Surface Engineering Design of Alumina/Molybdenum Fibrous Monolithic Ceramic to Achieve Continuous Lubrication from Room Temperature to 800 °C

Al₂O₃/Mo fibrous monolithic ceramics are potential candidates for high-temperature applications because of their excellent high-temperature self-lubricated and fracture properties. This study aims at achieving the good self-lubricating ability at a wide temperature variation from room temperature (RT) to 800 °C and avoiding the abrasive wear of the material at the starting moment of the friction test. Three-dimensional composite-lubricating layers were formed by considering texture pattern as storage dimples and burnishing BaSO₄ solid lubricant (SL) on the textured surface of Al₂O₃/Mo fibrous monolithic ceramics. The friction properties and wear mechanisms were studied from RT to 800 °C in a continuous heating process. The results show that the synergy effect of micro-texture, BaSO₄ SL and oxidation products derived from Mo containing MoO₃ improved the lubricating performances of the material at each temperature stage, thus realizing continuous lubrication in a wide temperature range. It is demonstrated that the friction coefficient of textured surface coated with BaSO₄ SL was kept lower 0.57 when subjected to dry sliding against Al₂O₃ ceramic pin at the temperature from RT to 800 °C, and it even can be as low as 0.30 at 600 and 800 °C. This work is an extension of study that was previously published in Tribology Letters journal.