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Phase diagrams of the systems Al2O3–ZrO2–Ln(Y)2O3 as a scientific base for creating new high-temperature structural ceramics

Sergij M. Lakiza 1,  Lidiya M. Lopato 

1. Institute for Problems of Materials Science, National Academy of Sciences of Ukraine, Krzizanovsky, Kyiv 38(044), Ukraine

Abstract

A search of heat-resistant materials with high strength and phase stability at temperatures above 1600 °C is actual taking into consideration the world energy and ecology crises. Up to this time there are no structural materials except directionally solidified oxide eutectics (DSE), which could be used in oxidizing environment and retain enough strength at such high temperatures.

They have many potentialities that the flexural and tensile strength are maintained right below the melting point temperature mainly due to fine phase interfaces, increased with decreasing of a characteristic dimension of the network microstructure without the reduction of creep resistance and plastically deformed over approximately up to 1550 °C. They also show a fairly good machinability and manufacturability of complex shape structural components in comparison with conventional sintered engineering ceramics.

However, low fracture toughness and thermal shock resistance originally resulted from the oxide/oxide composite are critical technical issues for a practical application.

For the further research of new eutectic composites it is still necessary to improve the materials reliability and durability. Binary to ternary and more eutectic composites are considered to be one of the possibilities to improve materials performances.

The systematic investigation of the Al2O3–ZrO2–Ln(Y)2O3 phase diagrams revealed the formation of numerous alumina-rich ternary eutectics, which have similar gross composition, but consist of different set of phases. In these systems according to the participated lanthanide atom one can get three sets of ternary eutectics: Al2O3/Ln3Al5O12/ZrO2, Al2O3/LnAlO3/ ZrO2 and β-Al2O3/LnAlO3/ZrO2. This fact increases number of objects for directional solidification and allows choosing material with desirable set of properties for every specific utilization
 

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Presentation: Oral at E-MRS Fall Meeting 2008, Symposium I, by Sergij M. Lakiza
See On-line Journal of E-MRS Fall Meeting 2008

Submitted: 2008-05-07 12:58
Revised:   2009-06-07 00:48