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

Herein, to alleviate the hard agglomeration of ZrO 2 nanoparticles (NPs) fabricated by the traditional sol-gel method (SGM), a novel sol-gel-flux method (SGFM) is applied to tailor ZrO 2 nanoparticles (NPs) stabilized by 5 mol% Y 2 O 3 (5Y–ZrO 2 ) by in situ introduction of NaCl NPs among xerogel particles. The phase composition, micromorphology, surface area, and sintering performances of 5Y–ZrO 2 products fabricated by SGM and SGFM are compared. The effects of calcination temperature on the phase composition, micromorphology, and particle size of 5Y–ZrO 2 products prepared by SGFM are systematically investigated. The results show that the 5Y–ZrO 2 particles prepared by SGM are severely agglomerated and irregular, while the 5Y–ZrO 2 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–ZrO 2 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 ZrO 2 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–ZrO 2 products synthesized by SGFM, and the optimal calcination temperature is suggested to be 790 °C.