An airfoil includes a ceramic matrix composite airfoil core that defines an airfoil portion and a root portion. The ceramic matrix composite airfoil core is subject to core thermal growth. A platform includes a ceramic matrix composite that wraps around the root portion. The platform is subject to platform thermal growth. A buffer layer is located between the root portion and the platform. The buffer layer absorbs a mismatch between the core thermal growth and the platform thermal growth.

A fluid heating component including: a pillar-shaped member made of ceramics and formed with through channels through which a fluid passes, and a conductive coating layer disposed on at least a part of a circumferential surface of the pillar-shaped member, wherein the conductive coating layer is disposed on coats the whole circumference of a cut surface of the pillar-shaped member in a state where the conducive coating layer is electrically connected, in the cut surface of the pillar-shaped member which is perpendicular to a passing direction of the fluid.

A fluid heating component including: a pillar-shaped member made of ceramics and formed with through channels through which a fluid passes, and a conductive coating layer disposed on at least a part of a circumferential surface of the pillar-shaped member, wherein the conductive coating layer is disposed on coats the whole circumference of a cut surface of the pillar-shaped member in a state where the conducive coating layer is electrically connected, in the cut surface of the pillar-shaped member which is perpendicular to a passing direction of the fluid.

A multi-layer coating arrangement includes an environmental barrier coating (EBC) over a substrate; and at least one dense vertically cracked (DVC) coating layer over the EBC. The at least one DVC layer is resistant to erosion, water vapor corrosion and to calcium-magnesium-aluminum-silicate (CMAS).

A multi-layer coating arrangement includes an environmental barrier coating (EBC) over a substrate; and at least one dense vertically cracked (DVC) coating layer over the EBC. The at least one DVC layer is resistant to erosion, water vapor corrosion and to calcium-magnesium-aluminum-silicate (CMAS).

A new class of multi-component rare earth multi-silicate materials has been created for use in harsh environments such as gas turbine engines. Moreover, by combining two-or-more rare earth disilicates the properties (for example, thermal expansion, thermal conductivity, etc.) can be tailored to fit specific applications, such as having a matching thermal expansion with that of silicon-based composites and a low thermal conductivity close to that of 1 W/m K. Applications can be extended for use with other material classes such as MCrAlY, MAX-phase, and refractory metal alloys, utilizing a thermal expansion of up to about 15−10.sup.−6 /° C. By mixing of specific sets of rare earth disilicates it is possible to obtain a high entropy or entropy stabilized mixture, and utilize features such as “sluggish diffusion”, and more.

A new class of multi-component rare earth multi-silicate materials has been created for use in harsh environments such as gas turbine engines. Moreover, by combining two-or-more rare earth disilicates the properties (for example, thermal expansion, thermal conductivity, etc.) can be tailored to fit specific applications, such as having a matching thermal expansion with that of silicon-based composites and a low thermal conductivity close to that of 1 W/m K. Applications can be extended for use with other material classes such as MCrAlY, MAX-phase, and refractory metal alloys, utilizing a thermal expansion of up to about 15−10.sup.−6 /° C. By mixing of specific sets of rare earth disilicates it is possible to obtain a high entropy or entropy stabilized mixture, and utilize features such as “sluggish diffusion”, and more.

An airfoil includes a ceramic matrix composite airfoil core that defines an airfoil portion and a root portion. The ceramic matrix composite airfoil core is subject to core thermal growth. A platform includes a ceramic matrix composite that wraps around the root portion. The platform is subject to platform thermal growth. A buffer layer is located between the root portion and the platform. The buffer layer absorbs a mismatch between the core thermal growth and the platform thermal growth.

An airfoil includes a ceramic matrix composite airfoil core that defines an airfoil portion and a root portion. The ceramic matrix composite airfoil core is subject to core thermal growth. A platform includes a ceramic matrix composite that wraps around the root portion. The platform is subject to platform thermal growth. A buffer layer is located between the root portion and the platform. The buffer layer absorbs a mismatch between the core thermal growth and the platform thermal growth.

In some examples, a method including depositing a plurality of particles on a ceramic or ceramic matrix composite (CMC) substrate to form a barrier coating on the ceramic or CMC substrate, the plurality of particles including a silica-rich rare earth (RE) disilicate material and a second material, wherein the silica-rich RE disilicate material includes excess silica compared to a stoichiometric RE disilicate material, wherein the barrier coating includes a first domain including the silica-rich RE disilicate material and a second phase, the second phase being disposed at grain boundaries, splat boundaries, or both of the barrier coating.