Processing of ultrafine ZrO2 toughened WC composites

The interrelationships between the dispersion of the secondary ZrO2 phase and the material properties of WC-based composites with up to 10 vol% of ZrO2 are investigated. The homogeneity of the ultrafine WC–nanometric ZrO2 powder mixtures was optimized by means of multidirectional milling and bead milling. In an alternative route, zirconium butoxide was used as a ZrO2 source. The composites were fully densified by means of pulsed electric current sintering (PECS), also known as spark plasma sintering, within a few minutes at 1700 °C allowing to maintain an ultrafine grained microstructure combining a hardness of 2600 kg/mm2 with an indentation toughness of 6 MPa m1/2. The ZrO2 content and Y2O3 stabilization were found to strongly influence the mechanical properties and especially strength of the WC–ZrO2 composites.