In recent years, the operating temperatures of land-based gas turbine engines have increased to improve efficiency. As a result, greater demands are placed on the materials used in the manufacture of the engine components.
In particular, hot section turbine blades must function in a very severe operating environment. The blades are usually manufactured from advanced nickel-based superalloys but these materials on their own are still not durable enough. To enhance their durability, they are protected from hot corrosion and high-temperature oxidation through the use of special coatings. The coatings form adherent oxide layers that inhibit the blade material from directly interacting with potentially damaging elements within the combustion gases like oxygen, sulphur, and other contaminants. A popular approach involves coating the blades with an MCrAlY bond coat topped with a thermal barrier coating (TBC) overlay. BY JEFF PRITCHARD
