Protective coating systems for gas turbine engine applications and methods for fabricating such protective coating systems are provided. An exemplary protective coating system includes a substrate formed of a ceramic matrix composite material, a first coating layer formed directly on to the substrate and comprising an oxygen barrier material, a compliance material, or a bonding material and a second coating layer formed directly on to the first coating layer and comprising a thermal barrier material. The exemplary protective coating optionally includes a third coating layer partially formed directly on to the second coating layer and partially formed within at least some of the plurality of pores of the second coating layer.

A coating composition consisting essentially of one or more aliphatic or aromatic polyisocyanates, or combinations thereof, one or more catalysts, and one or more solvents. The composition is capable of forming a hard clear protective paint coating when applied to a surface, and the polyisocyanate is allowed to react with ambient moisture. A method for applying the coating comprising filtering compressed air to reduce moisture and impurities and then applying the coating composition to a painted surface using the filtered compressed air.

Methods for fabricating protective coating systems for gas turbine engine applications are provided. An exemplary method of applying a protective coating to a substrate includes the steps of providing a substrate formed of a ceramic matrix composite material, forming a first coating layer directly on to the substrate and comprising an oxygen barrier material, a compliance material, or a bonding material and forming a second coating layer directly on to the first coating layer and comprising a thermal barrier material. The method optionally includes forming a third coating layer partially directly on to the second coating layer and partially within at least some of the plurality of pores of the second coating layer.