Oxidation and microstructure of SiCf/SiC composites in moist air up to 1600°C by X‐ray tomographic characterization. Issue 3 (5th January 2020) - Lu, Zilong
Abstract: SiCf /SiC composites that possess PyC or BN interface layers were fabricated and then oxidized in moist air at 1000, 1200, 1400, and 1600°C. High‐resolution CT was used for capturing 3D images and quantifying the SiC phase, mesophase, and voids. The oxidation behavior and microstructural evolution of SiCf /SiC with PyC or BN interface are discussed in this study. The microstructure of the SiCf /SiC with a PyC layer was seriously damaged in moist air at high temperature, whereas the BN interface layer enhanced the oxidation resistance of the SiCf /SiC. These results are also confirmed by using XRD, oxidation mass gain, tensile testing, and SEM measurements. The results of the oxidation behavior and microstructural evolution for SiCf /SiC oxidized in dry air are also compared with the results of this study. Comparing the SiCf /SiC with a PyC interface layer, the composite with a BN interface layer oxidized in moist air exhibits a high void growth rate and a low SiO2 grain growth rate from 1000 to 1600°C. This work will provide guidance for predicting the service life of SiCf /SiC for multiscale damage rate models of materials at a local scale and will also provide guidance on the life service design of SiCf /SiC materials.