Study of Structure and Phase Composition of Ni + B4C Composite Coatings Produced by Cold Gas-Dynamic Spraying

Abstract—The effect of thermal treatment on the microstructure, phase composition, and microhardness of Ni + B4C composite coatings is studied. The coatings are deposited onto the surface of an austenitic steel by cold gas-dynamic spraying. The initial coating is shown to be a nickel matrix containing distributed B4C particles. Thermal treatment causes diffusion processes in the coating, which results in the formation of Ni3B and Ni2B compounds. The average microhardness of the initial coating is 3.4 GPa, and heat treatment results in an increase in the coating microhardness due to the formation of hard nickel borides.