Thermal Stability and High-Temperature Super Low Friction of γ-Fe 2 O 3 @SiO 2 Nanocomposite Coatings on Steel.

The thermal stability of the γ-Fe₂O₃@SiO₂ nanocomposites and super low friction of the γ-Fe₂O₃@SiO₂ nanocomposite coatings in ambient air at high temperature are investigated in this paper. X-ray diffraction, scanning electron microcopy, transmission scanning electron microcopy, high-temperature tribometer, thermogravimetric analysis and differential scanning calorimetry were used to investigate the microstructure, surface morphology and high-temperature tribological properties of the γ-Fe₂O₃@SiO₂ nanocomposite coatings, respectively. The results show that the γ-Fe₂O₃@SiO₂ nanocomposite with the core–shell structure has excellent thermal stability because the SiO₂ shell inhibits the phase transition of the γ-Fe₂O₃ phase to the α-Fe₂O₃ phase in the nanocomposites. The temperature of the phase transition in γ-Fe₂O₃ can be increased from 460 to 829 °C. The γ-Fe₂O₃@SiO₂ nanocomposite coatings exhibit super low friction (0.05) at 500 °C. A high-temperature super low friction mechanism is attributed to γ-Fe₂O₃ and the tribochemical reactions during sliding. [ABSTRACT FROM AUTHOR]