Stability of SiC/SiC fibre composites exposed to Li4SiO4 and Li2TiO3 in fusion relevant conditions

The physico-chemical stability of a commercial 3D SiCf/SiC composite provided with an outer CVD SiC protective layer was studied after exposure to flowing helium with 0.1% H2 at 800°C in contact with lithium silicate and lithium titanate. Exposure tests were carried out for 216, 1000 and 10 000 h in an especially designed loop. The mechanical characteristics of the SiCf/SiC composite in contact with Li4SiO4 were almost unaffected by the exposure, while those in contact with Li2TiO3 were slightly worsened. SiC coating transformation was clearly detected on samples exposed to both lithium silicate and titanate.