High temperature characteristics of melt growth composites and their application to ultra high efficiency gas turbine components

Much attention has been paid to unidirectionally solidified ceramic composites as a candidate for a high-temperature structural material. We have recently developed eutectic composites, which are named as Melt Growth Composites (MGCs). The binary MGCs (Al2O3/YAG and Al2O3/GAP binary systems) have a novel microstructure, in which continuous networks of single-crystal Al2O3 phases and single-crystal oxide compounds (YAG or GAP) interpenetrate without grain boundaries. Therefore, the MGCs have excellent high-temperature strength characteristics, creep resistance, superior oxidation resistance and thermal stability in an air atmosphere at very high temperatures. Manufacturing processes for the MGCs are being examined under a Japanese national project, scheduled from 2001 - 2005. To achieve higher thermal efficiency for gas turbine systems, a bowed stacking nozzle vane has been fabricated on an experimental basis.