Study of solid-state reactions of SiC/SiCf composites using microbeams

Among the advanced materials with potential interest for applications in fusion technology the SiC/SiCf composites are considered to be one of the most promising. We used microbeam RBS and PIXE techniques to follow the structural changes of several SiC/SiCf samples in contact with lithium orthosilicate and lithium titanate breeders at 800 deg. C for different time intervals. After 216 h of exposure the strongest reaction taking place was the oxidation of the composites. The oxidation rate was faster in the samples exposed to the orthosilicate. Simultaneously, lithium diffuses into all the composites and there is a noticeable loss of carbon. For longer exposure the thickness of the oxide layers extends to values above the depth of ion beam analysis. The formation of Ti-rich precipitates was also observed in the samples in contact with the Li titanate