High temperature strength of silicon carbide sintered with 1Â wt.% aluminum nitride and lutetium oxide

A heat-resistant SiC ceramic was developed from submicron β-SiC powders using a small amount (1 wt.%) of AlN-Lu2O3 additives at a molar ratio of 60:40. Observation of the ceramic using high-resolution transmission electron microscopy (HRTEM) showed a lack of amorphous films in both homophase (SiC-SiC) boundaries and junction areas. The junction phase consisted of Lu-Si-O elements, and the homophase boundaries contained Lu, Al, O, and N atoms as segregates. The ceramic maintained its room temperature (RT) strength up to 1600 °C. The flexural strength of the ceramic was 630 MPa and 633 MPa at RT and 1600 °C, respectively.