Effect of tensile stress on thermal fatigue life of ZrB2-SiC-graphite composite

Abstract The thermal fatigue life of ZrB 2 -SiC-graphite composite under tensile stress of σ 0  = 30, 40, 50 and 60 MPa respectively was investigated, in which a newly developed approach was used to obtain the surface temperature distribution of the specimen. In each test the specimen was subjected to thermal cycles between 25 °C and 2000 °C under constant σ 0 . It was found that, with the increase of σ 0 , the thermal fatigue life decreases remarkably, accompanying different types of microcracks and different fracture morphologies. It was inferred that under smaller σ 0 fracture may take place due to the coalescence of a lot of small microcracks, while under larger σ 0 the specimen could possibly fracture due to the continuous propagation of large microcracks. The thermal fatigue life subjected to thermal cycles between 25 °C and 2200 °C under different σ 0 was also tested, and the results showed the extremely low thermal fatigue life.