GB2475023A

GB2475023A - Multi-layer armour and radiation screening plate

Info

Publication number: GB2475023A
Application number: GB8617242A
Authority: GB
Inventors: Jurgen Jung; Alfred Reck
Original assignee: Interatom Internationale Atomreaktorbau GmbH
Current assignee: Interatom Internationale Atomreaktorbau GmbH
Priority date: 1985-09-11
Filing date: 1986-07-15
Publication date: 2011-05-11
Anticipated expiration: 2006-07-15
Also published as: IT8648313A0; GB2475023B; GB8617242D0; FR2727507A1

Abstract

There is proposed a multi-layer armour which consists of (preferably light) metal layers (11, 13) and at least one ceramic layer (12). In addition, a pure metal layer (13) is applied to one plate or to a shaped part (11) by thermal spraying, which layer follows further layers (14, 15) produced in the same way, in which a part of the metal in the spraying material is gradually replaced by a suitable ceramic (e.g. aluminium oxide or titanium carbide) until finally a pure ceramic layer (12) is applied. Further layers, in which again a part of the ceramic is replaced by metal can follow until again a covering layer of pure metal is obtained. Further layers can be provided which serve for the screening against radio-active radiation (17, e.g. of boron carbide) or against electromagnetic impulses (18, e.g. of copper).

Description

MULTI-LAYER ARMOUR AND SCREENING PLATE AS WELL AS

PROCESS FOR ITS PRODUCTION

The present invention relates to a multi-layer armour plate according to the preamble of claim 1 and to a process for its production. It is known that such armourings are especially effective against the effect of projectiles which consist, on the impact side of the shell, of hard, therefore necessarily also brittle, material which is supported by a layer arranged therebehind of a softer ductile material. Almost exclusively there has been used for this purpose steel armouring hardened on its one surface by cementing or similar processes. The possibilities of its use in very great thickness are limited by its high specific gravity; moreover its resistance against explosive shells which are filled with a hollow charge is insufficient.

Therefore armourings have already been proposed in which the hard layer destroying as much as possible the impacting shell consists of a ceramic material which is connected with a layer of a high strength light metal alloy. The connection of the two layers takes place by use of adhesive or soldering. Operating difficulties occur here as soon shaped plates with curved surfaces rather than flat plates are to be produced. The solder or adhesive connection represents a weak point at which, as a result of the influence of the impulse energy of the impacting shell, a splitting off of parts of the ceramic material can take place. As a result of this, these bonded plates do not show the constant transition from the hard to the soft material as characterised by the above indicated steel armour. In nuclear technology, the use is known of layers with whose assistance the propagation of radio-active radiation can be limited.

In the same way, the screening of chambers against electromagnetic disturbing radiations by the inclusion in cages made of wire mesh or metal foils is known.

The object of the present invention belongs in S. contrast to this state of the art to create an armour material which is producible in almost any desired forms, makes use of the hardness and melting resistance of the ceramic like the high ductility of metal but however possesses an approximately uniform transition from one material to others. The build-up of stresses endangering the integrity or the bonding of the ceramic to metal should be reduced or avoided. Furthermore the material should optionally also be in the layer which screens off the object to be protected against radio-active radiation and/or electromagnetic impulses.

The solution of this object takes place by the means indicated in the characterising part of claim 1.

The mixture of metal and ceramic made possible by the use of the manufacturing process further discussed below allows a quasi uniform altering of the material properties from the hard brittle forward side of the plate to the relatively soft viscoelastic rear side of the plate in order to achieve the desired thickness of the plates by production following one after the other of component layers, each of which can be changed in its composition for this purpose and is only a few tens of millimetres in thickness. In this way an essentially improved bonding is achieved between the two materials.

The embodiment of the invention according to the second claim is concerned with an especially intimate connection of the layers with one another if, when not considering manufacturing or use regions, another metal than that for the basic plate is used for the construction of the transition layer. With the use of the light metal proposed in claim 3, bulk densities of about 4 g/cm3 may be realised, that is the here proposed armouring weighs only about half as much as a steel armouring of like thickness.

A construction of the armouring as proposed in claim 4 in which there are arranged about an intermediate ceramic layer in approximately mirror image fashion transition and metal layers, achieved by the arrangement of the hard layer between two ductile layers (an arrangement as was not possible with the above-mentioned metal armour), makes very difficult a separation of the parts of the ceramic layer as the result of impacting projectiles.

An embodiment of the invention according to the fifth claim reduces the stresses occurring in the ceramic and avoids the risk that cracks which were generated by the impacting of projectiles propagate over greater distances.

As a result of the embodiment of the invention according to the sixth claim, the armour can also remove the object to be protected at least partially from the influence of radio-active radiation (for example arising as a result of explosions of explosions of nuclear weapons). In particular, also as a consequence of such explosions there is to be considered with the occurrence of strong electromagnetic impulses which are capable of damaging electronic equipment in the chamber to be protected. The embodiment of the invention according to the seventh claim is also suitable for protecting against such a form of attack.

The thermal spraying process proposed in the eighth claim allows not only the coating of almost any desired shaped part but makes possible too by application of a plurality of relatively thin layers the achieving of greater armour thicknesses and the desired approximately uniform alteration of material properties.

The process defined according to the ninth claim allows the production of armourings with hard layer arranged in the middle.

In the tenth claim, it is indicated how the required joints are to be produced in the same working procedure as for the production of the plates as such; the mask defined in the eleventh claim is to be produced and used simply.

Should the hitherto given procedural steps be repeated as appropriate more than once, an armouring is producible with a plurality of metal and ceramic layers alternating with one another. This can be necessary if with given total thickness of the armour the individual layers for example should not exceed a definite thickness for the purpose of stress reduction.

The schematic simplified drawings show for reasons of clarity Figure 1 a cross-section through an armour plate according to the invention and Figure 2 in perspective representation an arrangement as is necessary for carrying out the process according to claim 9 or 10.

The production of an armour plate denoted in its entirety by 10 begins with a shaped part or plate 11 preferably of a hard light metal alloy. In Figure 1, proceeding from left to right, there takes place firstly the spraying of a metal layer 13, with the plate 11 and the layer 13 being able to consist of different metals.

Then further (shown excessively thickly) part layers 14, (which form in their totality a transition layer 16) are applied by means of thermal spraying, in which the metal is replaced gradually in the spraying nozzle by a suitable ceramic material, for example of aluminium oxide or titanium carbide. In the drawing, for reasons of simplicity, only two part layers are shown; in practice their number, can be essentially greater corresponding to the total thickness of armour plate to be obtained and for obtaining an approximately continuous concentration gradient of metal to ceramic or the reverse. Finally, (customarily also in several part steps) a layer 12 of pure ceramic is applied. This already represents an effective armour plate in the projectile flight path running from right to left. It can however be further improved by applying further part layers 15, 14 in the reverse sequence, in which gradually ceramic is replaced S. by metal in the spraying nozzle. For closing off, there is then a further layer 13 consisting only of metal. As required, still further layers, if necessary likewise being built up from part layers, can be included in the construction for the achieving of special effects, with their arrangement not necessarily having to take place at the positions chosen here, rather being able to take place even at other suitable positions therefor. A layer 17 of a radio-active radiation absorbing material, e.g. boron carbide and a layer 18 of a metal, e.g. copper or iron, which guarantees a high screening effect against electromagnetic impulses are shown. It also lies within the invention for the layers 17 and 18 not to possess discrete characters as shown here but to form an integral constituent of layers 12 or 13 as a result of corresponding mixing during the fabrication process.

The relative thicknesses of the individual layers must also not be the same as shown here but are varied according to the protection which is aimed at. This layer construction can be reproduced as necessary.

Number and thickness of the individual layers depend, apart from the total thickness of armouring to be obtained predominantly on the manufacturing technology viewpoints. In the representation according to Figure 2, it can be seen that at least the ceramic layer 12 is divided up by joints 19 into individual fields. The joints 19 can however even be propagated partially in the transition layer 16 (not shown here). This is achieved by arranging a mask 20 in the gap (here shown largely exaggerated) gap before the plates 10. This consists in the example of a frame 21 and wires or sheet metal strips 22 clamped therein horizontally and vertically. These then place in shadow the parts of the plate 10 lying in the projection, with the flow of the particles applied in the thermal spraying here being indicated by arrows.

Claims

Claims: - 1. Multi-layer armour plate (10) with at least one ceramic layer (12) and one metal layer (13), characterised in that the two layers are connected with one another by a transition layer (16) of a metal-ceramic mixture, whose content with respect to the one and the other components changes approximately uniformly and evenly from the metal layer (11) to the ceramic layer (12).
2. Armour plate (10) according to claim 1, characterised in that the metal layer (13) and the transition layer (16) contain the same metal.
3. Armour plate (10) according to claim 1 or 2, characterised in that the metal layer (11) and/or the transition layer (16) consists of or contains a light metal alloy or contain this.
4. Armour plate (10) according to claim 1, characterised in that the ceramic layer (12) is embedded between two transition layers (16) which for their part are enclosed by two metal layers (13).
5. Armour plate (10) according to claim 1, characterised in that the ceramic layer (12) and optionally a part of the transition layer (16) is dividedup by joints into individual fields.
6. Armour plate (10) according to one or several of the preceding claims, characterised in that one or several of the part layers of the ceramic layer (12) or transition layer (16), or an additional layer (17) contain or consist of a radio-active radiation absorbing material.
7. Armour plate (10) according to one or several of the preceding claims, characterised in that one or several of the metal layers (11, 13) or an additional metal layer (18) is connected as screening against electromagnetic impulses.
8. Process for the production of an armour plate (10) according to claim 1, characterised in that part layers (14, 15) of the transition layer (16) and the ceramic layer (12) are applied to a metal plate (11) or a metal shaped part by means of thermal spraying one after the other, with a further layer (13) of a metal being applied before the first partial layer, and a part of the metal being replaced progressively by ceramic material for the production of the partial layers (14, 15).
9. Process for the production of an armour plate (10) according to claim 4, characterised in that, after the steps set out in claim 7, further part layers (15, 14) are applied, for whose production a part of the ceramic is gradually replaced by metal, as soon as a layer (13) of pure metal as well as there being applied behind it a layer (13) of pure metal.
10. Process for the production of an armour plate (10) according to claim 5, characterised in that the spraying of individual part layers takes place through a mask (20) whose projection on the plate (10) corresponds to the arrangement of the joints (17).
11. Process according to claim 10, characterised in that a mask (20) of wires or sheet metal strips (22) running two dimensions is used.
12. Process for the production of an armour plate (10) according to claim 1, 4 or 5 with more than one ceramic layer (12), characterised in that the steps set out in claims 8, 9 and possibly 10 arerepeated more than once.i Amendments to the claims have been filed as follows 1. A multi-layer armour plate comprising at least one ceramic layer spaced apart from at least one all metal layer in a contiguous arrangement of layers, there being disposed between adjacent ceramic and all metal layers and connecting said layers a transition layer made up of a metal-ceramic mixture, whose content with respect to metal and ceramic components changes approximately uniformly and evenly from high metal/low ceramic material content adjacent an all metal layer to low metal/high ceramic material content adjacent a ceramic layer, a said all metal layer covering a metal support plate.2. An armour plate according to claim 1, wherein the metal of the metal support plate differs from that used in producing said arrangement of layers.3. An armour plate according to claim 1 or 2, wherein a light metal alloy is used in producing said arrangement of layers.4. An armour plate according to any preceding claim, wherein the ceramic layer is embedded between two transition layers which are respectively additionally enclosed by all metal layers.5. An armour plate according to any preceding claim, wherein the ceramic layer and optionally a part of a transition layer thereadjacent is divided up by jointsinto individual fields.6. An armour plate according to any preceding claim, wherein the ceramic layer is formed of aluminium oxide or titanium carbide.7. An armour plate according to one or more of the preceding claims, wherein one or more constituent layers included in a said ceramic layer or transition layer, or an additional layer, contain or consist of respectively a radio-active radiation absorbing material.8. An armour plate according to one or more of the preceding claims, wherein one or more said metal layers or an additional metal layer is connected as screening against electromagnetic impulses.9. A multi-layer armour plate substantially as hereinbefore described with reference to, and as shown in, Figure 1 of the accompanying drawings, optionally as modified by Figure 2.10. A process for the production of an armour plate wherein there are applied by thermal spraying to a metal plate or plate metal shaped part an all metal layer followed by a ceramic layer, with there being applied by thermal spraying between application of said layers a transition layer made up of constituent layers in which there takes place approximately uniformly and evenly from the applied all metal layer to the ceramic layer a transition from high metal/low ceramic content to low metal/high ceramic content.11. A process according to claim 10, wherein, following application of the ceramic layer, there is applied by thermal spraying a second transition layer followed by a further all metal layer, the second transition layer being made up of constituent layers in which there takes place approximately uniformly and evenly from the ceramic layer to the further all metal layer a transition from low metal/high ceramic content to low ceramic/high metal content.12. A process according to claim 11 or 12, wherein aluminium oxide or titanium carbide is employed in forming the ceramic layer.
13. A process according to claim 10, 11 or 12, wherein the spraying of individual or constituent layers containing ceramic material takes place through a mask whose projection onto the metal plate corresponds to an arrangement of joints which divide said layer(s) intofields.
14. A process according to claim 11 or claims 11 and 12, wherein a mask comprising wires or sheet metal lo 1 strips running in two dimensions is used.
15. A process according to any one of claims 10 to 14, wherein, when the armour plate is to comprise more than one ceramic layer and/or all metal layer, the steps set out in said claims are repeated more than once to produce a structure wherein all metal and ceramic layers alternate and are separated by said transition layers.
16. A process for the production of an armour plate, substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings, optionally as modified by Figure 2.