Silicon Carbide Material Fabricated using Sintering Additives of Y₂O₃ and Its Oxidation Characteristics

Silicon carbide (SiC) is widely recognized as a promising structural ceramic material owing to its outstanding mechanical and thermal properties, including high strength, hardness, wear resistance, corrosion resistance, and thermal stability. In this study, SiC specimens were fabricated via a liquid-phase sintering technique utilizing Y₂O₃ and SiO₂ as sintering additives. The mechanical performance of the sintered bodies was evaluated through measurements of bulk density and three-point flexural strength. To further investigate the high-temperature oxidation behavior, the mass change and oxide layer thickness of the specimens were examined after thermal exposure. Microstructural and morphological analyses of the oxidized surfaces and cross-sections were conducted using scanning electron microscopy. Additionally, flexural strength tests were performed on oxidized specimens to assess mechanical degradation due to oxidation. The liquid-phase sintered SiC specimens exhibited typical brittle fracture characteristics, with an average flexural strength of approximately 316 MPa in the as-sintered state. Upon oxidation at elevated temperatures, the flexural strength varied depending on the exposure temperature: 189 MPa at 1,200℃, 285 MPa at 1,300℃, and 267 MPa at 1,400℃. The specimen oxidized at 1,300℃ for 10 hours demonstrated the greatest oxide layer thickness and the highest post-oxidation flexural strength.