A heat-resistant SiC ceramic was developed from submicron β-SiC powders using a small amount (1wt.%) of AlN–Lu 2 O 3 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 630MPa and 633MPa at RT and 1600°C, respectively.