Dense tungsten carbide bulks by self-densification reaction sintering of nanodiamond with tungsten at 1700?C

Tungsten carbide (WC) bulks from the sintering of WC powders possess excellent physical and chemical prop-erties, widely used in high-precision optical molds, seals, nozzles and many other scenarios. To produce dense WC bulks, however, needs a very high sintering temperature (>1900 degrees C) and super fine WC powders due to the poor sinterability. The high sintering temperature required puts a huge strain on processing equipment, and the preparation of super fine WC powders involves many complex steps. In this work, dense WC bulks are prepared by spark plasmas sintering via self-densification reaction of nanodiamond with tungsten at 1700 degrees C. The use of nanodiamond enables dense WC bulks of a density of 98.1% and Vickers hardness of 21.8 GPa for a volume expansion associated with the change of diamond to graphite greatly reduces the porosity of as-prepared WC bulks, demonstrating a novel mechanism of self-densification reaction sintering. Besides, reaction between tungsten and diamond produces far less volume shrinkage than other allotropes of carbon, partly contributing to the densification of the as-prepared WC bulks. Our creative strategy has significant advantages over prevailing methods in preparing high-density WC bulks, facilitating the application of WC bulk materials in industrial production and providing a new insight into the preparation of dense bulks of other metal carbides.

Automated summary

Dense tungsten carbide (WC) bulks with a density of 98.1% were successfully prepared by spark plasmas sintering via self-densification reaction of nanodiamond with tungsten at 1700 degrees C. This method has significant advantages over conventional methods and provides a new insight into the preparation of dense bulks of other metal carbides.