Interface analysis of ceramic matrix composites by XPS, AES, SEM and XRD

The analysis of interfaces between silicon carbide or carbon fibres and a glassy sol-gel derived SiO 2 matrix in ceramic matrix composites (CMC) is presented. The x-ray photoelectron spectra (XPS) indicate a differential charging effect on all samples, potentially related to the adhesion strength at the interface. By Auger electron spectroscopy (AES) a silicon oxide layer is found on the surface of SiC fibres while no oxygen is detected on the C fibres. Effects of ageing in air or nitrogen at high temperature for 100 h were also studied. While no crystalline phases are present in the x-ray diffraction (XRD) patterns of sintered samples before ageing, different amounts of an SiO 2 (low cristobalite) phase appear on beating at 1200 o C in air or in N 2