Microstructure and Properties of Plasma Sprayed CoCrAl-B_4C Coating

CoCrAl-B4C coating was successfully deposited by air plasma spray technology.The coating microstructure,microhardness,bonding strength,thermal shock and tribological performance were analyzed.The results show that the microhardness and bonding strength of CoCrAl-B4C coating are 980HV0.2 and 17.5 MPa respectively,and no failure occurs after ten time's thermal shock tests at 900 ℃;The lower friction coefficients of CoCrAl-B4C coating appear when the coating in water vapor atmosphere or preheating treatment at 700 ℃,which are attributed to the formation of B2O3 and H3BO3 lubricating phases on the worn surface.