GB2117807A - Refractory material - Google Patents

Abstract

A refractory material suitable for use in protecting gas turbine parts comprises a felt covering impregnated with intumescent paint.

Description

SPECIFICATION Refractory material This invention relates to a refractory material and more particularly to such a material suitable for use as a fire protection device for protecting parts of gas turbine engines.

At present due to their relatively high operating temperatures, it is necessary to manufacture certain gas turbine engine components for example bulkheads, firewalls and ducts from titanium. However titanium is extremely expensive, due to raw material and forming operation costs, and is also becoming less readily available. Alternatively such structures may be manufactured from relatively inexpensive alloys or composite materials and thereafter provided with a refractory protective barrier of ceramic or intumescent paint, or ceramic felt.

The term "intumescent paint" is applied to a heat protective paint which when exposed to flame attack, bubbles and swells forming a relatively thick cellular carbonaceous foam.

However, the protective char so formed is relatively weak and will quickly become detached by the air or gas stream passing through the engine.

Ceramic paints suffer the disadvantage in that whilst they are capable of withstanding the temperatures involved, they are extremely brittle and quickly become detached.

The term "felt" is applied to a fabric which is either wholly or partly made from individual fibres without the intermediary of a yarn. The individual fibres are entangled in such a manner that a very firm tough yet flexible structure results. However such materials suffer disadvantages in that any engine fluid may be "wicked-up" by capillary action into the construction. This has two effects: (1 ) the weight of the component may be greatly increased and (2) the component may then constitute a fire hazard if fuel or other flammable fluid are absorbed. Furthermore felt structures manufactured with ceramic fibres are brittle and may fragment under certain conditions.

An object of the present invention is to provide a refractory material which substantially overcomes the aforementioned disadvantages.

According to the present invention a refractory material comprises a felt impregnated with intumescent paint.

Preferably the felt consists of a sheet of ceramic fibres.

Alternatively the felt consists of a sheet or organic textile fibres.

Preferably the intumescent paint is applied to the felt by painting or spraying.

Furthermore the impregnated felt may be attached to a gas turbine part to provide a refractory covering therefore.

Preferably the covering is attached to the gas turbine part by use of an adhesive.

For better understanding thereof an embodiment of the invention will be more particularly described by way of example only.

Felts made from both textile fibres and ceramic fibres are considered suitable, however textile felts have better handle ability and drape characteristics than ceramic felts. The textile fibre chosen for manufacture of such felt should be non-melting and yield a high proportion of carbon char. Typical fibres are phenolic, aromatic polyamide or alternatively felts made from both textile and ceramic fibres.

The intumescent paint may be impregnated into the felt by spraying or brushing and thereafter allowing the felt to dry. It is not the invention of this specification to teach methods either of manufacturing or formulating intumescent paint as such materials are commercially available. For example one widely known such type of paint is that made by the AVCO Corporation of America and sold under the trade name "Flamerest".

Set out below are two typical combinations of materials suitable for manufacturing a refractory covering material in accordance with the present invention.

A Gas turbine component substrate -- Carbon Fibre/Epoxy Resin Adhesive -- Flamerest 1 600B intumescent Paint Felt -- Carbon Fibre Sealant -- Fiamerest 1 600B Intumescent Paint.

B Gas turbine component substrate Aluminium Alloy Adhesive-Viton Per170 rubber Felt - Kynol S21 1 (Phenolic) Sealant -- Flamerest 1 600B Intumescent Paint.

Viton PR 170 rubber is the trade name of an adhesive manufactured by Du Pont Limited in the United States of America, and Kynol S211 is the trade name of a phenolic fibrous felt manufactured in Japan by Nippon Kynol Incorporated.

If during operation of the gas turbine engine, a fire occurs adjacent the refractory material, the paint impregnated within the felt will intumesce and form a relatively thick carbonaceous char which effectively serves to insulate and protect the underlying felt and component substrate. As previously stated under normal circumstances the charred cellular structure is relatively weak and friable, and may easily become detached.

However the intumescent char so formed is impregnated within the felt such that it is reinforced and held in position by the felt.

Furthermore the intumescent paint acts as a sealant in its cold state such that the engine fluids cannot become "wicked up" into the felt by capillary action.

It will be appreciated by those skilled in the art that whilst the embodiment of the present invention has been particularly directed to a refractory barrier for use on gas turbine components, the invention is not restricted to such an application, and may be used in a variety of situations where such a type of fibre protection would be suitable.

Claims (6)

1. A refractory material comprising a felt impregnated with intumescent paint.

2. A refractory material as claimed in claim 1 in which the felt comprises a sheet of ceramic fibres.

3. A refractory material as claimed in claim 1 in which the felt comprises a sheet consisting of organic textile fibres.

4. A refractory material as claimed in claim 1 in which the intumescent paint is applied to the felt by painting or spraying.

5. A refractory material as claimed in any preceding claim suitable for attaching to a gas turbine part to provide a refractory covering therefore.

6. A refractory material as claimed in any preceding claim and substantially as hereinbefore described by way of example only.