Development of WC-ZrO₂ Nanocomposites by Spark Plasma Sintering

In the present work, we report the processing of ultrahard tungsten carbide (WC) nanocomposites with 6 wt% zirconia additions. The densification is conducted by the spark plasma sintering (SPS) technique in a vacuum. Fully dense materials are obtained after SPS at 1300°C for 5 min. The sinterability and mechanical properties of the WC-6 wt% ZrO₂ materials are compared with the conventional WC-6 wt% Co materials. Because of the high heating rate, lower sintering temperature, and short holding time involved in SPS, extremely fine zirconia particles (∼100 nm) and submicrometer WC grains are retained in the WC-ZrO₂ nanostructured composites. Independent of the processing route (SPS or pressureless sintering in a vacuum), superior hardness (21-24 GPa) is obtained with the newly developed WC-ZrO₂ materials compared with that of the WC-Co materials (15-17 GPa). This extremely high hardness of the novel WC-ZrO ₂ composites is expected to lead to significantly higher abrasive-wear resistance.