Study On Performance Of WC/Ni Composite Coating And Coating Preparation On Sphere Surface

With the improvement of the industrial level,the demand for the surface properties of the material is more stringent,and the surface strengthening technology has developed rapidly.Vacuum brazing technology as a kind of surface strengthening method has been widely used from the ordinary metal to the aircraft,nuclear energy and other defense industries.In this project,the vacuum brazing technology was used.The casting spherical WC particles and Ni based solder were used as composite coating materials.A uniform and continuous composite coating was prepared on the surface of 304 stainless steel,and the thickness of the coating was 0.8-2mm.Through the micro characterization of the coating,elemental testing,hardness test and high temperature erosion test,we got the results:even WC particle distribution was observed without particle precipitation,no pore or crack.The diffusion interface was developed between 304 stainless steel and coating,achieving micro metallurgical bonding and enhancing.the interface bonding strength.Dissolved diffusion burning and collapsing burn were detected and their extent decreased with the increase in WC weight concentration.When the coating thickness is 4mm,there is a crack in the coating due to the difference of thermal expansion coefficient.The composite coating is a brittle material,and the erosion resistance increases with the decrease of the erosion angle.During high temperature erosion,the mechanism of the 304 matrix is erosion and oxidation interaction,in which the erosion plays the leading role.The erosion mechanism of the composite coating is micromachining.At 200? the 35%.wt WC composite coating has the best erosion resistance,and the45%.wt WC composite coating has the best erosion resistance at 300?.The WC/Ni composite coating was finally prepared on the surface of the 304 sphere.Through microscopic observation and hardness test,the coating particles inside the coating was uniform distribution,and there was no particle aggregation and sinking phenomenon.The hardness distribution decreases with the thickness direction of the coating...