To clarify the water vapor corrosion mechanism of the Lu2Si2O7 system, a high temperature water vapor corrosion test was performed on two microstructurally different specimens namely, polycrystalline and eutectic. From the results, we address the problem of the application of the Lu2Si2O7 system for environmental barrier coatings (EBC) with regard to their microstructure. In the case of the polycrystalline sample, the boundaries were easily corroded and the silicon nitride substrate underwent oxidation. In the case of the eutectic sample, no weight change was observed during the corrosion test. However, a trace of corrosion and poly-crystallization was observed on the sample surface. An easy processing technique for forming an eutectic protective layer on silicon nitride ceramics is also proposed.

Keywords: EBC, Lu2Si2O7, eutectic, water vapor corrosion