A Novel Approach for Direct Synthesis of Nanocrystalline Tungsten Carbide from Milled Scheelite Ore
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In recent years, nanostructured tungsten carbide (WC) has been synthesized mainly from precursors like WO3, W, WCl6, and WCl4. These pure precursors are obtained by multistep high temperature treatments from the ore. Single phase nanocrystalline WC has been synthesized for the first time from scheelite ore at significantly lower [923 K (650 °C)] temperature. The activated charcoal and Mg turnings have been used as carbon source and reducing agent, respectively. The effect of time and temperature on the reaction has been investigated. The reaction by-products and impurities were washed firstly with dilute HCl and then with dilute base. The powders were characterized by X-ray diffraction technique and high resolution transmission electron microscope. The XRD patterns were refined by Rietveld method. The WC crystallite size was observed to decrease with lowering of synthesis temperature. The average crystallite size of WC formed was 20 nm. This report presents an exclusive, straight forward, environment friendly, and reproducible method for synthesis of nanocrystalline WC directly from scheelite ore.
KeywordsHigh Resolution Transmission Electron Microscope Activate Charcoal Scheelite Reduce Particle Size CaWO4
The authors are thankful to Dr B.N. Chudasama and Ms Samita for help in Rietveld analysis. The financial assistance provided by Department of Science and Technology, New Delhi, India vide Letter No. SR/S3/ME/0037/2009-SERC dated 15/07/2010 is highly acknowledged.
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