Synthesis of nanosized WC/MgO powders by high energy ball milling and analysis of reaction thermodynamics

Author： Zhang M. L. Zhu S. G. Ma J. Wu C. X. Zhu S. X.

ISSN： 1743-2901

Source： Powder Metallurgy, Vol.53, Iss.2, 2010-06, pp. : 169-173

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Abstract

In the present work, a powder mixture of pure WO₃, graphite and Mg with a definite atomic ratio was milled at room temperature using a high energy ball mill method, and ball milled powders were analysed by X-ray diffraction, scanning electron microscopy and transmission electron microscopy. The results indicated that after ball milling for a period of time, an oxidation–reduction reaction was successfully achieved among the Mg, graphite and WO₃ powders to obtain MgO and WC. The extension of the ball milling led to the refinement of the powders. After ball milling 50 h, nanocrystalline WC grains (25 nm) were embedded into the fine matrix of MgO and formed fine nanocomposite MgO/WC powders (∼100 nm in diameter). The experimental results and thermodynamic analysis showed that the formation of nanocomposite MgO/WC was a mechanically induced self-propagating reaction, and very short milling time was needed to complete the reaction.