Processing of ultrafine ZrO_2 toughened WC composites

摘要

The interrelationships between the dispersion of the secondary ZrO_2 phase and the material properties of WC-based composites with up to 10 vol% of ZrO_2 are investigated. The homogeneity of the ultrafine WC-nanometric ZrO_2 powder mixtures was optimized by means of multidirectional milling and bead milling. In an alternative route, zirconium butoxide was used as a ZrO_2 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/mm~2 with an indentation toughness of 6 MPa m~(1/2). The ZrO_2 content and Y_2O_3 stabilization were found to strongly influence the mechanical properties and especially strength of the WC-ZrO_2 composites.