Influence of Al2O3 on the oxidation resistance of SiC ceramic: First-principle study and experiment

The influence of Al2O3 on the oxidation resistance of SiC was studied by first-principle calculation and oxidation test. The oxidation process of the Al2O3-doped SiC ceramic divides into three stages. At first, Al atom diffuses into the generated SiO2 and substitutes Si atom to form AlOSi ring. Then, the ring is damaged due to the reaction between the O atom in AlO bond and CO molecule, causing a CO2 molecule and an O vacancy formation. Finally, once O2 or another CO molecule approaches O vacancy, AlOOSi or AlOCSi ring will be formed to recover the network structure of SiO2.