JOINING COMPONENT BODIES

Abstract

A method of joining first and second component bodies comprises: cold-spraying a first joining surface of the first component body with a bond material which is harder than the first joining surface; cold-spraying a second joining surface of the second component body with the bond material; and joining the first and second component bodies by way of the first joining surface.

Claims

1. A method of joining first and second component bodies, the method comprising the steps of: cold-spraying a first joining surface of the first component body with a bond material which is harder than the first joining surface; cold-spraying a second joining surface of the second component body with the bond material; and joining the first component body and the second component body by way of the first joining surface.

2. The method of claim 1, wherein a difference between a Vickers hardness of the bond material and a Vickers hardness of the first joining surface is at least 100 HV when measured under the same conditions.

3. The method of claim 1, wherein a difference between the Vickers hardness of the bond material and a Vickers hardness of the second joining surface is at least 100 HV when measured under the same conditions.

4. The method of claim 1, wherein the method comprises: cold-spraying the bond material onto and between the first joining surface and the second joining surface to form a joint between the first joining surface and the second joining surface, thereby joining the first component body and the second component body to one another.

5. The method of claim 4, further comprising heating the joint.

6. The method of claim 5, wherein the method comprises heating the joint for at least 30 minutes.

7. The method of claim 5, wherein heating the joint comprises holding the joint at a temperature from about 200° C. to about 1000° C.

8. The method of claim 1, wherein the first joining surface and the second joining surface comprise different materials.

9. The method of claim 1, wherein the method comprises: cold-spraying the first joining surface with the bond material to form a first bond coating; and cold-spraying a second joining surface of the second component body with the bond material to form a second bond coating; and welding the first bond coating to the second component body.

10. The method of claim 9, wherein welding comprises arc welding, gas welding, resistance welding, friction welding, electron beam welding or laser welding.

11. The method of claim 1, wherein the first joining surface, and the second joining surface each comprises a metal or a metal alloy.

12. The method of claim 11, wherein the first joining surface, and the second joining surface each further comprises a non-metallic, intermetallic, ceramic or oxide phase.

13. The method of claim 1, wherein the bond material comprises a metal or a metal alloy, and/or a ceramic.

14. A component manufactured by joining first component body and the second component body by the method according to claim 1.

15. A component comprising: a first component body and a second component body joined to one another at a joint by a region of bond material in direct contact with the first component body and the second component body; wherein the first component body comprises a first body material, the second component body comprises a second body material, and the bond material is harder than the first body material when measured under the same conditions.

16. The component of claim 15, wherein the Vickers hardness of the bond material is at least 100 HV greater than the Vickers hardness of the first body material when measured under the same conditions.

17. The component of claim 16, wherein the Vickers hardness of the bond material is at least 100 HV greater than the Vickers hardness of the second body material when measured under the same conditions.

18. The component of claim 15, wherein the region of bond material comprises a weld and wherein a heat-affected zone of the weld is restricted to the region of bond material.

19. The component of claim 15, wherein the first body material and/or the second body material is a metal or a metal alloy.

20. The component of claims 15, wherein the bond material comprises a metal or a metal alloy, and/or a ceramic.

Description

DESCRIPTION OF THE DRAWINGS

[0073] Embodiments will now be described by way of example only, with reference to the Figures, in which:

[0074] FIGS. 1(a, b, c) illustrate schematically, in sectional side views, a first example process of joining first and second component bodies by cold-spraying;

[0075] FIGS. 2(a, b, c) illustrate schematically, in sectional side views, a second example process of joining first and second component bodies by cold-spraying;

[0076] FIGS. 3(a, b, c) illustrate schematically, in sectional side views, a third example process of joining first and second component bodies by cold-spraying;

[0077] FIGS. 4(a, b, c) illustrate schematically, in sectional side views, a fourth example process of joining first and second component bodies by cold-spraying;

[0078] FIGS. 5(a, b, c) illustrate schematically, in sectional side views, a fifth example process of joining first and second component bodies by cold-spraying;

[0079] FIG. 6 is a flowchart illustrating a cold-spraying method;

[0080] FIG. 7 is a photograph of a flat rivet joined to a portion of a fan containment case for a gas turbine engine by cold-spraying;

[0081] FIG. 8 is a photograph of a sample prepared for metallographic analysis showing a section through the flat rivet and the fan containment case of FIG. 7;

[0082] FIG. 9 is an optical micrograph (following grinding, polishing and etching) of a portion of the sample shown in FIG. 7 at an interface between fan containment case material, rivet material and a cold-sprayed bond material;

[0083] FIG. 10 is an enlarged image of a portion of the interface between fan containment case material and cold-sprayed bond material shown in FIG. 9;

[0084] FIG. 11 is an enlarged image of a portion of the interface between rivet material and cold-sprayed bond material shown in FIG. 9;

[0085] FIG. 12 is a photograph of a topped rivet joined to a portion of a fan containment case for a gas turbine engine by cold-spraying;

[0086] FIG. 13 is a photograph of a sample prepared for metallographic analysis showing a section through the topped rivet and the fan containment case of FIG. 12;

[0087] FIG. 14 is an optical micrograph (following grinding, polishing and etching) of a portion of the sample shown in FIG. 13 at an interface between cold-sprayed bond material and fan containment case material;

[0088] FIG. 15 is an optical micrograph (following grinding, polishing and etching) of a portion of the sample shown in FIG. 13 at an interface between cold-sprayed bond material and rivet material;

[0089] FIG. 16 is an optical micrograph (following grinding, polishing and etching) of a portion of the sample shown in FIG. 13 at a corner where cold-sprayed bond material, fan containment case material and rivet material meet; and

[0090] FIG. 17 is an SEM image of an interface between a cold-sprayed coating of a cobalt-chromium-molybdenum alloy and an aluminium alloy (Al-6061) substrate.

DETAILED DESCRIPTION

[0091] A first example method of joining a component body 1 and a component body 2 to one another is illustrated schematically by way of FIGS. 1(a) to (c).

[0092] FIG. 1(a) shows component bodies 1 and 2 in cross-section. Surfaces 3A, 3B, 3C and 3D of component body 1 and surfaces 4A, 4B, 4C and 4D of component body 2 are visible in FIG. 1(a).

[0093] In a first joining step, component bodies 1 and 2 are brought together such that surfaces 3B and 4B abut one another, as shown in FIG. 1(b). In this configuration, edges of surfaces 3A and 3B also abut one another at an interface 5.

[0094] In a subsequent cold-spraying step, as illustrated in FIG. 1(c), a bond coating 6 is formed on the surfaces 3A and 4A, across the interface 5, by cold-spraying a bond material. The bond coating 5 adheres to surfaces 3A and 4A and therefore forms a joint between the component bodies 1 and 2 which holds them together.

[0095] A second example method of joining a component body 10 and a component body 11 to one another is illustrated schematically by way of FIGS. 2(a) to (c).

[0096] FIG. 2(a) shows component bodies 10 and 11 in cross-section. Surfaces 12A, 12B, 12C and 12D of component body 11 and surfaces 13A, 13B, 13C and 13D of component body 11 are visible in FIG. 2(a).

[0097] In a first joining step, component bodies 10 and 11 are brought together such that surfaces 12B and 13B abut one another, as shown in FIG. 1(b). In this configuration, an edge of surface 13A abuts surface 12B at an interface 14.

[0098] In a subsequent cold-spraying step, as illustrated in FIG. 2(c), a bond coating 15 is formed on the surfaces 12B and 13A, across the interface 14, by cold-spraying a bond material. The bond coating 15 adheres to surfaces 12B and 13A and therefore forms a joint between the component bodies 10 and 11 which holds them together.

[0099] A third example method of joining a component body 20 and a component body 21 to one another is illustrated schematically by way of FIGS. 3(a) to (c).

[0100] FIG. 3(a) shows component bodies 20 and 21 in cross-section. Surfaces 22A, 22B, 22C, 22D, 22E and 22F of component body 21 and surfaces 23A, 23B, 23C and 23D of component body 21 are visible in FIG. 3(a).

[0101] In a first joining step, component bodies 20 and 21 are brought together such that surfaces 22C and 23C abut one another, as shown in FIG. 3(b). In this configuration, a space 24 is enclosed on three sides by portions of surfaces 22B, 22C and 23B. An edge of surface 23B also abuts surface 22B at an interface 25.

[0102] In a subsequent cold-spraying step, as illustrated in FIG. 3(c), a bond material 26 is cold-sprayed into the space 24. The bond material 26 adheres to exposed portions of the surfaces 22B, 22C and 23B and substantially fills the space 24, thereby forming a joint between the component bodies 20 and 21 which holds them together.

[0103] A fourth example method of joining a component body 30 and a component body 31 to one another is illustrated schematically by way of FIGS. 4(a) to (c).

[0104] FIG. 4(a) shows component bodies 30 and 31 in cross-section. Surfaces 32A, 32B, 32C and 32D of component body 30 and surfaces 33A, 33B, 33C and 33D of component body 31 are visible in FIG. 4(a).

[0105] In a cold-spraying step, as illustrated in FIG. 4(b), a bond coating 34 is formed on surface 32B of component body 30. The bond coating 34 adheres to the surface 32B. An external surface of the bond coating is labelled as 32B′ in FIG. 4(b).

[0106] In a joining step, as illustrated in FIG. 4(c), component bodies 30 and 31 are joined to one another by: bringing the component bodies 30 and 31 together such that surfaces 32B′ and 33B abut one another at an interface 35; and welding the bond coating 34 to the component body 31 at the interface 35.

[0107] A fifth example method of joining a component body 40 and a component body 41 to one another is illustrated schematically by way of FIGS. 5(a) to (c).

[0108] FIG. 5(a) shows component bodies 40 and 41 in cross-section. Surfaces 42A, 42B, 42C and 42D of component body 40 and surfaces 43A, 43B, 43C and 43D of component body 41 are visible in FIG. 5(a).

[0109] In a cold-spraying step, as illustrated in FIG. 4(b), a bond coating 44 of bond material is formed on surface 42B of component body 40 by cold-spraying and a bond coating 45 of bond material is formed on surface 43B of component body 41 by cold-spraying. The bond coating 44 adheres to the surface 32B and an external surface of the bond coating 44 is therefore labelled as 42B′ in FIG. 5(b). Similarly, the bond coating 45 adheres to the surface 43B, and an external surface of the bond coating 45 is therefore labelled as 43B′ in FIG. 5(b).

[0110] In a joining step, as illustrated in FIG. 5(c), component bodies 40 and 41 are joined to one another by: bringing the component bodies 40 and 41 together such that surfaces 42B′ and 43B′ abut one another at an interface 46; and welding the bond coating 44 to the bond coating 45 at the interface 46, Welding bond coating 44 to bond coating 45 results in the formation of a continuous region of bond material joining component bodies 40 and 41.

[0111] For each of the first to fifth methods, it Will be appreciated that different bond materials may be selected for different applications. However, the inventors have found that, in order to achieve good adhesion (and therefore a stronger joint between the component bodies), the bond material should be harder than the material from which at least one of the component bodies is formed. An even stronger joint between the component bodies may be achieved when the bond material is harder than the materials from which both component bodies are formed. In particular, the Vickers hardness of the bond material should be about 100 HV, for example about 150 HV, higher than the Vickers hardness of the surface of one of (or, more advantageously, both of) the component bodies to be cold-sprayed. Suitable bond materials include metals or metal alloys (such as Al-, Co- or Ti-based alloys (for example, a Co—Cr—W alloy)) or ceramics (such as alumina).

[0112] In any of the first to fifth methods, surfaces may be mechanically prepared prior to cold-spraying. For example, surfaces may be mechanically prepared using milling, grinding, sand blasting and/or polishing processes.

[0113] In any of the first to fifth methods, a heat treatment may be performed following cold-spraying. For example, cold-sprayed component bodies may be held at a temperature of about 500° C. for about 4 hours. The inventors have found that such a heat-treatment leads to a further improvement in adhesion between the bond-material and the or each component body.

[0114] The first to fifth methods may be used to join any type of component body. For example, the methods may be used to join vehicle component bodies (i.e. to form vehicle components) such as engine component bodies (i.e. to form engine components). In some examples, one of the component bodies may be a mechanical fastener such as a rivet, bolt or screw. In such examples, the joint formed between the mechanical fastener and the other component body by cold-spraying with the bond material may be a secondary joint which strengthens a primary joint between the mechanical fastener and the other component body (i.e. a primary joint achieved through the action of the mechanical fastener itself).

[0115] In each of the first to fifth methods, the component bodies may be formed from any suitable material. However, the methods may be particularly beneficial when joining component bodies formed from metals or metal alloys. The inventors have found that the use of a cold-sprayed bond material is also particularly effective in improving joining of component bodies made of dissimilar materials. The inventors have also found that the methods may be particularly effective when one or both component bodies include non-metallic, intermetallic, ceramic or oxide phases (which may be present in component bodies formed from metals or metal alloys, for example as metal oxide surface coatings or as non-metallic, intermetallic, ceramic or oxides phases in an alloy microstructure also including predominantly metallic phases, such as in ferrous alloys like cast iron).

[0116] Although the fourth and fifth example methods described hereinabove make use of welding to join the two component bodies, it will be appreciated that other joining methods may be used, dependent on the materials from which the component bodies are formed and on the bond material. Other possible joining methods include brazing and soldering. It will also be appreciated that different types of welding may be selected based on the materials used and the nature of the component bodies to be joined. Example types of welding include arc welding, gas welding, resistance welding, friction welding, electron beam welding and laser welding. The methods of the fourth and fifth examples may be particularly useful when joining component bodies formed of materials which are themselves not suited to welding, for example because of excessively low or high melting points or because properties (e.g. mechanical properties) of the component bodies are adversely affected by welding (e.g. where the microstructure of a component body may be negatively affected by changes induced in a heat affected zone (HAZ) of a weld).

[0117] It will also be appreciated that the cold-spraying conditions (for example, cold-spray apparatus parameters) may be varied dependant on the materials to be deposited and the thickness of the coatings to be obtained. Exemplary cold-spray parameters are provided below under Examples.

[0118] As illustrated in FIG. 6, each of the first to fifth example methods include the steps of: cold-spraying a bond material onto at least one surface of one of two component bodies (block 101); and joining the two component bodies together (block 102).

[0119] It will be understood that the invention is not limited to the embodiments above-described and various modifications and improvements can be made without departing from the concepts described herein. Except where mutually exclusive, any of the features may be employed separately or in combination with any other features and the disclosure extends to and includes all combinations and sub-combinations of one or more features described herein.

EXAMPLES

Example 1

[0120] A flat rivet 200 made of an aluminium alloy (Al-6061) was riveted to a fan containment case 201 for a gas turbine engine, as shown in FIG. 7. The fan containment case 201 was also made of an aluminium alloy (Al-6061). The flat rivet 200 and surrounding portions of the fan containment case 201 were cold-sprayed with a coating 202 of aluminium alloy (Al-6061) and alumina (Al.sub.2O.sub.3) bond material.

[0121] The bond material was cold-sprayed using the following cold-spraying parameters:

[0122] Propellant Gas: N.sub.2

[0123] Gas Temperature: 300-500° C.

[0124] Gas Pressure: 20-30 bar

[0125] Gun Scan Speed: 500 mm/second

[0126] Step Size: 1 mm

[0127] The adhesion of the bond material to the rivet 200 and fan containment case 201 was investigated by imaging a metallurgical sample (shown in FIG. 8) cut in cross-section through the rivet perpendicular to the fan containment case surface. The sample was ground, polished and etched according under standard metallurgical sampling conditions and was imaged in an optical microscope. FIGS. 9, 10 and 11 are optical micrographs showing, respectively: an interfacial region between the bond material, B, the rivet material, R, and the fan containment case material, F; an interface between the bond material, B, and the fan containment case material, F; and an interface between the bond material, B, and the rivet material, R.

[0128] The bond material was found to form a porous coating which bonded well with the fan containment case and the rivet material. A small gap is visible in FIG. 9 between the fan containment case and the rivet where the bond material did not bond well.

Example 2

[0129] A topped rivet 300 made of an aluminium alloy (Al-6061) was riveted to a fan containment case 301 for a gas turbine engine, as shown in FIG. 12. The fan containment case 301 was also made of an aluminium alloy (Al-6061). The topped rivet 300 and surrounding portions of the fan containment case 301 were cold-sprayed with a coating 302 of aluminium alloy (Al-6061) and alumina (Al.sub.2O.sub.3) bond material.

[0130] The bond material was cold-sprayed using the following cold-spraying parameters:

[0131] Propellant Gas: N.sub.2

[0132] Gas Temperature: 300-500° C.

[0133] Gas Pressure: 20-30 bar

[0134] Gun Scan Speed: 500 mm/second

[0135] Step Size: 1 mm

[0136] The adhesion of the bond material to the topped rivet 300 and fan containment case 301 was investigated by imaging a metallurgical sample (shown in FIG. 13) cut in cross-section through the rivet perpendicular to the fan containment case surface. The sample was ground, polished and etched according under standard metallurgical sampling conditions and was imaged in an optical microscope. FIGS. 14, 15 and 16 are optical micrographs showing, respectively: an interface between the bond material, B, and the fan containment case material, F; an interface between the bond material, B, and the rivet material, R; and an interfacial region between the bond material, B, the fan containment case material, F, and the rivet material, R.

[0137] The bond material was found to form a porous coating which bonded well with the fan containment case and the rivet material.

Example 3

[0138] A Co—Cr—Mo alloy bond material was cold-sprayed onto a substrate made of an aluminium alloy (Al-6061). A sample was cut perpendicular to an interface between the bond material, B, and the substrate, S. A scanning electron microscope (SEM) image obtained from this sample is shown in FIG. 17. Mechanical interlocking of the bond material and the substrate is visible at the interface (i.e. particles of the bond material penetrate into the substrate).