Strength of hot pressed ZrB2–SiC composite after exposure to high temperatures (1000–1700°C)

• Published in: Journal of the European Ceramic Society 2012-12, Vol.32 (16), p.4455-4467
• Main Authors: Patel, Manish, Reddy, J. Janardhan, Bhanu Prasad, V.V., Jayaram, Vikram
• Format: Article
• Language: English
• Subjects: A. Hot pressing; Ceramics; D. Borides; Flexural strength; Microstructure; Multilayers; Oxidation; Oxides; Residual strength; Scale formation; Silicon carbide; Strength; Ultra High Temperature Ceramics
• ISSN: 0955-2219; 1873-619X
• DOI: 10.1016/j.jeurceramsoc.2012.06.025

Residual strength (room temperature strength after exposure in air at high temperatures) of hot pressed ZrB2–SiC composites was evaluated as function of SiC contents (10–30vol%) as well as exposure temperatures for 5h (1000–1700°C). Multilayer oxide scale structures were found after exposures. The composition and thickness of these multilayered oxide scale structure was dependent on exposure temperature and SiC contents in composites. After exposure to 1000°C for 5h, the residual strength of ZrB2–SiC composites improved by nearly 60% compared to the as-hot pressed composites with 20 and 30vol% SiC. On the other hand, the residual strength of these composites remained unchanged after 1500°C for 5h. A drastic degradation in residual strength was observed in composites with 20 and 30vol% SiC after exposure to 1700°C for 5h in ZrB2–SiC. An attempt was made to correlate the microstructural changes and oxide scales with residual strength with respect to variation in SiC content and temperature of expsoure.