This invention relates to a composite material structure, and in particular to a composite material structure of good heat resistant properties.

The use of composite materials in the manufacture of a number of components is becoming widespread, the composite materials typically being of good strength and of relatively low weight, and so lending themselves for use in a wide range of applications. By way of example, carbon or glass fibre reinforced epoxy resin composite materials are in widespread use. Whilst these materials are of good strength and relatively low weight, they suffer from the disadvantage that they are only suitable for use in applications in which the operating temperature is relatively low. At higher temperatures, the resin materials used therein tend to soften with the result that the strength of the material is lost.

Ceramic based composite materials are also known, and have the benefit that they are suitable for use over a much wider range of operating temperatures. They, like epoxy resin based composites, are of low weight. However, it has been found that ceramic based composite materials tend to be relatively brittle, being of low bending strength and elongation under load, and so lack the strength characteristics of many resin based composite materials. Accordingly, the number of applications in which they can be used is relatively low. Furthermore, the nature of ceramic based composite materials is such that mounting components manufactured from such materials can be problematic as drilling into them or otherwise machining them in order to fix mounting brackets or the like thereto often results in damage to the components.

Metallic heat shields are known but are relatively heavy and so it is not preferred to use them in some applications. It is an object of the invention to provide a composite material structure in which at least some of the disadvantages associated with known composite materials are overcome or are of reduced effect.

According to the present invention there is provided a composite material structure comprising an element of a ceramic based composite material secured to an element of a resin based composite material, the ceramic based composite material element serving as a heat shield, shielding the resin based composite material element from heat produced, in use, from a heat source.

It will be appreciated that, in such an arrangement, the strength benefits associated with the use of a resin based composite material can be maintained, enabling the provision of a structure of good structural rigidity, the presence of the ceramic based composite material shielding the resin based composite material and so avoiding exposure of the resin based composite material to high temperatures despite being used in a high temperature environment. The disadvantages usually associated with resin based composite materials of having a restricted range of operating temperatures are thus overcome.

The ceramic based composite element is preferably arranged to shield the connections between the composite material elements from the heat produced, in use, from the heat source. As a result, a resin based adhesive or the like may be used to secure the composite material elements to one another.

The composite material elements are preferably adapted to, together, house a heat absorbing core. The core may further serve to provide thermal protection for the points at which the elements are secured to one another.

The resin based composite material element may have mounting fittings or the like secured thereto, for example being co-cured therewith or mechanically attached thereto. An arrangement of the type set out before may be used in the formation of, for example, a heat shield of low weight and good thermal performance, the heat shield also having good strength characteristics.

The invention will further be described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a diagram illustrating part of a structure in accordance with one embodiment of the invention; and

Figure 2 is a diagram illustrating part of a structure in accordance with another embodiment of the invention.

Referring firstly to Figure 1, a composite material structure 10 is illustrated. The structure 10 is intended to serve, in use, as a heat shield, providing thermal protection for a device or component 6 against heat output, in use, from a heat source 8. The structure 10 may be used in a wide range of applications in which heat shielding is required, for example protecting engine control components from heat emitted from parts of an engine or exhaust system in automotive applications. However, it will be appreciated that the invention is also suitable for use in other applications, for example in aerospace applications in which there are significant weight constraints.

The structure 10 comprises a ceramic based composite material element 12 and an epoxy resin based composite material element 14. As illustrated, the ceramic based composite material element 12 is of generally channel shaped form, defining a pair of side walls 16, the free edges of which terminate with inwardly extending fingers 18. The fingers 18, in this embodiment, are substantially coplanar. The resin based composite material element 14 is located within the channel defined by the ceramic based composite material element 12, abutting the inner faces of the fingers 18.

Between the ceramic based composite material element 12 and the resin based composite material element 14 is located a core 20 of a heat absorbing, for example microporous, material.

It is envisaged that the resin based composite material element 14 will be secured to the ceramic based composite material element 12 by means of a suitable adhesive, for example a resin based adhesive provided at the interfaces between the resin based composite material element 14 and the fingers 18. Similarly, the core 20 may be secured in position using a suitable adhesive.

In use, as illustrated, the structure 10 is orientated such that the ceramic based composite material element 12 is located closest to the heat source 8, shielding the resin based composite material element 14 from extreme temperatures. As a result, the strength properties associated with the resin based composite material element 14 are not significantly impaired despite the element 14 being used in an environment in which, in the absence of the protection provided by the ceramic based composite material element 12, it would not normally be suitable for use. The heat shielding provided by the ceramic based composite material element 12 further provides protection for the adhesive used to secure the elements 12, 14 to one another, and so the connection therebetween is not negatively impacted despite the structure 10 being used in a high temperature environment.

Both of the elements 12, 14 are of relatively low weight, thus the structure 10 is of low weight. The strength benefits associated with the use of a resin based composite material are maintained, as are the benefits associated with such materials being relatively easy to machine or process and secure to other components, and the ease with which fittings (for example fittings 22) may be attached thereto, for example by being co-cured therewith or subsequently mechanically attached thereto. It is envisaged that the process by which the structure 10 is manufactured will involve producing the ceramic based composite material element 12 as a standalone component, fabricated and cured independently of the other parts of the structure 10. Once the manufacture thereof has been completed, the core 20 and resin based composite material element 14 may be introduced thereto and secured in position. By completing the manufacture of the ceramic based composite material element 12 as a standalone component, the infiltration processes involved in the manufacture thereof will not result in resin materials used therein being absorbed into the pores of the core 20, which could negatively impact upon its thermal properties.

The structure 10 may be arranged to perform load bearing functions as permitted by the presence of the resin based composite material element 14. Whilst, the entirety of the element 14 may be shielded by the element 12, it is envisaged that in many applications only the part(s) of the element 14 that, in use, would be exposed to unacceptably high temperatures will be provided with the element 12 to provide shielding against such temperatures, for example as shown in Figure 2 described below.

With reference to Figure 2, it will be appreciated that in some arrangements, no core 20 may be required. Furthermore, there may be no need for the element 12 to include fingers 18 extending adjacent a rear face of the element 14. Instead, the element 12 may be adhered or otherwise secured just to part or all of the front face of the element 14. In such an arrangement, the element 12 still provides thermal protection for at least part of the element 14 and for the adhesive or the like located therebetween and used to secure the elements 12, 14 to one another.

In the arrangements described hereinbefore, one or more coatings and/or layers of materials serving to enhance the thermal properties of the structure 10 may be applied, laminated to, or otherwise provided, part or all of the structure 10. By way of example, a coating of a material that serves to enhance thermal radiation from the structure 10 by be applied to at least part thereof.

Whilst specific embodiments of the invention have been described hereinbefore with reference to the accompanying drawings, it will be appreciated that a wide range of modifications and alterations may be made without departing from the scope of the invention as defined by the appended claims. By way of example, the shapes and relative dimensions of the elements 12, 14 and core 20 may differ from those shown and may depend, for example, on the application in which the structure 10 is to be used.