Formation of Environmental Barrier Coating on SI3N4 by Gas‐Pressure Sintering

An easy processing technique was employed to form environmental barrier coating on silicon nitride ceramics by gas-pressure sintering. In this process, an amorphous silica layer was formed first on silicon nitride specimen by controlled oxidation and then the oxidized specimen was placed inside powder bed during gas pressure sintering for the formation of dense oxide coating by reaction sintering. Different powder beds were used for respective oxide coating on silicon nitride ceramics. The thickness of coating depends on the thickness of the oxide layer formed. The specimens were characterized and discussed in detail. As low cost method, specimens of any complicated shape can be coated by this novel oxidation reaction sintering technique.