作者: Fernando Rodríguez-Rojas , Angel L. Ortiz , Oscar Borrero-López , Fernando Guiberteau
DOI: 10.1016/J.JEURCERAMSOC.2012.05.004
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摘要: Abstract The long-term oxidation behaviour in air of pressureless liquid-phase-sintered SiC was investigated as a function the sintering-additive content (a mixture Y2O3 and Al2O3 3:5 molar ratio) at oxidizing temperatures interval 1100–1300 °C. It is shown that under these mild conditions always passive, with formation protective oxide scales. However, kinetics cannot be described appropriately by parabolic-rate law. Instead, due to gradual crystallization scales during oxidation, it more complex, exhibiting two different stretches given respectively arctan- laws. Furthermore, found rate-limiting mechanism initial arctan outward diffusion metal cations from secondary intergranular phase into scale, activation energy being very high decreasing 545 432 kJ/mol increasing 5 20 wt%. subsequent parabolic however inward oxygen through multicomponent lower than before also 345 205 kJ/mol increases resistance decreases content, but while decrease moderate up 10 wt%, marked for greater contents.