Fabrication and mechanical properties of binderless-WC and WC-CNT hard materials by pulsed current activated sintering method

Using the spark plasma sintering process, WC and WC-5, 10, 15 vol.%CNT hard materials were densified using ultra-fine WC and CNT powders. For the preparing the WC-x vol.%CNT mixed powders, First, the carbon nanotubes were dispersed in N, N-dimethylformamide (DMF) for 30 ~ 90 min using an ultrasonic shaker. WC powder was then added to the nanotube and the mixtures were dispersed ultrasonically for 30 min. Finally, the mixed powders were horizontal ball milled at 250 rpm for 4 hrs in DMF. The WC-vol.%CNT were almost completely dense with a relative density of up to 99% after the simultaneous application of 60 MPa of pressure and about 27 min of electric current without significant change in the grain size. The average grain size of WC, WC-5, 10, and 15 vol.% CNT hard materials were about 327, 348, 306, 302 nm. The compositional and microstructural analyses of the products were carried out through XRD and FE-SEM. The hardness and fracture toughness of the dense WC and WC-x vol.%CNT composites were also investigated.