Composite thermal insulation material suitable for 400 DEG C high-temperature environment and preparation method of composite thermal insulation material

Abstract

The invention discloses a composite thermal insulation material suitable for a 400 DEG C high-temperature environment and a preparation method thereof, and belongs to the technical field of high-temperature thermal insulation materials. The composite thermal insulation material comprises a structure reinforcing layer, a core thermal insulation layer and a high-temperature protection layer which are sequentially arranged from inside to outside, and the structure reinforcing layer is glass fiber reinforced mica paper; the core heat insulation layer is an aerogel core layer, and the aerogel core layer is prepared by doping alumina nanowire aerogel with a wave-transparent anti-radiation agent; and the high-temperature protective layer is an aluminized polyester film. Through the design of the nanowire framework, the anti-radiation agent and the multi-layer reflection, the high-temperature heat insulation bottleneck of a traditional material is broken through, the contradiction that a single material cannot give consideration to high-temperature stability and ultralow heat conduction in the prior art is solved, the thickness is reduced by 60% or above, and the material is particularly suitable for the fields of new energy automobile battery thermal protection, aviation and aerospace engine compartment heat insulation and the like and has wide application prospects. And the practicability is high.

Description

Technical Field

[0001] This invention belongs to the technical field of high-temperature thermal insulation materials, specifically relating to a composite thermal insulation material suitable for high-temperature environments of 400℃ and its preparation method. Background Technology

[0002] Thermal insulation material is a material that can impede the transfer of heat; it is also known as thermal insulation material. Traditional thermal insulation materials include fiberglass, asbestos, rock wool, and silicates, while newer thermal insulation materials include aerogel felt and vacuum panels. However, existing thermal insulation materials have the following drawbacks: (1) The thermal conductivity of traditional ceramic fiber materials increases sharply at temperatures above 300℃; (2) Although traditional aerogel materials have ultra-low thermal conductivity (0.02W / m·K), infrared radiation heat transfer increases significantly at >300℃, resulting in a significant increase in thermal conductivity. They also have poor mechanical strength and are prone to pulverization at high temperatures. (3) Mica and fiberglass composite materials require a thickness of ≥6mm to achieve similar heat insulation effects, but they lack flexibility and lightweight. (4) Organic-inorganic composite layers are prone to delamination, and ultralight materials (density < 0.1 g / cm³) have low mechanical strength. Summary of the Invention

[0003] The purpose of this invention is to provide a composite thermal insulation material suitable for high-temperature environments of 400℃ and its preparation method, in order to solve the above-mentioned problems.

[0004] This invention is mainly achieved through the following technical solutions: A composite thermal insulation material suitable for high-temperature environments of 400℃ includes a structural reinforcement layer, a core thermal insulation layer, and a high-temperature protection layer arranged sequentially from the inside out. The structural reinforcement layer is glass fiber reinforced mica paper; the core thermal insulation layer is an aerogel core layer, which is prepared by alumina nanowires and chromium oxide powder, and the mass ratio of alumina nanowires to chromium oxide powder is 85:2.5; the high-temperature protection layer is an aluminized polyester film.

[0005] To better realize the present invention, the wave-transparent radiation-resistant agent is further described as chromium oxide and / or beryllium oxide.

[0006] To better realize the present invention, the thicknesses of the structural reinforcement layer, the core heat insulation layer and the high temperature protection layer are further 0.05 mm, 2.0 ± 0.2 mm and 0.1 mm, respectively.

[0007] This invention is mainly achieved through the following technical solutions: A method for preparing a composite thermal insulation material suitable for a 400℃ high-temperature environment, comprising the following steps: Step S1: Prepare the aerogel core layer; Step S11: Preparation of alumina nanowires: Nanoscale alumina powder and a HCl-H2SO4 mixture with a volume ratio of 1:1 are hydrothermally reacted at 200℃ for 5 hours to generate alumina nanowire clusters with a diameter of 30nm and a length of 400μm~500μm. Step S12: Doping with radiation agent: The alumina nanowires prepared in step S11 are mixed with chromium oxide powder in a two-dimensional kneader for 30 minutes, and then molded. Step S13: Hydrophobic reinforcement and drying: The material prepared in step S12 is immersed in a mixture of methyltrimethoxysilane and ammonium fluoride with a mass ratio of 100:15 while being magnetically stirred. Then, a gradient solvent replacement (ethanol-petroleum ether) is performed, and finally, subcritical drying is carried out. Step S2: Multilayer composite: The aerogel core layer, the aluminized polyester film and the glass fiber mica layer are hot-pressed together.

[0008] To better realize the present invention, in step S11, the alumina powder has a particle size of 20nm, and 85g of nanowires are mixed with 2.5g of chromium oxide (1250 mesh) and 10g of fumed silica in a kneader.

[0009] To better realize the present invention, in step S11, the mixing rate of the bidirectional kneader is 50 r / min; during the molding process, it is first pre-pressed at 0.5 MPa and then shaped at 2 MPa.

[0010] To better realize the present invention, in step S13, the magnetic stirring speed is 200 r / min; finally, subcritical drying is carried out at 80°C.

[0011] To better realize the present invention, in step S2, the temperature of hot pressing is 90°C, the pressure is 10MPa, and the duration is 15min.

[0012] The beneficial effects of this invention are as follows: This invention breaks through the high-temperature insulation bottleneck of traditional materials by using a nanowire skeleton + radiation-resistant agent + multi-layer reflection design. It solves the contradiction that a single material in the existing technology cannot simultaneously achieve high-temperature stability and ultra-low thermal conductivity, and the thickness is reduced by more than 60%. It can be applied to the fields of aerospace, new energy battery thermal protection and industrial pipeline thermal insulation. It is particularly suitable for the fields of new energy vehicle battery thermal protection, aviation and aerospace engine compartment thermal insulation, etc., and has good practicality. Attached Figure Description

[0013] Figure 1 This is a schematic diagram of the composite thermal insulation material of the present invention, which is suitable for high-temperature environments of 400℃.

[0014] Among them: 1-Structural reinforcement layer, 2-Core heat insulation layer, 3-High temperature protection layer. Detailed Implementation

[0015] Example 1: A composite thermal insulation material suitable for high-temperature environments up to 400℃, such as Figure 1 As shown, it includes: The outer layer is a high-temperature protective layer: 0.1mm aluminized polyester film, which reflects ≥90% of heat radiation.

[0016] The middle layer is the core heat insulation layer 2: alumina nanowire aerogel doped with a wave-transparent radiation-resistant agent (chromium oxide / beryllium oxide), with a thickness of 2.0±0.2mm.

[0017] The inner layer is structural reinforcement layer 1: glass fiber reinforced mica paper, 0.05mm thick, which improves tear resistance.

[0018] The preparation of the composite thermal insulation material includes the following steps: 1. Synthesis of alumina nanowires: Alumina powder with a particle size of 20 nm was hydrothermally reacted with a mixture of HCl-H2SO4 (1:1) at 200 °C for 5 hours to generate nanowire clusters with a diameter of 30 nm and a length of 500 μm.

[0019] 2. Radiation doping and molding: Nanowires and chromium oxide powder (mass ratio 85:2.5) are mixed in a two-way kneader (50 r / min) for 30 minutes and then molded (pre-pressed at 0.5 MPa and then shaped at 2 MPa).

[0020] 3. Hydrophobic reinforcement and drying: Immerse in a mixture of methyltrimethoxysilane / ammonium fluoride (100:15), stir magnetically (200 r / min), then perform gradient solvent replacement (ethanol-petroleum ether), and finally perform subcritical drying (80℃, 6 cycles of venting).

[0021] 4. Multi-layer composite: Roller pressing process: The aerogel core layer is hot-pressed together with the aluminized polyester film and the glass fiber mica layer at 90℃ (pressure 10MPa, duration 15min).

[0022] Example 2: A method for preparing a composite thermal insulation material suitable for high-temperature environments of 400℃ includes the following steps: 1. Synthesis of alumina nanowires: Alumina nanowires with a particle size of 30 nm and a length of 400 μm were synthesized. 2. Radiation doping and molding: 85g of alumina nanowires, 2.5g of chromium oxide (1250 mesh), and 10g of fumed silica were mixed in a kneader; then, the mixture was molded. 3. Hydrophobic reinforcement and drying: Immerse in 15% methyltrimethoxysilane solution and age with ammonia catalysis for 12 hours; then, gradient solvent replacement and subcritical drying to obtain aerogel core material (density 0.18 g / cm³).

[0023] 4. Multi-layer composite: hot-pressed composite with 0.1mm aluminized polyester film and 0.05mm glass fiber mica layer.

[0024] Experimental tests yielded the following results: Test conditions: ambient temperature 350℃ for 2 hours, sample thickness 2.0mm, covering a steel pipe with an inner diameter of 50mm.

[0025] Conclusion: As shown in Table 1, the composite thermal insulation material prepared in this embodiment has an internal temperature stability of ≤200℃ under steady state and a heat loss of ≤120W / m² (60% of the allowable value of GB 50264-1997).

[0026] Table 1 Test results of Example 2 Table 2 Comparison of Test Performance The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. Any simple modifications or equivalent changes made to the above embodiments based on the technical essence of the present invention shall fall within the protection scope of the present invention.

Claims

1. A composite thermal insulation material suitable for use in a high temperature environment of 400°C, characterized in that, The structure includes, from inside to outside, a structure reinforcing layer, a core thermal insulation layer and a high temperature protection layer, the structure reinforcing layer is a glass fiber reinforced mica paper; the core thermal insulation layer is an aerogel core layer, the aerogel core layer is prepared from aluminum oxide nanowires and chromium oxide powder, and the mass ratio of the aluminum oxide nanowires to the chromium oxide powder is 85: 2.5; the high temperature protection layer is an aluminized polyester film.

2. The composite thermal insulation material suitable for a high temperature environment of 400°C according to claim 1, characterized in that, The wave-transparent anti-radiation agent is chromium oxide and / or beryllium oxide.

3. The composite thermal insulation material suitable for a high temperature environment of 400°C according to claim 1 or 2, characterized in that, The thicknesses of the structure reinforcing layer, the core thermal insulation layer and the high temperature protection layer are 0.05 mm, 2.0±0.2 mm and 0.1 mm respectively.

4. A method for preparing a composite thermal insulation material suitable for use in a high temperature environment of 400 °C, for preparing a composite thermal insulation material suitable for use in a high temperature environment of 400 °C according to any one of claims 1 to 3, characterized in that The method comprises the following steps: Step S1: preparing an aerogel core layer; Step S11: preparing aluminum oxide nanowires: nanoscale aluminum oxide powder is mixed with a volume ratio of 1:1 HCl-H2SO4 mixed solution at 200 DEG C for hydrothermal reaction for 5 hours to generate aluminum oxide nanowire clusters with a diameter of 30 nm and a length of 400 μm-500 μm; Step S12: doping a radiation agent: the aluminum oxide nanowires prepared in step S11 are mixed with chromium oxide powder in a double kneader for 30 minutes, and then molded; Step S13: hydrophobic strengthening and drying: the material prepared in step S12 is immersed in a methyltrimethoxysilane and ammonium fluoride mixed solution with a mass ratio of 100:15, while being magnetically stirred, then gradient solvent replacement, and finally subcritical drying; Step S2: multilayer compounding: the aerogel core layer, the aluminized polyester film and the glass fiber mica layer are hot-pressed and bonded.

5. The method for preparing a composite thermal insulation material suitable for a high-temperature environment of 400℃ according to claim 4, characterized in that, In the step S11, the particle size of the aluminum oxide powder is 20 nm, and 85 g of nanowires are mixed with 2.5 g of chromium oxide and 10 g of fumed silica in a kneader.

6. The method for preparing a composite thermal insulation material suitable for a high-temperature environment of 400°C according to claim 4 or 5, characterized in that, In the step S11, the mixing rate of the double kneader is 50 r / min; in the molding process, first pre-press at 0.5 MPa, then shape at 2 MPa.

7. The method for preparing a composite thermal insulation material suitable for a high-temperature environment of 400℃ according to claim 4, characterized in that, In the step S13, the speed of the magnetic stirring is 200 r / min; finally, subcritical drying is carried out at 80 DEG C.

8. The method for preparing a composite thermal insulation material suitable for a high-temperature environment of 400℃ according to claim 4, characterized in that, In the step S2, the temperature of the hot-pressing and bonding is 90 DEG C, the pressure is 10 MPa, and the time is 15 min.

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