A NiCr-based high temperature self lubricating coating PM304 prepared by powder metallurgy

PM304 coating comprised of 60% Ni80Cr20 and self-lubricating additives of 20% Cr₂O₃, 10% Ag and 10% BaF₂/CaF₂ eutectic has been prepared by high-energy ball milling and powder metallurgy. Experimental results showed that the sizes of Cr₂O₃ and BaF₂/CaF₂ in PM304 coating sintered at 1100°C for 2 h are about 100 nm and 1 μm, respectively, and that of Ag particles is below 5 μm, the relative density of the coating is 94%, and the mean tensile strength is 47 MPa, 33% greater than that of PS304 coating prepared by plasma spraying. The mean thermal expansion coefficient of PM304 is about 12.6 × 10^-6°C in the temperature range of 200-800°C. The friction coefficient of PM304 coating is lower than that of PS304 coating at temperatures from 20 to 650°C.