The influence and the effectivity of VC and Cr3C2 grain growth inhibitors on sintering of binderless nanocrystalline tungsten carbide powders

For the production of hard, high temperature and abrasion resistant parts, like water-jet nozzles or pressing tools for forming glass lenses, binderless cemented carbide is used. In this work, the consolidation of tungsten carbide with minor additions of VC and Cr3C2 grain growth inhibitors is studied. Tungsten carbide powder dry or wet milled was consolidated by dry pressing, debindering and pressurized sintering and, alternatively, by Spark-Plasma-Sintering (SPS). The effect of small additions of VC, Cr3C2 and their mixtures on grain growth was studied with the total content being 0; 0. 1; 0. 3; 0. 5; 0. 7 and 1. 0 wt-%. Samples with an ultrafine microstructure free of abnormal grain growth, a hardness of 25. 5 GPa and a fracture toughness of 7. 2 MPa·m1/2 were archived by conventional sintering. Both carbides reduce grain growth. Compared to the same amount of Cr3C2, the addition of VC results in smaller grains but lower hardness and fracture toughness.