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1.
Šárka Houdková Michaela Kašparová František Zahálka 《Journal of Thermal Spray Technology》2010,19(5):893-901
The spraying angle is one of the deposition parameters that influence the quality of thermally sprayed coatings. In theory,
decreasing the spraying angle results in lower process deposition efficiency, whereas the porosity of coatings increases,
becoming a cause of poorer microstructure and mechanical properties. In this study, the dependence of microstructure together
with the basic mechanical properties and wear of WC-Co and Cr3C2-NiCr high-velocity oxyfuel (HVOF) sprayed coatings on the spraying angle was investigated. For each coating, the maximum
spraying angle was determined that can be used without significantly decreasing coating quality. Based on the changes in properties
of coatings and requirements for the process deposition efficiency, a maximum 30° diversion from the normal spray direction
is recommended for WC-Co and 15° diversion for Cr3C2-NiCr coatings. 相似文献
2.
Mahantayya Mathapati Mrityunjay Doddamani M. R. Ramesh 《Journal of Materials Engineering and Performance》2018,27(4):1592-1600
This research examines the deposition of Cr3C2-NiCr/cenosphere and Cr3C2-NiCr coatings on MDN 321 steel through the process of plasma spray. In this process, the solid particle erosion test is established at 200, 400, 600 °C with 30° and 90° impact angles. Alumina erodent is adopted to investigate the erosive behavior of the coating at higher temperatures. The properties of the Cr3C2-NiCr/cenosphere coating are established based on the microhardness, the adhesive strength, the fracture toughness, and the ductility. To quantify volume loss as a result of erosion, an optical profilometer is used. At higher temperature, decrease in the erosion volume loss of Cr3C2-NiCr/cenosphere and Cr3C2-NiCr coatings is observed. The erosion-resistive property of Cr3C2-NiCr/cenosphere coating is higher than that of MDN 321 steel by 76%. This property is influenced by high-temperature stability of mullite, alumina, and protective oxide layer that is formed at elevated temperatures. The morphology of eroded coating discloses a brittle mode of material removal. 相似文献
3.
Guan-Jun Yang Chang-Jiu Li Shi-Jun Zhang Cheng-Xin Li 《Journal of Thermal Spray Technology》2008,17(5-6):782-787
The comparison of the high-temperature erosion behavior of a High-velocity oxyfuel (HVOF) sprayed Cr3C2-NiCr coating with mild steel for circulating fluidized bed boiler tubes was investigated. Results showed that the erosion rate of the mild steel at 800 °C was four times that at 300 °C at an erosion angle of 30°. However, the erosion rate of the HVOF sprayed Cr3C2-NiCr coating was not influenced by the temperature in the range of 300-800 °C. It was found that the erosion resistance of HVOF sprayed Cr3C2-NiCr coating was more than three times higher than that of the mild steel at 700-800 °C. In addition to the ploughing on the coating surface, the cracking along splat interfaces in the coating was clearly observed on the cross-sectional microstructure. The results indicate that the erosion performance of the HVOF sprayed Cr3C2-NiCr coating is controlled by the cohesion between splats and can be further enhanced by improving splat cohesion. 相似文献
4.
Cr3C2-NiCr thermal spray coatings are extensively used to mitigate high temperature erosive wear in fluidised bed combustors and power generation/transport turbines. The aim of this work was to characterise the variation in oxide erosion response as a function of the Cr3C2-NiCr coating microstructure. Erosion was carried out at 700 °C and 800 °C with erodent impact velocities of 225-235 m/s. The erosion behaviour of the oxide scales formed on these coatings, was influenced by the coating microstructure and erosion temperature. Development of the carbide microstructure with extended heat treatment lead to variations in the erosion-corrosion response of the Cr3C2-NiCr coatings. 相似文献
5.
Šárka Houdková Zdeněk Česánek Eva Smazalová František Lukáč 《Journal of Thermal Spray Technology》2018,27(1-2):179-195
Three commercially available chromium carbide-based powders with different kinds of matrix (Cr3C2-25%NiCr; Cr3C2-25%CoNiCrAlY and Cr3C2-50%NiCrMoNb) were deposited by an HVOF JP-5000 spraying gun, evaluated and compared. The influence of heat treatment on the microstructure and properties, as well as the oxidation resistance in a hot steam environment (p = 24 MPa; T = 609 °C), was evaluated by SEM and XRD with respect to their potential application in the steam power industry. The sliding wear resistance measured at room and elevated (T = 600 °C) temperatures according to ASTM G-133. For all three kinds of chromium carbide-based coatings, the precipitation of secondary carbides from the supersaturated matrix was observed during the heat treatment. For Cr3C2-25%NiCr coating annealed in hot steam environment as well as for Cr3C2-25%CoNiCrAlY coating in both environments, the inner carbide oxidation was recorded. The sliding wear resistance was found equal at room temperature, regardless of the matrix composition and content, while at elevated temperatures, the higher wear was measured, varying in dependence on the matrix composition and content. The chromium carbide-based coating with modified matrix composition Cr3C2-50%NiCrMoNb is suitable to replace the Cr3C2-25%NiCr coating in a hot steam environment to eliminate the risk of failure caused by inner carbide oxidation. 相似文献
6.
Lingzhong Du Chuanbing HuangWeigang Zhang Tiegang LiWei Liu 《Surface & coatings technology》2011,205(12):3722-3728
NiCr clad hexagonal BN powder (NiCr/hBN) was added to NiCr/Cr3C2 feedstock to improve the tribological properties of chromium carbide nichrome coating. The microstructure, flowability and apparent density of the composite powder, as well as the structure and mechanical properties of the plasma sprayed coating were characterized. The friction and wear behavior of the NiCr/Cr3C2-NiCr/hBN coating from ambient temperature up to 800 °C was evaluated on a ball-on-disk wear tester and compared with that of NiCr/Cr3C2 coating and NiCr/Cr3C2-NiCr/BaF2·CaF2 coating. The results show that NiCr cladding can reduce the decarburization of Cr3C2 and oxidation of hBN during the thermal spray. The main wear mechanisms of the NiCr/Cr3C2-NiCr/hBN composite coating are ploughing and adhesive wear. Layered hexagonal BN particle reduce the direct contact and severe adhesion between friction pairs, thus decreasing the friction coefficient. The NiCr/Cr3C2-NiCr/hBN composite coating shows a promising application in the high temperature environment with the request of both wear resistance and friction reduction. 相似文献
7.
Zichun Zhao Hui Li Tianlong Yang Hongbin Zhu 《Journal of Thermal Spray Technology》2018,27(4):718-726
Boride materials have drawn great attention in surface engineering field, owing to their high hardness and good wear resistance. In our previous work, a plasma-sprayed TiB2-based cermet coating was deposited, but the coating toughness was significantly influenced by the formation of a brittle ternary phase (Ni20Ti3B6) derived from the reaction between TiB2 and metal binder. In order to suppress such a reaction occurred in the high-temperature spraying process, the high-velocity oxygen-fuel spraying technique was applied to prepare the TiB2-NiCr coating. Emphasis was paid on the microstructure, the mechanical properties, and the sliding wearing performance of the coating. The result showed that the HVOF-sprayed coating mainly consisted of hard ceramic particles including TiB2, CrB, and the binder phase. No evidence of Ni20Ti3B6 phase was found in the coating. The mechanical properties of HVOF-sprayed TiB2-NiCr coating were comparable to the conventional Cr3C2-NiCr coating. The frictional coefficient of the TiB2-NiCr coating was lower than the Cr3C2-NiCr coating when sliding against a bearing steel ball. 相似文献
8.
Jianhong He Michael Ice Julie M. Schoenung Enrique J. Lavernia Dong H. Shin 《Journal of Thermal Spray Technology》2001,10(2):293-300
The thermal stability behavior of nanostructured Cr3C2-NiCr coatings was investigated. The nanostructured Cr3C2-NiCr coatings, synthesized using mechanical milling and high-velocity oxygen fuel (HVOF) thermal spraying, were thermally
exposed in air at 473, 673, 873, and 1073 K for 8 h. The results show that microhardness of the conventional coating increased
slightly with increasing temperature, while that of the nanostructured coating drastically increased from 1020 to 1240 HV300 for the same temperature increases. Heat treatment led to increases in scratch resistance and decreases in the coefficient
of friction for the nanostructured Cr3C2-NiCr coatings. A high density of Cr2O3 oxide particles with average size of 8.3 nm was found in the nanostructured coatings exposed to high temperatures, which
is thought to be responsible for the observed increase in microhardness and scratch resistance and the decrease in the coefficient
of friction of the nanostructured coatings. 相似文献
9.
Erosion Performance of HVOF-Sprayed Cr3C2-NiCr Coatings 总被引:1,自引:0,他引:1
Gang-Chang Ji Chang-Jiu Li Yu-Yue Wang Wen-Ya Li 《Journal of Thermal Spray Technology》2007,16(4):557-565
Cr3C2-NiCr coatings were deposited by high-velocity oxygen fuel (HVOF) spraying process under spray conditions of different flows
of oxygen and propane gases, and spray distances. The orthogonal regression experimental design method was used for systematic
investigation of the influence of spray parameters on the erosion performance of Cr3C2-NiCr coatings. Erosion tests were performed at different jet angles of abrasive particles. The erosion mechanism of Cr3C2-NiCr coatings was examined through the surface morphology and cross-sectional microstructure of the eroded coatings. The
correlations of the carbide particle size and carbide content with the erosion rate were examined. It was found that the erosion
occurred dominantly by spalling of splats from the lamellar interfaces. The spalling resulted from the propagation of cracks
parallel to the interfaces between the lamellae exposed to the surface and underlying coating. The carbide particle size and
content in the coating influenced significantly the erosion performance of Cr3C2-NiCr coatings. 相似文献
10.
Mechanical and tribological properties of plasma-sprayed Cr3C2-NiCr, WC-Co, and Cr2O3 coatings 总被引:1,自引:0,他引:1
Mechanical properties such as Young’s moduli and fracture toughness of plasma-sprayed Cr3C2-NiCr, WC-Co and Cr2O3 coatings were measured. The tribological properties of the three kinds of coatings were investigated with a block-on-ring
self-mated arrangement under water-lubricated sliding. Furthermore, the influences of the mechanical properties on the tribological
properties of the coatings were also examined. It was found that the Young’s moduli, bend strengths and fracture toughness
of the coatings were lower than the corresponding bulk materials, which may be attributed to the existence of pores and microcracks
in the coatings. Among the three kinds of coatings, the magnitude of wear coefficients, in decreasing order, is Cr3C2-NiCr, WC-Co and Cr2O3, and the wear coefficient of Cr2O3 coating was less than 1 × 10−6mm3N−1m−1. The wear mechanisms of the coatings were explained in terms of microcracking and fracturing, and water deteriorated wear
performance of the coatings. The higher the fracture toughness and the lower the porosity and length of microcracking of the
coating, the more the wear-resistance of the coating. 相似文献
11.
A selection of WC-Co and Cr3C2-25%NiCr coatings produced by plasma spray and high velocity oxygen fuel (HVOF) deposition techniques were subjected to various
wear tests designed to simulate abrasion, cavitation, sliding, and particle erosion type wear mechanisms. All of the coatings
were at least 200 μm thick and were deposited onto stainless steel substrates. In Part 1 of this contribution, the microstructures
of the coatings were characterized and their mechanical properties were assessed using microindentation procedures. In this
second part of the article, the behavior of the coatings when subjected to the various wear tests is reported and the utility
of microhardness testing as an indication of relative wear resistance is discussed. It is shown that correctly performed,
appropriate microhardness measurements are a good indication of abrasion resistance and sliding wear resistance, and also
correlate well with cavitation resistance in Cr3C2-NiCr. The measurements were less useful for predicting erosion resistance for both Cr3C2-NiCr and WC-Co, however, and for abrasion resistance when WC-Co was ground against SiC. Here the contribution of micromechanisms
involving fracturing and brittle failure is greater than that indicated by the coating microhardness, which is essentially
a measurement of resistance to plastic deformation under equilibrium conditions. 相似文献
12.
HVOF spraying was used to prepare coatings from mechanical blends of Cr3C2-25NiCr and NiCrBSi powders. The aim of this study is to study the tribological behavior of coatings prepared from such powder blends. The coatings were studied under dry sliding conditions particularly at high temperatures. Tribological properties of the coatings were characterized using a specific hot-button tribological tester at the temperature of 300 °C in air, and a pin-on-disk test at room temperature. Addition of NiCrBSi resulted in coatings, which showed low coefficient of friction in high temperatures, and in high levels of contact pressure and sliding speed. 相似文献
13.
Jie Chen Yulong An Xiaoqin Zhao Fengyuan Yan Huidi Zhou Jianmin Chen 《Journal of Thermal Spray Technology》2014,23(3):363-372
Four types of NiCr-Cr2O3 composite coatings doped with different mass fraction of Nd2O3 were deposited by atmospheric plasma spraying. The microstructure and phase composition of as-sprayed coatings were analyzed by scanning electron microscope (SEM) and X-ray diffraction (XRD). Furthermore, their friction and wear behaviors at 20 and 600 °C under unlubricated condition were evaluated using CSM high temperature tribometer. The results showed that Nd2O3 could refine microstructure of NiCr-Cr2O3 composite coating and make Cr2O3 distribution more uniform in the coating, which leads to the increase of average microhardness. In addition, NiCr-Cr2O3 composite coatings doped with Nd2O3 had better wear resistance than that without Nd2O3 at experimental temperatures. Especially, the coating containing 8 wt.% Nd2O3 showed the best wear resistance at 20 and 600 °C, which was attributed to the refined microstructure and improved microhardness. At 20 °C, the wear mechanism of the coating was abrasive wear, brittle fracture and splat detachment. At 600 °C, the wear mechanism was adhesion wear and plastic deformation. 相似文献
14.
Yan Liu Zongqiu Hang Guiying Yang Hao Fu Naiyuan Xi Hui Chen 《Journal of Thermal Spray Technology》2018,27(7):1143-1152
In this work, WC-12Co coatings were prepared by high-velocity oxygen fuel spraying (HVOF) technology. The high-temperature sliding wear tests at 450, 550 and 650 °C were conducted on a pin-on-disk tribometer, and effects of CeO2 on the high-temperature wear behavior were investigated. The results showed that CeO2-modified WC-12Co coating possessed better sliding wear resistance than that of conventional WC-12Co coating at the tested temperatures. The maximum microhardness value of 1333 ± 25HV0.5 was available at the temperature of 550 °C for CeO2-modified WC-12Co coating worn track. The oxides formed on the worn surface played a significant role on the wear behavior. W2C, Co3O4 and ratio of CoWO4/WO3 dominated the wear behavior of the coating at 450, 550 and 650 °C, respectively. 相似文献
15.
Liam P. Ward Antony Pilkington 《Journal of Materials Engineering and Performance》2014,23(9):3266-3278
WC-based cermet coatings containing various metallic binders such as Ni, Co, and Cr are known for their superior tribological properties, particularly abrasion resistance and enhanced surface hardness. Consequently, these systems are considered as replacements for traditional hard chrome coatings in critical aircraft components such as landing gear. The purpose of this investigation was to conduct a comparative study on the dry sliding wear behavior of three WC-based cermet coatings (WC-12Ni, WC-20Cr2C3-7Ni, and WC-10Co-4Cr), when deposited on carbon steel substrates. Ball on disk wear tests were performed on the coatings using a CSEM Tribometer (pin-on-disk) with a 6-mm ruby ball at 20 N applied load, 0.2 m/s sliding velocity, and sliding distances up to 2000 m. Analysis of both the coating wear track and worn ruby ball was performed using optical microscopy and an Alphastep-250 profilometer. The results of the study revealed both wear of the ruby ball and coated disks allowed for a comparison of both the ball wear and coating wear for the systems considered. Generally, the use of Co and Cr as a binder significantly improved the sliding wear resistance of the coating compared to Ni and/or Cr2C3. 相似文献
16.
Marzanna Ksiazek Lukasz Boron Marta Radecka Maria Richert Adam Tchorz 《Journal of Materials Engineering and Performance》2016,25(8):3185-3193
The aim of the investigations was to compare the microstructure, mechanical, and wear properties of Cr3C2-NiCr+Ni and Cr3C2-NiCr coatings deposited by HVOF technique (the high-velocity oxygen fuel spray process) on ductile cast iron. The effect of nickel particles added to the chromium carbide coating on mechanical and wear behavior in the system of Cr 3 C 2 -NiCr+Ni/ductile cast iron was analyzed in order to improve the lifetime of coated materials. The structure with particular emphasis of characteristic of the interface in the system of composite coating (Cr 3 C 2 -NiCr+Ni)/ductile cast iron was studied using the optical, scanning, and transmission electron microscopes, as well as the analysis of chemical and phase composition in microareas. Experimental results show that HVOF-sprayed Cr3C2-NiCr+Ni composite coating exhibits low porosity, high hardness, dense structure with large, partially molten Ni particles and very fine Cr3C2 and Cr7C3 particles embedded in NiCr alloy matrix, coming to the size of nanocrystalline. The results were discussed in reference to examination of bending strength considering cracking and delamination in the system of composite coating (Cr 3 C 2 -NiCr+Ni)/ductile cast iron as well as hardness and wear resistance of the coating. The composite structure of the coating provides the relatively good plasticity of the coating, which in turn has a positive effect on the adhesion of coating to the substrate and cohesion of the composite coating (Cr3C2-NiCr+Ni) in wear conditions. 相似文献
17.
In the current study, Cr3C2-NiCr coating was deposited on the Ni-base superalloys by using high velocity oxyfuel (HVOF) process for high temperature
corrosive environment applications. Optical microscopy (OM), x-ray diffraction (XRD), scanning electron microscopy/energy-dispersive
analysis (SEM/EDAX), microhardness tester, and electro probe microanalyzer (EMPA) techniques were used to characterize the
coating with regard to coating thickness, porosity, microhardness, and microstructure. The thermogravimetric technique was
used to establish kinetics of corrosion. The hot corrosion behaviors of the bare and Cr3C2-NiCr coated superalloys were studied after exposure to aggressive environment of Na2SO4-60% V2O5 salt mixture at 900 °C under cyclic conditions. The structure of the as-sprayed Cr3C2-NiCr coating mainly consisted of γ-nickel solid solution along with minor phases of Cr7C3 and Cr2O3. Coating has porosity less than 1.5% and microhardness in the range of 850–900 Hv (Vickers hardness). Some inclusions, unmelted
and semimelted powder particles were observed in the structure of the coatings. The Cr3C2-NiCr coating has imparted necessary resistance to hot corrosion, which has been attributed to the formation of oxides of
nickel and chromium, and spinel of nickel-chromium.
This article was originally published inBuilding on 100 Years of Success, Proceedings of the 2006 International Thermal Spray Conference (Seattle, WA), May 15–18, 2006, B.R. Marple, M.M. Hyland, Y.-Ch. Lau, R.S. Lima, and J. Voyer, Ed., ASM International, Materials
Park, OH, 2006. 相似文献
18.
The advantageous oxidation and wear properties of Cr3C2-NiCr thermal spray coatings have resulted in them being extensively applied to combat erosion at high temperatures. Under these conditions, oxide layers take on an ever more significant role in determining the composite response. The response of blended powder-based carbide coatings for erosion applications has formed the basis for application of cermet-based coatings at elevated temperature. In this study, the oxidation mechanisms of as-sprayed and heat-treated Cr3C2-NiCr blended powder-based coatings are characterized. Interdiffusion between the coating phases with long-term exposure increased the Cr content of the matrix phase. This had a significant effect on the oxidation mechanism. The implications of the change in oxidation mechanism and oxide morphology on the coating response to high-temperature erosion are discussed. 相似文献
19.
T. S. Sidhu S. Prakash R. D. Agrawal 《Journal of Materials Engineering and Performance》2006,15(1):122-129
This article demonstrates the successful formulation of NiCrBSi, Cr3C2-NiCr, Ni-20Cr, and Stellite-6 coatings on an Fe-based superalloy by a high-velocity oxyfuel (HVOF) process for hot corrosion
applications. The microstructure, porosity, coating thickness, phase formation, and microhardness properties of the coatings
have been characterized using the combined techniques of optical microscopy, x-ray diffraction, scanning electron microscopy/energy-dispersive
x-ray analysis. A microhardness tester was used to determine the hardness of the coatings. The coatings in general exhibit
characteristic splat-like, layered morphologies due to the deposition and resolidification of successive molten or semimolten
powder particles. The NiCrBSi, Cr3C2-NiCr, and Ni-20Cr coatings have shown a nickel-base face-centered cubic (fcc) structure as a principal phase, whereas Stellite-6
coating has an fcc Co-rich metallic matrix. Oxides/spinel oxides are formed in small fraction as intersplat lamellae or globules
oriented parallel to the substrate surface. Coatings possess some unmelted/partially melted particles, inclusions, and porosity
less than 2%. The microhardness of the coatings is found to be higher than the superalloys. The Cr3C2-NiCr coating has indicated a maximum microhardness of 990 Hv, while a Ni-20Cr coating has shown a minimum value of about
600 Hv. This article is focused on the characterization of HVOF coatings. The hot corrosion behavior of these coatings in
a molten salt (Na2SO4-60%V2O5) environment at 900 °C under cyclic conditions is being presented as part II included in this issue. 相似文献
20.
Xinyi Li Chaofang Dong Qing Zhao Yu Pang Fasong Cheng Shuaixing Wang 《Journal of Materials Engineering and Performance》2018,27(4):1642-1653
Titania-based composite coatings were prepared by plasma electrolytic oxidation (PEO) treatment of Ti6Al4V alloy in electrolyte with α-Al2O3, Cr2O3 or h-BN microparticles in suspension. The microstructure, composition of PEO composite coatings were analyzed by SEM, EDS and XRD. The wear resistance of composite ceramic coatings was studied by ball-on-disk wear test at ambient temperature and 300 °C. The results showed that the addition of microparticles accelerated the growth rate of PEO coating and changed the microstructure and composition of PEO coating. PEO coating was porous and mainly composed of rutile-TiO2, anatase-TiO2 and Al2TiO5. PEO/α-Al2O3 (Cr2O3 or h-BN) composite coating only had small micropores and appeared some α-Al2O3 (Cr2O3 or h-BN) phase. Besides, the addition of α-Al2O3 (Cr2O3 or h-BN) microparticles greatly improved the wear resistance of PEO coating. At ambient temperature, abrasive wear dominated the wear behavior of PEO coating, but abrasive wear and adhesive peel simultaneously happened at 300 °C. Whether at ambient temperature or 300 °C, PEO composite coating had better wear resistance than PEO coating. Besides, PEO/h-BN composite coating outperformed other composite coatings regardless of the temperature. 相似文献