Static fatigue behavior of mullite/ 15 vol% SiC whiskers/ 10 vol% SiC particles multi-composite crack-healed was investigated at room temperature and high temperatures from 1000°C to 1200°C. The multi-composite is the most candidate material as ceramic spring, because it has low Young's modulus as well as its reliability is guaranteed by excellent crack-healing ability. For estimating the usefulness of the composite as ceramic spring at high temperature, we must know the static fatigue limit at high temperature. The multi-composite having pre-crack was crack-healed at 1300°C for 2 h in air. The times to failure were investigated when the crack-healed specimens were applied the elevated tensile stress in air at room temperature and high temperatures from 1000°C to 1200°C. From the obtained results, the static fatigue limit was determined. Below 1000°C, the static fatigue limit of the composite crack-healed was found to be almost equal to the corresponding bending strength. Alternatively the static fatigue limit of the composite crack-healed was found to have lower value than the corresponding bending strength above 1100°C. Thus, the heat-resistance limit temperature for static fatigue of the multi-composite was determined to be 1000°C.
