CHANG Longfei, RU Hongqiang, ZHANG Meiyun, YUE Xinyan, WANG Wei
(Key Laboratory for Anisotropy and Texture of Materials of the Ministry of Education, Northeastern University,
Shenyang 110819, Liaoning, China)
Abstract: In this work, WC powders (average particle diameter 2 µm) with different Co content (0.0wt.%, 0.3wt.%, 0.5wt.%, 1.0wt.% and 3.0wt.%) were mixed in a high energy ball mill using ethanol as a medium. Specimens were sintered by SPS at 1500 °C for 5 min under a pressure of 50 MPa. The influence of Co content on the sintering behavior, phase composition, microstructure and mechanical properties was studied by X-ray diffraction, scanning electron microscopy, Vickers hardness tester, etc. It was found that the densification process of WC was greatly promoted through the addition of cobalt, and WC single phase was identified in samples. When 0.3wt.% Co was added, the properties of WC were the best, the relative density was 99.2 %, the Vickers hardness was 23.7 GPa, the fracture toughness was 9.58 MPa·m1/2, and the average WC grain size was 342 nm. Abnormal grain growth was observed after adding Co, and the sizes of some large WC grains increased to 6 µm when 3.0wt.% Co was added to the carbide.
Key words: WC; Co; spark plasma sintering; microstructure; Vickers hardness.