A comparative study of laser cladding high temperature wear-resistant composite coating with the addition of self-lubricating WS2 and WS2/(Ni–P) encapsulation

In order to inhibit its decomposition and improve its compatibility with the metal matrix during laser cladding, WS2 powder was encapsulated with a layer of micro Ni–P by electroless plating. The microstructure and tribological properties of the NiCr–Cr3C2/30%WS2 and NiCr–Cr3C2/30%WS2(Ni–P) high temperature self-lubricating wear-resistant composite coatings at RT (room temperature), 300 °C and 600 °C were investigated, respectively. It was found that the NiCr–Cr3C2/30%WS2(Ni–P) coating had a microstructure consisting of primary Cr7C3 dendrite, γ-(Fe,Ni)/Cr7C3 eutectic and solid lubricant particles WS2 and CrS, Ni–P electroless plating had decreased the decomposition of WS2 to some extent, the WS2 solid lubricant particles dispersed in the ductile γ-(Fe,Ni)/Cr7C3 matrix. Friction and wear experiments indicated that the tribological properties of the NiCr–Cr3C2/30%WS2(Ni–P) coating was better than that of NiCr–Cr3C2/30%WS2 coating, the NiCr–Cr3C2/30%WS2(Ni–P) coating presents lower friction coefficient at RT and 300 °C and lower wear rate from RT to the elevated temperature of 600 °C.

► A novel approach of Ni–P electroless plating was employed to encapsulated the solid lubricants WS2.
► The coating added with WS2(Ni–P) has a lower microhardness because of the formation of more volume fraction of relatively soft Ni based solid solution.
► The coating added with WS2(Ni–P) has a lower friction coefficient at room temperature, 300 °C, and a lower wear rate at all test temperatures.
► Ni–P electroless plating had inhibited the decomposition of WS2 and increased the compatibility with the metal matrix to some extent.