High-Temperature Superlubricity Realized with Chlorinated-Phenyl and Methyl-Terminated Silicone Oil and Hydrogen-Ion Running-in.

Abstract

Ceramic friction pairs lubricated with chlorinated-phenyl and methyl-terminated silicone oil (CPSO) systems have potential applications in the aerospace industry. In this study, the effects of the running-in process and temperature on the lubricating performance of CPSO were investigated. The superlubricity of Si3N4/sapphire lubricated with CPSO was realized at >190 °C after H+-ion running-in. The mechanism of this high-temperature superlubricity was investigated by determining the stable adsorption configurations and adsorption energies of CPSO on different surfaces using density functional theory calculations. Compared with that on the Si3N4 surface, the adsorption capacity of CPSO on the hydroxylated SiO2 surface generated by H+-ion running-in increased, whereas the steric hindrance decreased. The viscosity-temperature curve of CPSO was measured, wherein the viscosity and pressure-viscosity coefficient of CPSO considerably decreased with increasing temperature, leading to high-temperature superlubricity in a wide speed/load range. This is the first paper to report oil-based superlubricity at temperatures of 190 °C, or even higher-temperature conditions. Furthermore, it provides guidance for the use of ceramic-CPSO systems in high-temperature conditions, including in the aerospace industry.