Hot Pressing of Tungsten Monocarbide Nanopowder Mixtures by Electroconsolidation

EDWIN GEVORKYAN, MIROSLAW RUCKI, VLADIMIR CHISHKALA, MAKSIM KISLITSA, ZBIGNIEW SIEMIATKOWSKI, DMITRIJ MOROZOW

Abstract


The paper presents theoretical and experimental results in the field of the manufacturing of cemented tungsten carbide materials. The important issue of avoiding any additional substances like plasticizers was challenged in order to reach the maximal possible density of sintered material while keeping its purity. To solve the problem, the electroconsolidation method of hot pressing supported by direct current was applied. The respective apparatus was constructed that enabled WC nanopowders to be sintered under pressure and high temperature during a very short time of ca. 3 minutes. In the experiments, because of the short heating time, grain size of the sintered bulk WC increased insignificantly, in general, remaining smaller than 1 μm. Similarly, sintering under hot pressing with direct current, a mixture of 3% by weight Y2O3 stabilized ZrO2 and 50% by weight WC, produced a fine structure with a uniformly distributed WC grains. The applied electric field led to the formation of a temperature gradient around the pores, with a favourable impact on the compaction of large pores and an increase in the final density of the bulk material. The experimental research confirmed that the main mechanism of the densification of nanodispersed powders of tungsten monocarbide was a locally inhomogeneous diffusion-viscous flow with intergranular slipping.

Keywords


nanopowders, electroconsolidation, compaction, hot pressing, nanostructure.Text


DOI
10.12783/dtcse/fe2019/30678

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