Wear performance of ZrO2 reinforced stellite 6 matrix coatings prepared by laser cladding at elevated temperature

Abstract

In order to modify the wear resistance of Stellite 6 superalloy as wear resistant coating at room temperature-1000 °C, the different contents (1.0, 2.5 and 4.0 wt%) of ZrO₂ reinforced Stellite 6 matrix coatings were fabricated over the Inconel 718 nickel alloy substrate by laser cladding technology. The microstructure, hardness and high-temperature wear behavior of Stellite 6 matrix coatings with ZrO₂ was systematically studied. The sliding wear test were done using a ball-on-disk tribometer against Si₃N₄ at room temperature-1000 °C. The results showed that the ZrO₂ showed obvious fine-grain strengthening and dispersion strengthening effect. The hardness of coatings reinforced by ZrO₂ were 470–540 Hv. A critical valve of ZrO₂ content was existed for the wear performance of Stellite 6 matrix coatings. The coating with 2.5 wt% ZrO₂ had the desirable wear resistance, and the wear rate was in the order of 10⁻⁵ mm³/N.m. This was attributed to the high microhardness and the formation of solid lubricants, as well as the friction film on the sliding surfaces.