Corrosion of a unidirectionally solidified Al2O3/YAG eutectic composite in a combustion environment

The water vapor hot gas corrosion of MGC materials with Al2O3 as a phase constituent in a combustion atmosphere

“…After long time corrosion exposure, a dynamic equilibrium between the formation of the porous passivation layer and the spalling of it was reached. The observed preferred corrosion degradation of the alumina phase in the MGC materials is in agreement with water vapor corrosion studies of these materials done by low gas flow velocities 12,13 or by high gas flow velocities and short corrosion times. 3,14 In both cases an increase in the surface roughness was reported due to selective corrosion and degradation of the alumina phase.…”

“…doi:10.1016/j.jeurceramsoc.2008.01.007 cated a high corrosion stability of the MGC material. 3,[12][13][14] To evaluate the potential for a future use of such materials in real gas turbines, long time corrosion tests under gas turbine simulating environments with high gas flow velocities are needed. In the present study, the hot gas corrosion stability of two melt grown composite materials in comparison to alumina and sapphire is presented.…”

Directionally solidified eutectics in the Al2O3–ZrO2–Ln(Y)2O3 systems (Review)

“…When quenched (abruptly cooled), the samples cracked. Therefore, special cooling conditions must be ensured to use the composite as a structural material at high temperatures [74].…”

Superplastic deformation of directionally solidified nanofibrillar Al2O3–Y3Al5O12–ZrO2 eutectics

“…7 In particular, they present a high melting point, excellent microstructural stability up to temperatures very close to the eutectic point, as well as chemical stability in combustion environments. 8 This behavior is associated with an outstanding strength retention at high temperature and creep resistance due to the large area fraction of clean and strong interfaces without glassy phases, a major difference with standard ceramic oxides which present a marked degradation in strength below 1000 °C. 9 ' 10 The best mechanical properties in terms of high temperature strength and creep resistance have been reported for AI2O3 -based eutectics (in particular AI2O3-YAG, AI2O3-Er3 AI5012 (EAG) and AI2O3-YAG-YSZ) with an interpenetrating microstructure [10][11][12][13] but these systems present very low toughness (in the range 2-4 MPam 1/2 ).…”