Addition of nano-ZrO2 effects on microstructures and properties of WC-8Co hard alloys

This paper carries out the research on using the toughening mechanism of phase transition of ZrO2 to inhibit the WC grain and improve the toughness of the hard alloys. WC-ZrO2-8wt%Co hard metals was mixed with 0-2 wt% nano-ZrO2 and prepared by conventional sintering (CS) for 2 h at 1440 degrees C to see whether the addition of ZrO2 could improve densification behavior, the microstructure and mechanical properties of the samples. Experimental results showed that the use of ZrO2 nanoparticles could decrease the relative density because of the worse wetting effects; it could also inhibit the growth of the grains of WC-Co hardmetal to enhance the hardness of the alloy. The fracture toughness of sample has an increasing tendency as a whole because of the phase transition during the sintering process.