Effect of applied stress on microstructural evolution during the sintering of nanocrystalline tetragonal zirconia below 1000 °C

Abstract

Microstructural evolution during the sintering of tetragonal ZrO2 nanoparticles was investigated using stress-free sintering and sinter forging. The green body prepared via gel casting had a densely packed structure with a narrow pore size distribution. Special attention was paid to the evolution of pore structures in the initial and intermediate stages of sintering. Pore coarsening, which is considered an important issue in the nanoceramics densification, was not remarkable in sinter forging. The accelerated densification rate, coupled with the retention of finer pore size than that in stress-free sintering throughout densification, lowered the sintering temperature requirement. This temperature reduction effectively inhibited grain growth, allowing samples prepared via pressure-assisted sintering to maintain a nanometric structure.