Structure, Phase Composition, and Mechanical Properties of Composites Based on ZrO2 and Multi-Walled Carbon Nanotubes

In this work, composites based on yttria-stabilized zirconia (3Y-TZP) with additives of 1.5 and 10 wt % multi-walled carbon nanotubes (MWCNTs) were studied. Samples were obtained by spark plasma sintering (SPS) at a temperature of 1500°C. It was found that, after high-temperature sintering, MWCNTs retain their structure and are located along the ZrO2 grain boundaries forming a network structure. It was found that the addition of 1 wt % MWCNTs increases the relative composite density from 98.3 to 99.0%. It was noted that nanotubes can significantly affect the phase composition of composites. The addition of 5 wt % MWCNT partially limits the monoclinic–tetragonal phase transition of ZrO2, and the addition of 10 wt % MWCNTs leads to the formation of a cubic phase of zirconium carbide. It was found that fracture toughness of the composite with 10 wt % MWCNTs increases from 4.0 to 5.7 MPa m1/2.