N. Nakagawa (Sp), H. Ohtsubo, K. Shimizu, K. Shibata, A. Mitani, Y. Waku, Ube Industrie,Ltd., Ube City (Japan)
Unidirectionally solidified Al2O3/YAG and Al2O3/GAP eutectic composites, known as Melt Growth Composites (MGCs), have a microstructure, in which continuous networks of single-crystal Al2O3 phases and single-crystal complex oxides (YAG (Y3Al5O12), GAP (GdAlO3)) interpenetrate without grain boundaries. Therefore, the MGCs show superior oxidation resistance with no changes in microstructures, surface roughness and flexural strengths after heat treatment for 1000 hours at 1700 ºC in an air atmosphere. This is attributed to the MGC’s unique microstructure without grain boundaries and its interfacial effect. Recently, it has been found that the recession of silicon-based ceramics mainly caused by water vapor is progressing in the combustion gas flow environment In this study, the high temperature strength characteristics and the thermal stability of the MGCs after the exposure test for 10-30 hours at T = 1500-1600 ºC, P = 0.1-0.3 MPa, V = 150-250 m/s, PH2O = 15-45 kPa in the combustion gas flow environment will be reported.
