PM304 coating on a Ni-based superalloy by PM technique

A PM304 coating for high-temperature lubrication has been prepared on a Ni-based superalloy by high-energy ball milling and powder metallurgy techniques. The microstructure of the PM304 coating is fine and dense and the size of the self-lubricating particles in the coating is very small. The size of the self-lubricating Cr2O3 particles is about 100 nm, that of BaF2/CaF2 and Ag particles about 1 and 5 μm, respectively, while those of BaF2/CaF2 and Ag particles precipitated from the NiCr matrix are less than 50 nm. The fine and dense microstructure result in increased tensile strength and crack-growth resistance of the PM304 coating, with a mean tensile strength of about 46 MPa.