The oxidation and water vapor corrosion behavior of sintered HfSiO4, ZrSiO4, TiSiO4 compacts and high density HfSiO4 coated silicon nitride ceramics were examined at 1500 oC in a static state water vapor environment. The bulk weights of HfSiO4 and ZrSiO4 decreased after the water vapor corrosion test with a weight loss rate of 7.080 × 10−6 and 1.333 × 10−6 g/cm2·h, respectively. The weight of TiSiO4 remained unchanged within the experimental error after the corrosion test. A trace of corrosion was observed on the surface of grains of corrosion-tested compacts. On the other hand, the weight of high density HfSiO4 layer (Environmental Barrier Coating, EBC layer) coated silicon nitride specimens increased with a weight gain rate 1.495 × 10−6 g/cm2·h, which is attributed by the oxidation of the silicon nitride substrate.

Keywords: Water vapor corrosion, oxidation, HfSiO4, ZrSiO4, TiSiO4, silicon nitride