Crystal-size dependence of the spark-plasma-sintering kinetics of ZrB2 ultra-high-temperature ceramics

The crystal-size dependence of the spark-plasma-sintering (SPS) kinetics of ZrB2 ultra-high-temperature ceramics (UHTCs) was investigated. It was found that refining the starting powder enhances the SPS kinetics, reducing the onset temperatures of sintering and of the intermediate and final sintering regimes, as well as promoting a greater maximum shrinkage rate at lower temperatures. This enhancement was only relevant with reduction in crystal size to the nanoscale. Finally, the implications for low-temperature sintering of ZrB2 UHTCs are discussed.