Microstructure-mechanical-tribological property correlation of multistage spark plasma sintered tetragonal ZrO2

We report here the development of dense yttria-stabilized t-ZrO2 ceramics with more uniform and finer grain sizes and concomitantly better mechanical and tribological properties via multistage spark plasma sintering (SPS). The dense tetragonal ZrO2 ceramics were obtained by adopting three different SPS heating cycles, designed on the basis of fundamental sintering theory. The suppression of grain growth to nanosize regime (∼100–150 nm), along with the development of more uniform grain size distribution was achieved with multistage sintering (MSS), as compared to normal single stage sintering (SSS). Finer microstructural scale, along with superior hardness also led to improved fretting wear resistance for the ZrO2 samples processed via MSS. Based on the experimental results and analysis, a correlation has been established between the SPS processing schemes, microstructural development and mechanical as well as tribological properties of the tetragonal ZrO2. The effectiveness of MSS to produce tetragonal ZrO2 ceramics with better mechanical and tribological properties was confirmed at two different levels of yttria content (3 and 2 mol%).