Water vapor corrosion behavior of SiC-Al40Y ceramics fabricated by reactive melt infiltration and thermal diffusion
The corrosion resistance of Y-Al diffused SiC ceramics (SiC-Al40Y) at 1100–1300 °C was investigated. The results show that the weight gain curves comply with the parabolic fitting formula, then the oxidation rate constant and the activation energy were calculated to be 1.653 × 10 −5 (1100 °C), 3.704 × 10 −5 (1200 °C), 9.306 × 10 −5 (1300 °C) mg 2 /cm 4 s and 154.7 kJ/mol. Compared with reported SiC (41–147 kJ/mol), the higher activation energy indicates the better corrosion-resistant performance. And it is found that the Y-Al diffusion layers can be transformed to corrosion-resistant YAlSi x O y layers under corrosive atmosphere. Eventually, based on experimental results, the corrosion-resistant mechanism is analyzed: chemical potential gradient caused by preferential oxidation of Y-Al prompts the immigration of Y-Al from matrix to surface, gradually forming a continuous Y/Al-silicate layer on the surface and thus can hinder the further corrosion of H 2 O, O 2 .
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