The water vapor corrosion resistance of silicon nitride ceramics with Lu2Si2O7, Yb2Si2O7 and ZrSiO4 environmental barrier coating (EBC) layers prepared by a reaction sintering method were examined at 1500 oC in a static state water vapor environment. The weights of these samples slightly increased during the corrosion test. The weight gain rates for Lu, Yb and zircon EBC samples were 2.218 × 10−6, 4.688 × 10−6 and 2.989 × 10−6 g/cm2·h, respectively. In the corrosion mechanism of Lu and Yb cases, the gas path through channels in the EBC layer were generated by the elimination of the boundary silica phase and then, the silicon nitride substrate was slightly oxidized. On the other hand, in the case of ZrSiO4, many cracks were introduced in the EBC layer during the corrosion test due to the difference in thermal expansion coefficient between the EBC layer and the substrate. However, the adhesion between the substrate and the EBC layer of ZrSiO4 was better than that of Lu and/or Yb EBC samples.

Keywords: EBC, water vapor corrosion, Lu2Si2O7, Yb2Si2O7, ZrSiO4