A multi-layer thermal protection material and its preparation method

Abstract

The present invention relates to a multi-layer thermal protection material and a preparation method thereof, belonging to the fields of high-temperature thermal protection and structural design. The thermal protection material is composed of four layers of materials, which are, from outside to inside, an inorganic fiber felt, a glass fiber cloth, a heat sink layer, and a low thermal conductivity layer. First, prepare a zirconia fiber felt and a glass fiber cloth; dissolve the phase change wax in the silicone rubber, and use the brushing process to make a heat sink layer on the glass fiber cloth; then make a polysiloxane or polyborosiloxane film on the heat sink layer of the glass fiber cloth as the low thermal conductivity layer. The thermal protection material of the present invention has high flexibility and good heat resistance, especially has a low density. Compared with the traditional thermal protection material of the same size and thickness, after being tested at 500 kw / m<supgt;2< / supgt; for 50 s, the temperature rise on the back of the thermal protection material with different thicknesses drops significantly, and the weight of the material is reduced by about 10%. Its preparation method is simple and the process is convenient and easy to implement.

Description

Technical Field

[0001] The present invention relates to a novel multi-layer thermal protection material and a preparation method thereof. During the flight of a rocket and its related aircraft, the heat generated by the engine heats the instruments and equipment. The thermal protection material of the present invention is mainly applied to the heat protection of instruments and equipment, belonging to the field of high-temperature thermal protection and also belonging to the field of structural design. Background Art

[0002] Heat transfer is a complex phenomenon, which is often divided into three basic modes, namely heat conduction, heat convection and heat radiation. The heat transfer phenomena encountered in production and life are often combinations of these three basic modes with different priorities. During the ignition and flight of a rocket engine, the generated heat is usually propagated outward in the form of radiation, which causes the heat to gradually accumulate to a certain extent during the flight of the rocket and its related aircraft, exceeding the allowable temperature of the instruments and equipment. Therefore, in order to protect the instruments and equipment, a material is needed to block the heat outside the instruments and equipment, and this material is called a thermal protection material.

[0003] At present, the radiative heat flux of a rocket and its related aircraft can reach up to 500 kw / m 2 , and according to the Stefan-Boltzmann law, the equivalent temperature is about 2000 °C. Such a high radiative temperature makes many thermal protection materials unable to meet the actual needs. Usually, the thermal protection material is a foam metal or a ceramic material. Although such materials have good temperature resistance, they have a relatively large density and hardness, which cause many problems in actual application. For example, a large density results in a significant reduction in the effective payload of the rocket and its related aircraft; a large hardness makes installation difficult and operation inconvenient. Therefore, a novel multi-layer flexible thermal protection material is newly developed in the current work. Compared with the traditional single-layer thermal protection material, it not only has a lighter weight, better heat protection performance but also is softer. Summary of the Invention

[0004] The purpose of the present invention is to prevent the heat generated by the engine during the flight of a rocket and its related aircraft from damaging the instruments and equipment, and to develop a novel multi-layer flexible thermal protection material and a preparation method thereof. The present invention provides a new idea for the development of other heat protection materials. The newly developed thermal protection material has high flexibility and good heat resistance, especially a low density.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] A multi-layer thermal protection material, which is composed of four layers of materials, namely an inorganic fiber felt, a glass fiber cloth, a heat sink layer and a low thermal conductivity layer from outside to inside.

[0007] Preferably, the inorganic fiber felt is a zirconia fiber felt, which is the outermost layer of the thermal protection material. The density of the zirconia fiber felt is 0.75 g / cm 3 ~2.50 g / cm 3 , and the thickness is 0.25 mm to 1.00 mm.

[0008] Preferably, the thickness of the glass fiber cloth is 0.03 mm to 1.00 mm, which is the sub-outer layer of the thermal protection material; the glass fiber cloth can be an alkali-free glass fiber cloth or a high-silica glass fiber cloth, that is, it is made of alkali-free glass fiber or high-silica glass fiber.

[0009] Preferably, the heat sink layer is the sub-inner layer of the thermal protection material, which is composed of phase change wax and silicone rubber, and the mass content of the phase change wax is 5% to 35%; the thickness of the heat sink layer is 0.45 mm to 1.00 mm. The silicone rubber can be an addition-cured vinyl silicone rubber or an addition-cured propylene silicone rubber; the phase change wax can be prepared according to actual needs so as to have different phase change temperatures. In the present invention, the phase change temperature of the phase change wax can be between 20 - 80 °C.

[0010] The heat sink layer can be made by a brushing process. The mixture of phase change wax and silicone rubber is brushed onto the glass fiber cloth by the brushing process to form the heat sink layer.

[0011] Preferably, the low thermal conductivity layer is the innermost layer of the thermal protection material, which is composed of polysiloxane or polyborosiloxane, and the thickness of the innermost layer is 0.3 mm to 1.00 mm.

[0012] The low thermal conductivity layer can be made by a brushing process. The polysiloxane or polyborosiloxane is brushed onto the heat sink layer of the glass fiber cloth by the brushing process to form the low thermal conductivity layer.

[0013] When the multi-layer thermal protection material is a tubular product, there is no need for stitching or bonding between the inorganic fiber felt and the glass fiber cloth coated with the heat sink layer and the low thermal conductivity layer; when the multi-layer thermal protection material is a sheet product, the inorganic fiber felt and the glass fiber cloth coated with the heat sink layer and the low thermal conductivity layer are stitched and connected by a fiber rope.

[0014] In the present invention, the inorganic fiber felt is used as the outermost layer to resist high temperature, then the glass fiber cloth is used as a low thermal conductivity layer to block heat, then the heat sink layer absorbs the heat to make the temperature rise slowly, and then there is the innermost layer, which is the low thermal conductivity layer, so that the temperature on the surface of the final instrument and equipment is very low.

[0015] The present invention also provides a preparation method of the above multi-layer thermal protection material, which adopts the following technical process:

[0016] Step 1: Prepare (manufacture or purchase) zirconia fiber felts with different densities; Step 2: Prepare (manufacture or purchase) fiberglass cloths with different weaving thicknesses; Step 3: Dissolve phase change waxes with different contents in silicone rubber, and use the brushing process to make a heat sink layer on the fiberglass cloth; Step 4: Use the brushing process to make a polysiloxane or polyborosiloxane film as a low thermal conductivity layer on the heat sink layer of the fiberglass cloth, which is the innermost layer; Arrange the zirconia fiber felt and the fiberglass cloth in sequence to obtain a thermal protection material with a four-layer structure.

[0017] A preparation method of a multi-layer thermal protection material includes the following specific technological steps:

[0018] (1) Manufacture or purchase zirconia fiber felts with different densities, where the density of the zirconia fiber felt ranges from 0.75 g / cm 3 ~2.50 g / cm 3 , and the thickness is 0.25 mm to 1.00 mm;

[0019] (2) Manufacture or purchase fiberglass cloths with different weaving thicknesses, where the thickness of the fiberglass cloth is 0.03 mm to 1.00 mm;

[0020] (3) Dissolve phase change waxes with different contents in silicone rubber, brush it on the fiberglass cloth to make a heat sink layer, where the mass content of the phase change wax is 5% to 35%, and the thickness is 0.45 mm to 1.00 mm;

[0021] (4) Brush polysiloxane or polyborosiloxane on the heat sink layer of the fiberglass cloth to make polysiloxane or polyborosiloxane films with different thicknesses and low thermal conductivities as the low thermal conductivity layer, and the innermost layer has a thickness of 0.3 mm to 1.00 mm; Arrange the zirconia fiber felt and the fiberglass cloth in sequence, from the outside to the inside are the zirconia fiber felt, the fiberglass cloth, the heat sink layer, and the low thermal conductivity layer.

[0022] Manufacturing method of the heat sink layer and the low thermal conductivity layer: Adopt the brushing process. After brushing once or one layer, let it dry naturally, and then brush the next time or layer until the required thickness is reached; Generally, brushing 200 times or layers forms a film with a thickness of 2 mm.

[0023] The prepared multi-layer thermal protection material can be a tubular or sheet product. If it is a tubular product, there is no need to suture or bond between the zirconia fiber felt and the fiberglass cloth coated with the heat sink layer and the low thermal conductivity layer; if it is a sheet product, the zirconia fiber felt and the fiberglass cloth coated with the heat sink layer and the low thermal conductivity layer are sutured with a fiber rope used in the industry.

[0024] In the multi-layer flexible thermal protection material of the present invention, zirconia fibers are first used. The melting point of this fiber is 2593 °C. The zirconia fiber felt has very good heat resistance. At the same time, the zirconia fiber felt itself has a very low thermal conductivity. The radiant heat of the rocket and its related aircraft first acts on the surface of the zirconia fiber felt, and the zirconia fiber felt completely blocks the heat. Subsequently, the zirconia fiber felt conducts heat inward. Then, a fiberglass cloth is used because the fiberglass cloth has very high density, making it impossible for the infrared rays of radiant heat to directly pass through the fiberglass cloth. Immediately afterwards, a heat sink layer made of a phase change material with a large heat capacity absorbs the heat passing through the fiberglass and slowly raises the temperature through phase change. Finally, polyborosiloxane is used as the innermost layer because polyborosiloxane has very good flexibility and smoothness, facilitating contact with instruments and equipment.

[0025] The thermal protection material of the present invention has high flexibility and good heat resistance, especially has a low density. Compared with traditional thermal protection materials of the same size and thickness, after being tested at 500 kw / m 2 for 50 s, the temperature rise on the back of the thermal protection materials with different thicknesses drops significantly, and the weight of the material decreases by about 10%. Its preparation method is simple, the process is convenient and easy to implement, and the heat protection effect of the prepared material is far better than that of existing thermal protection materials. Description of the Drawings

[0026] Figure 1 It is a schematic structural diagram of the multi-layer thermal protection material of the present invention.

[0027] A Zirconia fiber felt B Fiberglass cloth

[0028] C Heat sink layer D Low thermal conductivity layer Detailed Embodiments

[0029] The present invention will be further described below through embodiments, and the application of the present invention is not limited to the cited embodiments.

[0030] As Figure 1 shown, it is a schematic structure of the multi-layer thermal protection material of the present invention, which from the outside to the inside are A zirconia fiber felt, B fiberglass cloth, C heat sink layer and D low thermal conductivity layer in sequence. The specific process steps for its preparation are as follows:

[0031] The first step: Make zirconia fiber felts with different densities. The density of the zirconia fiber felt ranges from 0.75 g / cm 3 to 2.50 g / cm 3, with a thickness of 0.25 mm to 1.00 mm; Step 2: Produce fiberglass cloths with different weaving thicknesses, where the thickness of the fiberglass cloth is 0.03 mm to 1.00 mm; Step 3: Dissolve phase change wax with different contents in silicone rubber to make a heat sink layer, where the content of the phase change wax is 5% to 35%, and the thickness is 0.45 mm to 1.00 mm; Step 4: Use polydimethylsiloxane with different low thermal conductivities as the innermost layer, and the inner layer thickness is 0.3 mm to 1.00 mm. The made four-layer thermal protection material measures the back surface temperature rise of thermal protection materials with different thicknesses under a heat flux of 500 kw / m 2 to evaluate the heat protection effect of the thermal protection material. At the same time, to prove the advantages of the present invention, a comparative experiment is conducted on traditional thermal protection materials with the same thickness.

[0032] Example 1:

[0033] Step 1: Prepare zirconia fiber felt with a density of 0.75 g / cm 3 , and a thickness of 0.25 mm, which can be purchased from Huolong Thermal Ceramics Co., Ltd. in Jinan, Shandong or other companies, and the same applies hereinafter; Step 2: Prepare alkali-free fiberglass cloth with a thickness of 0.03 mm, which can be purchased from Shaanxi Huate Fiberglass Materials Group Co., Ltd. or other companies, and the same applies hereinafter; Step 3: Dissolve phase change wax in silicone rubber and brush it on the fiberglass cloth. After brushing once, let it dry naturally, and then brush the next time. Generally, after brushing 200 times, the thickness of the formed film is about 2 mm to make a heat sink layer, where the mass content of the phase change wax is 5%, and the thickness is 0.45 mm; Step 4: Brush polydimethylsiloxane on the heat sink layer of the fiberglass cloth. After brushing once, let it dry naturally, and then brush the next time. Generally, after brushing 200 times, the thickness of the formed film is about 2 mm. Use polydimethylsiloxane with low thermal conductivity as the innermost layer, and the inner layer thickness is 0.30 mm. The made four-layer thermal protection material measures the back surface temperature rise of thermal protection materials with different thicknesses under a heat flux of 500 kw / m 2 to evaluate the heat protection effect of the thermal protection material. At the same time, to prove the advantages of the present invention, a comparative experiment is conducted on a traditional thermal protection material with a thickness of 1.03 mm (fiberglass cloth coated with silicone rubber, and the thickness of the fiberglass cloth is the same as that in this example, which is 0.03 mm). The test sample size is 10 cm × 10 cm. The test results show that: the back surface temperature rise of the traditional thermal protection material is 547 °C, while the temperature rise of the thermal protection material of the present invention is 233 °C. And the weight of the traditional thermal protection is 9.13 g, while the weight of the thermal protection material in the present invention is 8.11 g; that is, the weight is reduced by 1.02 g, and the weight reduction rate is 11.17%, and the temperature rise is reduced by 314 °C, and the reduction rate is 57.4%.

[0034] Example 2:

[0035] Step 1: Prepare a zirconia fiber felt with a density of 1.00 g / cm 3 , and a thickness of 0.50 mm; Step 2: Prepare a high-silica glass fiber cloth with a thickness of 0.20 mm; Step 3: Dissolve the phase change wax in silicone rubber and apply it to the glass fiber cloth. After brushing once, let it dry naturally, and then brush the next time to make a heat sink layer. The mass content of the phase change wax is 10%, and the thickness is 0.55 mm; Step 4: Apply polyborosiloxane on the heat sink layer of the glass fiber cloth. After brushing once, let it dry naturally, and then brush the next time. The low-thermal-conductivity polyborosiloxane is used as the innermost layer with an inner layer thickness of 0.50 mm. For the made four-layer thermal protection material, measure the back surface temperature rise of the thermal protection materials with different thicknesses under a heat flux of 500 kw / m 2 . Usually, the test time is 50 seconds to measure the heat protection effect of the thermal protection material. At the same time, to prove the advantages of the present invention, a comparative experiment is carried out on a 1.75-mm-thick traditional thermal protection material (glass fiber cloth coated with polyurethane rubber, and the thickness of the glass fiber cloth is the same as that in this embodiment, which is 0.2 mm). The test sample size is 10 cm × 10 cm. The test results show that the back surface temperature rise of the traditional thermal protection material is 447 °C, while the temperature rise of the thermal protection material of the present invention is 192 °C. And the weight of the traditional thermal protection is 25.83 g, while the weight of the thermal protection material in the present invention is 22.61 g; that is, the weight is reduced by 3.22 g, the weight reduction rate is 12.47%, the temperature rise is reduced by 255 °C, and the reduction rate is 57.8%.

[0036] Example 3:

[0037] Step 1: Prepare a zirconia fiber felt with a density of 1.25 g / cm 3 , and a thickness of 0.65 mm; Step 2: Prepare a high-silica glass fiber cloth with a thickness of 0.30 mm; Step 3: Dissolve the phase change wax in silicone rubber and apply it to the glass fiber cloth. After brushing once, let it dry naturally, and then brush the next time to make a heat sink layer. The mass content of the phase change wax is 20%, and the thickness is 0.75 mm; Step 4: Apply polysiloxane on the heat sink layer of the glass fiber cloth. After brushing once, let it dry naturally, and then brush the next time. The low-thermal-conductivity polysiloxane is used as the innermost layer with an inner layer thickness of 0.40 mm. For the made four-layer thermal protection material, under a heat flux of 500 kw / m 2Under a heat flux, the temperature rise on the back side of thermal protection materials with different thicknesses is tested. The usual test time is 50 seconds to measure the heat protection effect of the thermal protection materials. At the same time, to prove the advantages of the present invention, a traditional thermal protection material with a thickness of 2.10 mm (a glass fiber cloth coated with silicone rubber, the thickness of the glass fiber cloth is the same as that of this embodiment, which is 0.3 mm) is used for a comparative experiment. The test sample size is 10 cm × 10 cm. The test results show that the temperature rise on the back side of the traditional thermal protection material is 409 °C, while the temperature rise of the thermal protection material of the present invention is 123 °C. And the weight of the traditional thermal protection is 31.52 g, while the weight of the thermal protection material in the present invention is 28.05 g; that is, the weight is reduced by 3.47 g, the weight reduction rate is 11.01%, the temperature rise is reduced by 286 °C, and the reduction rate is 69.93%.

[0038] Example 4:

[0039] The first step: Prepare zirconia fiber felt with a density of 2.50 g / cm 3 , and a thickness of 1.00 mm; the second step: Prepare an alkali-free glass fiber cloth with a thickness of 1.00 mm; the third step: Dissolve the phase change wax in silicone rubber and brush it on the glass fiber cloth. After brushing once, it is naturally dried, and then the next layer is brushed to make a heat sink layer. The mass content of the phase change wax is 35% and the thickness is 1.00 mm; the fourth step: Brush polysiloxane on the heat sink layer of the glass fiber cloth. After brushing once, it is naturally dried, and then the next layer is brushed. The low thermal conductivity polysiloxane is used as the innermost layer with an inner layer thickness of 1.00 mm. The made thermal protection material with a four-layer structure is tested for the temperature rise on the back side of thermal protection materials with different thicknesses under a heat flux of 500 kw / m 2 , and the usual test time is 50 seconds to measure the heat protection effect of the thermal protection materials. At the same time, to prove the advantages of the present invention, a traditional thermal protection material with a thickness of 4.00 mm (a glass fiber cloth coated with silicone rubber, the thickness of the glass fiber cloth is the same as that of this embodiment, which is 1.00 mm) is used for a comparative experiment. The test sample size is 10 cm × 10 cm. The test results show that the temperature rise on the back side of the traditional thermal protection material is 156 °C, while the temperature rise of the thermal protection material of the present invention is 33 °C. And the weight of the traditional thermal protection is 61.22 g, while the weight of the thermal protection material in the present invention is 55.07 g; that is, the weight is reduced by 6.15 g, the weight reduction rate is 10.05%, the temperature rise is reduced by 123 °C, and the reduction rate is 78.85%.

[0040] Example 5:

[0041] The first step: Prepare zirconia fiber felt with a density of 2.00 g / cm 3, with a thickness of 0.90 mm; Step 2: Prepare a high-silica glass fiber cloth with a thickness of 0.90 mm; Step 3: Dissolve the phase change wax in silicone rubber and apply it to the glass fiber cloth. After brushing once, let it dry naturally, and then brush the next time to make a heat sink layer. The mass content of the phase change wax is 30%, and the thickness is 0.90 mm; Step 4: Apply polyborosiloxane on the heat sink layer of the glass fiber cloth. After brushing once, let it dry naturally, and then brush the next time. The low-thermal-conductivity polyborosiloxane is used as the innermost layer with an inner layer thickness of 0.90 mm. The made four-layer thermal protection material, under a heat flux of 500 kw / m 2 The back surface temperature rise of thermal protection materials with different thicknesses is tested under a heat flux of 2 . Usually, the test time is 50 seconds to measure the heat protection effect of the thermal protection material. At the same time, to prove the advantages of the present invention, a 3.60-mm-thick traditional thermal protection material (glass fiber cloth coated with polyurethane rubber, and the thickness of the glass fiber cloth is the same as that in this embodiment, which is 0.9 mm) is used for a comparative experiment. The test sample size is 10 cm × 10 cm. The test results show that the back surface temperature rise of the traditional thermal protection material is 239 °C, while the temperature rise of the thermal protection material of the present invention is 45 °C. And the weight of the traditional thermal protection is 55.01 g, while the weight of the thermal protection material in the present invention is 49.22 g; that is, the weight is reduced by 5.79 g, and the weight reduction rate is 10.53%, and the temperature rise is reduced by 194 °C, and the reduction rate is 81.17%.

[0042] Example 6:

[0043] Step 1: Prepare a zirconia fiber felt with a density ranging from 1.75 g / cm 3 , with a thickness of 0.85 mm; Step 2: Prepare an alkali-free glass fiber cloth with a thickness of 0.70 mm; Step 3: Dissolve the phase change wax in silicone rubber and apply it to the glass fiber cloth. After brushing once, let it dry naturally, and then brush the next time to make a heat sink layer. The mass content of the phase change wax is 25%, and the thickness is 0.80 mm; Step 4: Apply polyborosiloxane on the heat sink layer of the glass fiber cloth. After brushing once, let it dry naturally, and then brush the next time. The low-thermal-conductivity polyborosiloxane is used as the innermost layer with an inner layer thickness of 0.80 mm. The made four-layer thermal protection material, under a heat flux of 500 kw / m 2Under a heat flux, the temperature rise on the back surface of thermal protection materials with different thicknesses is measured. The usual test time is 50 seconds to measure the heat protection effect of the thermal protection materials. At the same time, to prove the advantages of the present invention, a traditional thermal protection material with a thickness of 3.15 mm (glass fiber cloth coated with polyurethane rubber, and the thickness of the glass fiber cloth is the same as that of this embodiment, which is 0.7 mm) is used for a comparative experiment. The test sample size is 10 cm × 10 cm. The test results show that the temperature rise on the back surface of the traditional thermal protection material is 287 °C, while the temperature rise of the thermal protection material of the present invention is 59 °C. And the weight of the traditional thermal protection is 47.31 g, while the weight of the thermal protection material in the present invention is 41.29 g; that is, the weight is reduced by 6.02 g, and the weight reduction rate is 12.72%, the temperature rise is reduced by 228 °C, and the reduction rate is 79.44%.

[0044] Example 7:

[0045] The first step: Prepare zirconia fiber felt with a density of 2.50 g / cm 3 , and the thickness is 0.25 mm; The second step: Prepare high-silica glass fiber cloth with a thickness of 0.03 mm; The third step: Dissolve the phase change wax in silicone rubber and brush it on the glass fiber cloth. After brushing once, it is dried naturally, and then the next layer is brushed to make a heat sink layer. The mass content of the phase change wax is 35% and the thickness is 0.45 mm; The fourth step: Brush polysiloxane on the heat sink layer of the glass fiber cloth. After brushing once, it is dried naturally, and then the next layer is brushed. The low-thermal-conductivity polysiloxane is used as the innermost layer with an inner layer thickness of 1.00 mm. The made thermal protection material with a four-layer structure is tested for the temperature rise on the back surface of thermal protection materials with different thicknesses under a heat flux of 500 kw / m 2 , and the usual test time is 50 seconds to measure the heat protection effect of the thermal protection materials. At the same time, to prove the advantages of the present invention, a traditional thermal protection material with a thickness of 1.73 mm (glass fiber cloth coated with polyurethane rubber, and the thickness of the glass fiber cloth is the same as that of this embodiment, which is 0.03 mm) is used for a comparative experiment. The test sample size is 10 cm × 10 cm. The test results show that the temperature rise on the back surface of the traditional thermal protection material is 461 °C, while the temperature rise of the thermal protection material of the present invention is 199 °C. And the weight of the traditional thermal protection is 26.09 g, while the weight of the thermal protection material in the present invention is 23.87 g; that is, the weight is reduced by 2.22 g, and the weight reduction rate is 8.51%, the temperature rise is reduced by 262 °C, and the reduction rate is 56.8%.

[0046] Example 8:

[0047] The first step: Prepare zirconia fiber felt with a density of 0.75 g / cm 3, with a thickness of 1.00 mm; Step 2: Prepare an alkali-free glass fiber cloth with a thickness of 1.00 mm; Step 3: Dissolve the phase change wax in silicone rubber and apply it to the glass fiber cloth. After brushing once, let it dry naturally, and then brush the next time to make a heat sink layer. The mass content of the phase change wax is 5%, and the thickness is 0.45 mm; Step 4: Apply polysiloxane on the heat sink layer of the glass fiber cloth. After brushing once, let it dry naturally, and then brush the next time. The low thermal conductivity polysiloxane is used as the innermost layer, and the inner layer thickness is 0.30 mm. The made four-layer thermal protection material, under a heat flux of 500 kw / m 2 The back surface temperature rise of thermal protection materials with different thicknesses is tested under a heat flux of 2 . Usually, the test time is 50 seconds to measure the heat protection effect of the thermal protection material. At the same time, to prove the advantages of the present invention, a comparative experiment is carried out on a 2.75 mm thick traditional thermal protection material (glass fiber cloth coated with silicone rubber, and the thickness of the glass fiber cloth is the same as that in this embodiment, which is 1.00 mm). The test sample size is 10 cm × 10 cm. The test results show that the back surface temperature rise of the traditional thermal protection material is 333 °C, while the temperature rise of the thermal protection material of the present invention is 95 °C. And the weight of the traditional thermal protection is 41.98 g, while the weight of the thermal protection material in the present invention is 38.05 g; that is, the weight is reduced by 3.93 g, and the weight reduction rate is 9.4%. The temperature rise is reduced by 238 °C, and the reduction rate is 71.5%.

[0048] From the above 8 embodiments, it can be clearly seen that for thermal protection materials with the same size and thickness, after testing for 50 s under 500 kw / m 2 , the back surface temperature rises of thermal protection materials with different thicknesses are listed in Table 1, and the weight reduction is approximately 10%. The present invention is simple to manufacture, and the process is convenient and easy to implement. Most importantly, the heat protection effect is much better than that of existing thermal protection materials.

[0049] Table 1 Back surface temperature rise of thermal protection materials with different thicknesses

[0050]

[0051] The above embodiments are only used to illustrate rather than limit the technical solutions of the present invention. Although the above embodiments have described the present invention in detail, those skilled in the relevant art should understand that the present invention can be modified or equivalently replaced, but any modification and partial replacement without departing from the spirit and scope of the present invention should be covered within the scope of the claims of the present invention.

Claims

1. A multi-layer thermal protection material, characterized in that: the thermal protection material is composed of four layers of materials, which are, from outside to inside, an inorganic fiber felt, a fiberglass cloth, a heat sink layer, and a low thermal conductivity layer; the inorganic fiber felt is a zirconia fiber felt; the heat sink layer is composed of a phase change wax and a silicone rubber, wherein the mass content of the phase change wax is 5% to 35%; the silicone rubber is an addition-cured vinyl silicone rubber or an addition-cured propylene-based silicone rubber; the phase change temperature of the phase change wax is between 20 and 80 °C; the low thermal conductivity layer is composed of a polysiloxane or a polyborosiloxane.

2. The multi-layer thermal protection material according to claim 1, characterized in that: The density of the inorganic fiber felt described is 0.75 g / cm 3 ~2.50 g / cm 3 .

3. The multi-layer thermal protection material according to claim 1, characterized in that: the fiberglass cloth is prepared from an alkali-free fiberglass or a high-silica fiberglass.

4. The multi-layer thermal protection material according to claim 1, characterized in that: the thickness of the zirconia fiber felt is 0.25 mm to 1.00 mm, the thickness of the fiberglass cloth is 0.03 mm to 1.00 mm, the thickness of the heat sink layer is 0.45 mm to 1.00 mm, and the thickness of the low thermal conductivity layer is 0.3 mm to 1.00 mm.

5. The preparation method of the multi-layer thermal protection material according to any one of claims 1-4, comprising the following steps: First, prepare a zirconia fiber felt; second, prepare a fiberglass cloth; third, dissolve the phase change wax in the silicone rubber and use a brushing process to make a heat sink layer on the fiberglass cloth; fourth, use a brushing process to make a polysiloxane or polyborosiloxane film as the low thermal conductivity layer on the heat sink layer of the fiberglass cloth to obtain a thermal protection material with a four-layer structure.

6. The preparation method of the multi-layer thermal protection material according to claim 5, characterized in that: when making the heat sink layer and the low thermal conductivity layer, use a brushing process. After brushing once, let it dry naturally, and then brush the next time until the required thickness is reached.

7. The preparation method of the multi-layer thermal protection material according to claim 5, characterized in that: the prepared multi-layer thermal protection material is a tubular or sheet product; when the multi-layer thermal protection material is a sheet product, the zirconia fiber felt and the fiberglass cloth coated with the heat sink layer and the low thermal conductivity layer are stitched together with a fiber rope.

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