Enhanced thermal shock response of Al2O3–graphite composites through a layered architectural design

Abstract

AbstractThe use of ceramics such as alumina in moving components often requires the addition of low friction materials such as graphite. A new strategy for improving toughness, strength, and thermal‐shock resistance of Al2O3–graphite self‐lubricating composites was proposed in this study. Alumina layers embedded between Al2O3–graphite layers were fabricated and tested after thermal shock conditions ranging between 500 °C and 800 °C maximum temperature. Retained strength and apparent fracture toughness after the tests were compared to room temperature values. Results show that compressive residual stresses generated in the outer Al2O3–graphite layers during cooling down from sintering improve the failure resistance of the materials. The introduction of heat‐resistant particles (Al2O3 particles) into graphite layers combined with a layered architecture can greatly decrease the oxidation degradation of the materials below 500 °C. In addition, the retained strength and toughness in the layered architectures after thermal shock between 550 °C and 800 °C remains constant, thus indicating that the new‐developed Al2O3/Al2O3–graphite laminated composites may be reliable candidates for self–lubricating applications also for elevated temperatures.