Abstract:

Using sodium tungstate as tungsten source, natural soil shaped graphite as carbon source, an experiment is provided for researching the transformation process and rules of them in argon atmosphere at high temperature. The final products are studied by X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrometer (EDS), etc. The result shows that the mixed samples of sodium tungstate and graphite can generate different tungsten carbon compounds in an argon atmosphere with heat treatment. First, reduction reaction occurs between mixed graphite and sodium tungstate dihydrate at the reaction interface, reducing sodium tungstate dihydrate to α-W₂C and β-W₂C. Second, when the mass ratio of Na₂WO₄ : C is less than 1:1, reduction of α-W₂C to α-WC occurs, till the mass ratio was 1:5, and α-W₂C can be reduced to α-WC completely.

Key words: graphite, sodium tungstate, tungsten carbide, high-temperature treatment, XRD, SEM, EDS

摘要：

以 Na₂WO₄为钨源, 天然土状石墨为碳源, 研究二者在高温氩气气氛下的转化过程及规律, 利用 X 射线衍射(XRD)、扫描电子显微镜(SEM)及电子能谱(EDS)对产物进行分析。结果表明, Na₂WO₄ 与石墨的混合样品在氩气气氛下经高温处理, 可以生成不同的碳钨化合物。首先, 石墨与 Na₂WO₄ 在接触界面发生还原反应, 将Na₂WO₄还原为α-W₂C和β-W₂C; 然后, 随着石墨增多, 当Na₂WO₄与石墨的质量比小于1:1时, 石墨开始将 α-W₂C 还原为 α-WC, 直至 Na₂WO₄ 与石墨的质量比为 1:5 时, 石墨可以将 α-W₂C 完全转化为 α-WC。

关键词: 石墨, Na₂WO₄, WC, 高温处理, X射线衍射(XRD), 扫描电子显微镜(SEM), 电子能谱(EDS)