Abstract: Coating system for reducing CMAS infiltration of substrates includes at least an inner ceramic layer and an outer alumina-containing layer. The outer layer includes up to 50 percent by weight titania. Additional ceramic layers and alumina-containing layers may be provided. The coating may be used for gas turbine engine components. Deposition techniques for the coating layers may depend on the end use of the component. Coated articles include a substrate, an optional bond coat on the substrate and a coating over the bond coat or on at least a portion of the substrate in the absence of a bond coat. The inner ceramic layer(s) exhibit a microstructure indicative of a deposition technique selected from thermal spray, physical vapor deposition, and suspension plasma spray, whereas the outer alumina-containing layer exhibits a microstructure indicative of suspension plasma spray, solution plasma spray, and a high velocity oxygen fuel spray.

Abstract: Methods for providing a coating system for reducing CMAS infiltration of substrates exposed to hot and harsh climates. Exemplary methods include optionally disposing a bond coat on a substrate, disposing an inner ceramic layer over the bond coat, or on the substrate in the absence of a bond coat, and disposing an outer alumina-containing layer including up to 50 percent by weight titania, using a high velocity oxygen fuel (HVOF) technique. Additional ceramic layers and alumina-containing layers may be provided to achieve a CMAS resistant coating. One or more suitable heat treatments may be utilized to phase-stabilize the alumina. The coating may be used for gas turbine engine components. Deposition techniques for the ceramic layer(s) may depend on the end use of the component.