In some examples, an article for a high-temperature mechanical system including a substrate and a doped calcia-magnesia-alumina-silicate resistant (doped CMAS-resistant) layer on the substrate. The doped CMAS-resistant layer is a thermal barrier coating or an environmental barrier coating and includes a calcia dopant.

In some examples, an article for a high-temperature mechanical system including a substrate and a doped calcia-magnesia-alumina-silicate resistant (doped CMAS-resistant) layer on the substrate. The doped CMAS-resistant layer is a thermal barrier coating or an environmental barrier coating and includes a calcia dopant.

A method for processing a component is provided and includes masking a first portion of the component with a maskant. The maskant includes a slurry having a plurality of particles in a fluid carrier. The plurality of particles comprises at least one of silicon, carbon, one or more rare earth disilicates, monosilicates or oxides, and combinations thereof. The method includes depositing a silicon-based coating on a second portion of the component via a chemical vapor deposition process and removing the maskant and any overlying silicon-based coating from the first portion of the component.

A method for processing a component is provided and includes masking a first portion of the component with a maskant. The maskant includes a slurry having a plurality of particles in a fluid carrier. The plurality of particles comprises at least one of silicon, carbon, one or more rare earth disilicates, monosilicates or oxides, and combinations thereof. The method includes depositing a silicon-based coating on a second portion of the component via a chemical vapor deposition process and removing the maskant and any overlying silicon-based coating from the first portion of the component.

In one example, a method for forming an environmental barrier coating (EBC) and/or abradable coating on a substrate. The method may include depositing a coating on a ceramic or ceramic matrix composite (CMC) substrate to form an as-deposited coating, wherein the coating includes at least one of an environmental barrier coating (EBC) and an abradable coating. The method further comprises heat treating the as-deposited coating at or above a first temperature for a first period of time following the deposition of the as-deposited coating on the substrate, wherein heat treating the as-deposited coating includes heating the as-deposited coating to or above the first temperature at a controlled rate. The heat treatment may be configured to at least one of decrease the open pores and/or microcracks of the heat-treated coating compared to the as-deposited coating or control a grain size of the heat-treated coating.

In one example, a method for forming an environmental barrier coating (EBC) and/or abradable coating on a substrate. The method may include depositing a coating on a ceramic or ceramic matrix composite (CMC) substrate to form an as-deposited coating, wherein the coating includes at least one of an environmental barrier coating (EBC) and an abradable coating. The method further comprises heat treating the as-deposited coating at or above a first temperature for a first period of time following the deposition of the as-deposited coating on the substrate, wherein heat treating the as-deposited coating includes heating the as-deposited coating to or above the first temperature at a controlled rate. The heat treatment may be configured to at least one of decrease the open pores and/or microcracks of the heat-treated coating compared to the as-deposited coating or control a grain size of the heat-treated coating.

A gas turbine engine article includes a substrate and a silicate-resistant barrier coating disposed on the substrate. The silicate-resistant barrier coating is composed of a refractory matrix and a calcium aluminosilicate additive (CAS additive) dispersed in the refractory matrix.

A gas turbine engine article includes a substrate and a silicate-resistant barrier coating disposed on the substrate. The silicate-resistant barrier coating is composed of a refractory matrix and a calcium aluminosilicate additive (CAS additive) dispersed in the refractory matrix.

A method to produce a ceramic matrix composite with controlled surface characteristics includes: applying a scrim ply to a surface of a fiber preform, where the fiber preform includes silicon carbide fibers coated with boron nitride; infiltrating the fiber preform and the scrim ply with a slurry, thereby forming an impregnated ply on an impregnated fiber preform; infiltrating the impregnated fiber preform and the impregnated ply with a melt comprising silicon, and then cooling, thereby forming a ceramic matrix composite having a ceramic surface layer thereon, where the ceramic surface layer has a predetermined thickness and is devoid of boron; machining or grit blasting the ceramic surface layer to form an intermediate layer suitable for coating; and depositing an environmental barrier coating on the intermediate layer. Thus, a ceramic matrix composite coated with the environmental barrier coating is formed with the intermediate layer in between.

A method to produce a ceramic matrix composite with controlled surface characteristics includes: applying a scrim ply to a surface of a fiber preform, where the fiber preform includes silicon carbide fibers coated with boron nitride; infiltrating the fiber preform and the scrim ply with a slurry, thereby forming an impregnated ply on an impregnated fiber preform; infiltrating the impregnated fiber preform and the impregnated ply with a melt comprising silicon, and then cooling, thereby forming a ceramic matrix composite having a ceramic surface layer thereon, where the ceramic surface layer has a predetermined thickness and is devoid of boron; machining or grit blasting the ceramic surface layer to form an intermediate layer suitable for coating; and depositing an environmental barrier coating on the intermediate layer. Thus, a ceramic matrix composite coated with the environmental barrier coating is formed with the intermediate layer in between.