Synthesis of WC-Co composite powders with two-step carbonization and sintering performance study

• Published in: International journal of refractory metals & hard materials Vol. 81; pp. 127 - 136
• Main Authors: Pan, Yifu, Xiong, Huiwen, Li, Zhiyou, Long, Xuehu
• Format: Journal Article
• Language: English
• Published: Shrewsbury Elsevier Ltd 01.06.2019; Elsevier BV
• Subjects: Carbonization; Cemented carbide; Cemented carbides; Cobalt; Creep rupture strength; Electron backscatter diffraction; Fracture toughness; Morphology; Phase distribution; Raw materials; Sintering (powder metallurgy); Synthesis; Tungsten carbide; Two-step carbonization; WC-Co composite powders; X-ray diffraction; η phase; Cemented carbide; Two-step carbonization; η phase; WC-Co composite powders
• ISSN: 0263-4368; 2213-3917
• DOI: 10.1016/j.ijrmhm.2019.02.019

In this study, WC-Co composite powder was synthesized by two-step carbonization method using W, Co and C as raw materials. X-ray diffraction (XRD) showed that the η phase (Co6W6C) was kept at 1100 °C for 1 h under vacuum, and it could be completely carbonized into WC-Co composite powders. The surface morphology of WC-Co composite powders was analyzed by scanning electron microscope (SEM). The effects of η phase and second phase (W phase) on WC morphology and Co phase distribution were investigated. Electron backscattered diffraction (EBSD) was used to analyze WC-10 wt% Co cemented carbide particle distribution. Comparison of transverse rupture strength, hardness and fracture toughness of two kinds of WC-10 wt% Co cemented carbides synthesized by WC-Co composite powders + WC and WC + Co respectively, the cemented carbide of composite powders + WC increases the fracture toughness from 11.4 ± 0.3 MPa·m1/2 to 12.4 ± 0.3 MPa·m1/2. •The enablement of preparing WC–Co composite powders via a two-step carbonization•The effects of η phase size on the morphology of WC grains•The uniform Co phase distribution after liquid phase sintering of WC-Co composite