Journal articles: 'HVOF SPRAYED'

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Ishikawa, Yasunari, Jin Kawakita, and Seiji Kuroda. "Development of Corrosion and Wear Resistant Coatings by an Improved HVOF Spraying Process." Materials Science Forum 475-479 (January 2005): 237–40. http://dx.doi.org/10.4028/www.scientific.net/msf.475-479.237.

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We have developed an improved HVOF spray process called “Gas-shrouded HVOF” (GS-HVOF) over the past several years. By using an extension nozzle at the exit of a commercial HVOF spray gun, GS-HVOF is capable of controlling the oxidation of sprayed materials during flight as well as achieving higher velocity of sprayed particles. These features result in extremely dense and clean microstructure of the sprayed coatings. The process has been successfully applied to corrosion resistant alloys such as SUS316L, Hastelloy C, and alloy 625 as well as cermets such as WC-Cr3C2-Ni. The spray process, coatings microstructure and property evaluation will be discussed with potential industrial applications in the near future.

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Itoh, Y., M. Saitoh, and M. Tamura. "Characteristics of MCrAlY Coatings Sprayed by High Velocity Oxygen-Fuel Spraying System." Journal of Engineering for Gas Turbines and Power 122, no. 1 (July 30, 1999): 43–49. http://dx.doi.org/10.1115/1.483173.

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High velocity oxygen-fuel (HVOF) spraying system in open air has been established for producing the coatings that are extremely clean and dense. It is thought that the HVOF sprayed MCrAlY (M is Fe, Ni and/or Co) coatings can be applied to provide resistance against oxidation and corrosion to the hot parts of gas turbines. Also, it is well known that the thicker coatings can be sprayed in comparison with any other thermal spraying systems due to improved residual stresses. However, thermal and mechanical properties of HVOF coatings have not been clarified. Especially, the characteristics of residual stress, that are the most important property from the view point of production technique, have not been made clear. In this paper, the mechanical properties of HVOF sprayed MCrAlY coatings were measured in both the case of as-sprayed and heat-treated coatings in comparison with a vacuum plasma sprayed MCrAlY coatings. It was confirmed that the mechanical properties of HVOF sprayed MCrAlY coatings could be improved by a diffusion heat treatment to equate the vacuum plasma sprayed MCrAlY coatings. Also, the residual stress characteristics were analyzed using a deflection measurement technique and a X-ray technique. The residual stress of HVOF coating was reduced by the shot-peening effect comparable to that of a plasma spray system in open air. This phenomena could be explained by the reason that the HVOF sprayed MCrAlY coating was built up by poorly melted particles. [S0742-4795(00)00701-8]

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Torkashvand, Kaveh, Shrikant Joshi, and Mohit Gupta. "Advances in Thermally Sprayed WC-Based Wear-Resistant Coatings: Co-free Binders, Processing Routes and Tribological Behavior." Journal of Thermal Spray Technology 31, no. 3 (February 2022): 342–77. http://dx.doi.org/10.1007/s11666-022-01358-4.

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AbstractA growing understanding of wear behavior of various thermally sprayed ceramic–metallic matrix coatings has occurred over recent years. This has resulted from the continuous evolution in spraying methods as well as material feedstock, and the corresponding new aspects of the field that have been thoroughly explored. This paper aims to review recent developments in thermally sprayed tungsten carbide-based coatings, with specific emphasis on evaluating alternative binders, processing routes and tribological behavior of the coatings. A comprehensive evaluation of various compositions as binders for WC-based coatings, considering environmental concerns and market requirements has been carried out. The properties and performance of various potential alternatives for cobalt as a conventional binder for these coatings have been assessed. Moreover, different thermal spray methods have been reviewed, particularly highlighting the role of processing parameters, phase change and feedstock characteristics in the high-velocity oxy-fuel (HVOF) and high-velocity air fuel (HVAF) techniques. A comparison is made between HVAF and HVOF coatings in terms of their performance under different wear environments. Finally, various scenarios of material removal in HVAF and HVOF coatings, under various wear conditions, have also been reviewed.

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Meekhanthong, K., and S. Wirojanupatump. "Characterization and Comparison of Thermally Sprayed Hard Coatings as Alternative to Hard Chrome Plating." Advanced Materials Research 974 (June 2014): 183–87. http://dx.doi.org/10.4028/www.scientific.net/amr.974.183.

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Thermal spray coatings have become one of the most potential for hard chrome replacement, particularly for wear and corrosion applications. In this study four types of hard coating materials were selected and thermally sprayed by suitable processes as the following designated codes (material/spray technique): Cr-Fe/HVOF, Cr-Ni/HVOF, WC-Ni/SF and Cr-Fe/AS. All of starting materials were characterized in order to create a correlation between spray materials and coating characteristics. SEM was employed for morphology and microstructure investigation. Particle size analysis was investigated by SEM and laser particle size analyzer. Coating characterization included surface roughness measurment by profilometer, porosity evaluation by image analysis and hardness test by Vicker microhardness tester. Microstructure of coatings was also revealed by SEM. Wear performance was evaluated by pin on disc test and dry sand rubber wheel abrasion test. Corrosion resistance was tested by potentiodynamic method. The results showed that particle size and morphology of starting powders were various depending on manufacturing method. Chemical compositions of starting materials showed great effect on coating properties and performance. Coatings deposited by HVOF and spray & fuse (SF) method showed typically dense and homogeneous structure than arc sprayed coating. WC-Ni/SF coating showed lowest abrasive wear rate compared to other thermally sprayed coatings. All Ni base coatings had significantly lower corrosion rates while Cr-Ni/HVOF coating had lowest corrosion rate. Although Cr-Ni/HVOF and WC-Ni/SF could be applicable for both wear and corrosion applications, for heat sensitive parts, Cr-Ni/HVOF coating could be a better alternative to spray and fuse.

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Ma, Ning, Zhen Xiong Cheng, Huan Tao Wu, and Fu Xing Ye. "Influence of Powder Structure on Decarburization and Microstructure of HVOF Sprayed WC-12wt.%Co Coatings." Advanced Materials Research 834-836 (October 2013): 609–12. http://dx.doi.org/10.4028/www.scientific.net/amr.834-836.609.

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In order to examine the influences of tungsten carbide particle size on decarburization behavior and microstructure of HVOF sprayed WC-Co coating, four kinds of agglomerated WC-12wt.%Co powders were deposited on mild steel substrates by using a high velocity oxy-fuel (HVOF) spray system. The phase compositions and microstructure of the feedstock powders and sprayed coatings were investigated by X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM), respectively. The results showed that the decarburization became more serious with the decreasing of tungsten carbide particle size in the starting powder. W phase was detected in the as-sprayed nanocomposite WC-12wt.%Co coating. All the coatings showed very compact microstructure with the hard phases embedded in Co matrix. The microstructure of HVOF sprayed WC-12wt.%Co coatings depended on the feedstock powder structure. The shape of tungsten carbide particles was rounder and the volume fraction of carbide phase decreased in coatings as the tungsten carbide particle size decreased.

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Zha, Bai Lin, Su Lei Qiao, Ding Yuan Huang, Wei He, Zhi Hong Zha, and Xiang Bin Li. "Study of Properties of Nanostructured and Conventional WC-12Co Coatings Deposited by HVO/AF." Advanced Materials Research 709 (June 2013): 166–71. http://dx.doi.org/10.4028/www.scientific.net/amr.709.166.

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The three kinds of WC-12Co coatings were sprayed by High Velocity Oxygen/Air Fuel Spray (HVO/AF) in three different spray conditions, HVOF、HVO-AF and HVAF. The high velocity flame flow was produced by HVO/AF with the burning of kerosene and propellant which was mixed by oxygen and air at different ratio, it can be controlled from 1400°C to 2800°C.The microstructure was investigated by SEM, the phase composition was tested by XRD, and the microhardness and elastic modulus of coatings were investigated. The results indicate that the coatings with better adhesive strength and little porosity than conventional ones are dense and have a large value of elasticity and a high microhardness which is 0.4 times harder than the conventional coatings. The coatings are mainly composed of WC and Co, and there are also traces of W2C and Co6W6C. As temperature decreased, the decomposition of WC is being reduced.

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Laha, T., Y. Liu, and A. Agarwal. "Carbon Nanotube Reinforced Aluminum Nanocomposite via Plasma and High Velocity Oxy-Fuel Spray Forming." Journal of Nanoscience and Nanotechnology 7, no. 2 (February 1, 2007): 515–24. http://dx.doi.org/10.1166/jnn.2007.114.

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Free standing structures of hypereutectic aluminum-23 wt% silicon nanocomposite with multiwalled carbon nanotubes (MWCNT) reinforcement have been successfully fabricated by two different thermal spraying technique viz Plasma Spray Forming (PSF) and High Velocity Oxy-Fuel (HVOF) Spray Forming. Comparative microstructural and mechanical property evaluation of the two thermally spray formed nanocomposites has been carried out. Presence of nanosized grains in the Al–Si alloy matrix and physically intact and undamaged carbon nanotubes were observed in both the nanocomposites. Excellent interfacial bonding between Al alloy matrix and MWCNT was observed. The elastic modulus and hardness of HVOF sprayed nanocomposite is found to be higher than PSF sprayed composites.

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Laha, T., Y. Liu, and A. Agarwal. "Carbon Nanotube Reinforced Aluminum Nanocomposite via Plasma and High Velocity Oxy-Fuel Spray Forming." Journal of Nanoscience and Nanotechnology 7, no. 2 (February 1, 2007): 515–24. http://dx.doi.org/10.1166/jnn.2007.18044.

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Free standing structures of hypereutectic aluminum-23 wt% silicon nanocomposite with multiwalled carbon nanotubes (MWCNT) reinforcement have been successfully fabricated by two different thermal spraying technique viz Plasma Spray Forming (PSF) and High Velocity Oxy-Fuel (HVOF) Spray Forming. Comparative microstructural and mechanical property evaluation of the two thermally spray formed nanocomposites has been carried out. Presence of nanosized grains in the Al–Si alloy matrix and physically intact and undamaged carbon nanotubes were observed in both the nanocomposites. Excellent interfacial bonding between Al alloy matrix and MWCNT was observed. The elastic modulus and hardness of HVOF sprayed nanocomposite is found to be higher than PSF sprayed composites.

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Prashar, Gaurav, Hitesh Vasudev, and Lalit Thakur. "Influence of heat treatment on surface properties of HVOF deposited WC and Ni-based powder coatings: a review." Surface Topography: Metrology and Properties 9, no. 4 (December 1, 2021): 043002. http://dx.doi.org/10.1088/2051-672x/ac3a52.

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Abstract Post-spray treatments have recently been popular as a means of improving the overall quality of thermally sprayed coatings, particularly those done using the HVOF technique. Thermally assisted surface treatment of deposited coatings is an effective way to improve the characteristics of coated components for specific applications. The tribomechanical properties of post-treated WC and Ni-based coatings deposited with high-velocity oxy-fuel (HVOF) technique have been addressed. The structure-property correlations concerning the as-sprayed and post-treated coatings have been considered to understand the various mechanisms responsible for improved performance in terms of wear and corrosion resistance. The recent advancement in the post-treatments such as post-processing using microwave hybrid heating, laser-assisted processing and Stationary friction processing have been incorporated in the current review. Comparative studies have been presented to understand the structure-property relationship and performance of WC and Ni-based HVOF sprayed coatings with the help of various characterization techniques in this review article.

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Saghi Beyragh, Mohammad Reza, Shahin Khameneh Asl, Rahim Vasfpour, Farshid Tazesh, and Parisa Khallagi. "A Comparison between the Corrosion Resistances of High Velocity Oxy Fuel (HVOF) Sprayed Coatings and Hard Chromium Coatings." Materials Science Forum 673 (January 2011): 173–78. http://dx.doi.org/10.4028/www.scientific.net/msf.673.173.

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HVOF-sprayed coatings (WC–17%Co) and hard chromium coatings corrosion resistances have been compared through electrochemical polarization test in 3.5% NaCl solution. WC–17%Co alloy coatings were deposited on mild steel substrates by High Velocity Oxy-Fuel (HVOF) spray process. The layers of standard and crack free hard chromium coatings were prepared by using Direct Current (DC) and Pulse Current (PC) electroplating process on the mild steel substrates. Hard chromium coatings was characterized as a reference material, to verify whether HVOF-sprayed coatings are suitable as a hard chromium coatings replacement. The microstructure of the coatings was examined by OM, SEM and XRD. Standard hard chromium coatings passivate in NaCl environment, but crack free hard chromium coatings were prepared by using Pulse Current (PC) electroplating do not passivate. The lowest corrosion current densities (Icorr) were recorded for crack free hard chromium coatings. Comparative electrochemical test results showed that, the Standard hard chromium coating has the highest Icorr and were significantly damaged after the electrochemical tests. It is seem to be that WC–17%Co alloy coatings can be substituted for standard hard chromium coatings but crack free chromium coatings bring new challenge for HVOF-sprayed coatings!

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Kiilakoski, Jarkko, Richard Trache, Stefan Björklund, Shrikant Joshi, and Petri Vuoristo. "Process Parameter Impact on Suspension-HVOF-Sprayed Cr2O3 Coatings." Journal of Thermal Spray Technology 28, no. 8 (October 31, 2019): 1933–44. http://dx.doi.org/10.1007/s11666-019-00940-7.

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Abstract Chromium oxide (Cr2O3) is commonly used as an atmospheric plasma-sprayed (APS) coating from powder feedstock in applications requiring resistance to sliding wear and corrosion, as well as amenability to texturing, e.g., in anilox rolls. Recently, high-velocity oxy-fuel spray methods involving suspension feedstock have been considered an extremely promising alternative to produce denser and more homogeneous chromium oxide coatings with lower as-sprayed surface roughness, higher hardness and potentially superior wear performance compared to conventional APS-sprayed coatings. In this study, the impact of process parameters namely auxiliary air cleaning nozzles and a transverse air curtain on suspension high-velocity oxy-fuel-sprayed Cr2O3 suspensions is presented. The produced coatings are characterized for their microstructure, mechanical properties and wear resistance by cavitation erosion. The results reveal the importance of optimized air nozzles and air curtain to achieve a vastly improved coating structure and performance.

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Bansal, P., P. H. Shipway, and S. B. Leen. "A hybrid implicit—explicit finite element methodology for coating formation in the high-velocity oxy-fuel spraying process." Proceedings of the Institution of Mechanical Engineers, Part L: Journal of Materials: Design and Applications 221, no. 4 (October 1, 2007): 285–97. http://dx.doi.org/10.1243/14644207jmda159.

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A finite element (FE) based methodology is presented for simulating the high-velocity oxy-fuel (HVOF) coating process. The methodology involves a hybrid of explicit and implicit FE analyses to simulate both particle impact and layer deposition and thus furnish both temperature and residual stress distributions resulting from the process. The methodology is illustrated for an HVOF sprayed copper coating on a copper substrate and for a SS 316 HVOF sprayed coating on a SS 316 substrate.

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Bang, Hee-Seon, Han-Sur Bang, and Yoon-Ki Lee. "The Functional TiO2-Biodegradable Plastic Composite Material Produced by HVOF Spraying Process." Journal of Nanoscience and Nanotechnology 7, no. 11 (November 1, 2007): 3830–33. http://dx.doi.org/10.1166/jnn.2007.038.

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Photocatalytic TiO2 coatings on bio-degradable plastic(polybutylene succinate: PBS) were prepared by HVOF spraying using three kinds of agglomerated powders (P200: 200 nm, P30: 30 nm, P7: 7 nm). The microstructures of the coatings were characterized with SEM and XRD analysis, and the photocatalytic efficiency of the coatings was evaluated by photo degradation of gaseous acetaldehyde. For both the HVOF sprayed P200 and P30 coatings, high anatase ratio of 100% was achieved, regardless of the fuel gas pressure. On the other hand, for the HVOF sprayed P7 coating, the anatase ratio decreased from 100% to 49.1% with increasing fuel gas pressure. This decrease may be attributed to the much higher susceptibility to heat of the 7 nm agglomerated powders than the 30 nm and 200 nm agglomerated powders. In terms of the photocatalytic efficiency, HVOF sprayed P200 and P30 coatings seemed to outperform the P7 coatings because of their higher anatase ratios. However, the HVOF sprayed P7 coatings did not show photocatalytic activity possibly because of the extremely small reaction surface area to the photo-catalytic activity and low anatase ratio. Therefore, the present study found that functional PBS plastic with photocatalytic performance could be produced by spraying of ceramics such as TiO2.

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Michalak, Monika, Paweł Sokołowski, Mirosław Szala, Mariusz Walczak, Leszek Łatka, Filofteia-Laura Toma, and Stefan Björklund. "Wear Behavior Analysis of Al2O3 Coatings Manufactured by APS and HVOF Spraying Processes Using Powder and Suspension Feedstocks." Coatings 11, no. 8 (July 23, 2021): 879. http://dx.doi.org/10.3390/coatings11080879.

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Thermally sprayed ceramic coatings are applied for the protection of surfaces that are exposed mainly to wear, high temperatures, and corrosion. In recent years, great interest has been garnered by spray processes with submicrometric and nanometric feedstock materials, due to the refinement of the structure and improved coating properties. This paper compares the microstructure and tribological properties of alumina coatings sprayed using conventional atmospheric plasma spraying (APS), and various methods that use finely grained suspension feedstocks, namely, suspension plasma spraying (SPS) and suspension high-velocity oxy-fuel spraying (S-HVOF). Furthermore, the suspension plasma-sprayed Al2O3 coatings have been deposited with radial (SPS) and axial (A-SPS) feedstock injection. The results showed that all suspension-based coatings demonstrated much better wear resistance than the powder-sprayed ones. S-HVOF and axial suspension plasma spraying (A-SPS) allowed for the deposition of the most dense and homogeneous coatings. Dense-structured coatings with low porosity (4 vol.%) and good cohesion to the metallic substrate, containing a high content of α–Al2O3 phase (56 vol.%) and a very low wear rate (0.2 ± 0.04 mm3 × 10−6/(N∙m)), were produced with the S-HVOF method. The wear mechanism of ceramic coatings included the adhesive wear mode supported by the fatigue-induced material delamination. Moreover, the presence of wear debris and tribofilm was confirmed. Finally, the coefficient of friction for the coatings was in the range between 0.44 and 0.68, with the highest values being recorded for APS sprayed coatings.

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Zha, Bai Lin, Xiao Jing Yuan, and De Wen Wang. "Study on Replacement of EHC Using HVOF Sprayed Coatings." Advanced Materials Research 518-523 (May 2012): 3984–88. http://dx.doi.org/10.4028/www.scientific.net/amr.518-523.3984.

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Environmental protection and worker safety measures against the extensively used hard chrome plating (EHC) is becoming more stringent, which leads to the development and application of alternative technology. As one of the most promising replacement technology of EHC, WC/Co coatings deposited by High Velocity Oxygen Fuel (HVOF) have well performances in corrosion and wear resistance. The paper analyzed technical characteristics, property and cost of EHC and HVOF deposited WC-Co coatings, while results show that performance of HVOF sprayed WC-Co coatings is superior or equal to EHC with much higher expense, so current replacement of EHC by HVOF centers airplane and military arm field which have relatively higher profit.

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Neiser, R. A., M. F. Smith, and R. C. Dykhuizen. "Oxidation in Wire HVOF-Sprayed Steel." Journal of Thermal Spray Technology 7, no. 4 (December 1, 1998): 537–45. http://dx.doi.org/10.1361/105996398770350765.

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Matějíček, Jiří, František Zahálka, Jan Bensch, Weiguang Chi, and Josef Sedláček. "Copper-Tungsten Composites Sprayed by HVOF." Journal of Thermal Spray Technology 17, no. 2 (March 14, 2008): 177–80. http://dx.doi.org/10.1007/s11666-008-9165-5.

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Islak, Serkan, and Cihan Özorak. "HVOF İLE ÜRETİLEN NiCr KAPLAMASININ MİKROYAPI ÖZELLİKLERİ." e-Journal of New World Sciences Academy 1, no. 1 (September 10, 2016): 186–91. http://dx.doi.org/10.12739/nwsa.2016.2a4pb.

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Wang, Hong Tao, Gang Chang Ji, Qing Yu Chen, Xue Fei Du, and Wei Fu. "Microstructure and Abrasive Wear Behaviour of HVOF Sprayed Carbide-Based Cermet Coatings." Advanced Materials Research 211-212 (February 2011): 182–85. http://dx.doi.org/10.4028/www.scientific.net/amr.211-212.182.

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Thermally sprayed carbide-based cermet coatings are being widely used for a variety of wear resistance applications. These coatings deposited by high velocity oxy-fuel (HVOF) technique are known to provide improved wear performance. In the present study, WC-12Co and Cr3C2-25NiCr carbide-based cermet coatings are deposited by HVOF. The microstructure and abrasion wear resistance of these coatings are compared. The correlation between coating microstructure and the coating wear behavior was investigated. The results indicated that WC-12Co coating has higher microhardness and better abrasive wear resistance in comparison to Cr3C2-25NiCr coating. The two HVOF sprayed carbide-based coatings have different abrasive wear behaviour.

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Cui, Shiyu, Qiang Miao, Wenping Liang, Yi Xu, and Baiqiang Li. "Comparative analysis of tribological behavior of plasma- and high-velocity oxygen fuel-sprayed WC-10Co-4Cr coatings." Industrial Lubrication and Tribology 69, no. 2 (March 13, 2017): 325–32. http://dx.doi.org/10.1108/ilt-09-2015-0129.

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Purpose The purpose of this study is to prepare WC-10Co-4Cr coatings using two processes of plasma spraying and high-velocity oxygen fuel (HVOF) spraying. The decarburization behaviors of the different processes are analyzed individually. The microstructural characteristics of the as-sprayed coatings are presented and the wear mechanisms of the different WC–10Co–4Cr coatings are discussed in detail. Design/methodology/approach The WC–10Co–4Cr coatings were formed on the surface of Q235 steel by plasma and HVOF spraying. Findings Plasma spraying causes more decarburizing decomposition of the WC phase than HVOF spraying. In the plasma spraying process, η(Cr25Co25W8C2) phase appears and the C content decreases from the top surface of the coating to the substrate. Practical implications In this study, two WC–10Co–4Cr coatings on Q235 steel prepared by plasma and HVOF spraying were compared with respect to the sliding wear behavior. Originality/value The wear mechanisms of the plasma- and HVOF-sprayed coatings were abrasive and oxidation, respectively.

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Jech, David, Ladislav Čelko, Lenka Klakurková, Karel Slámečka, Miroslava Horynová, and Jiří Švejcar. "Formation of Thermally Sprayed Coatings on Grid-Like Structure Substrate." Solid State Phenomena 258 (December 2016): 387–90. http://dx.doi.org/10.4028/www.scientific.net/ssp.258.387.

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The main goal of this contribution is to investigate the influence of the substrate morphology on the resulting thermally sprayed coatings microstructure. Therefore, three different representative coating systems and/or thermal spray techniques were utilized to produce the coatings on grid-like structure substrates: (i) CoNiCrAlY bond coat (BC) sprayed by high velocity oxygen fuel (HVOF) technique and yttria stabilized zirconia (YSZ) top coat (TC) sprayed by means of atmospheric plasma spray (APS) technique, (ii) YSZ coating sprayed by means of APS and (iii) YSZ coating sprayed by means of nanoparticle colloid suspension plasma spraying (SPS). The shadowing effect of thermal spray coatings in relation with the grid-like substrate structure was investigated in detail. Resulting microstructure of sprayed samples was studied utilizing light microscopy, digital image analysis, scanning electron microscopy, energy-dispersive spectrometer and X-ray diffraction techniques.

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Li, Yang, Ying Lian, Jingjing Cao, and Li Li. "Solid particle erosion behavior of HVOF/HVAF sprayed WC-Co-Cr coatings." Proceedings of the Institution of Mechanical Engineers, Part J: Journal of Engineering Tribology 230, no. 6 (September 24, 2015): 634–43. http://dx.doi.org/10.1177/1350650115608209.

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Lindner, Thomas, Martin Löbel, Ralph Hunger, Robin Berger, and Thomas Lampke. "Boriding of HVOF-sprayed Inconel 625 coatings." Surface and Coatings Technology 404 (December 2020): 126456. http://dx.doi.org/10.1016/j.surfcoat.2020.126456.

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Bolelli, Giovanni, Alberto Colella, Luca Lusvarghi, Pietro Puddu, Rinaldo Rigon, Paolo Sassatelli, and Veronica Testa. "Properties of HVOF-sprayed TiC-FeCrAl coatings." Wear 418-419 (January 2019): 36–51. http://dx.doi.org/10.1016/j.wear.2018.11.002.

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Sassatelli, Paolo, Giovanni Bolelli, Magdalena Lassinantti Gualtieri, Esa Heinonen, Mari Honkanen, Luca Lusvarghi, Tiziano Manfredini, Rinaldo Rigon, and Minnamari Vippola. "Properties of HVOF-sprayed Stellite-6 coatings." Surface and Coatings Technology 338 (March 2018): 45–62. http://dx.doi.org/10.1016/j.surfcoat.2018.01.078.

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Bolelli, Giovanni, Luca Lusvarghi, Tommi Varis, Erja Turunen, Matteo Leoni, Paolo Scardi, Cristy Leanor Azanza-Ricardo, and Massimilano Barletta. "Residual stresses in HVOF-sprayed ceramic coatings." Surface and Coatings Technology 202, no. 19 (June 2008): 4810–19. http://dx.doi.org/10.1016/j.surfcoat.2008.04.066.

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Lyphout, Christophe, Per Nylen, and Lars Gösta Östergren. "Adhesion Strength of HVOF Sprayed IN718 Coatings." Journal of Thermal Spray Technology 21, no. 1 (October 18, 2011): 86–95. http://dx.doi.org/10.1007/s11666-011-9689-y.

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Guilemany, J. M., J. Nin, C. Lorenzana, J. M. Miguel, and J. R. Miguel. "Tribología de recubrimientos Cermet/NiCrBSi depositados mediante HVOF." Boletín de la Sociedad Española de Cerámica y Vidrio 43, no. 2 (April 30, 2004): 483–87. http://dx.doi.org/10.3989/cyv.2004.v43.i2.575.

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Mohd Zulkifli, S., Muhammad Azizi Mat Yajid, Mohd Hasbullah Idris, M. Daroonparvar, and Halimaton Hamdan. "TGO Formation with NiCoCrAlYTa Bond Coat Deposition Using APS and HVOF Method." Advanced Materials Research 1125 (October 2015): 18–22. http://dx.doi.org/10.4028/www.scientific.net/amr.1125.18.

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Formation of thin and continuous layer of thermally grown oxide (TGO) in thermal barrier coating (TBC) are essential in order to avoid coating failure for high temperature applications. As-sprayed high velocity oxy-fuel (HVOF) bond coat can provide more uniform TGO layer in TBC system and much less oxide compare to air plasma spray (APS). In this paper, both APS and HVOF method are used to deposit NiCoCrAlYTa bond coat on Inconel 625 substrate followed by topcoat, YSZ deposition. Pre-oxidation process was done in normal oxygen furnace at 1000°C for 12 to 24 hours to study the characteristic of TGO formation via these two different methods. From the result obtained, it shows that HVOF method provide better TGO formation as compared to APS.

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Hsiao, W. T., W. H. Liao, M. S. Leu, and Cherng Yuh Su. "A Splats Obtaining System for Thermal Spray Deposits." Materials Science Forum 561-565 (October 2007): 1169–72. http://dx.doi.org/10.4028/www.scientific.net/msf.561-565.1169.

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The image of thermal spray splats is difficult to collect due to its high velocity of droplets. Especial in High Velocity Oxy-Fuel (HVOF) process, the process present higher velocity of flame jet correlated to other thermal spray process. The system presents at this article describes a useful splats catching method to obtaining splats during thermal spray deposited. Capabilities and advantages of using this instrument are declared at this theme. The final result presented the instrument caught the single spot of HVOF sprayed splats at sub-micro second. Splats of spot were dispersed well on the glass substrate at the obtaining system, and presented various information of droplets impact at different location on the substrate.

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Hulka, Iosif, Viorel Aurel Şerban, Kari Niemi, Petri Vuoristo, and Johannes Wolf. "Comparison of Structure and Wear Properties of Fine-Structured WC-CoCr Coatings Deposited by HVOF and HVAF Spraying Processes." Solid State Phenomena 188 (May 2012): 422–27. http://dx.doi.org/10.4028/www.scientific.net/ssp.188.422.

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The aim of the work was to study the microstructure and wear properties of fine-structured HVOF and HVAF sprayed WC-10Co-4Cr coatings prepared from powder having submicron-sized tungsten carbides. The coatings were deposited by HVOF (High Velocity Oxygen Fuel) and HVAF (High Velocity Air Fuel) using propane as a fuel gas in both processes, and using oxygen or air as oxidizing gas for combustion, respectively. Nitrogen was used as carrier gas for the powder. Commercially available agglomerated and sintered cermet powder with main carbide sizes under 500 nm was used in this study. Scanning electron microscopy (SEM) and X-ray diffraction were performed in order to characterize the powder and the microstructures formed during the spraying processes. The microhardness HV0.3 of the coatings was investigated and the pin on disk test was used to determine the sliding wear behaviour. The rubber wheel abrasion test was performed in order to determine the abrasion wear resistance of the coatings.

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Li, Ming Cheng, Ming Der Jean, Jyh Horng Chou, and Bor Tsuen Lin. "The Enhancement of Integrated Properties of WC-Co Coatings Fabricated Using an HVOF Spraying." Materials Science Forum 675-677 (February 2011): 541–45. http://dx.doi.org/10.4028/www.scientific.net/msf.675-677.541.

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This study reported on Taguchi-Fuzzy logic model with statistical experiments to characterize the tungsten carbide/cobalt (WC-Co) deposited quality properties of the high-velocity oxygen-fuel (HVOF) process. The eight control factors were designed in a factorial orthogonal array experiment, and the effects of control parameters on the integrated surface properties were critically evaluated in the Taguchi designed experiments. A fuzzy logic system with knowledge bases in the inference engine was used to explore the relationships between variables and responses in the modified structures. In addition, the structure and properties of HVOF sprayed WC-Co coating were reported. Furthermore, a confirmation experiment of the optimal process was conducted. It was clear that HVOF sprayed WC-Co coating estimations are greatly improved through the Taguchi-Fuzzy logic operation, and these findings achieved the desired values in the modified properties.

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Wu, Wen Tung, Ming Der Jean, and Jeng Der Lin. "Improving the Performance of HVOF Sprayed WC-Co Coatings Using Statistical Design." Advanced Materials Research 314-316 (August 2011): 284–91. http://dx.doi.org/10.4028/www.scientific.net/amr.314-316.284.

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This study reports the statistical optimization of experiments, designed by Taguchi, to improve the wear-resistance of the tungsten carbide/cobalt-based coatings applied using high-velocity oxygen-fuel (HVOF) spraying processes. In this study, a group of needlelike textures appeared in the HVOF WC-Co coatings. The structures were evenly distributed and compacted closely, showing a more dense and homogenous configuration. The coating that formed with a large amount of pores, microcracks and unmolten particles was much looser, and the interface was locally prone to defects. The coatings were obviously not homogenous. Experimental results show that the wear-resistant coatings are highly dense, with an elastic lamellar structure. The tribological properties were significantly improved and the surface textures showed uniformity, in a molten droplet flattened formation. A homogenous, morphological structure, with local small aggregation, was more obvious after HVOF WC-Co coating. Accordingly, it is clear that the surface properties determined proved favorable to the mechanical properties of the WC/Co coatings. In addition, we compared the linear models with the quadric models, using RSM methods, in all the experiments. Statistically, the linear models produced an average error of 8.285％, while the quadric models generated an average error of 1.399％. It is clear that the RSM models successfully fitted the HVOF WC-Co coating process and the quadric models yielded more accurate predictions than the linear models, in most cases. The proposed procedure was applied to HVOF spraying of WC-CO coatings. The results demonstrated its feasibility and its effectiveness in improving the HVOF WC-Co coating.

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Brioua, S., K. Belmokre, V. Debout, P. Jacquot, E. Conforto, S. Touzain, and J. Creus. "Influence of Spray Parameters on the Metallurgical and Functional Properties of HVOF WC Based Cermets Deposited onto Low Alloy Steel." Journal of Material Science and Technology Research 9, no. 1 (February 20, 2022): 1–10. http://dx.doi.org/10.31875/2410-4701.2022.09.01.

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Abstract: Tungsten carbide based spray coatings are widely used in industry for application requiring abrasion, sliding, fretting and erosion corrosion resistance. High velocity oxy-fuel (HVOF) flame spraying was used for producing high quality carbide composite coatings. In this study, a WC-CoCr and WC-CoCrNi powders were thermal sprayed using a HVOF process. The spray parameters were varied in order to investigate their influence on microstructure and mechanical properties of coatings. It is possible to produce homogeneous coating by controlling the flame temperature, the velocity of the gun transverse, the powder feed rate and the nature of the powders. The mechanical properties and the porosity rate could be optimized in order to improve the functional properties.

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Houdková, Šárka, Jan Černý, Zdeněk Pala, and Petr Haušild. "High Temperature Resistance of Selected HVOF Coatings." Key Engineering Materials 662 (September 2015): 111–14. http://dx.doi.org/10.4028/www.scientific.net/kem.662.111.

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The HVOF (high velocity oxygen fuel) thermal spraying technology is widely used for creation of coatings notable for their resistance against various kinds of loading. Depending on the sprayed material, the coatings suitable for high temperature applications can be sprayed as well. The coatings, based on CrC or Co/Ni alloys, offer the advantageous combination of high temperature oxidation resistance and the wear resistance. In the paper, the attention is paid to the evaluation of the influence of the high temperature on the coatings microstructure and mechanical properties, namely hardness. The stability of the hardness values in respect to the time of the high temperature exposure is presented and related to the phase composition changes.

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Hannula, Simo Pekka, Erja Turunen, Jari Keskinen, Tommi Varis, Teppo Fält, Tom E. Gustafsson, and Roman Nowak. "Development of Nanostructured Al₂O₃-Ni HVOF Coatings." Key Engineering Materials 317-318 (August 2006): 539–44. http://dx.doi.org/10.4028/www.scientific.net/kem.317-318.539.

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HVOF thermal spraying has been developed to deposit dense Al2O3-coatings for improved protective properties. As compared to generally used plasma sprayed coatings HVOF coatings can be prepared much denser and thus are better suited for applications where protective properties of the coating are needed. In this paper we describe the development of HVOF spraying technologies for nanocrystalline Al2O3- and Al2O3-Ni-coatings. The microstructure and the mechanical properties of these novel coatings are reported and compared to a conventionally processed Al2O3-coating.

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Ko, J. H., and D. B. Lee. "Microstructural Observation of Scales formed on HVOF-sprayed NiCoCrAlY Coatings." Korean Journal of Materials Research 14, no. 2 (February 1, 2004): 110–14. http://dx.doi.org/10.3740/mrsk.2004.14.2.110.

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Bolelli, G., L. M. Berger, T. Börner, H. Koivuluoto, L. Lusvarghi, C. Lyphout, N. Markocsan, et al. "Tribology of HVOF- and HVAF-sprayed WC–10Co4Cr hardmetal coatings: A comparative assessment." Surface and Coatings Technology 265 (March 2015): 125–44. http://dx.doi.org/10.1016/j.surfcoat.2015.01.048.

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Sadeghimeresht, E., N. Markocsan, and P. Nylén. "Microstructural characteristics and corrosion behavior of HVAF- and HVOF-sprayed Fe-based coatings." Surface and Coatings Technology 318 (May 2017): 365–73. http://dx.doi.org/10.1016/j.surfcoat.2016.11.088.

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Jean, Ming Der, and Tzu Hsuan Chien. "Optimization of Surface Properties and Performances for HVOF Sprayed WC-Co Coatings on Mild Steel." Applied Mechanics and Materials 52-54 (March 2011): 324–30. http://dx.doi.org/10.4028/www.scientific.net/amm.52-54.324.

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This study presented the application of Taguchi designed experiments to optimize the tungsten carbide/cobalt (WC-Co) deposited quality properties of the high-velocity oxygen-fuel (HVOF) process. The eight control factors were designed in a L18 factorial orthogonal array experiment, and the effects of control parameters on the surface properties were critically evaluated in the experiments. The surface anti-wear properties by optimal design have been studied comparatively. By optimization from Taguchi S/N ratios and analysis of variance, the surface wear volume values are decreased by 37%. It was clear that anti-wear performance estimations of HVOF sprayed WC-Co coatings are greatly improved by way of the optimal experiment, and these findings achieved the desired values in the WC-CO coatings. The experimental results indicated that the proposal method offers an effective and efficient approach for developing a robust and highly quality HVOF sprayed WC-Co coating.

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Salman, Asma, Brian Gabbitas, and De Liang Zhang. "Titanium Based Composite Coatings Deposited by High Velocity Oxygen Fuel (HVOF) and Plasma Spraying Methods." Key Engineering Materials 551 (May 2013): 127–32. http://dx.doi.org/10.4028/www.scientific.net/kem.551.127.

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The study involves a special class of composites called interpenetrating phase composites (IPCs). The Ti(Al,O)/Al2O3 composite was produced using high energy mechanical milling of a mixture of TiO2 and Al followed by a high temperature self-propagating reaction. Characteristics of the feedstock powder were improved by treating it with an organic binder. The feedstock powder was thermally sprayed on to a substrate using high velocity oxygen fuel (HVOF) and air plasma spraying methods. The spraying methods resulted in coatings with significantly different microstructures. Compared with plasma sprayed coating, the coating produced by a HVOF spraying method showed a much finer and densely packed microstructure.

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Gadow, Rainer, D. López, and A. Candel. "Ceramic and Cermet Coatings for Cylinder Liner in Ultra Light Weight Engines - Novel Processing and Manufacturing of Ceramic Layer Composites." Advances in Science and Technology 45 (October 2006): 1330–35. http://dx.doi.org/10.4028/www.scientific.net/ast.45.1330.

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Actual requirements in the automotive industry are the reduction of fuel consumption and pollution emission, engine efficiency improvement, as well as cost reduction. Most of these requirements are fulfilled by reducing the total weight of the vehicle. This results in an increasing utilization of light metal components for engine applications. Significant weight savings are obtained by changing the engine block material from cast iron to aluminum or even to magnesium aluminum hybrid constructions. Despite of all advantages the industrial implementation of light metals is often inhibited by their poor surface properties especially concerning wear and tribological behavior. Due to the highly loaded operation conditions a cylinder liner surface reinforcement is necessary. A very promising technological alternative is the internal cylinder reinforcement by using HVOF (high velocity oxygen fuel) sprayed coatings. By using these advanced high energetic coating technologies, material combinations containing solid lubricant ceramic dispersions can be deposited. The thermal spray processes represent a cost effective and flexible solution for ultra light weight engine technology. This research is focused on the development of HVOF sprayed coating systems for cylinder liners, the coating optimization and the cost effective implementation of this hypersonic spray technology in a series production process. It will be shown that cast engine block bores can be directly coated by using an automated HVOF process, obtaining improved coating results. The internal coating process by hypersonic flame spraying is a superior technological alternative to the APS process for high quality cylinder liner and engine crankcase applications.

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Raza, Ali, Faiz Ahmad, Thar M. Badri, M. R. Raza, and Khurshid Malik. "An Influence of Oxygen Flow Rate and Spray Distance on the Porosity of HVOF Coating and Its Effects on Corrosion—A Review." Materials 15, no. 18 (September 12, 2022): 6329. http://dx.doi.org/10.3390/ma15186329.

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Thermal spray coating, exceptionally high-velocity oxyfuel (HVOF), improves the corrosion resistance and wear of metal. Coating parameters play a vital role in the properties of the coating. The quality of coating can be increased by selecting appropriate coating parameters. In the case of HVOF, the oxygen flow rate and spray distance are the most significant parameters that directly influence the porosity and corrosion resistance of the coating. Porosity is essential in thermal barrier coatings for low thermal conductivity, but there is a limit of porosity beyond which it can cause failure. Hence, understanding the effects of these parameters is essential to evaluate and further minimize the porosity in order to improve the corrosion resistance and durability of the thermal barrier coating. This article reviews hot corrosion in thermal barrier coatings, the stages of corrosion, the importance of spray parameters, and the effect of the oxygen flow rate and spray distance on the corrosion resistance of HVOF-sprayed coatings. Afterwards, the coating materials, the substrate, the flow rate of oxygen, the spray distance, and the fuel used during the HVOF spraying process from recent articles are summarized. In summary, this review compares the flow rate of oxygen and the spray distance with the corrosion capacity of the coating under different corrosive environments and materials to optimize these parameters for high-quality coating, which would sustain under high temperatures for future applications.

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Chen, Dianying. "Suspension HVOF Sprayed Ytterbium Disilicate Environmental Barrier Coatings." Journal of Thermal Spray Technology 31, no. 3 (February 2022): 429–35. http://dx.doi.org/10.1007/s11666-022-01343-x.

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Houdková, Šárka, Zdeněk Česánek, and Pavel Polach. "Solid Particle Erosion of Selected HVOF Sprayed Coatings." Applied Mechanics and Materials 827 (February 2016): 39–46. http://dx.doi.org/10.4028/www.scientific.net/amm.827.39.

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The paper involves the subject and the chosen results of up to now solving of work package “Development of advanced surface treatment of components used in parts of turbines working under the condition of operational temperatures of steam using the HP/HVOF technology of thermal spraying” of the Competence Centre project “Centre of Research and Experimental Development of Reliable Energy Production”. The subject belongs to the field of material engineering and results of solving contribute to fulfilling the main project aim, which is a long time safeguarding of safe, reliable and financially available both classical thermal and nuclear sources of electric power, which consists in extending service life of existing and building new turbo generator blocks. The erosion wear resistance is one of the areas, which were observed. The impact of hard particles on the surface under variable impact angles was simulated in laboratory conditions using an in-house equipment. The wear resistance of selected HVOF sprayed hardmetal and super-alloy coatings was measured and the wear mechanism was evaluated. A strong influence of impact angle on both material volume loss and wear mechanism was monitored. The superior erosion wear properties of super-alloy coatings were proved, regardless the higher hardness of hardmetal coatings.

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Mateen, A., Fazal Ahmad Khalid, T. I. Khan, and G. C. Saha. "Wear Behaviour of HVOF Sprayed WC-Cobalt Coatings." Advanced Materials Research 326 (September 2011): 144–50. http://dx.doi.org/10.4028/www.scientific.net/amr.326.144.

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Tungsten carbide cobalt coating has been extensively used for cutting and mining tools, aerospace, automotive and other wear resistance applications. These coatings not only have superior mechanical properties like high hardness, toughness and compressive strength but have also excellent controllable tribological properties. In this paper a comparison of wear properties and structural phases has been presented to consider for tribological applications. It is found that nanocrystalline duplex coatings have shown much superior properties as compared to the microcrystalline coatings. Evidence of clusters of WC particles was found in microcrystalline coating as compared to homogeneous dense coating structure observed in the nanocrystalline coating. These results are discussed to assess their suitability for super hard wear resistance applications.

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Ajdelsztajn, Leonardo, Josep A. Picas, George E. Kim, Fernando L. Bastian, Julie Schoenung, and V. Provenzano. "Oxidation behavior of HVOF sprayed nanocrystalline NiCrAlY powder." Materials Science and Engineering: A 338, no. 1-2 (December 2002): 33–43. http://dx.doi.org/10.1016/s0921-5093(02)00008-4.

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Kawakita, Jin, Seiji Kuroda, and Toshiaki Kodama. "Evaluation of through-porosity of HVOF sprayed coating." Surface and Coatings Technology 166, no. 1 (March 2003): 17–23. http://dx.doi.org/10.1016/s0257-8972(02)00719-3.

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Stokes, J., and L. Looney. "Residual stress in HVOF thermally sprayed thick deposits." Surface and Coatings Technology 177-178 (January 2004): 18–23. http://dx.doi.org/10.1016/j.surfcoat.2003.06.003.

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Ji, Gang-Chang, Chang-Jiu Li, Yu-Yue Wang, and Wen-Ya Li. "Erosion Performance of HVOF-Sprayed Cr3C2-NiCr Coatings." Journal of Thermal Spray Technology 16, no. 4 (November 1, 2007): 557–65. http://dx.doi.org/10.1007/s11666-007-9052-5.

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Journal articles on the topic 'HVOF SPRAYED'

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