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Room temperature reduction of scheelite (CaWO4)

Published online by Cambridge University Press:  31 January 2011

N. J. Welham
N. J. Welham
Affiliation:
Petrochemistry and Experimental Petrology, Research School of Earth Sciences and Department of Electronic Materials Engineering, Research School of Physical Sciences and Engineering, Australian National University, Canberra. ACT 0200, Australia
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Abstract

A mixture of scheelite and magnesium has been mechanically milled together for 100 h, either with graphite or in a nitrogen atmosphere, with the intention of forming tungsten carbide or nitride. The resultant powders were examined by thermal analysis, isothermal annealing, and x-ray diffraction to determine the effect of milling on the reduction of scheelite. With graphite, nanocrystallite W2C was the exclusive tungsten product; WC was not detected even after annealing at 1000 °C. No nitride formed in the system milled with nitrogen; however, 10 nm crystallites of elemental tungsten were formed. The unwanted phases, MgO and CaO, were readily removed by leaching in acid, leaving a fine powder composed of impact welded aggregates of either carbide or 99% pure tungsten metal.

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Articles
Information
Journal of Materials Research , Volume 14 , Issue 2 , February 1999 , pp. 619 - 627
Copyright
Copyright © Materials Research Society 1999

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