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Abstract
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Possibility of synthesis of tungsten carbide–alumina composite powder from WO3–Al–C mixture via microwave-assisted SHS process in a domestic microwave oven has been investigated. By comparison of the results of thermodynamic calculations with experimental findings, it was found that during microwave heating of WO3:2Al:C mixture, synthesis process initiates by vigorous exothermic reaction of WO3 with Al which results in a great deal of heat. Major portion of tungsten carbide phase in the product is W2C, whose formation is supposed to be related to the high thermodynamic stability of this compound at high temperatures. W2C formation could also be related to carbon loss phenomenon in the mixture, as a consequence of some carbon burn. It has been concluded that addition of excess carbon to the initial mixture together with extension of the microwave processing time, increase the amount of WC phase in the product in expense of W2C. Experimental results showed that only small amounts of W2C remain in the product with around 80 mol% excess initial carbon and about 10 min of microwave heating time.
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