Microstructure and Sliding Wear Performance of Cr₇C₃-(Ni,Cr)₃(Al,Cr) Coating Deposited from Cr₇C₃ In Situ Formed Atomized Powder

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• 作者：Hong-Bin Zhu ; Jie Shen ; Feng Gao ; Yueguang Yu…
• 关键词：Cr7C3 ; (Ni ; Cr)3(Al ; Cr) ; gas atomization ; HVOF ; wear resistance
• 刊名：Journal of Thermal Spray Technology
• 出版年：2017
• 出版时间：January 2017
• 年：2017
• 卷：26
• 期：1-2
• 页码：254-264
• 全文大小：
• 刊物类别：Chemistry and Materials Science
• 刊物主题：Surfaces and Interfaces, Thin Films; Tribology, Corrosion and Coatings; Characterization and Evaluation of Materials; Operating Procedures, Materials Treatment; Analytical Chemistry;
• 出版者：Springer US
• ISSN：1544-1016
• 卷排序：26

文摘

This work is aimed at developing a new type of Cr₇C₃-(Ni,Cr)₃(Al,Cr) coating for parts used in heavy-duty diesel engines. The feedstock, in which the stripe-shaped Cr₇C₃ was in situ formed, was firstly prepared by vacuum melting and gas atomization and then subjected by high-velocity oxy-fuel spraying to form the coatings. The carbon content, microstructure and phase constitution of the powders, as well as the sprayed coatings, were analyzed by chemical analysis, SEM and XRD. The hardness and sliding wear performance of the sprayed coatings were also tested and compared to a commercial Cr₃C₂-NiCr coating used on piston rings. The results showed that the content of carbon in feedstock was almost the same as designed, and that the volume content of in situ formed Cr₇C₃ was increased with carbon and chromium added. The major phases of the powders and sprayed coatings are Cr₇C₃ and Cr-alloyed Ni₃Al. Only a small amount of carbon lost during the spraying process. As Cr₇C₃ content increased in the coatings, the microhardness at room temperature was firstly increased to about 1000Hv_0.3. The microhardness of the coatings stayed almost constant, while the testing temperature was raised up to 700 °C for 0.5 h, which illustrates the potential application of the investigated coatings under high temperature conditions. The coatings containing 70 and 77 vol.% Cr₇C₃ showed the most promising wear resistance, lower friction coefficient and better tribological compatibility to gray cast iron counterpart than other tested Cr₇C₃-(Ni,Cr)₃(Al,Cr) coatings and the reference Cr₃C₂-NiCr coating.