WC颗粒尺寸对超音速火焰喷涂WC–10Co4Cr涂层组织及力学性能的影响

Effect of WC grain size on the microstructure and mechanical properties of HVOF-sprayed WC–10Co4Cr coatings

采用超音速火焰喷涂技术(high velocity oxygen-fuel,HVOF)制备了纳米结构、亚微米结构及常规结构的WC-10Co4Cr涂层,研究了沉积过程中颗粒尺寸对WC脱碳行为的作用,分析了WC颗粒尺寸对复合涂层微观组织、硬度、断裂韧性及界面结合强度的影响。结果表明:随着WC颗粒尺寸的增大,WC脱碳率和涂层孔隙率先增大后减小,而涂层硬度和断裂韧性先减小后增大,界面结合强逐渐降低。在100 g压痕载荷下,亚微米和常规结构涂层硬度的Weibull分布呈双峰特征,而在300 g压痕载荷下,3种结构涂层硬度的Weibull分布均呈单峰特征,这是3种结构涂层的WC脱碳程度、层间结合力和孔隙率综合作用结果。WC-10Co4Cr纳米结构涂层呈现出低脱碳率、高硬度、高界面结合强度和适中断裂韧性的优异综合性能。

WC–10Co4Cr coatings were fabricated by high-velocity oxygen-fuel spraying technology(HVOF)with the nano-structure,submicron-structure and regular microstructure.The influence of grain size on the decarburization of WC powder particles during the deposition processes was studied,and the effects of WC grain size on the microstructure,microhardness distribution,fracture toughness,and interfacial bonding strength were investigated systematically.In the results,with the increasing of the WC grain size,the WC decarburization and porosity of the WC–10Co4Cr coatings firstly increase and then decrease,while the microhardness and fracture toughness firstly decrease and then increase,and the interfacial bonding strength shows a trend of gradual decrease.The Weibull analysis of microhardness for the submicron-structured and regular microstructured coatings exhibits a bimodal distribution under the indentation load of 100 g,whereas the coatings with three kinds of microstructures exhibit a monomodal distribution under the indentation load of 300 g,which is mainly attributed to the mutual effect of the WC decarburization,interlaminar binding force,and porosity of the coatings.The nanostructured coating exhibits the best comprehensive performance of low decarburization,high interfacial bonding strength,superior microhardness,and fracture toughness.