Assembly for controlling thermal stresses in ceramic matrix composite articles

Abstract

An assembly and method for controlling thermal stresses within ceramic-based articles when subjected to high temperatures while supported by a metallic article. The assembly includes a first body formed of a metallic material and having oppositely-disposed first and second surfaces, and a second body formed of a ceramic-based material and supported by the first body from the first surface thereof. The first and second bodies are located in a hot gas path such that the second body and the first surface of the first body are directly impinged by flowing hot gases. The assembly further includes a substantially uniform pattern of fins protruding from the second surface of the first body, and/or an interface structure between the first and second bodies that positively retains the second body to the first body and thermally insulates the first body from the first body.

Description

BACKGROUND OF THE INVENTION [0001] This invention relates to ceramic matrix composite (CMC) articles, such as CMC components of gas turbine engines. More particularly, this invention is directed to an assembly and method for controlling thermally-induced stresses that exist within CMC articles when subjected to high temperatures while supported by metallic structures. [0002] Higher operating temperatures for gas turbine engines are continuously sought in order to increase their efficiency. However, as operating temperatures increase, the high temperature durability of the components of the engine must correspondingly increase. Significant advances in high temperature capabilities have been achieved through the formulation of iron, nickel and cobalt-base superalloys. Nonetheless, superalloy components must often be air-cooled and / or protected by some form of thermal and / or environmental coating system in order to exhibit suitable service lives in certain sections of a gas turbine eng...

AI Technical Summary

Benefits of technology

[0008] The assembly includes a first body formed of a metallic material and having oppositely-disposed first and second surfaces, and a second body formed of a ceramic-based material and supported by the first body from the first surface thereof. The first and second bodies are located in a hot gas path such that the second body and the first surface of the first body are directly impinged by flowing hot gases. According to a first aspect of the invention, the assembly further includes a substantially uniform pattern of fins protruding from the second surface of the first body. The fins are of sufficient size to increase the rigidity of the first body and promote heat transfer from the first body. According to a preferred aspect of the invention, the fins further serve to achieve more uniform temperatures within the first and second bodies and increase the stiffness of the first body to the extent that the thermal mass of the first body can be minimized.

[0009] According to a second aspect of the invention, the assembly further has an interface structure between the first and second bodies. The interface structure comprises a resilient sealing member disposed between the first and second bodies and received in a recess in the first surface of the first body, and a ceramic saddle formed separately from the first and second bodies, received in the recess with the resilient sealing member, and disposed between the resilient sealing member and the second body. According to this aspect of the invention, the ceramic saddle and resilient sealing member cooperate to assist in positively retaining the second body to the first body and thermally insulating the first body from the first body in a manner that reduces thermal stresses within the second body, such as those caused by thermal gradients within the second body.

Problems solved by technology

However, as operating temperatures increase, the high temperature durability of the components of the engine must correspondingly increase.

However, CMC materials are also much less ductile and have significantly lower thermal conductivities than those of superalloys, rendering CMC vanes particularly prone to damage from thermally-induced stresses and strains.

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