WC粉末粒度对超音速火焰喷涂WC-CoCr涂层组织性能的影响

采用超音速火焰喷涂(HVOF)工艺制备了纳米结构、双峰结构和常规结构3种WC-CoCr复合涂层。探讨了不同WC粉末粒度对涂层沉积过程的脱碳行为、涂层微观组织及力学性能的影响。结果表明:随WC颗粒尺寸减小,涂层脱碳率增大,W_2C含量增加,孔隙率降低,涂层的显微硬度和界面结合强度增大;但是纳米结构涂层中粘结相的非晶化现象严重,断裂韧度显著下降;双峰结构涂层因纳米、亚微米WC颗粒的合理搭配和协同效应表现出最好的断裂韧性,同时兼具较高的显微硬度和界面结合强度。

Effect of WC particle size on the microstructure and properties of WC-CoCr coatings prepared by high velocity oxy-fuel spraying

WC-CoCr coatings with three kinds of microstructure of nanostructure,bimodal and conventional were fabricated by HVOF spraying.The influence of WC particle size on decarburization,microstructure and mechanical properties of coatings were discussed.Results show that,with the WC particle size decreasing,the decarburization rate of coating increases,the content of W2C increases,the coating porosity decreases,the micro-hardness of the coating and bonding strength of the interface increases.Nevertheless,more serious amorphization of binder in the nanostructured coating causes significant fracture toughness deterioration.Bimodal WC-CoCr coating combines the best fracture toughness as well as higher micro-hardness and interfacial bonding strength since reasonable collocation and synergistic effect of nano-sized and submicron-sized WC particles.