5Y–ZrO2 NPs with high dispersity and excellent sintering performance prepared by a novel sol-gel-flux method in the NaCl system

Abstract

Herein, to alleviate the hard agglomeration of ZrO2 nanoparticles (NPs) fabricated by the traditional sol-gel method (SGM), a novel sol-gel-flux method (SGFM) is applied to tailor ZrO2 nanoparticles (NPs) stabilized by 5 mol% Y2O3 (5Y–ZrO2) by in situ introduction of NaCl NPs among xerogel particles. The phase composition, micromorphology, surface area, and sintering performances of 5Y–ZrO2 products fabricated by SGM and SGFM are compared. The effects of calcination temperature on the phase composition, micromorphology, and particle size of 5Y–ZrO2 products prepared by SGFM are systematically investigated. The results show that the 5Y–ZrO2 particles prepared by SGM are severely agglomerated and irregular, while the 5Y–ZrO2 NPs prepared by SGFM are well dispersed, uniformly distributed, and quasispherical. The former can hardly be densified by sintering, while the latter shows excellent sintering performance. By sintering 5Y–ZrO2 NPs prepared by SGFM at 1200 °C for 3 h, 5Y-TZP with a high density and an average grain size of 0.29 μm is fabricated. The in situ generated NaCl particles effectively separate ZrO2 particles during sintering. The calcination temperature plays a crucial role in controlling the phase composition, agglomeration degree, micromorphology, particle size distribution, and particle size of 5Y–ZrO2 products synthesized by SGFM, and the optimal calcination temperature is suggested to be 790 °C.