Method of bonding a metallic component to a non-metallic component using a compliant material

Abstract

A means for attaching a metallic component to a non-metallic component using a compliant material having thermal properties intermediate those of the metallic component to a non-metallic component is provided. The method can accommodate CTE mismatches and wear-type problems common to many assemblies of dissimilar materials. In particular, the method provides a sufficient wear surface to accommodate relative motion and provide a durable wear surface that does not excessively wear/gall/mico-weld itself together and provides the necessary damping and motion for proper operation in aeronautical applications.

Claims

1. A bonded assembly comprising: a metallic component; a ceramic matrix composite component; and a compliant material located in a bonding region between the metallic component and the ceramic matrix composite component and diffused into the metallic component and the ceramic matrix composite component, the compliant material having coefficient of thermal expansion intermediate those of the metallic component and the non-metallic component wherein the compliant material consists essentially of a single homogenous interlayer selected from the group consisting of a foil of aluminum, an aluminum powder and an aluminum paste.

2. The bonded assembly of claim 1 wherein: the interlayer is a foil of aluminum.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 is a schematic representation illustrating an assembly for forming a compliant wear surface between a metallic material and a non-metallic material in accordance with the present disclosure.

(2) FIG. 2 is a schematic representation illustrating another assembly for forming a compliant wear surface between a metallic material and a non-metallic material in accordance with the present disclosure.

(3) FIG. 3 is a flow diagram illustrating steps involved in the creation of a compliant wear surface in accordance with a method of the present disclosure.

(4) It should be understood that the drawings are not necessarily drawn to scale and that the disclosed embodiments are sometimes illustrated diagrammatically and in partial views. In certain instances, details which are not necessary for an understanding of this disclosure or which render other details difficult to perceive may have been omitted. It should be understood, of course, that this disclosure is not limited to the particular embodiments disclosed herein.

DETAILED DESCRIPTION

(5) For the purpose of this disclosure the following definition applies:

(6) Thermal property means a physical property related to the application of heat energy, such as but not limited to the coefficient of thermal expansion (CTE), thermal conductivity and heat capacity.

(7) The present disclosure relates to a method for attaching a metallic component 12 to a non-metallic component 14 using a compliant material 16 having thermal properties intermediate those of the metallic component 12 and the non-metallic component 14. The resulting bonded assembly 10 has a robust mechanical attachment along the bonding region 13 of the metallic component. The method can accommodate CTE mismatches and wear-type problems common to many assemblies of dissimilar materials. In particular, the method provides a sufficient bonding surface to accommodate relative motion and provide a durable wear surface that does not excessively wear/gall/mico-weld itself together, and provide the necessary damping and motion for proper operation.

(8) FIG. 1 is a schematic of a bonded assembly 10 according to the disclosure. The assembly 10 comprises a compliant material 16 interposed between a non-metallic component 14 and a metallic component 12.

(9) The metallic component 12 may be a structure made of metallic or composite materials. The metallic component 12 may be a component of a jet engine such as a platform for a vane or fin structure.

(10) The non-metallic component 14 may be made of ceramic, a ceramic matrix composite (CMC) or any non-metallic material suitable for aeronautical use. The non-metallic component 14 may be a component of a jet engine such as a vane or fin structure.

(11) The compliant material 16 may be non-metallic or metallic (such as aluminum). In the embodiment shown in FIG. 1 the compliant material 16 is a single thin homogenous layer of material. The compliant material 16 may be in the form of a thin foil, powder, paste or other suitable form.

(12) The compliant material 16 should have one or more thermal properties, such as the coefficient of thermal expansion (CTE), intermediate those of the metallic component and the non-metallic component.

(13) The compliant material 16 may be capable of imparting the non-metallic component 14 with one or more properties favorable to its operation and use, such as hardness or enhanced thermal stability.

(14) FIG. 2 is a schematic representation illustrating another assembly 100 for forming a compliant wear surface between a metallic material 12 and a non-metallic material 14 in accordance with the present disclosure. In this embodiment the complaint material 16 comprises multiple layers. For example and without limitation, the compliant material 16 may comprise a relatively thicker middle layer 30 interposed between a first outer layer 32 and a second outer layer 34. The middle layer 30 and the outer layers 32, 34 may be metal, metal alloys or any suitable materials. The compliant material 16 may comprise layers of thin foil, powder or paste or combinations thereof.

(15) FIG. 3 is a flow-chart diagram illustrating steps involved in the creation of a bonded assembly 10 in accordance with a method of the present disclosure. The method may comprise the following steps:

(16) Step 100: Applying a thin layer of compliant material 16 between a metallic component 12 and a non-metallic component 14 to create an assembly 10. The compliant material 16 may be applied to the bonding region 13 of the metallic component 12 by any suitable means, including without limitation foil layup, powder application, plating, chemical vapor deposition, physical vapor deposition, cold spraying, or plasma spraying. The compliant material 16 may be applied to the bonding region 15 of the non-metallic component 14 by a process such as transient liquid phase (TLP) bonding, partial TLP (PTLP) bonding, brazing, etc. TLP and PTLP bonding are preferred due to their refractory nature, i.e., the bonds can be used at or above the bonding temperature.

(17) Step 102: Heating the assembly 10 to a first temperature suitable to temporarily liquefy the compliant material 16 in the bonding region, e.g., the region between the non-metallic component 14 and the metallic component 12. Heating may be accomplished by any conventional means, such as radiation, conduction, radio-frequency induction, resistance, laser, or infrared heating, and can cause direct or eutectic melting in the interlayer.

(18) Step 104: Bonding the metallic component 12 and the non-metallic component 14 by maintaining the assembly 10 at a bonding temperature until the compliant material 16 forms a solid bonding layer, wherein the bonding layer has a higher melting point than the first temperature. The bonding temperature may or may not be the same as the first temperature.

(19) The bonding step may involve diffusion of the compliant material 16 into both the metallic component 12 and into the non-metallic component 14.

(20) The bonding step may involve precipitation hardening the compliant material 16 by holding the assembly 10 at a hardening temperature T.sub.PH lower than the bonding temperature T.sub.bond for a specified period of time, thereby creating a precipitation-hardened bond. The assembly 10 may be cooled below the hardening temperature T.sub.PH and then heated back up to the hardening temperature T.sub.PH, or simply cooled down from the bonding temperature T.sub.bond to the hardening temperature T.sub.PH and held there until the compliant material forming the bond is hardened.

(21) During the bonding step 104 TLP or PTLP bonding may occur. In TLP and PTLP bonding, at least one component of the compliant material 16 reacts with the non-metallic component 14 to wet it (adhere to it) while at least one component of the compliant material 16 diffuses into the metallic component 12. If the compliant material 16 is non-metallic, then the compliant material reacts with the metallic component rather than diffusing into the metallic component.

(22) These multiple purposes of the TLP or PTLP bonding materials can be accomplished using an alloy foil, multiple layers of elemental foils or any combination therefor. While foils may be suitable for this purpose, the compliant material 16 may also be a powder, powder compact, braze paste or applied via electroplating or physical vapor deposition (PVD). The selection of bonding materials can be used to further accommodate CTE or compliance mismatches.

(23) Where the compliant layer 16 comprises multiple layers of different materials, the method may include the additional step 106 of homogenizing the compliant material that forms the bond by maintaining the assembly at a suitable second temperature. The second temperature may be higher, lower or the same as the first temperature. The homogenizing step may involve diffusion of the middle layer 30 into the outer layers 32, 34.

Benefits/Industrial Applicability

(24) From the foregoing, it can therefore be seen that the present disclosure can find industrial applicability in many situations, including, but not limited to, industries requiring light-weight and high-strength hybrid components having improved strength and wear resistance, including components that operate in high-temperature environments, such as combustors in jet engines. The disclosure can facilitate the optimal selection of non-metallic materials independent of the optimal selection of the metallic materials.

(25) For example, the technology as disclosed herein can provide CMC components mated to metallic components to increase the temperature resistance of the metallic component and improve the resistance of the compliant material against environmental effects such as erosion and foreign-object damage. Furthermore, as disclosed herein, CMCs may be mated with metallic or metallic composite components to provide hybrid composite structures. The technology as disclosed herein may find wide industrial applicability in a wide range of areas including, but not limited to, aerospace industries, automotive industries, and sporting industries.

(26) While the present disclosure has been shown and described in terms of one or more exemplary embodiments, it will be understood by one skilled in the art that various changes in detail may be effected therein without departing from the spirit and scope of the disclosure as defined by claims that may be supported by the written description and drawings. Further, where these exemplary embodiments (and other related derivations) are described with reference to a certain number of elements it will be understood that other exemplary embodiments may be practiced utilizing either less than or more than the certain number of elements.