Cfiber/SiCfiller/Si–B–C–Nmatrix composites with extremely high thermal stability

Precursor-derived Si–B–C–N ceramics are well known for their outstanding thermal stability up to 2000 °C. However, if they are integrated with long ceramic fiber fabrics, the thermal stability of the respective fiber–matrix composites decreases, and the associated thermomechanical properties worsen. A method of improving the thermal stability of a fiber-reinforced Si–B–C–N-based composite up to 1700 °C by the application of SiC filler particulates is reported. The mass loss of such composites is very low even after heating to 2100 °C. Remarkably, a pre-heat treatment of the SiC filler is essential in order to achieve the thermal stability of the ceramic matrix composites by removing surface SiO2. The composite described here retained 96% of its room-temperature strength and possessed non-brittle fracture behavior after heating at 1700 °C for 10 h in Ar. The flexural creep deformation of the composite at 1400 °C was only 0.25% after 60 h under 100 MPa pressure.