Surface studies of SiC/SiCf composites exposed to relevant fusion reactor conditions

SiC/SiCf ceramic composites are interesting materials for applications in f usion technology due to their high performance and low activation character istics. Combining microbeam RES and proton-induced x-ray emission (PIXE) wi th XPS and x-ray diffraction techniques, we study the structural changes th at occurred in SiC/SiCf composites exposed to Li silicate and Li titanate b reeder materials in fusion-relevant conditions, After 216 h of exposure at 800 degrees C the RES spectra show the surface oxidation in all composites. Diffusion of Li and Ti into the composites was also observed. After 1000 h , the oxide layer extends for several micrometres, Microbeam analyses show the presence of titanium-rich precipitates in the samples exposed to the Li 2TiO3 ceramic breeder, together with some iron contamination, The x-ray dif fraction spectra reveal the formation of SiO2 and some Li-rich phases. Thes e findings are supported by the results of the XPS measurements. Copyright (C) 2000 John Whey & Sons, Ltd.