Characterization of the oxidation of C/C/SiC composites by Xray micro-tomography

The objective of this paper is to determine the influence of the nature of the C/C/SiC composite on the oxidation rate of fibers and the interphase and the development of oxidation pathways using characterization techniques such as Xray micro-tomography (mu CT), scanning electron microscope (SEM) and optical microscopy (OM). The microstructure of two C/C/SiC composites (named 2D-RMI and 2D-CVI) was characterized before and after ageing tests performed by Thermogravimetric Analysis (TGA) under dry air at 1000 degrees C and 1300 degrees C. The three techniques are complementary and tomography appears to be a promising means for monitoring the oxidation of parts in service. Moreover, the oxidation of a fiber does not develop in a parallel plan to the section but as conical shape. To calculate the oxidation kinetics related to the surface, it is therefore necessary to take into account the geometry of the fibers that offers a much more important reactive surface.