COMPOSITE MATERIAL

Abstract

A method of manufacturing a composite material includes forming a conductive layer comprising one or more conductive filaments embedded in a polymeric matrix, forming a composite substrate comprising a polymeric matrix with fibre reinforcement and curing the polymeric matrix of the conductive layer and the polymeric matrix of the composite substrate.

Claims

1. A method of manufacturing a composite material, the method comprising: forming a conductive layer comprising one or more conductive filaments embedded in a polymeric matrix; forming a composite substrate comprising a polymeric matrix with fibre reinforcement; and curing the polymeric matrix of the conductive layer and the polymeric matrix of the composite substrate.

2. A method as claimed in claim 1, wherein the one or more conductive filaments are metal filaments.

3. A method as claimed in claim 2, wherein the one or more conductive filaments have a diameter of at least 0.08mm

4. A method as claimed in claim 1, wherein the conductive layer is formed first and the composite substrate layer is formed on top of the conductive layer.

5. A method as claimed in claim 1, wherein the composite substrate layer is formed first and the conductive layer is formed on top of the composite substrate layer.

6. A method as claimed in claim 1, comprising curing the composite substrate simultaneously with said conductive layer so as to bond the composite substrate and the conductive layer together via polymeric crosslinking.

7. A method as claimed in claim 1, wherein forming the conductive layer comprises winding the one or more conductive filaments.

8. A method as claimed in claim 7, comprising winding the one or more conductive filaments as a high angle hoop winding.

9. A method as claimed in claim 7, wherein the conductive layer comprises a single layer of conductive filament formed by winding a single conductive filament.

10. A method as claimed in claim 7, wherein the one or more conductive filaments are first coated with the polymeric matrix material and then both the one or more conductive filaments and their coating of polymeric matrix material are wound simultaneously to form the conductive layer.

11. A method as claimed in claim 1, comprising at least partially exposing the one or more conductive filaments.

12. A method as claimed in claim 1, comprising at least partially exposing the one or more conductive filaments by removing material from the conductive layer.

13. A method as claimed in claim 1, comprising eroding the one or more conductive filaments after curing the polymeric matrix.

14. A method as claimed in claim 13, wherein eroding the one or more conductive filaments comprises a grinding process.

15. A method as claimed in claim 1, further comprising: depositing a coating layer on a surface of the conductive layer.

16. A method as claimed in claim 15, wherein the coating layer comprises a nano-crystalline Co-P alloy.

17. A method as claimed in claim 1, wherein the polymeric matrix of the composite substrate and/or the polymeric matrix of the conductive layer comprises an epoxy anhydride.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0056] One or more non-limiting examples will now be described, with reference to the accompanying drawings, in which:

[0057] FIG. 1 illustrates a cross-section of a coated composite material according to the prior art;

[0058] FIG. 2 illustrates a cross-section of an exemplary coated composite material according to the present disclosure;

[0059] FIGS. 3a-3d illustrate a first example process for forming a hollow bore; and

[0060] FIGS. 4a-4d illustrate a second example process for forming a shaft.

DETAILED DESCRIPTION

[0061] FIG. 1 illustrates a prior art arrangement of a coated composite material comprising layers A to E. The lowermost composite substrate A is coated with intermediate layers B, C and D before an upper coating layer E, such as a metallic coating, is applied, e.g. by electroplating. The intermediate layer B is required to act as an adhesive enabling layer C to be bonded to the structure. Layer C is typically a nickel layer, applied by electroless plating and is required in order to provide a suitable surface for layer D, e.g. copper, to be applied via electroplating. Layer D is required in order to provide a suitable surface for applying the top coating layer. The intermediate layers B, C and D may add undesirable thickness to the surface of the composite substrate A and each layer adds undesirable cost and process time to the production of the end component.

[0062] FIG. 2 illustrates a coated composite material according to an example of the present disclosure, wherein a composite substrate A is bonded to a conductive layer X before adhering a top coating layer E to the outer surface of the conductive layer X. Once the conductive layer X has been applied to a surface of the composite substrate A, the top coating layer E may be deposited using standard techniques such as electroplating, ensuring good adhesion of the top coating layer E. This example clearly demonstrates the advantage of fewer layers and thus reduced weight, cost and production time.

[0063] FIG. 3a illustrates a first example process of winding a conductive filament 1 (such as copper wire) which has been pre-wetted with polymeric matrix 2a onto a mandrel 3. FIG. 3b illustrates the second stage of winding fibres 4 such as carbon fibre (typically wound in bundles), also coated in polymeric matrix 2b over the conductive filament 1 to form the composite substrate. FIG. 3c illustrates a curing stage (e.g. by application of heat or UV radiation) via curing apparatus 5 which simultaneously cures the polymer matrix 2a of the conductive layer and the polymer matrix 2b of the composite substrate (which may be the same or different) and a grinding stage in which grinding apparatus 6 removes a layer of material to expose the conductive filaments 1 (partially exposed and eroded filaments are indicated at 7). At least the grinding stage takes place after removal of the mandrel 3. The curing stage preferably takes place before mandrel removal. FIG. 3d shows the end product with a hard coating 8 applied on the interior surface of the cylinder.

[0064] FIGS. 4a to 4d are similar to FIGS. 3a-3d, but illustrate a second example process in which the composite substrate is first filament wound onto a mandrel 3, then the conductive filament 1 wound over the top of the composite substrate before curing and grinding and mandrel removal to form the finished product with a hard coating 8 on the outside as shown in FIG. 4d. In this process, the conductive filaments are essentially wound on as the last layer of the composite substrate windings.

[0065] As a variation to the process illustrated in FIGS. 4a-4d, an alternative process for forming a conductive layer on the outside of a composite part is to cure the composite substrate layer prior to winding on the conductive filaments. The cured substrate layer may also be machined (e.g. honed or ground) to provide a more even (e.g. straighter) surface finish before winding on the conductive filaments. This means that the conductive layer does not need to be laid as thickly in order to achieve a complete conductive layer.

[0066] The conductive filaments may benefit from a further physical or chemical treatment such as a corona treatment in order to aid the bonding to the resin system.

[0067] It will be understood that the description above relates to a non-limiting example and that various changes and modifications may be made from the arrangement shown without departing from the scope of this disclosure, which is set forth in the accompanying claims.