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.
Technology for the formation of gradient oxide composites
We have obtained functionally gradient materials by slip casting of aqueous suspensions of various oxide materials. We have produced gradient materials with 6 to 20 layers and layer thickness from 0.1 to 0.3 mm. We have determined the requirements for the starting powders and aqueous suspensions (pH, content of solid phase, stability relative to sedimentation).