Design and preparation of high-performance alumina functional graded self-lubricated ceramic composites

High-performance self-lubricated ceramic composites are regarded as potential candidates for space applications. This paper proposes a new design for alumina ceramic self-lubricating composites in order to overcome the conflict between their mechanical and tribological properties. Complying with the design principle of bionic and graded composites, Al2O3/Al2O3-ZrO2(3Y)/SL composites with laminated-gradient structure were prepared, and their mechanical and tribological properties were studied. The results show that this newly-developed ceramic composite achieves satisfactory strength and tribology properties compared with the traditional ceramic self-lubricated composites. The bending strength, which was five times higher than that of traditional Al2O3 self-lubricated composites, reached the same level as the properties of general monolithic Al2O3 ceramics. In the temperature range of 25-800 °C, the friction coefficient of Al2O3/Al2O3-ZrO2(3Y)/SL composite was less than 0.54, which was about half of that of monolithic Al2O3 ceramics.