Wear behavior of Co-free hardmetals doped by zirconia and produced by conventional PM and SPS routines

• Co-free hardmetals doped by tetragonal zirconia were produced by conventional pressureless and spark plasma sintering routines.
• Stress induced zirconia phase transformation allows increase in wear resistance.
• An optimized technological process is of outmost importance for wear resistance.
• Tetragonal zirconia transformability depends on a route of processing.

In this work, the microstructural features and mechanical properties of Co-free hardmetals doped by 3 mol% yttria stabilized tetragonal zirconia and densified by means of conventional vacuum pressureless sintering as well as spark plasma sintering were studied. Influence of dispersed zirconia clusters on mechanical behavior and erosive and abrasive wear resistance of hardmetals with 6 wt% of stabilized ZrO2 was investigated. It was shown that zirconia transformability affects the wear performance of the composites. For utilization of the mechanism of transformation toughening some essential requirements such as grain size and grain size distribution should be met. Simultaneous increase in fracture toughness due to stress induced transformation toughening of tetragonal zirconia with increase in hardness due to grain growth inhibition during processing allows considering the cemented carbides doped by zirconia as promising tribomaterials.