Tribological properties of hot-pressed SrSO4 ceramic at elevated temperatures in dry sliding against alumina ball

SrSO₄ ceramic was prepared by hot-pressed sintering and its friction behavior was investigated against the Al2O3 ball under the dry sliding condition from room temperature to 800 °C. From room temperature to 400 °C, the tribological properties of SrSO₄ ceramic are quite poor with the friction coefficients of 0.65-0.83 and the wear rates of about 10-3 mm3/Nm. With the testing temperature increasing to 600 °C and 800 °C, a brittle to ductile transition of SrSO₄ takes place because of the activated slip systems. The friction coefficient and wear rate of SrSO₄ ceramic also obviously decrease to 0.37 and about 10-4 mm3/Nm at 800 °C. The significant improvement of the tribological properties is ascribed to the formation of a smooth and continuous SrSO₄ lubricating film with excellent ductility and low shear strength at elevated temperature. SrSO₄ is considered to be a potential candidate for high-temperature solid lubricant with excellent lubricity.