Tribological properties of Ni-based composite coatings with addition of Ag@Ni core−shell particles over multiple thermal cycles

Abstract

In order to inhibit the diffusion of Ag, Ag@Ni core−shell structure particles were prepared by the electroless plating, and then the NiCrAlY−Mo−Ag@Ni coatings were prepared by atmospheric plasma spraying. The effects of core−shell structure design on the mechanical and tribological properties of the coatings over multiple thermal cycles were researched in detail. The results show that the core−shell structure design of Ag could enhance the interfacial bonding strength between Ag and NiCrAlY by the Ni-coated layer, and then improve the hardness of the coating obviously. The Ni-coated layer inhibits the diffusion and dissipation of Ag effectively in the friction process at high temperatures. The friction coefficient and wear rate of the NiCrAlY−Mo−Ag@Ni coating tested at 800 °C are only about 0.25 and 1×10−5 mm3/(N·m), respectively, which are obviously lower than those of the NiCrAlY−Mo−Ag coating. Meanwhile, the core−shell structure design of Ag endows the coating with excellent self-lubricating and wear resistance over multiple thermal cycles.