LAMINATED COMPOSITE COATING FOR PROTECTING AN AIRCRAFT STRUCTURE AGAINST FIRE AND HEAT PROPAGATION

Abstract

The invention relates to a laminated composite coating (1) for protecting an aircraft structure (100) against fire and heat propagation, comprising a flame-retardant layer (2) of an intumescent polymeric material selected from the group of intumescent materials capable of expanding under the effect of heat from 180°C, and at least one protective layer of an inorganic material that retards the intumescent reaction of the flame-retardant layer (2), the retardant material being selected from the group of elastomers. Figure to be published with the abstract: Fig. 1

Description

Title of the invention: LAMINATED COMPOSITE COATING FOR PROTECTING AN AIRCRAFT STRUCTURE AGAINST FIRE AND HEAT PROPAGATION TECHNICAL FIELD OF THE INVENTION

[0001] The present invention relates to the field of fire barrier coatings, and more particularly to a laminated composite coating for protecting an aircraft structure against fire and heat propagation.

[0002] The laminated composite coating (or laminated coating) according to the invention is intended in particular, but not exclusively, to be affixed to aircraft nacelles to serve as a fire barrier between the engine located inside the nacelle and the nacelle on which it is fixed. STATE OF THE ART

[0003] In the aeronautical field, it is known to equip aircraft fuselage panels and nacelles with thermal protections comprising a thermally insulating and fire-resistant mattress sandwiched between two metal panels. In the particular case of nacelles, the mattress is formed of one or more layers generally made of insulators or ceramic wools. The thermal protections are fixed to the structure concerned by riveting.

[0004] These thermal protections, however, have the disadvantage of being relatively heavy and bulky due to the presence of metal panels and their fixing systems, making the installation and maintenance of the thermal protections long and complex.

[0005] The invention aims to overcome this drawback by proposing a coating for the protection of an aircraft structure, of the wall (or panel) type, having a reduced mass and size compared to those of the thermal protections of the prior art, while fulfilling the required specifications of the ISO 2685 standard in terms of thermal protection and fire resistance.

[0006] Another object is to provide a covering which can be fixed to the wall of the aircraft. without alteration of it. SUBJECT OF THE INVENTION

[0007] To this end, and according to a first aspect, the invention proposes a laminated composite covering for protecting an aircraft structure against fire and heat propagation, comprising a flame-retardant layer comprising an intumescent polymeric material chosen from the group of materials capable of expanding under the effect of heat from 180°C, and at least one protective layer of an intumescent material organic retarder of the intumescent reaction of the flame retardant layer, the retarder material being chosen from the group of elastomers.

[0008] Thanks to this arrangement of layers of materials, the coating obtained offers a reduced mass and volume compared to those of the thermal protections of the prior art, so that the coating according to the invention can be fixed directly to the structure concerned without it being necessary to resort to rivet-type fixing means, while ensuring the functionality required in terms of thermal protection and protection against fire by the ISO 2685 standard.

[0009] Advantageously, said at least one protective layer comprises within it a reinforcing fabric composed of fibers chosen from the group of ceramic, aramid, carbon, glass fibers or a combination of these fibers. The insertion within the strips of fabric(s) within an elastomer has the advantage of improving the retardant effect of the latter. According to a particular embodiment, the reinforcing fabric is impregnated with the elastomer, advantageously by calendering.

[0010] Advantageously, the intumescent material is an ethylene-vinyl acetate (EVM) copolymer.

[0011] Advantageously, the flame-retardant layer and said at least one protective layer respectively have a thickness greater than or equal to 2.5 millimeters.

[0012] Advantageously, the protective layer is provided with a coating of low-emissivity material. According to a preferred embodiment, the coating is a paint loaded with metal particles.

[0013] Advantageously, the coating comprises two protective layers of elastomer, one of the layers being reinforced by a fabric composed of fibers, the other protective layer being unreinforced (i.e. devoid of fabric). Advantageously, the unreinforced protective layer is arranged interposed between the flame-retardant layer and the reinforced protective layer.

[0014] The invention also relates to an aircraft structure, such as a nacelle, coated in whole or in part with a laminated composite coating as described above. BRIEF DESCRIPTION OF THE FIGURES

[0015] Other characteristics and advantages of the invention will emerge from the detailed description of the invention which follows, given by way of example and with reference to the appended figure in which:

[0016] [Fig.l] [Fig.l] represents a detailed view of an exemplary embodiment of a laminated composite covering fixed on the interior wall of a nacelle of an aircraft. DETAILED DESCRIPTION OF THE INVENTION

[0017] In relation to [Fig.l], an exemplary embodiment of a laminated composite covering 1 equipping the inner face 110 of the wall 100 of a nacelle of a aircraft capable of protecting the nacelle wall against fire and heat, or at least of delaying the spread of flames and heat towards it.

[0018] The laminated coating 1 according to the invention comprises a flame-retardant layer 2 comprising an intumescent polymeric material chosen from the group of materials capable of expanding under the effect of heat from 180°C and one or more protective layers 3, 4 of an inorganic material retarding the intumescent reaction of the flame-retardant layer 2. Preferably, the retardant material is chosen from the group of elastomers.

[0019] In order to improve the retarding effect of the elastomer, the protective layer(s) advantageously comprise within it one or more strips of fabric 5 composed of fibers chosen from the group of ceramic, aramid, carbon, glass fibers or a combination of these fibers. The protective layers comprising at least one strip of fabric will be referred to below as a reinforced protective layer.

[0020] In the example illustrated, the laminated coating 1 comprises a protective layer 4 reinforced by fabric strips 5 and an unreinforced protective layer 3 interposed between the flame-retardant layer 2 and the protective layer 4 containing the fabric strips 5. By "unreinforced protective layer" is meant in the present application a protective layer of retardant material not comprising a fabric strip as described previously. This is of course an exemplary embodiment, the laminated coating according to the invention possibly consisting of one or more protective layer(s) that are only unreinforced, one or more protective layer(s) that are only reinforced, or a combination of reinforced and unreinforced layers.

[0021] The laminated coating 1 further comprises a low-emissivity coating 6 covering the face of the protective layer furthest from the flame-retardant layer 2. Advantageously, the coating is a paint loaded with metal particles.

[0022] As shown in [Fig.l], the laminated coating 1 is applied to the inner face 110 of the wall 100 of the nacelle, in whole or in part depending on the areas to be protected, the flame-retardant layer 2 being placed opposite the inner face 110 of the wall 100, in contact with the latter. According to a particular embodiment, the coating is applied raw to the wall of the nacelle, then vulcanized via a vacuum compression molding process with an adhesive agent.

[0023] The invention is of course not limited to the example of the laminated covering 1 which has just been described, other arrangements at the level of the protective layers 3, 4 being able to be provided without departing from the scope of the invention.

[0024] The table above gives examples of arrangements of a laminated covering 1 according to the invention having variations at the level of the protective layers 3, 4 (reinforced or not with fabric strips) in terms of thickness and the number of these layers. Configuration Total thickness: substrate 4 coating [Number] Nacelle wall thickness Grufi layer thickness Protective layer thickness silicone member / thickness Thickness Protective layer silicone member / thickness 1 5mm 1mm 2mm 2 / 2ir!m 2 4.5in | 1mm 2 mm 1 / 0.5IWI la» 3 5mm | 1mm 2 mm 2 / 1mm l.'In-m 4 6mm | 1mm 2mm 0 3 / 1mm 5 5.25mm | 1mm 2 mm 0 1 / 2.2501111 6 3.5mm J 1mm 2 mm 1 / 0.5 0

[0025] In this example, the wall of the nacelle on which the laminated coating 1 will be applied has a thickness of 1 millimeter while the fireproof layer 2 has a thickness of 2 millimeters. These are of course dimensional examples, the thicknesses being able to vary depending on the structure to be protected by the coating and the level of protection sought.

[0026] The invention is described in the above by way of example. It is understood that a person skilled in the art is able to carry out different variant embodiments of the invention without departing from the scope of the invention.

Claims

Claims

1. Laminated composite covering (1) for protecting a structure (100) of an aircraft against fire and heat propagation, comprising: - a flame retardant layer (2) comprising an intumescent polymeric material chosen from the group of intumescent materials capable of expanding under the effect of heat from 180°C, and - at least one protective layer (3, 4) of an inorganic material retarding the intumescent reaction of the flame retardant layer (2), the retardant material being chosen from the group of elastomers.

2. Laminated composite coating (1) according to claim 1, characterized in that said at least one protective layer (4) comprises within it a reinforcing fabric composed of fibers chosen from the group of ceramic, aramid, carbon, glass fibers or a combination of these fibers.

3. A laminated composite covering (1) according to claim 2, characterized in that the reinforcing fabric is impregnated with the elastomer.

4. A laminated composite coating (1) according to any preceding claim, characterized in that the intumescent material is an ethylene-vinyl acetate copolymer.

5. Laminated composite coating (1) according to any one of the preceding claims, characterized in that the flame-retardant layer (2) and said at least one protective layer (3, 4) respectively have a thickness greater than or equal to 2.5 millimeters.

6. A laminated composite coating (1) according to any preceding claim, characterized in that the protective layer (3, 4) is provided with a coating of low-emissivity material (6).

7. A laminated composite covering (1) according to any one of the preceding claims, characterized in that it comprises two protective layers (3, 4) of elastomer, one of the protective layers (4) being reinforced by a fabric (5) composed of fibers, the other protective layer (3) being devoid of fabric, said protective layer (3) devoid of fabric being interposed between the flame-retardant layer (2) and the

8. Reinforced protective layer (4). Aircraft structure, such as a nacelle, coated in whole or in part with a laminated composite coating (1) according to any one of the preceding claims.