CeO2-stabilised ZrO2 nanoparticles with excellent sintering performances synthesized by sol-gel-flux method

Abstract

ZrO2 nanoparticles (NPs) stabilised by 12 mol% CeO2 (12Ce-ZrO2) with high sintering ability were prepared using a novel sol-gel-flux method (SGFM) for the first time, where NaCl flux was introduced into a citric acid-based sol-gel system. The microstructure and sintering performances of the as-prepared NPs were compared with those of the product synthesised using the traditional citric acid-based sol-gel method (SGM). The effect of the calcination temperature on the phase compositions and micromorphologies of the as-prepared 12Ce-ZrO2 products was investigated. The results showed that the optimum calcination temperature for the SGFM was 800 °C, and the corresponding 12Ce-ZrO2 product (SGFM-800) was composed of well-dispersed 20–40 nm t-ZrO2 NPs with homogenous micromorphology, while the 12Ce-ZrO2 NPs synthesised using the SGM (SGM-800) were severely agglomerated. The SGM-800 NPs could not be fully densified up to the sintering temperature of 1450 °C owing to severe agglomeration. However, the SGFM-800 NPs exhibited good sintering ability, and a relative density of 99.67 % could be achieved at 1150 °C for 4 h. The fully dense 12Ce-TZP ceramics prepared with SGFM-800 had an average grain size of 0.46 μm. To the best of our knowledge, such a fine grain size has not been reported to date for 12Ce-TZP ceramics obtained by single-step pressless sintering.