Crack‐healing and mechanical behaviour of Al₂O₃/SiC composites at elevated temperature

ABSTRACT Alumina/silicon carbide (Al 2 O 3 /SiC) composite ceramics with large self‐crack‐healing ability, high strength and high heat‐resistance limit temperature for strength were developed and subjected to three‐point bending. A semicircular surface crack 100 μm in diameter was made on each sample. Crack‐healing behaviour was systematically studied, as functions of crack‐healing temperature and healing time, and the fatigue strengths of the crack‐healed sample at room temperature and 1373 K were investigated. Four main conclusions were drawn from the present study. (1) Al 2 O 3 /SiC composite ceramics have the ability to heal after cracking from 1273to 1673 K in air. (2) The heat‐resistance limit temperature for strength of the crack‐healed sample is ≅1573 K, and ≅68% of the samples fractured from outside the crack‐healed zone in the testing‐temperature range 873–1573 K. (3) The crack‐healed sample exhibited very high fatigue limit at room temperature and also 1373 K. (4) The large self‐crack‐healing ability is a desirable technique for the high structural integrity of ceramic component.