Wear behavior of a NiCr/AgVO3 self-lubricating composite

Abstract

NiCr/AgVO3 self-lubricating composite was prepared by powder cold-pressed method with the NiCr alloy as the matrix and 10 wt.% additive of AgVO3 as solid lubricant. The AgVO3 additive powder was synthesized by the precipitation method which exhibits a melting point of 460 °C. Microstructure, phase composition and thermal properties of the AgVO3 powder, as well as the composite of NiCr/AgVO3 were analyzed using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray diffraction (XRD) and differential scanning calorimeter (DSC). The friction and wear behavior of the specimens from room temperature (R.T.) to 800 °C was evaluated using a ball-on-disk tribometer and 3D white light interference (WLI). The results showed that the friction coefficient of this material under atmosphere decreases with temperature increasing from R.T. to 800 °C. However, the wear rate firstly increases from R.T. to 200 °C, almost remains stable from 200 °C to 600 °C, and then decreases with further increasing the temperature up to 800 °C. It is also found that the prepared composite materials show a better frictional behavior than NiCr alloy over the whole range of temperatures, which is mainly attributed to solid lubrication of AgVO3 exhibiting a lamella-slip structure at temperatures below 460 °C and forms liquid-film at elevated temperatures above the melting point.