A systematic study of the effect of calcium on the production and properties of WC precursor powders and alloys. (August 2018)

• Record Type: Journal Article
• Authors: He, Wen; Tan, Dunqiang; Kuang, Hai; Zou, Zhihang; Yang, Xin; Wang, Xiaoru
• Is Part Of: International journal of refractory metals & hard materials. Volume 74(2018)
• Page Start: 61
• Page End: 69
• Publication Date: 2018-08
• Subjects: Ca-rich phase -- Precursor powders -- WC-Co cemented carbide -- Mechanical property -- Mechanisms; Heat resistant alloys -- Periodicals; Refractory materials -- Periodicals; Metallography -- Periodicals; Alliages réfractaires -- Périodiques; Matériaux réfractaires -- Périodiques; Métallographie -- Périodiques; Heat resistant alloys; Metallography; Refractory materials; Periodicals; Electronic journals; 669.73
• DOI: 10.1016/j.ijrmhm.2018.03.002
• Languages: English
• ISSNs: 0263-4368

Abstract

Abstract: Effect of calcium on tungsten oxide, tungsten, tungsten carbide and WC-Co cemented carbides, and the evolution of Ca during the preparation of cemented carbides were investigated studied by the liquid-solid doping method. X-ray diffraction, scanning electron microscopy and transmission electron microscopy were employed to analyze the phase compositions, particle sizes and morphologies of them, respectively. The results showed that 1% Ca-doped tungsten oxide consisted of WO3 and CaWO4 phases. After hydrogen reduction, the size of Ca-doped tungsten decreased slightly. During carbonization, most of the CaWO4 and Ca4.26 W10 O30 transformed to CaC2 . After that, the majority rest of the CaWO4 and Ca4.26 W10 O30 both reduced to CaO in the sintering process. The microhardness, flexural strength and fracture toughness of 1%Ca-doped WC-6wt.%Co cemented carbide were 14.83 GPa, 1456 MPa and 9.98 MPa m 1/2, decrement of 10.12%, 29.53%, and 10.57%, respectively. A refining mechanism for tungsten and a weakening mechanism for WC-Co cemented carbides were proposed. Graphical abstract: Highlights: The size of Ca doped W powder decreased slightly. A refining mechanism for tungsten was proposed. The evolution of Ca-rich phase was studied in every production process of WC-Co cemented carbide. Ca-doped WC-Co cemented carbide with poor mechanical properties was obtained. A weakening mechanism for WC-Co cemented carbide was proposed.