Fracture strength of melt-infiltrated SiC-mullite composite

The fracture strength of a melt-infiltrated SiC-mullite composite was measured from room temperature to 1500°C using a three-point bending test. The strength under argon at atmospheric pressure was not high. Mullite decomposition was found to be severe even at 1100°C in a reducing atmosphere, thus significantly degrading its strength. The strength in air, where the decomposition was suppressed, was moderately high and retained up to 1100°C. The composite revealed typical brittle failure up to the highest investigated temperature of 1500°C, with an indication of failure by slow crack growth at high temperature.