High-temperature low-friction behaviors of γ-Fe2O3@SiO2 nanocomposite coatings obtained through sol–gel method

In the present paper, the γ-Fe2O3@SiO2 nanocomposite is prepared by sol–gel method and the γ-Fe2O3@SiO2 nanocomposite coatings are deposited on the steel substrate. The microstructure, surface topography, and tribological properties of the γ-Fe2O3@SiO2 nanocomposite were measured and investigated by X-ray diffraction (XRD), fourier transform infrared spectrometry (FTIR), transmission electron microcopy (TEM), and high-temperature tribometer, respectively. The tribotest were performed by high-temperature tribometer in the temperature ranges from 400 to 600 °C to investigate the tribological properties of the nanocomposites under high temperature. The experimental results show that there is the core-shell structure in the γ-Fe2O3@SiO2 nanocomposite. It is also found that the γ-Fe2O3@SiO2 nanocomposite coatings exhibit low friction (0.05) from 500 to 600 °C. XRD measurements show that low-friction behavior of the friction pair under high temperature is involved in the transformation between α-Fe2O3 and γ-Fe2O3 and the oxidations of the steel substrate during sliding. The core-shell structure of the nanocomposites inhibits γ-Fe2O3 of the soft phase changing into α-Fe2O3 phase and the thermal energy of the friction heat activates the oxidation of the steel substrate in ambient air, which are beneficial to form low shear interface and achieve high temperature low friction.