ZrO 2–WC nanocomposites with superior properties

Abstract

Fully dense ZrO 2-based nanocomposites with 5–40 vol.% WC were produced by hot pressing at 1450 °C for 1 h. The hardness and bending strength of the composites increases with increasing WC content, whereas the toughness hardly changes. An exceptionally high strength of 2 GPa combined with a hardness of 14.80 GPa and an excellent fracture toughness of 9.4 MPa m 1/2 was obtained for the 2 mol% Y 2O 3 stabilised ZrO 2-based composite with 40 vol.% WC. Such an attractive combination of properties is quite unique for a ceramic composite and is only matched by WC–Co cermets. The composites are substantially harder and stronger than the fine-grained Y-TZP, whereas the excellent toughness of Y-TZP is maintained. The strength improvement was accompanied with a change in fracture mode of the ZrO 2 grains from intergranular to transgranular. The ZrO 2–WC nanocomposites were found to slightly plastically deform before fracturing during bending.