One-step synthesis of WC-xTaC powders improves the mechanical properties of binderless WC cemented carbides

Tungsten carbide (WC) cemented carbide plays a crucial role in cutting and mechanical processing. However, the grain coarsening that inevitably occurs during the high temperature sintering process of WC leads to a reduction in mechanical properties. This study presents a strategy for the one-step synthesis of tantalum carbide (TaC) grain inhibitors to enhance ultrafine grain WC ceramics. Specifically, WC-xTaC (where x = 0 wt%, 1 wt%, 2 wt%, 3 wt%, and 4 wt%) powders were synthesized directly in one step using a liquid phase method, thereby eliminating the effects of the ball milling process on the defect density and surface energy of the powders. The mechanical properties of the sintered blocks were evaluated after the synthesized WC-xTaC powders underwent hot press sintering. The results demonstrate a reduction in the grain size of WC from 1.96 μm to 850 nm after sintering compared to WC ceramics without TaC doping. The density of the material improved from 91.4 % to 97.8 %, while the hardness increased from 16.3 GPa to 24 GPa, reflecting an overall enhancement of 47.2 %. This research provides an optimized approach for the fabrication of ultrafine grained WC ceramics.