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Recently, the authors developed Si 3 N 4 , Al 2 O 3 and mullite ceramics with good self-crackhealingabilities. It was shown that the optimized crack-healing condition to get hightemperature strength was: 1573K, 1 h, in air, and the healed zone exhibited the same strengthas the base material. Using this good healing ability, a new methodology to guarantee thereliability of ceramic components “crack-healing + proof test” was proposed. However, if acrack initiated during service, reliability would be severely impaired. Therefore, if a materialcan crack-heal during service, and if the healed zone has enough strength at the temperatureof healing, it would be very desirable for structural integrity. From the above points of view,a new methodology to guarantee the structural integrity of ceramic components using in-situcrack-healing ability was proposed and the usefulness was discussed using the test results interms of crack-healing behavior and proof test theory by the authors.