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.