Prediction of Mechanical Properties of Void Defect-Containing Cf/SiBCN Ceramic Matrix Composite Based on a Multiscale Analysis Approach

Carbon fiber-reinforced SiBCN ceramic matrix composite (Cf/SiBCN CMC) is emerging as a promising candidate for advanced thermal protection systems, owing to its superior thermal stability and notable ablation resistance. In this study, the mechanical properties of Cf/SiBCN CMC are investigated theoretically and experimentally. Utilizing a multiscale approach, a representative volume element (RVE) is developed to predict mechanical properties based on detailed microstructural characterization. The predictions derived from the RVE demonstrate agreement with the experimental findings. The experimental results show dispersion in the mechanical properties of Cf/SiBCN CMC. To investigate whether the dispersion of mechanical properties is associated with defects, this study examines the impact of the location, content, and size of defects on the mechanical properties of the Cf/SiBCN CMC. The analysis reveals that the location, content, and size of defect all impact the mechanical properties of the Cf/SiBCN CMC, with overall porosity having the most significant effect. When the porosity is constant, variations in defect location and size also contribute to the observed variability in the mechanical performance of the Cf/SiBCN CMC.