NEW ABLATIVE COMPOSITE MATERIAL

Abstract

An ablative composite material including a matrix and a reinforcement, characterised in that: the matrix is a phenolic resin or an epoxy resin and the reinforcement is formed of short carbon fibres with a length of between 0.5 mm and 20 mm, and a diameter of between 6 μm and 20 μm.

Claims

1. An ablative composite material comprising a matrix and a reinforcement, wherein: the matrix is a phenolic resin or an epoxy resin, and the reinforcement is formed of short carbon fibres with a length of between 0.5 mm and 20 mm, and a diameter of between 6 μm and 20 μm, having a porosity of less than 15%.

2. The ablative composite material of claim 1, wherein the matrix is a phenolic resin, and comprises at most 60% by weight of short carbon fibres relative to the total weight of said material.

3. The ablative composite material of claim 2, wherein the phenolic resin is selected from novolac resins or resol resins.

4. The ablative composite material of claim 1, wherein the matrix is an epoxy resin, and comprises at most 60% by weight of short carbon fibres relative to the total weight of said material, said short carbon fibres having a porosity of less than 15%.

5. The ablative composite material of claim 4, wherein the epoxy resin is selected from flame-retardant epoxy resins.

6. The ablative composite material of claim 4, further comprising carbon powder, preferably in a mass content of between 5% and 20% relative to the total mass of said material.

7. A method of preparing the ablative composite material according to claim 1, comprising mixing the matrix and the reinforcement.

8. A piece of ablative composite material according to claim 1.

9. (canceled)

10. The piece of ablative composite material of claim 8, which is a part of a fuel-propelled munition launcher.

Description

EXAMPLES

Example 1: Preparing a Piece of Ablative Material Comprising a Phenolic Resin

[0048] A piece of material comprising a phenolic resin according to the invention is prepared according to the method described in Table 1 below.

TABLE-US-00001 TABLE 1 Step 1 Preparation Preparation of the mixture: mixing the components and inserting them into the hot mould. Step 2 Moulding Pressurisation of the mixture with a multi-stage pressurisation and temperature-raising cycle. The holding times allow for optimal firing of the plate with the required characteristics. Step 3 Demoulding The piece exits.

Example 2: Preparing a Piece of Ablative Material Comprising an Epoxy Resin

[0049] A piece of material comprising an epoxy resin according to the invention is prepared according to the method described in Table 2 below.

TABLE-US-00002 TABLE 2 Step 1 Preparation Preparation of the mixture: Mixing the components and inserting them into the hot mould. Step 2 Moulding Pressurisation of the mixture with a multi-stage pressurisation and temperature-raising cycle. The holding times allow for optimal firing of the plate with the required characteristics. Step 3 Demoulding The piece exits.

Example 3: Ablative Properties of Materials

[0050] Inventions based on phenolic and epoxy resins have a homogeneous distribution of carbon fibres without any preferential orientation.

[0051] The main thermo-physical characteristics are shown in the table below.

TABLE-US-00003 TABLE 3 Phenolic Epoxy Characteristic material material Thermal <1 W .Math. m.sup.−1 .Math. K.sup.−1 >1 W .Math. m.sup.−1 .Math. K.sup.−1 conductivity Density >1,000 Kg .Math. m.sup.−3 >1,000 Kg .Math. m.sup.−3 Porosity <15% <15% Specific heat >1,000 J .Math. kg.sup.−1 .Math. K.sup.−1 >1,000 J .Math. kg.sup.−1 .Math. K.sup.−1 Ablation rate on 0.5 mm/s 1 mm/s liquid hydrogen/ oxygen bench (M = 3 and T = 1900° C.)

[0052] During degradation, the material must degrade in a safe, linear manner. This means that the erosion must be gradual, and controlled with good linearity of cratering as the exposure time increases. During degradation, the charcoal from the degradation must remain confined to the upper part of the plate, and the thermal setting must not lead to deep degradation of the thermal protection.