酸化物共晶セラミックスの一方向凝固

抄録

New unidirectionally solidified eutectic ceramics such as Al_2O_3/YAG or Al_2O_3/GdAlO_3 has recently been fabricated by controlling accurately the unidirectional solidification. The eutectic composite has a new microstructure, in which single crystal Al_2O_3 and single crystal complex oxide compounds (YAG or GdAlO_3) are three-dimensionally and continuously connected and finely entangled without grain boundaries. The eutectic composite fabricated is thermally stable and has the following properties: l) the flexural strength at room temperature can be maintained up to just below melting point (about 2040〜2150 K), 2) it shows neither weight gain nor grain growth, even upon heating at 1973 K in an air atmosphere for 1000 hours (in cases of Al_2O_3/YAG). Consequently, several useful applications can be considered: for example, new aero gas turbine and power generation system with non-cooled turbine blades at ultrahigh temperature above 1773 K.