzed on the basis of temperature fields in gradient coatings during fabrication. The distribution of residual thermal stresses including radial, axial and shear stresses shows stress concentration at the interface between the coatings and substrate. The mismatch between steel substrate and composite coating is still the dominant factor for the residual stresses.
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Ning, Cheng Yun, Ying Jun Wang, W. W. Lu, Xiao Feng Chen, Gang Wu, and Na Ru Zhao. "Microstructure and Mechanical Performances of Plasma-Sprayed Functionally Gradient HA-ZrO2-Bioglass Coatings." Key Engineering Materials 280-283 (February 2007): 1893–98. http://dx.doi.org/10.4028/www.scientific.net/kem.280-283.1893.
Повний текст джерелаАнотація:
For practical applications such as artifical joints and dental implants, there is a strong demand for hydroxyapatite coatings with excellent performances to ensure long-term fixation. In the present study, functionally gradient HA-ZrO2-Bioglass coatings were prepared using net-energy controlled plasma spraying technology. The structural characteristics andmechanical performances of the coatings were examined by scanning electron microscopy (SEM), X-ray diffraction (XRD) and nanoindentation. The results showed that: (1) Pore sizes and compositions of the coatings changed gradually along the vertical substrate, crystal HA with few calcium phosphates was presented in the heat-treated coatings. (2) Surface of the coating was very rough with nano-sized crystalline grains and micropores; (3) Young’s modulus and hardness changed gradually at the range of coating-Ti6Alo4V interface. Compared with HA coatings, the tensile adhesive strength of the functionally graded HA-ZrO2-Bioglass coatings reached 38.6 MPa, much higher than that of single HA coatings.
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Chu, Xi, Shu-sen Hu, and Zhen Dai. "High temperature chlorine corrosion resistance of gradient high entropy alloy coatings prepared by high-velocity-oxygen-fuel spraying." Journal of Physics: Conference Series 2713, no. 1 (2024): 012024. http://dx.doi.org/10.1088/1742-6596/2713/1/012024.
Повний текст джерелаАнотація:
Abstract The effect of different gradient structures on the high temperature chlorine corrosion resistance of gradient high entropy alloy coating was studied to improve the service life of the heating surface of a waste-incinerated boiler. NiCrAl ceramic composite coating (NC), high entropy ceramic composite coating (HC), and gradient high entropy alloy coating (TC) were prepared on 12Cr1MoV substrate by high-velocity-oxygen-fuel spraying. The effects of morphology and microstructure of different coatings on thermal shock resistance and high temperature chlorine corrosion resistance were studied. The results indicate that the porosity of NC coating, HC coating, and TC coating decreased in turn. In the thermal shock resistance test from 800°C to room temperature, the average number of thermal shock of TC coating can reach 21. The mass change of TC coating in 650°C high temperature Cl corrosion resistance test is less than 30 mg/cm2 after 50 hours. In summary, the gradient high entropy alloy coating with HEA as the metal bonding phase can improve the density of thermal spraying gradient coating, and enhance the thermal shock resistance and high temperature Cl corrosion resistance of the coating. Based on the comprehensive on-site application results, it can be concluded that the use of high velocity oxygen flame gradient high entropy alloy coating can effectively improve the density, thermal shock resistance, and high temperature Cl corrosion resistance of the thermal spraying gradient coating on the heating surface of the boiler, and has broad application prospects.
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Buitkenov, Dastan, Bauyrzhan Rakhadilov, Aiym Nabioldina, Yerkat Mukazhanov, Meruert Adilkanova, and Nurmakhanbet Raisov. "Investigation of Structural Phase, Mechanical, and Tribological Characteristics of Layer Gradient Heat-Protective Coatings Obtained by the Detonation Spraying Method." Materials 17, no. 21 (2024): 5253. http://dx.doi.org/10.3390/ma17215253.
Повний текст джерелаАнотація:
This paper presents the results of a study of layer gradient thermal protection coatings based on NiCrAlY and YSZ obtained by detonation spraying. Modern gas turbines and high-temperature units operate under extreme temperatures and aggressive environments, which requires effective protection of components from wear, corrosion, and thermal shocks. In this study, the use of layer gradient coatings consisting of alternating layers of NiCrAlY and YSZ was investigated with the aim of solving the problem of thermal stress accumulation due to a smooth change in the composition of the layers. Microstructural and phase analysis showed that alternating layers of NiCrAlY and YSZ formed a dense layer gradient structure with clear interphase boundaries and low porosity. Detonation spraying led to a complete transformation of the monoclinic ZrO2 phase into a tetragonal one, which significantly increased the mechanical strength of the coating and its resistance to thermal shocks. Sample 1D1 demonstrated excellent tribological and corrosion properties in a 3.5% NaCl solution, which can be explained by its higher density and reduced number of pores. Mechanical tests revealed stable values of hardness and wear resistance of the coating, especially for the 1D1 coating. Studies have shown that coatings are resistant to thermal shocks, but thicker layers show a tendency to peel off after thermal cycling. The obtained results indicate high prospects for the use of layer gradient coatings based on NiCrAlY and YSZ for the protection of gas turbine components and other high-temperature installations operating under extreme loads and aggressive environments.
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Bobkova, T. I., A. F. Vasiliev, I. S. Prudnikov, and B. V. Farmakovsky. "Functional gradient coatings obtained by supersonic cold gas dynamic spraying." Voprosy Materialovedeniya, no. 1(97) (August 10, 2019): 74–78. http://dx.doi.org/10.22349/1994-6716-2019-97-1-74-78.
Повний текст джерелаАнотація:
The paper studies the development of a technology for obtaining a wear-resistant functional gradient coating during supersonic cold gas dynamic spraying. The process goes due to the variation of the composition of the gas phase in a heterophase flow. The coating has a high microhardness (up to 12 GPa) on the peripheral layers and wear resistance is 3 times higher than that of coatings obtained by traditional technology.
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Tian, Tian, Bo Dang, Feng Ding, et al. "Study on the ZrN/Ag2O Micro–Nano Gradient Composite Structure Constructed on Pure Ti for Biomaterials." Coatings 11, no. 6 (2021): 677. http://dx.doi.org/10.3390/coatings11060677.
Повний текст джерелаАнотація:
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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Huo, Yan Li, Yu Feng Chen, Jie Tang, Hai Lin Liu, and Chun Peng Wang. "Fabrication of Multiple Oxidation-Resistant Coating on C/SiC Matrix." Advanced Materials Research 105-106 (April 2010): 406–8. http://dx.doi.org/10.4028/www.scientific.net/amr.105-106.406.
Повний текст джерелаАнотація:
Oxidation-resistant coatings with gradient structures on C/SiC composites were fabricated. The gradient oxidation-resistant coatings were composed of three layers. The inner layer was reaction-bonded SiC which was fabricated by silicon infiltration. The middle layer was dense CVD SiC with the gradient component which was produced by the pyrolysis of methyltrichlorosilan (MTS) in excess hydrogen. The outer layer was a sealed layer with B4C and MoSi2 powders which was fabricated by slurry process. Optical microscope and SEM were used to observe the cross-section morphology and microstructure of coatings. XRD and EDS were used to characterize the phase composition and component distribution of coatings. EDS analysis showed the component distribution of CVD SiC coating changed significantly with the change of ratio of MTS to H2. The result indicated that C/SiC composite had good oxidation resistance when it was used at high temperature in the environment of high-speed combustion gas.
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Zhang, Yu, Zhanqi Cheng, and Hu Feng. "Dynamic Fracture Analysis of Functional Gradient Material Coating Based on the Peridynamic Method." Coatings 9, no. 1 (2019): 62. http://dx.doi.org/10.3390/coatings9010062.
Повний текст джерелаАнотація:
Functional gradient materials (FGMs) have tremendous potential due to their characteristic advantage of asymptotic continuous variation of their properties. When an FGM is used as a coating material, damage and failure of the interface with the substrate component can be effectively inhibited. In order to study the dynamic crack propagation in FGM coatings, a new method, peridynamics (PD), was used in the present study to simulate dynamic fractures of FGM coatings bonded to a homogeneous substrate under dynamic loading. The bond-based PD theory was employed to study crack propagation and branching in the FGM coating. The influences of the coating gradient pattern, loading, and the geometry and size of the structure on crack curving and propagation under impact loading were investigated. The numerical results show that different forms of the elastic modulus of graded material, the geometry of the structure, and the loading conditions have considerate effects on crack propagation in FGM coatings, but a specific form of elastic modulus had a limited effect on the dynamic fracture of FGM coating.
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Baronins, Janis, Vitali Podgursky, Maksim Antonov, Sergei Bereznev, and Irina Hussainova. "Electrochemical Behaviour of TiCN and TiAlN Gradient Coatings Prepared by Lateral Rotating Cathode Arc PVD Technology." Key Engineering Materials 721 (December 2016): 414–18. http://dx.doi.org/10.4028/www.scientific.net/kem.721.414.
Повний текст джерелаАнотація:
TiCN and TiAlN gradient coatings were deposited on the AISI 316L stainless steel substrates by lateral rotating cathode arc (LARC) physical vapour deposition (PVD) technology. Corrosion and tribocorrosion behaviour was studied in 3.5 wt. % NaCl solution. The thickness of coatings was about 3 μm. For both coatings the corrosion potential shifted to more positive values as compared to the uncoated substrate. The corrosion current density decreased for TiCN and TiAlN coatings indicating up to 40 folds higher polarization resistance. The coefficient of friction value of TiCN coating is three times lower and durability is six times higher than that of TiAlN coating under the same tribocorrosion conditions.
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Żukowska, L. W., A. Śliwa, J. Mikuła, et al. "Finite Element Prediction for the Internal Stresses of (Ti,Al)N Coatings." Archives of Metallurgy and Materials 61, no. 1 (2016): 149–52. http://dx.doi.org/10.1515/amm-2016-0027.
Повний текст джерелаАнотація:
The general topic of this paper is the computer simulation with use of finite element method (FEM) for determining the internal stresses of selected gradient and single-layer PVD coatings deposited on the sintered tool materials, including cemented carbides, cermets and Al2O3+TiC type oxide tool ceramics by cathodic arc evaporation CAE-PVD method. Developing an appropriate model allows the prediction of properties of PVD coatings, which are also the criterion of their selection for specific items, based on the parameters of technological processes. In addition, developed model can to a large extent eliminate the need for expensive and time-consuming experimental studies for the computer simulation. Developed models of internal stresses were performed with use of finite element method in ANSYS environment. The experimental values of stresses were calculated using the X-ray sin2ψ technique. The computer simulation results were compared with the experimental results. Microhardness and adhesion as well as wear range were measured to investigate the influence of stress distribution on the mechanical and functional properties of coatings. It was stated that occurrence of compressive stresses on the surface of gradient coating has advantageous influence on their mechanical properties, especially on microhardness. Absolute value reduction of internal stresses in the connection zone in case of the gradient coatings takes profitably effects on improvement the adhesion of coatings. It can be one of the most important reasons of increase the wear resistance of gradient coatings in comparison to single-layer coatings.
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Meng, Xiang Cai, Xing Yi Li, and Tao Wang. "Effect of Electrodeposited Hydroxyapatite Coatings on Biomedical Titanium by Cathode Revolving." Key Engineering Materials 280-283 (February 2007): 1525–28. http://dx.doi.org/10.4028/www.scientific.net/kem.280-283.1525.
Повний текст джерелаАнотація:
The paper deals with a kind of new method of the electro-deposition on titanium by a cathode revolves. The depositing characteristic and mechanic were studied by scanning electron microscopy and X-ray diffraction. The experimental results show that the more fine uniformity and compact calcium phosphate bioactive coatings could be produced, compared with the conventional methods. The gradient Coating, which is fine inside and porous outside, could be obtained by controlling revolving velocity. The coating would transform to the hydroxyapatite after heat-treatment. After soaking in a simulated body fluid (SBF), nano-depositions were formed on the surface of the coating, then those particles would grow up needle-like, net-like, and an apatite-like layer could be observed finally. The gradient porosity coatings produced by cathode revolving electrochemical deposition would have high anti-dissolution and bioactive.