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Abstract
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WC–Al2O3 composite powder potentially could be synthesized through milling of WO3–C–2Al mixture. High temperature resulted from reduction of WO3 by Al, activates the reduction reaction of WO3 by C and brings about carbon deficiency in the system which consequently causes the formation of undesirable W2C phase. Hence, addition of excess amounts of C becomes necessary. The aim of the present study has been to find out some appropriate routes for the fabrication of WC–Al2O3 composite powder from WO3–2Al–C mixtures in such a way that the formation of W2C is prevented. Results of high energy milling showed that the mode of reaction in WO3–2Al–C mixture is MSR (mechanically induced self-propagating reaction). In this system, evolution of CO gas and high value of C loss were evidences for the need of excess C. For samples produced via suggested routes, no CO evolution was observed and the amounts of total carbon were constant. These observations showed that the proposed routes have been capable of producing WC phase without the presence of W2C. Mechanism of the reactions in each route has been discussed.
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