Nanocrysrtalline Powders in the A12O3-ZrO2-CeO2-Y2O3 system for high-performance ceramics
X-ray diffraction, BET measurements, scanning electron and optical microscopy were used to analyze the properties variation of hydrothermal nanocrystalline powder with a composition 90 wt% Al<inf>2</inf>O<inf>3</inf>-10 wt%ZrO<inf>2</inf> (CeO<inf>2</inf>, Y<inf>2</inf>O<inf>3</inf>) after thermal treatment in the temperature range 400–1300 °C. The composition of the ZrO<inf>2</inf>-based solid solution was (mol %) 90ZrO<inf>2</inf>-8CeO<inf>2</inf>-2Y<inf>2</inf>O<inf>3</inf>. It was found that α-Al<inf>2</inf>O<inf>3</inf> is formed at 850 °C. Phase transformation F-ZrO<inf>2</inf>⇆T-ZrO<inf>2</inf> occurred at 1000 °C. Produced powder was sintered at 1300 °C. The present investigation demonstrates that heat treatment of composite nanocrystalline powders gives rise to complex processes. Understanding of such processes makes it possible to optimize conditions for fabrication of advanced ceramics with tailored properties.
Microstructural design of ZrO2–Y2O3–CeO2–Al2O3 materials
It is shown that microstructural design of ZrO2–Y2O3–CeO2–Al2O3 ceramics is based on interrelated processes in the synthesis of starting powders and their formation and sintering. Hydrothermal nanocrystalline powders are examined to establish the formation of self-reinforced and multilayer composites with high strength and bioinert implants of femoral heads resistant to ageing processes in the human body. The results serve as a scientific basis for microstructure design of fine-grained ZrO2-based composites in the ZrO2–Y2O3–CeO2–Al2O3 system with high strength and other properties.
Nonisothermal Synthesis of Yttria‐Stabilized Zirconia Nanopowder through Oxalate Processing: II, Morphology Manipulation
A novel, nontraditional route for controlling the morphology of yttria-stabilized zirconia nanopowders is explained. For understanding the real nature of yttrium zirconium oxalate nonisothermal decomposition and for the development of nanosize 3 mol% Y2O3·97mol% ZrO2, mass spectrometry, X-ray, and TEM investigation were used. Characteristics of zirconia crystallization under nonisothermal heating conditions were studied. Morphology evolution during Y-Zr oxalate nonisothermal decomposition was investigated to optimize the heating schedule of calcination. The nonlinear heating regime has been used to produce nanosized Y2O3-stabilized tetragonal ZrO2 powder with the finest primary crystallites and narrowest secondary aggregate size distribution.