GB2120580A

GB2120580A - Intumescent paint layers

Info

Publication number: GB2120580A
Application number: GB08215399A
Authority: GB
Inventors: John William Johnson
Original assignee: Rolls Royce PLC
Current assignee: Rolls Royce PLC
Priority date: 1982-05-26
Filing date: 1982-05-26
Publication date: 1983-12-07

Abstract

A reinforcement for an intumescent paint layer used in a gas turbine engine comprises a plurality of fibres or tufts of fibres which serve to prevent the intumescent paint from flaking.

Description

SPECIFICATION Fibrous reinforcement This invention relates to the fibrous reinforcement of intumescent material layers and more particularly the reinforcement of such material layers when used in a paint form within a gas turbine engine.

The term "intumescent paint" is applied to a heat protective paint which when exposed to a flame or high temperature bubbles and swells forming a relatively thick cellular flame-resistant protective layer. This layer prevents the substrate to which the paint is adherent from being charred or burned by the flame or high temperature. The use of such paints are well known in the gas turbine engine field.

The main problem associated with the use of such paint is that when they are in their expanded state they become relatively weak and brittle and tend to flake from the substrate to which they are attached.

An object of the present invention is to provide an intumescent paint layer in which the aforementioned disadvantages have been substantially eliminated.

According to the present invention an intumescent layer includes a composite reinforcement comprising a tufted fibrous structure within the layer, said fibrous tufts serving to reinforce the intumescent layer when the layer is in its expanded operative state.

Preferably the tufted fibrous structure comprises a plurality of tufts or filaments of carbon, glass, silica, aiumina or boron fibres secured to or woven such as to form a common backing member which is encapsulated within the intumescent layer.

Furthermore the intumescent layer comprises a layer or layers of intumescent paint.

Preferably the fibrous structure is secured to a gas turbine engine part and then painted with a layer or layers of intumescent paint. Alternatively the intumescent paint may be included within the fibrous structure which may then be attached to the gas turbine engine part.

For better understanding thereof an embodiment of the invention will be more particularly described by way of example only and with reference to the accompanying drawings in which: Figure 1 shows a pictorial side view of a gas turbine engine having a broken away casing portion showing a diagrammatic embodiment of the present invention.

Figure 2 shows an enlarged cross-sectional view of the embodiment shown diagrammatically at Figure 1 before it has been subjected to an elevated temperature.

Figure 3 shows an enlarged cross-sectional view of the embodiment shown diagrammatically at Figure 1 after it has been subjected to an elevated temperature.

Referring to the drawings, a gas turbine engine shown generally at 10 comprises in flow series compressors 12, combustion equipment 13, turbines 14, and the engine terminates in an exhaust nozzle 1 5. A portion of the casing of the exhaust nozzle section of the engine is broken away to disclose a diagrammatic embodiment of a fibre reinforced intumescent paint structure made in accordance with the present invention.

Figure 2 shows a cross-sectional view of the structure in greater detail which comprises a portion of the gas turbine exhaust section 1 5 to which is attached a backing member 1 7 to which the fibres 1 8 are secured. The backing member 1 7 and the fibres 1 8 may be formed integrally such as for example by a weaving process in which the fibres are formed as a plurality of loops which may if required be cut to produce separate fibres.

Alternatively the fibres may be tufted or bonded in bundles or single fibres into a separate backing member. The fibres may be either glass, carbon, metallic, refractory or in fact may be made from any material which is capable of withstanding the temperatures to which they are to be subjected in an overheat condition in the respective portion of the gas turbine engine where the material is proposed to be used.

The backing member may be bonded to the gas turbine engine casing portion 1 5 using an adhesive and the fibres 1 8 then coated with intumescent paint and the paint tends to make the fibre lie flat. Fibres may project through the intumescent paint layer, however this is believed not to effect efficient operation of the device.

Alternatively the intumescent paint may be applied to the backing member prior to fixing within the engine. The intumescent paint will then swell and expand through the fibres attached to the backing sheet.

As previously mentioned use of intumescent paint in gas turbine engines is well known and there are many such products commercially available. However such a paint can be conveniently manufactured using the following constituents. Epoxy resin ester 700 gms, Melamine-formaldehyde resin 175 gms, Dicyandiamide 420 Polyammonium phosphate 700 gms, Melamine 1 50 gms, Pentaerythritol 300 gms, Titanium dioxide 100 gms, Xylene 400 gms and n-butonol 100 gms.

Figure 3 of the drawings shows a crosssectional view of the structure after being exposed to a temperature sufficient to cause the intumescent paint to expand to form a thick cellular flame resistant layer. It can be seen from the drawings that the swelling of the paint layer has caused the fibres 1 8 to project out substantially at right angles to the backing sheet.

The fibres 1 8 thus serve to reinforce and restrain the intumescent paint and prevent it from being detached from the casing portion 1 5 by the fast moving exhaust flow through the exhaust duct.

1. An intumescent layer including a composite reinforcement comprising a tufted fibrous structure within the layer, said fibrous tufts serving

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. SPECIFICATION Fibrous reinforcement This invention relates to the fibrous reinforcement of intumescent material layers and more particularly the reinforcement of such material layers when used in a paint form within a gas turbine engine. The term "intumescent paint" is applied to a heat protective paint which when exposed to a flame or high temperature bubbles and swells forming a relatively thick cellular flame-resistant protective layer. This layer prevents the substrate to which the paint is adherent from being charred or burned by the flame or high temperature. The use of such paints are well known in the gas turbine engine field. The main problem associated with the use of such paint is that when they are in their expanded state they become relatively weak and brittle and tend to flake from the substrate to which they are attached. An object of the present invention is to provide an intumescent paint layer in which the aforementioned disadvantages have been substantially eliminated. According to the present invention an intumescent layer includes a composite reinforcement comprising a tufted fibrous structure within the layer, said fibrous tufts serving to reinforce the intumescent layer when the layer is in its expanded operative state. Preferably the tufted fibrous structure comprises a plurality of tufts or filaments of carbon, glass, silica, aiumina or boron fibres secured to or woven such as to form a common backing member which is encapsulated within the intumescent layer. Furthermore the intumescent layer comprises a layer or layers of intumescent paint. Preferably the fibrous structure is secured to a gas turbine engine part and then painted with a layer or layers of intumescent paint. Alternatively the intumescent paint may be included within the fibrous structure which may then be attached to the gas turbine engine part. For better understanding thereof an embodiment of the invention will be more particularly described by way of example only and with reference to the accompanying drawings in which: Figure 1 shows a pictorial side view of a gas turbine engine having a broken away casing portion showing a diagrammatic embodiment of the present invention. Figure 2 shows an enlarged cross-sectional view of the embodiment shown diagrammatically at Figure 1 before it has been subjected to an elevated temperature. Figure 3 shows an enlarged cross-sectional view of the embodiment shown diagrammatically at Figure 1 after it has been subjected to an elevated temperature. Referring to the drawings, a gas turbine engine shown generally at 10 comprises in flow series compressors 12, combustion equipment 13, turbines 14, and the engine terminates in an exhaust nozzle 1 5. A portion of the casing of the exhaust nozzle section of the engine is broken away to disclose a diagrammatic embodiment of a fibre reinforced intumescent paint structure made in accordance with the present invention. Figure 2 shows a cross-sectional view of the structure in greater detail which comprises a portion of the gas turbine exhaust section 1 5 to which is attached a backing member 1 7 to which the fibres 1 8 are secured. The backing member 1 7 and the fibres 1 8 may be formed integrally such as for example by a weaving process in which the fibres are formed as a plurality of loops which may if required be cut to produce separate fibres. Alternatively the fibres may be tufted or bonded in bundles or single fibres into a separate backing member. The fibres may be either glass, carbon, metallic, refractory or in fact may be made from any material which is capable of withstanding the temperatures to which they are to be subjected in an overheat condition in the respective portion of the gas turbine engine where the material is proposed to be used. The backing member may be bonded to the gas turbine engine casing portion 1 5 using an adhesive and the fibres 1 8 then coated with intumescent paint and the paint tends to make the fibre lie flat. Fibres may project through the intumescent paint layer, however this is believed not to effect efficient operation of the device. Alternatively the intumescent paint may be applied to the backing member prior to fixing within the engine. The intumescent paint will then swell and expand through the fibres attached to the backing sheet. As previously mentioned use of intumescent paint in gas turbine engines is well known and there are many such products commercially available. However such a paint can be conveniently manufactured using the following constituents. Epoxy resin ester 700 gms, Melamine-formaldehyde resin 175 gms, Dicyandiamide 420 Polyammonium phosphate 700 gms, Melamine 1 50 gms, Pentaerythritol 300 gms, Titanium dioxide 100 gms, Xylene 400 gms and n-butonol 100 gms. Figure 3 of the drawings shows a crosssectional view of the structure after being exposed to a temperature sufficient to cause the intumescent paint to expand to form a thick cellular flame resistant layer. It can be seen from the drawings that the swelling of the paint layer has caused the fibres 1 8 to project out substantially at right angles to the backing sheet. The fibres 1 8 thus serve to reinforce and restrain the intumescent paint and prevent it from being detached from the casing portion 1 5 by the fast moving exhaust flow through the exhaust duct. CLAIMS

1. An intumescent layer including a composite reinforcement comprising a tufted fibrous structure within the layer, said fibrous tufts serving to reinforce the intumescent layer when the layer is in its expanded operative state.

2. An intumescent layer as claimed in claim 1 in which the tufted structure comprises a plurality of tufts or filaments of carbon, glass, silica, alumina or boron fibres secured to or woven such as to form a common backing member which is encapsulated within the intumescent layer.

3. An intumescent layer as claimed in claim 1 in which the intumescent layer comprises a layer or layers of intumescent paint.

4. An intumescent layer as claimed in claim 1 in which the fibrous composite structure is secured to a gas turbine engine part and then painted with a layer or layers of intumescent paint.

5. An intumescent layer as claimed in claim 1 in which the intumescent paint is included within the fibre reinforcing structure prior to the structure being attached to a gas turbine engine part.

6. An intumescent layer for use on gas turbine parts as claimed in any preceding claim substantially as hereinbefore described by way of example only and as illustrated in the accompanying drawings.