超音速等离子喷涂制备金属陶瓷涂层的抗冲蚀性能

Erosion Resistance of Cermet Coatings Deposited by Supersonic Atmospheric Plasma Spraying

通过高效能超音速等离子喷涂(SAPS)制备WC-Co及WC-Ni Cr金属陶瓷涂层,对比研究了2种涂层的抗冲蚀性能及在热腐蚀条件下的结构和性能演变。结果表明:2种涂层在喷涂过程中均会发生一定程度的脱碳,表现为W_2C相的形成;同时在WC-Co涂层中有少量的Co_3W_3C和Co_6W_6C相生成,且该涂层在热腐蚀后表层的WC相出现了分解与氧化,形成了W_3C、W_6C_(2.54)等脱碳相与CoWO_4、WO_3等氧化物相。在普通冲蚀条件下,WC-Co涂层的抗冲蚀性能更为优异,但热腐蚀会极大降低WC-Co涂层的抗冲蚀性能;与之相反,WC-NiCr涂层中的NiCr相在热腐蚀环境下生成的Cr_2O_3可以有效阻挡涂层内部与外部之间的物质扩散,从而降低了热腐蚀对涂层结构的破坏,在热腐蚀条件下表现出了优良的抗冲蚀性能。

WC-Co and WC-NiCr cermet coatings were deposited by high-efficiency supersonic atmospheric plasma spraying. The erosion resistance of both coatings was comparatively studied in normal or hot corrosion condition. Results indicate that the decarburization happens during the spray of WC-Co or WC-NiCr powders, which leads to the formation of W2C. Meanwhile, Co3W3 C and Co6W6 C are also found in the WC-Co coating. Some new phases, such as W3C, W6C（2.54）, CoWO4 and WO3, are observed in the WC-Co coating due to the decomposition and oxidation of WC during hot corrosion. WC-Co coating shows a higher erosion resistance than WC-NiCr coating; however, the erosion resistance of the former significantly decreases after hot corrosion. On the contrary, the Cr2O3 formed during hot corrosion can effectively protect WC from oxidation and thus improve the erosion resistance of the WC-NiCr coating.