Tribological Properties and Lubrication Mechanism of Al₂O₃/Graphite–BaSO₄ Laminated Composites

Al₂O₃/Graphite-BaSO₄ laminated composites, combining graphite and BaSO₄ in a certain proportion as weak interfacial layer, were prepared by a layer-by-layer method, dry-pressing and spark-plasma-sintering. The influence of the composition of the multi-lubricant on the self-lubrication performance of laminated ceramics during continuous heating from room temperature to 800 ℃ was investigated, and the synergistic lubrication mechanism in a wide temperature range was discussed by analyzing the worn surfaces. Results show that combined strategies, i.e. incorporating different lubricants adapted for room temperature and medium high temperature, and unique layered structure of bionic laminated composites, effectively improved the tribological properties of materials at elevated temperatures, and hence the lubrication over a wide temperature range was realized. The friction coefficients of the optimal laminated materials coupled with Al₂O₃ pin were in a range of 0.20~0.48 from room temperature to 800 ℃, which was 60% lower than that of monolithic alumina ceramics.