Synthesis and physico-chemical properties of nanodispersed powder with eutectic composition in the Al₂O₃—ZrO₂ (Y₂O₃, СеО₂) system

Abstract

Zirconia-Toughened Alumina (ZTA) — composites that combines the advantageous properties of alumina and zirconia — are widely investigated to optimize the composite properties. The strength behavior of ZTA — composites depends on the starting particle size of Al₂O₃ and ZrO₂- based solid solution, the homogeneity of ZrO₂-based solid solution particles in the Al2O3 matrix, and the volume fraction of metastable tetragonal ZrO₂-based solid solution (T-ZrO₂). In this research, physico=chemical properties of nanodispersed ZTA powder of eutectic composition (% (mass.)) : 58,5Al₂O₃—41,5ZrO₂ (Y₂O₃, CeO₂) were investigated. The starting powder was produced by hydrothermal method in an alkaline medium. The composition of the solid solution based on ZrO₂ is (% (mol.)): 90ZrO₂—8CeO₂—2Y₂O₃. The properties of synthesized ZTA powder were characterized by X-ray diffraction (XRD), differential thermal analysis (DTA), scanning electron microscopy (SEM), and specific surface measurements (BET). There were two phases in the ZTA powder: crystallized boehmite AlO(OH) and partially crystallized tetragonal ZrO₂ (TZrO₂) — based solid solution after hydrothermal synthesis. The specific surface area of the hydrothermal nanodispersed ZTA powder is 71 m² / g. After thermal treatment in the air at 550 °C for 2 hours, AlO(OH) was converted to δ-Al₂O₃ and zirconia was fully crystallized in the tetragonal form. It was determined that irregular and round form agglomerates of the І and ІІ order (from 4 to 20 microns) were formed in the soft-agglomerated hydrothermal powder. AMIS software (microstructure automatic analyzer) was used for processing the research results on the morphology of the nanodispersed ZTA powder. The research results will be used for the microstructural design of ZTA-composites.