Effect of temperature and oxidative atmosphere on the oxidation behavior of yttrium-containing ceramics

Yttrium-containing ceramics exhibit excellent resistance to water-oxygen corrosion, making them an attractive choice as the modified matrix for SiCf/SiC composites. However, the oxidation products of yttrium-containing ceramics are complex and vary widely in performance. In this study, YSOC ceramics, which are composed of yttrium silicate, SiO2, and SiC, were prepared using Y2O3, SiO2, SiC, and Li2CO3. This research investigated the effects of high temperatures, air oxidation, and water-oxygen corrosion on the phase compositions of YSOC ceramics. The influence of environmental factors on the synthesis and decomposition of yttrium silicate was analyzed. Moreover, the study explored the compatibility of different oxidation products with SiC. The results suggest that Y2SiO5 and Y2Si2O7 are formed through the low eutectic of SiO2, Y2O3, and Li2CO3. The high SiO2 content likely contributes to the relatively low formation temperature of Y2Si2O7. In the oxidizing environment, Y2SiO5 reacts with SiO2 to produce Y2Si2O7. Conversely, in the water vapor-containing atmosphere, Y2Si2O7 undergoes hydrolysis to form Y2SiO5. Y2Si2O7 displays a reduced elastic modulus in comparison to SiC fibers and exhibits favorable physical and chemical compatibility with SiC fibers. However, the hydrolysis of Y2Si2O7 may potentially affect the water-oxygen corrosion resistance of the ceramics. These findings will significantly advance research and enhance understanding of the water-oxygen corrosion behaviors of yttrium-containing matrixmodified composites.