Spark plasma sintering of ZrO2-Al2O3 nanocomposites at low temperatures aided by amorphous powders

In present work, ZrO2-5 wt% Al2O3 and ZrO2-10 wt% Al2O3 nanocomposites are fabricated through spark plasma sintering. Al2O3-ZrO2 amorphous powders and polycrystal Al2O3 powders and are doped in the polycrystalline ZrO2 powders, respectively. When doped with amorphous powders, the sintering of ZrO2-Al2O3 nanocomposites is promoted, and ZrO2-5 wt% Al2O3 and ZrO2-10 wt% Al2O3 nanocomposites with relative densities of 99% are obtained after spark plasma sintering at 1200 degrees C; however, when sintering of polycrystalline ZrO(2 )and polycrystalline Al2O3 powders, the relative densities are merely 93%. The enhanced sinterability is due to the metastability and phase transformation of the amorphous powders, which act as sintering aids. The nanocomposites with near-theoretical density show refined microstructure with homogenous mixture of ZrO(2)and Al2O3 grains, which further leads to excellent mechanical properties. This article provides new ideas for low-temperature sintering of nanocomposites via using doping amorphous powders.