ABSTRACT
Ceramics and ceramic-matrix composites are promising as structural materials with excellent heat resistance, oxidation resistance and abrasion resistance, arid are therefore being researched and developed on a global scale. However, the strength of nearly all ceramic polycrystalline materials drops off rapidly with increasing temperature. The thermal stability of the microstructures of the unidirectionally solidified eutectic ceramics is also superior. The solidification structures were examined in order to explain the excellent high-temperature characteristics of the unidirectionally solidified eutectic ceramics. The control of solidification structures in eutectic ceramics is essential for getting better properties. For the practical application of unidirectionally solidified eutectic ceramics, not only their strength but also their weaknesses should be considered. A12O3/ yttrium aluminium garnet and A12O3/ gadolinium aluminium perovskite have better high-temperature strengths than conventional ceramics. Eutectic composites have new microstructures, in which single-crystal A12O3 and single-crystal complex oxide compounds are three-dimensionally, continuously connected and finely entangled without grain boundaries.
