Effects of powder preparation and sintering temperature on consolidation of ultrafine WC-8Co tool material produced by spark plasma sintering |
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| Affiliation: | 1. State Key Laboratory of Powder Metallurgy, Central South University, Changsha, Hunan 410083, China;2. State Key Laboratory of Cemented Carbide, Zhuzhou, Hunan 412000, China;3. Institute for Materials Microstructure, Central South University, Changsha, Hunan 410083, China;4. School of Materials Science and Engineering, Central South University, Changsha, Hunan 410083, China;1. Institute of Engineering & Research, Jiangxi University of Science and Technology, Ganzhou 341000, China;2. Engineering Research Center of High-efficiency Development and Application Technology of Tungsten Resources, Ministry of Education, Ganzhou 341000, China;3. State Key Laboratory of Powder Metallurgy, Central South University, Changsha 410083, China |
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| Abstract: | In this study, ultrafine tool materials were produced by spark plasma sintering using three sets of WC-8Co nanopowders mixed by different methods. Effects of powder preparation method and sintering temperature on the consolidation of WC-8Co cemented carbides were investigated. At sintering temperature of 1250 °C, cemented carbide sintered from the powder mixed by ultrasonic vibration method exhibited homogeneous microstructure, high relative density (99.1%), small average grain size (280 nm), and excellent mechanical properties (HV: 18.8 GPa, KIC: 11.4 MPa⋅m1/2). However, cemented carbide sintered from heavily ball-milled powder (ball milling for 24 h) showed increased grain coalescence and microdefects as well as lower relative density of 94.6%. Moreover, its hardness decreased to 17.7 GPa due to the decrease in relative density. Furthermore, straight cracks along grain boundary became dominant, causing fracture toughness to decrease to 10.5 MPa⋅m1/2. Additionally, high sintering temperature caused grain coarsening, which was detrimental to mechanical properties of cemented carbides. |
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| Keywords: | WC-8Co Spark plasma sintering Microstructure Mechanical properties |
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