High temperature stability of SiC/mullite mini composites

Abstract To clarify the failure behavior of SiC/mullite composites, the microstructure, micro‐ and macro‐mechanical properties of the mini composites after annealing were investigated to estimate the high temperature stability. The as‐received composites presented favorable flexural strength (∼629.6 MPa) and applicable interfacial bonding strength (∼26.2 MPa). The composites exhibited well high temperature stability at the temperature not exceeded 1400°C. Meanwhile, SiC fiber and mullite displayed relatively stable micro mechanical properties. The enhanced interfacial bonding strength caused by the further shrinkage of mullite matrix during annealing was responsible for the decreased flexural strength of the composites. The carbothermal reduction between SiC fiber and mullite matrix occurred at 1500°C, the microstructure of the composites was damaged and a strong chemical bonding formed. Consequently, the annealed composites showed remarkable weight loss and mechanical properties degradation.