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 degrees C allowing to maintain an ultrafine grained microstructure combining a hardness of 2600 kg/mm(2) with an indentation toughness of 6 MPa m(1/2). The ZrO2 content and Y2O3 stabilization were found to strongly influence the mechanical properties and especially strength of the WC-ZrO2 composites. (C) 2009 Elsevier Ltd. All rights reserved.