Using Si3N4 to Improve Efficiency ofThermal Barrier Coatings on Blades inGas Turbine/Jet Engines

Yttria Stabilized Zirconia (YSZ) is an effective thermal barrier coating used on the blades of gas turbine engines. However it is prone to degradation from attacks caused by heated Calcium Magnesium Aluminum Silicon (CMAS) oxide powder that infiltrates into the Nickel superalloy substrate. In this experiment a thin Si3N4 layer was applied on top of the YSZ layer using Plasma Enhanced-Chemical Vapor Deposition (PE-CVD) and then subject to heat after being coated with a slurry CMAS oxide powder. The samples coated with a 10um layer of Si3N4 blocked the CMAS from entering and layed on the top of the sample, while not showing signs of damage caused by the heat. Silicon rich samples were also tested after being deposited onto the YSZ by Air Plasma Spray (APS) and proved to be inadequate due to degradation that occurred during the heat treatment. Si3N4 is a promising solution to degradation caused by CMAS infiltration.