The Effect of cBN Additions on Densification, Microstructure and Properties of WC-Co Composites by Pulse Electric Current Sintering

• Published in: Journal of the American Ceramic Society Vol. 95; no. 8; pp. 2499 - 2503
• Main Authors: Wang, Bo, Matsumaru, Koji, Yang, Jianfeng, Fu, Zhengyi, Ishizaki, Kozo
• Format: Journal Article
• Language: English
• Published: Columbus Blackwell Publishing Ltd 01.08.2012; Wiley Subscription Services, Inc
• Subjects: Cemented carbides; Cobalt; Composite materials; Densification; Electric current; Fracture toughness; Mechanical properties; Microstructure; Sintering; Temperature effects; Tungsten carbide
• ISSN: 0002-7820; 1551-2916
• DOI: 10.1111/j.1551-2916.2012.05218.x

Cubic boron nitride/Tungsten carbide‐cobalt (cBN/WC–Co) composites were fabricated at low temperature by pulse electric current sintering (PECS) using Ni–P as sintering additives to promote low temperature densification. Effect of c–BN addition on the densification behavior, microstructure and mechanical properties of WC–Co composites was investigated. It was found that near‐fully dense WC/Co with 0 ~ 20 vol% cBN composites could be obtained at temperatures between 1100°C and 1200°C under 50 MPa, while no phase transformation of cBN into the low‐hardness hexagonal hBN. The 20 vol% cBN/WC–Co sample sintered at 1100°C under a pressure of 50 MPa for 10 min has a combination of hardness 16.5 GPa and fracture toughness KIC 13.7 MP·m1/2. The homogeneously dispersed cBN particles in the WC/Co composites promoted a slight increase of hardness, but a significant improvement of fracture toughness. The cBN particle bridging or deflection and pullout contribute to the high toughness.