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 SiC_f/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 matrix-modified composites.