Elevated-Temperature Toughness and Hardness of a Hot-Pressed Al2O3-WC-Co Composite

• Published in: Journal of the American Ceramic Society Vol. 81; no. 1; pp. 257 - 259
• Main Authors: Tai, Weon-Pil, Watanabe, Tadahiko
• Format: Journal Article
• Language: English
• Published: Westerville, Ohio American Ceramics Society 01-01-1998; Blackwell
• Subjects: Applied sciences; Building materials. Ceramics. Glasses; Ceramic industries; Chemical industry and chemicals; Exact sciences and technology; Structural ceramics; Technical ceramics; Mechanical properties; Dispersion reinforced material; High temperature; Hardness; Experimental study; Cobalt; Composite material; Structural ceramic; Fracture toughness; Hot pressing; Cermet; Tungsten Carbides; Sintering; Manufacturing; Alumina
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/j.1151-2916.1998.tb02328.x

The fracture toughness and hardness of an Al2O380WC10Co composite were investigated in air at elevated temperatures. The primary phases in the composite were WC, α‐Al2O3, and Co3W3C, but small amounts of Co and C (graphite) appeared at elevated temperatures, related to decomposition of the Co3W3C phase. The fracture toughness of the composite was constant with increasing temperature up to 330°C and then increased in the range 400° to 550°C. A transition of brittle to ductile behavior occurred at about 700°C. The enhancement of fracture toughness at elevated temperature is attributed to the decomposition of Co3W3C to Co and C, and enhanced crack deflection and bridging. Decreases in hardness with increasing temperature are attributed to the softening of WC matrix and decomposition of Co3W3C.