GB2229954A

GB2229954A - High pressure container

Info

Publication number: GB2229954A
Application number: GB9003598A
Authority: GB
Inventors: Herbert Krumm
Original assignee: Rheinmetall GmbH
Current assignee: Rheinmetall Industrie AG
Priority date: 1989-03-04
Filing date: 1990-02-16
Publication date: 1990-10-10
Also published as: DE3907087A1; GB9003598D0; FR2643966A1

Description

1 - TITLE 40719/wsw HiF-rh Pressure Container This invention relates to a

high pressure container, such as a gun barrel, with a wall made of a fibre composite material.

Known high pressure containers with a wall of fibre composites are characterised by:

- a high strength, - a direction of fibre orientation in accordance with loading (winding technique), - a light weight, - good shaping possibilities, and - good corrosion-resisting properties.

High pressure containers of this kind are mainly made of fibre composites in a plastic matrix but in this case they cannot be used at temperatures above 2500C.

To enable high pressure containers of this kind to be used under more exacting conditions such as those arising in the chemical industry, high temperature turbines or barrels of weapons, experiments have been carried out in which fibre materials have been embedded in other matrix materials. With conventional production methods, however, these experiments have hitherto failed 407 19/wsw as a result of the poor wettability of the fibres, possible chemical reaction between fibre and matrix and thermal incompatibility (for example recrystallisation of the fibres, caused by excessive production temperatures).

More recent technology in the field of explosion techniques provide explosive compression and/or explosive welding which enable an intimate combination of fibre and matrix to take place under quasi-cold conditions.

Taking this new technology into account an object of this invention is to provide a high-pressure container with a wall made of a fibre composite which, without foregoing the advantages mentioned earlier, can even be used at very high temperatures such as those occurring in a gun barrel.

According to this invention there is provided a high pressure container with a wall including a fibrous composite material layer wherein the fibre composite material layer comprises a ceramic and/or metallic powder as a matrix as well as a fibre material and produced by means of an explosive compression process.

The invention combines the advantages of known high pressure containers of FVW with the following additional advantages: resistance to high temperatures, satisfactory resistance to mechanical and 1 407 19/wsw thermal shock; and limited absorption of moisture.

In addition, the use of a metallic and/or a cerami matrix in the fibre composite enables the wall of the high-pressure container to be provided with either an electrically conductive or with an insulating layer of fibrous composite according to the purpose for which it is to be used.

The invention will be explained further by reference to embodiments by way of examples and shown in the accompanying drawings.

In the drawings:

Figure 1 shows a cross section through a first embodiment of the invention for a gun barrel, Figure 2 shows a cross section through a second embodiment of the invention for a gun barrel, Figure 3 shows a section through a third embodiment of the invention for the wall of a high temperature/high pressure container, Figure 4 shows a section through a fourth embodiment of the invention for a container wall which can be subjected to high stresses, and - 4 40719/wsw Figure 5 shows a section through a fifth embodiment of the invention for a container wall which can be subjected to high stresses.

The versions shown in Figures 1 and 2 are intended for gun barrels and include walls 10, 20 forming a highpressure container which can be subjected to extreme pressures and temperatures. The drawing shows only characteristics essential to the invention and the actual gun barrels, for the sake of simplicity, have been omitted as the construction is in itself known to a skilled man in the art. The form of cut-out parts over the length of the barrel is also known. A barrel bore axis forming the central longitudinal axis is illustrated but not referenced.

The gun barrel wall 10 shown in Figure 1 includes a wear- and temperatureresistant internal coating 11 characterised by heat insulating properties. This internal coating 11 preferably comprises a metal-ceramic powder advantageously embodying tantalum powder, and is produced by an explosive compression method. A layer 12 is a tough temperatureresistant layer having a poorer thermal conductivity than pure steel and likewise preferably comprising a pulverous metal-ceramic mixture.

A further layer is characterised by high thermal conductivity and preferably comprises tungsten compounds.

1 407 19/wsw A subsequent layer 14 is made of a fibre compound in which an aligned high-strength long fibre (filament applied by a winding technique) is embedded in a metal matrix of good thermal conductivity. The fibre composite of the layer 14 preferably comprises a carbon fibre in a matrix of copper alloy powder. The gun barrel wall 10 terminates on the outside in a layer formed by a high-strength steel tube of, for example 35 NiCrMoV 12. 10.

All the layers of the gun barrel wall 10 are preferably compressed by an explosive method in a suitable matrix (not shown) and welded together, likewise by an explosive process. The adoption of this explosion technique offers the additional advantage of auto or prestressing (fretting) the steel tube layer 15.

The actual advantage of the gun barrel wall 10 shown in Figure 1 resides in the fact that on the one hand the supporting layer 14 of fibre composite, due to the suitably cross-wound long fibre introduced, is capable of absorbing (above all) the tangential stresses undergone by the gun barrel, while on the other hand the M layer is protected by a temperature-resistant second layer 12 from the high peak temperatures occurring in the interior of the gun barrel when the weapon is fired.

The second version of a gun barrel wall 20 according - 6 407 19 /ws w to the invention, as shown in Figure 2, comprises a first layer 21, which serves as a wear- and temperatureresistant internal layer of good thermal conductivity preferably of chromium or tantalum. The subsequent second layer 22 is provided in the form of a fibre composite comprising a high strength short fibre in a metal matrix with good thermal conductivity and a high melting point, such as tungsten alloys. A subsequent third layer 23 consists of an aligned high-strength long fibre, preferably likewise cross-wound, such as a carbon fibre in a copper matrix. A fourth layer 24 comprises a high strength steel tube such as 45 NiCrMoV 14.4. The fifth layer 25 of this version is provided in the form of an outer barrel coating with good heat radiation, comprising for example a black varnish or a black metallic layer.

In the second example illustrated in Figure 2, as in the first shown in Figure 1, the second layer 22 and 12, the third layer 23 and 13 and the fourth layer 24 and 14 respectively can be compressed and welded by explosive technology, the tube steel layer 24 being here again autostressed (frettable) by the explosion process. The wear and temperature resistant internal coating 21 can equally well be applied in a subsequent step, for example by galvanisation.

51 407 19/wsw By comparison with conventional gun barrels of steel normally used for these latter the barrel walls to which the invention relates and which are shown in Figures 1 and 2 enable the required wall thickness and thus the weight of the barrel to be considerably reduced. This results in a noticeable reduction in vibration of the gun barrel and in the unbalance force exerted on its mounting system, thus improving the overall firing accuracy. The gun barrel walls according to the invention also make it possible, by the selection of suitable materials, to reduce the extensions and elastic expansions undergone by the barrel during firing.

If electrical insulation is required between the interior and the exterior of the gun barrel, as in the case of barrels designed for electromagnetic or electrothermal artillery, this can be provided in a simple manner by adopting a different composition for the material of the fibrous composite layers 14 (Figure 1) or 22 or 23 (Figure 2). For such cases glass in a ceramic matrix can be used.

The examples illustrated in Figures 3 and 4 for high pressure container walls 30 and 40 and according to the invention serve to make the invention still clearer and are provided with layers 32 and 42 made of fibre composites and shown in an initial situation preceding an 8 - 407 19/wsw explosive compression. These layers 32, 42 show anisotropic properties after the explosive compression.

The FC layer 32 shown in Figure 3 has a wound long fibre 33 embedded in a powder matrix 34. The fibre 35, such as carbon fibre, is preferably arranged with a very dense cross-winding in a number of layers in such a way that when a high pressure container wall constructed on these lines is subject to the expected high pressure it is rendered highly resistant in the directions in which the main stresses occur.

For other applications the FC layer 42 shown in Figure 4 has been devised in which metal foils 43 are interposed between the individual layers of a wound long fibre 44, these foils 43 possibly comprising the same material as a powder matrix 45. The structure of the matrix can be rendered homogeneous by a subsequent explosive compression. Even if this latter happens to rupture the long fibres 33 and 44 the composite materials of the layers 32 and 42 retain their anisotropic properties.

In contrast to the above Figure 5 shows, prior to an explosive compression, a high-pressure container wall 50 according to the invention with an FC layer 52 in which anisotropic properties are required. In this case short fibres 54, such as glass fibres, are embedded in a matrix - 9 407 19/wsw of pulverous metal or ceramic 53. A system of this kind is particularly suitable when ceramic powder is to be used for the production of an electrically insulating layer.

1

Claims

407 19/wsw 1. A high pressure container with a wall including a fibrous composite material layer wherein the fibre composite material layer comprises a ceramic and/or metallic powder as a matrix as well as a fibre material and produced by means of an explosive compression process.
2. A high pressure container in accordance with Claim 1, wherein the fibre material is used in the form of wound long fibre or a short fibre.
3. A high pressure container in accordance with Claim or 2, wherein the wall includes a number of layers of fibre composite.
4. A high pressure container in accordance with Claim 1, 2 or 3, wherein one of the layers in the wall comprises a high-strength steel tube.
5. A high pressure container in accordance with Claim 4, wherein the layer of high-strength steel tube, during the explosive compression, is at the same time prestressed to improve the strength of the overall 11 structure.

40719/wsw
6. A high pressure container in accordance with Claim 5, wherein the wall comprises a number of layers combined with one another as regards thermal capacity and thermal conductivity to avoid thermal overloading of any one layer.
7. A high pressure container in accordance with any preceding claim, wherein the fibre material comprises carbon fibre or glass fibre.
8. A high pressure container or vessel constructed and arranged substantially as described herein and exemplified with reference to the drawings.
9. A barrel for a weapon comprising a high pressur container in accordance with any preceding claim.

Pued 1990atThe Patent 0Mce. State House. C671 High Holbo.-n. loondonWC1R4TP. Further copies ineybe ObtUned&om The PatentOffice.