Part comprising a fire barrier

Abstract

The invention relates to a part (11), in particular for an aircraft turbine engine (1), the part (11) comprising: - a body (12) comprising a first composite material comprising an organic matrix and fibres embedded in the matrix; and - a fire barrier (13) comprising a fire-resistant layer (14) which is arranged on at least one surface of the body (12), characterised in that the fire-resistant layer (14) is able to expand and has a first thickness (e1) when it is subjected to a temperature lower than a threshold temperature, and a second thickness when it is subjected to a temperature greater than or equal to the threshold temperature, the second thickness being greater than the first thickness (e1), the fire-resistant layer (14) comprising a second composite material comprising a thermoplastic polymer matrix and non-woven fibres embedded in the matrix of the second material.

Description

[0001] DESCRIPTION

[0002] TITLE: PART COMPRISING A FIRE BARRIER

[0003] Technical field of the invention

[0004] The invention relates to the technical field of parts comprising a body made of organic matrix composite material and a fire barrier.

[0005] The invention relates in particular to aircraft turbomachine parts. The invention also relates to the method of manufacturing these parts.

[0006] Technical background

[0007] Among composite materials, we know organic matrix composite materials, also known by the acronym "OMC". These composite materials typically include an organic matrix and fibers embedded in the organic matrix.

[0008] Such composite materials have good mechanical strength and low density compared to metallic materials such as steel. Given these advantageous properties, these materials are increasingly favored in the aeronautics field. It is thus known to equip aircraft turbomachines with parts made of organic matrix composite material.

[0009] An aircraft turbomachine typically extends around and along a longitudinal axis. It comprises, from upstream to downstream in the direction of gas flow along the longitudinal axis, a fan compartment zone in which a fan is arranged and a downstream zone in which a low-pressure compressor, a high-pressure compressor, at least one combustion chamber, a high-pressure turbine and a low-pressure turbine are arranged.

[0010] The downstream zone is an area where temperatures can reach several hundred degrees or even temperatures of up to 1500°C. Therefore, parts located in this zone, such as casings, must withstand such temperatures. Also, the fan zone, like the downstream zone, are fire risk zones in which a fire is likely to spread. Therefore, parts located in this zone must also withstand high temperatures.

[0011] However, parts comprising a body made of organic matrix composite material are not resistant to high temperatures and such materials are likely to degrade quickly in an environment subject to high temperatures such as the downstream zone. In addition, due to their low thermal resistance, such parts must have additional safety devices to be applied in areas of the turbomachine subject to fire risks.

[0012] In this context, it was proposed to equip these parts with a fire barrier to protect the composite material body from thermal degradation and allow their implementation in the downstream or fan zone.

[0013] Document FR-B1 -3 016 187 proposes a part, in particular a fan casing, having a body made of composite material comprising a matrix and fibers embedded in the matrix. According to this document, the part further comprises a fire barrier comprising strips of glass fibers pre-impregnated with a polymerized resin. The resin is for example an epoxy resin, a phenolic resin or a cyanate ester resin. The strips of glass fibers embedded in the resin form a sacrificial fire-resistant layer. Indeed, under the effect of the increase in temperature during for example a fire, the resin degrades creating a thermally insulating air gap. It is therefore the degradation of the resin which allows the body of the part to be protected against a thermal attack.

[0014] Although such a fire barrier can limit damage to the composite part body in the event of an increase in temperature, it is not entirely satisfactory. Indeed, such a fire barrier must be of significant thickness to limit thermal damage to the composite part body, which tends to increase the mass and size of the part. Also, the manufacture of such a fire barrier is complex since it involves a step of draping pre-impregnated glass fibers. The manufacturing cost of such a part is therefore high.

[0015] There is therefore a need to provide a part comprising a body made of organic matrix composite material which can be implemented in an environment subject to a risk of fire or high temperatures, which is light, compact, easy to manufacture and inexpensive.

[0016] Summary of the invention

[0017] For this purpose, the invention proposes a part, in particular for an aircraft turbomachine, the part comprising:

[0018] - a body comprising a first composite material comprising an organic matrix and fibers embedded in the matrix, and

[0019] - a fire barrier comprising a fire-resistant layer arranged on at least one surface of the body.

[0020] The part is remarkable in that the fire-resistant layer has an expansion capacity and has a first thickness when subjected to a temperature below a threshold temperature, and a second thickness when subjected to a temperature greater than or equal to the threshold temperature, the second thickness being greater than the first thickness, the fire-resistant layer comprising a second composite material comprising a thermoplastic polymer matrix and non-woven fibers embedded in the matrix of the second material.

[0021] Thus, according to the invention, the fire-resistant layer is expandable. It is capable of swelling under the effect of an increase in temperature. This expansion capacity allows the fire-resistant layer to thermally insulate the body of the part in the event of an increase in temperature, for example in the event of a fire. It has thus been demonstrated that the fire-resistant layer according to the invention allows a thermal reduction of at least 170°C in the event of a fire compared to a part without a fire-resistant layer. The part can thus be implemented in an environment subject to high temperatures or in which there is a risk of fire.

[0022] Furthermore, as long as the temperature does not exceed the threshold temperature, the fire-resistant layer has the first thickness and the transition to the second thickness only occurs when the temperature reaches or exceeds the threshold temperature. Thus, the thickness of the fire-resistant layer can be minimal in order to minimize the impact on the mass of the part.

[0023] The invention may comprise one or more of the following features, taken in isolation from each other or in combination with each other:

[0024] - the fibers are discontinuous,

[0025] - the fire-resistant layer has a mass content of fibers between 40% and 80%, preferably between 40% and 50%,

[0026] - the thermoplastic polymer of the second composite material has a glass transition temperature equal to the threshold temperature,

[0027] - the thermoplastic polymer of the second composite material has a density of between 1 and 1.5, preferably 1.38 as measured at 20°C,

[0028] - the thermoplastic polymer of the second composite material is chosen from phenylene polysulfides and the fibers are carbon fibers,

[0029] - the fireproof layer is glued to the body,

[0030] - the fire-resistant layer is co-molded with the body,

[0031] - the fire-resistant layer has the capacity to expand by swelling,

[0032] - the ratio between the second thickness and the first thickness is between 400% and 450%.

[0033] The invention also relates to a method of manufacturing a part for an aircraft turbomachine, comprising the following steps: (a) providing a body comprising a first composite material comprising an organic matrix and fibers embedded in the matrix of the first material,

[0034] (b) provide a fire barrier comprising a fire-resistant layer, and

[0035] (c) arranging this fire-resistant layer on at least one surface of the body.

[0036] The method is remarkable in that the fire-resistant layer has an expansion capacity and has a first thickness when subjected to a temperature below a threshold temperature, and a second thickness when subjected to a temperature above the threshold temperature, the second thickness being greater than the first thickness, the fire-resistant layer comprising a second composite material comprising a thermoplastic polymer matrix and non-woven fibers embedded in the matrix of the second material.

[0037] The method according to the invention may comprise one or more of the following characteristics, taken in isolation from one another or in combination with one another:

[0038] - (d) compress the fire-resistant layer (14) until it reaches the thickness (e1),

[0039] - step (d) is carried out at a temperature between 100°C and 400°C, preferably at 300°C and at a pressure between 40 bars and 100 bars, preferably 60 bars,

[0040] -step (d) is carried out before step (c).

[0041] Brief description of the figures

[0042] Other characteristics and advantages will emerge from the following description of non-limiting embodiments of the invention with reference to the appended drawings in which: Figure 1 is a schematic perspective representation of an aircraft turbomachine to which the invention can be applied, Figure 2 is a schematic sectional representation of a part according to the invention when the temperature is lower than the threshold temperature, Figure 3 is a schematic sectional representation of a part according to the invention when the temperature is greater than or equal to the threshold temperature, Figure 4 is a block diagram of a method for manufacturing the part according to the invention, Figure 5 is a graph illustrating the evolution of the temperature of a part equipped with a thermal barrier according to the invention and without a thermal barrier as a function of time when subjected to a fire test according to the ISO2685 standard.

[0043] Detailed description of the invention

[0044] An example of a turbomachine 1 for an aircraft and to which the invention can be applied is shown in figure 1.

[0045] The invention can be applied to any type of technical field in which resistance to temperature or even fire is sought.

[0046] The turbomachine 1 extends around and along a longitudinal axis A.

[0047] The turbomachine 1 is for example a turbojet. It comprises from upstream to downstream along the longitudinal axis X in the direction of flow of the gases F in the turbomachine 1, a fan 2, at least one compressor 3 such as a low pressure compressor and a high pressure compressor, a combustion chamber 4, at least one turbine 5 such as a high pressure turbine and a low pressure turbine, and a gas exhaust nozzle.

[0048] The low and high pressure compressors and the high and low pressure turbines each comprise at least one rotor. The rotor of the low pressure compressor is connected to the rotor of the low pressure turbine by a low pressure shaft and the rotor of the high pressure compressor is connected to the rotor of the high pressure turbine by a high pressure shaft. The high pressure shaft is centered on the longitudinal axis A and arranged coaxially around the low pressure shaft. The fan 2 comprises a disc 6 rotatable about the longitudinal axis A and blades 7 extending radially from the disc. The fan 2 further comprises a fan shaft (not shown) connected to the low pressure shaft via a speed reducer for example. The fan 2 is of the shrouded type. The turbomachine 1 thus further comprises a fan casing 8. The fan casing 8 is annular and centered on the longitudinal axis A. It is arranged around the blades 7.The fan housing 8 delimits a fan zone.

[0049] Advantageously, the turbomachine 1 further comprises an intermediate casing 9 arranged downstream of the fan casing 8. It is connected to the fan casing 8 for example by flanges. The intermediate casing 9 is annular, centered on the longitudinal axis A and delimits an intermediate zone in which the low pressure compressor can be located.

[0050] The turbomachine 1 further comprises a downstream casing 10 axially connected to the fan casing 8 by the intermediate casing 9. The downstream casing 10 is arranged downstream of the fan casing 8 and the intermediate casing 9. It is connected to the intermediate casing 9 for example by flanges. The downstream casing 10 extends around the high-pressure compressor, the combustion chamber 4 and the turbine 5. The downstream casing 10 is annular, centered on the longitudinal axis A and delimits a downstream zone.

[0051] The temperature within the downstream zone is between 100°C and 1500°C, in particular due to the presence of the combustion chamber 4. Furthermore, in particular due to the risk of fire within the fan zone and the intermediate zone, it is required that the fan casing 8 and the intermediate casing 9 can withstand temperatures of up to 1100°C.

[0052] With reference to Figure 2, the turbomachine 1 is further equipped with parts 11 comprising a body 12 comprising a first composite material. These parts 11 can form one of the casings 8, 9, 10 of the turbomachine 1 or be arranged within one of the zones of the turbomachine 1 such as the fan, intermediate or downstream zone. Each part 11 can be of revolution or planar. It can have an annular, tubular, polygonal shape or any shape depending on its application. The first composite material of the body 12 comprises a matrix and fibers embedded in the matrix. The matrix is ​​of organic type. The organic material of the matrix is ​​a polymer chosen from thermoplastics or thermosets or a mixture thereof. The thermoplastic polymer is for example chosen from polyolefins such as polypropylene, polyethylene, fluorinated polymers or polyaryletherketones such as polyetheretherketone or a mixture thereof.The thermosetting polymer is chosen, for example, from epoxy resins.

[0053] The fibers are chosen, for example, from carbon fibers, glass fibers, or aramid fibers. The fibers are, for example, woven. They are, for example, organized in the form of a three-dimensional fiber preform.

[0054] The part 11 further comprises a fire barrier 13. The fire barrier 13 comprises a fire barrier layer 14 arranged on at least one surface of the body 12.

[0055] According to the invention, the fire-resistant layer 14 comprises a second composite material comprising a polymer matrix and fibers embedded in the matrix. Advantageously, the polymer of the matrix of the second composite material has a density of between 1 and 1.5, preferably 1.38, as measured at 20°C.

[0056] According to the invention, the polymer of the matrix of the second composite material is of the thermoplastic type. Preferably, the thermoplastic polymer has a glass transition temperature of between 80°C and 150°C, preferably between 80°C and 100°C. The thermoplastic polymer is for example chosen from polyolefins such as a polypropylene, a polyethylene, fluorinated polymers, polyaryletherketones such as a polyetheretherketone, polyphenylene sulfides or a mixture thereof. Preferably, the thermoplastic polymer is a polyphenylene sulfide.

[0057] Furthermore, according to the invention, the fibers are of the non-woven type and advantageously discontinuous. As known to those skilled in the art, non-woven fibers are fibers bonded by any type of process other than weaving. In contrast to filaments, discontinuous fibers designate cut fibers and therefore of short length. The fibers have a length for example between 10 mm and 50 mm, in particular between 12.5 mm and 50 mm. The fibers have a diameter for example between 5 μm and 10 μm, in particular between 5 μm and 6 μm. The fibers have a count for example between 2,230 dtex and 4,460 dtex. The fibers have a density for example between 1.5 and 2, preferably 1.8.

[0058] The fibers are chosen from carbon, glass, aramid fibers or a mixture thereof. Preferably, the fibers are carbon fibers.

[0059] The fibers may be randomly oriented in the matrix of the second composite material or in an ordered manner. They are preferably randomly oriented. The fibers are advantageously present in the second composite material at a mass rate of between 40% and 80%, preferably between 40% and 50%.

[0060] The fire-resistant layer 14 is, for example, a fiber mat. The fire-resistant layer 14 has a weight, for example, between 400 gr / m 2 and 3200 gr / m 2 .

[0061] The fire-resistant layer 14 is expandable under the effect of temperature. In particular, the fire-resistant layer 14 is expandable by swelling. Thus, according to the invention, the fire-resistant layer 14 has a first thickness e1 when it is subjected to a temperature lower than a threshold temperature and a second thickness e2 when it is subjected to a temperature greater than or equal to the threshold temperature. In other words, under the effect of an increase in temperature, the fire-resistant layer 14 swells. Figure 2 illustrates the part 11 according to the invention when it is subjected to a temperature lower than the threshold temperature. In this case, the fire-resistant layer 14 has the first thickness e1.

[0062] Figure 3 illustrates the part 11 according to the invention when it is subjected to a temperature greater than or equal to the threshold temperature. In this case, the fire-resistant layer 14 has swollen and has the second thickness e2 which is greater than the first thickness e1.

[0063] The expandable nature of the fire-resistant layer 14 by swelling under the effect of temperature makes it possible to ensure thermal insulation of the body 12 in the event of an increase in temperature, for example during a fire. Indeed, the thickness differential of the fire-resistant layer limits the transfer of heat to the body 12 of the part 11.

[0064] The ratio between the second thickness e2 and the first thickness e1 is advantageously between 400% and 450%. This ratio represents the swelling rate of the fire-resistant layer 14.

[0065] The first thickness e1 is preferably between 0.5 mm and 5 mm, preferably between 1 mm and 3 mm and even more preferably between 1.8 mm and 2.2 mm. Such a first thickness e1 makes it possible to minimize the mass and size of the part 11.

[0066] The second thickness e2 is preferably between 5 mm and 20 mm, preferably between 5 and 10 mm and even more preferably between 8.5 mm and 9 mm. Such a second thickness e2 makes it possible to effectively thermally insulate the body 12 from the part 11 without considerably increasing the size of the part 11.

[0067] The threshold temperature is for example between 80°C and 200°C. Preferably, the threshold temperature is equal to the glass transition temperature of the matrix of the second composite material, i.e. of the matrix of the fire-resistant layer 14.

[0068] The fire barrier 13 according to the invention is, according to a particularly preferred embodiment, obtained by compression coupled with a heat treatment of the fire-resistant layer 14. Indeed, the compression under temperature of the fire-resistant layer 14 makes it possible to reduce the thickness of the fire-resistant layer 14 and to apply compressive stresses in the fire-resistant layer 14. When the temperature rises, for example in the event of a fire, the matrix of the fire-resistant layer 14 can reach its glass transition temperature. The change of state of the matrix makes it possible to release the stresses within the fire-resistant layer 14 which were previously applied during its manufacture, thus causing it to swell. The fire-resistant layer 14 then has a thickness greater than its initial thickness and ensures the thermal insulation of the body 12 of the part 11.

[0069] The fire-resistant layer 14 is connected to the body 12 of the part 11. According to a first embodiment, the fire-resistant layer 14 is bonded to the body 12 of the part 11. According to this embodiment, the part 11 further comprises a layer of adhesive (not shown) arranged between the body 12 and the fire-resistant layer 14. The layer of adhesive comprises, for example, an epoxy material. The layer of adhesive has, for example, a thickness of between 50 μm and 500 μm, preferably between 100 μm and 200 μm.

[0070] According to another embodiment, the fire-resistant layer 14 is co-molded with the body 12.

[0071] A method of manufacturing such a part 11 will now be described with reference to FIG. 4.

[0072] The method according to the invention comprises the following steps:

[0073] (a) provide body 12,

[0074] (b) providing the fire barrier 13 comprising the fire layer 14,

[0075] (c) arranging the fire-resistant layer 14 on at least one surface of the body 12,

[0076] (d) preferably, compress the fire-resistant layer 14.

[0077] According to an exemplary embodiment, step (a) may comprise the following sub-steps:

[0078] (aO) producing a fibrous preform of the body 12,

[0079] (a1) densifying the fiber preform with a resin, and (a2) optionally polymerizing the resin.

[0080] Sub-step (a1) can be carried out by resin transfer molding also known by the English acronym RTM for “Resin Transfer Molding”. For this purpose, the fiber preform is arranged in a mold.

[0081] Substep (a2) may be carried out by heating the resin to form the matrix of the first composite material.

[0082] Step (b) can be carried out by agglomerating the fibers on a support and then projecting the thermoplastic matrix onto the support in order to bind the fibers together.

[0083] In step (c), the fire-resistant layer 14 can be bonded to the body 12.

[0084] According to another example, in step (c), the fire-resistant layer 14 may be co-molded. According to this example, the fire-resistant layer 14 is bonded to the body 12 using, for example, an adhesive and steps (a1) and (a2) are carried out after step (c) to co-mold the fire-resistant layer 14 and the body 12.

[0085] Before step (d), the fire-resistant layer 14 has a third thickness e3 greater than the first thickness e1. The third thickness e3 is in particular equal to the second thickness e2.

[0086] In step (d), the fire-resistant layer 14 is compressed until it reaches the first thickness e1. Advantageously, step (d) is carried out at a temperature between 100°C and 400°C, preferably at 300°C and at a pressure between 40 bars and 100 bars, preferably 60 bars.

[0087] Step (d) is performed before step (c).

[0088] The compression step (d) is particularly preferred because it makes it possible to reduce the thickness of the fire-resistant layer 14 and to apply compressive stresses in the fire-resistant layer 14. When the temperature rises, for example in the event of a fire, the matrix of the fire-resistant layer 14 can reach its glass transition temperature. The change in state of the matrix makes it possible to release the stresses within the fire-resistant layer 14 which were previously applied during its manufacture, thus causing it to swell. The fire-resistant layer 14 then has a thickness greater than its initial thickness and ensures the thermal insulation of the body 12 of the part 11.

[0089] EXAMPLES

[0090] Example 1: fire test according to ISO 2685 standard

[0091] Fire resistance tests were carried out in order to evaluate the thermal insulation properties of the fire barrier 13 according to the invention. These tests were carried out on coupons measuring 120 mm x 120 mm and comprising a first composite material according to the invention. A first series S1 of coupons is devoid of fire-resistant layer 14 according to the invention and a series S2 of coupons was equipped with a fire barrier 13 according to the invention.

[0092] In the context of these tests, the fire barrier 13 according to the invention comprises a fire barrier layer 14 comprising a composite material comprising two plies of non-woven fibers and a thermoplastic matrix. The non-woven fibers comprise 47.5% by mass of polyphenylene sulfide (PPS) fibers and 47.5% by mass of carbon fibers. The thermoplastic matrix represents 5% by mass of the composite material.

[0093] The folds are dried in an oven for 4 hours at a temperature of 150°C and are thermocompressed at a temperature of 350°C and at a pressure of at least 60 bar.

[0094] The first and second series S1, S2 of coupons were subjected to a fire resistance test according to ISO 2685 standard. The burner used is a propane burner.

[0095] The results of these tests are presented in Figure 5. The graph illustrates the temperature revolution of the coupons of the first and second series S1, S2 as a function of time.

[0096] The graph shows that the temperature of the coupons of the first series S1 quickly reaches 450°C while the temperature of the coupons of the second series S2 is maintained at a maximum of 280°C. Thus, the fire-resistant layer 14 according to the invention allows a thermal reduction A of approximately 170°C.

[0097] The coupons of the second series S2 are heat resistant, particularly at temperatures up to 1100°C, and meet the ISO 2685 standard.

Claims

CLAIMS 1. Part (11), in particular for an aircraft turbomachine (1), the part (11) comprising: - a body (12) comprising a first composite material comprising an organic matrix and fibers embedded in the matrix, and - a fire barrier (13) comprising a fire-resistant layer (14) arranged on at least one surface of the body (12), characterized in that the fire-resistant layer (14) has an expansion capacity and has a first thickness (e1) when subjected to a temperature lower than a threshold temperature, and a second thickness (e2) when subjected to a temperature greater than or equal to the threshold temperature, the second thickness (e2) being greater than the first thickness (e1), the fire-resistant layer (14) comprising a second composite material comprising a thermoplastic polymer matrix and non-woven fibers embedded in the matrix of the second material.

2. Part according to the preceding claim, characterized in that the fibers are discontinuous.

3. Part according to one of claims 1 or 2, characterized in that the fire-resistant layer (14) has a mass content of fibers of between 40% and 80%, preferably between 40% and 50%.

4. Part according to any one of the preceding claims, characterized in that the thermoplastic polymer of the second composite material has a glass transition temperature equal to the threshold temperature.

5. Part according to any one of the preceding claims, characterized in that the thermoplastic polymer of the second material composite has a density of between 1 and 1.5, preferably 1.

38.

6. Part according to any one of the preceding claims, characterized in that the thermoplastic polymer of the second composite material is chosen from phenylene polysulfides and the fibers are carbon fibers.

7. Part according to any one of the preceding claims, characterized in that the fire-resistant layer (14) is bonded to the body (12).

8. Part according to any one of claims 1 to 6, characterized in that the fire-resistant layer (14) is co-molded with the body (12).

9. Part according to any one of the preceding claims, characterized in that the fire-resistant layer (14) has the capacity to expand by swelling.

10. Part according to any one of the preceding claims, characterized in that the ratio between the second thickness (e2) and the first thickness (e1) is between 400% and 450%.

11. Method for manufacturing a part (11) for an aircraft turbomachine (1), comprising the following steps: (a) providing a body (12) comprising a first composite material comprising an organic matrix and fibers embedded in the matrix of the first material, (b) providing a fire barrier (13) comprising a fire barrier layer (14), and (c) arranging this fire-resistant layer (14) on at least one surface of the body characterized in that the fire-resistant layer (14) has an expansion capacity and has a first thickness (e1) when it is subjected to a temperature below a threshold temperature, and a second thickness (e2) when it is subjected to a temperature above the threshold temperature, the second thickness (e2) being greater than the first thickness (e1), the fire-resistant layer (14) comprising a second composite material comprising a thermoplastic polymer matrix and non-woven fibers embedded in the matrix of the second material.

12. Method according to the preceding claim, characterized in that it further comprises the following step: (d) compress the fire-resistant layer (14) until it reaches the thickness (e1).

13. Method according to the preceding claim, characterized in that step (d) is carried out at a temperature between 100°C and 400°C, preferably at 300°C and at a pressure between 40 bars and 100 bars, preferably 60 bars.

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