Abstract: Ni₃Al-based composite coatings containing different mass-fractions of Ag solid lubricant were prepared on the 310S austenitic stainless steel by laser cladding technology, and the effects of Agmass-fraction(5%, 10%, 15%) on the phase composition, microhardness, tribological properties and worn surface phase composition of the coatings were investigated. The results showed that the microhardness of the composite coatings decrease with the increasing of Ag content due to its soft nature, and the coating still has relatively high microhardness when the Ag content reach 10%, which is about 198.37 HV. The introduction of 10% Ag into the Ni₃Al coatingreduce the friction coefficients of the coating from 0.69~0.55 to0.62~0.41 at 25~800 ℃, and the wear ratesof the coating decrease from (2.27~1.60)×10^－5 mm³/(N·m)to (1.28~0.44)×10^－5 mm³/(N·m)at 400~800 ℃. The enhancement of the anti-friction ability of the composite coating is related to the synergistic lubrication of the diffusive migration of soft metal Ag within 25~400 ℃ and the oxidation products of Ni₃Al and Ag within 400~800 ℃; while the improvement of the wear resistance of the coating is associated with its higher mechanical strength and the formation of a continuous protective film on the worn surface.

Key words: laser cladding, Ni₃Al-based, tribological properties, lubricating