Fiber-reinforced structural thermal insulation composite material, method for producing same, and use thereof

Abstract

The present application relates to the technical field of thermal insulation materials, and provides a fiber-reinforced structural thermal insulation composite material and a preparation method and application thereof.The raw materials for preparing the fiber-reinforced structural thermal insulation composite material include silica sol, zirconium-containing silicon micro powder, fused quartz glass powder, glass fiber, active antifoaming agent, interface modifier and fiber wetting agent.The obtained thermal insulation composite material has excellent mechanical properties and thermal insulation performance.The fiber-reinforced structural thermal insulation composite material can be obtained by pouring, defoaming, drying and sintering after mixing the raw materials, and the preparation method is simple.The appropriate mold can be selected according to the different use places, so that the thermal insulation composite material with the required size can be obtained, which is helpful to reduce the cost.Furthermore, the arrangement direction of the glass fiber in the obtained thermal insulation composite material is anisotropic, and the anisotropic fiber structure can provide toughness to the material in different directions, so that the mechanical properties of the thermal insulation composite material are improved.

Description

Technical Field

[0001] This invention relates to the field of thermal insulation materials technology, and in particular to a fiber-reinforced structural thermal insulation composite material, its preparation method, and its application. Background Technology

[0002] Fiber-reinforced structural thermal insulation composites refer to composite materials with thermal insulation properties that significantly impede heat flow. They are characterized by low density, high strength, and low thermal conductivity. Currently, the high-temperature thermal efficiency of thermal equipment worldwide is around 50%. The linings of traditional thermal equipment are usually made of heavy refractory materials. Due to the high thermal conductivity of heavy refractory materials, internal air heat conduction and convection are significant, which is one of the important reasons for heat loss in the equipment.

[0003] Currently, based on the different fiber materials, fiber-reinforced structural thermal insulation composites can be divided into three types: mullite fiber-reinforced structural thermal insulation composites, high-silica fiber-reinforced structural thermal insulation composites, and glass fiber-reinforced structural thermal insulation composites. Mullite fiber has good high-temperature resistance and is a commonly used reinforcing fiber in composites; however, due to its high high-temperature thermal conductivity, the operating temperature of the composites prepared with it is limited. While zirconia fiber itself possesses high-temperature resistance and low thermal conductivity, its tetragonal crystalline phase exhibits good stability but poor compatibility with sols. Furthermore, stable zirconia fiber lacks functional groups, making it difficult to disperse evenly through mechanical stirring alone. Compared to mullite and zirconia fibers, glass fiber offers advantages such as low cost, high strength, low thermal conductivity, good temperature resistance, and easy dispersion, thus achieving a better thermal insulation effect.

[0004] In this field, traditional thermal insulation materials often utilize increased pore count to achieve relatively low thermal conductivity, such as glass fiber-reinforced SiO2 aerogel composites. However, higher porosity reduces the mechanical properties of thermal insulation materials, thus limiting their application. Therefore, ensuring the mechanical properties of thermal insulation materials while achieving lower thermal conductivity is crucial in this field. Summary of the Invention

[0005] In view of this, the present invention provides a fiber-reinforced structural thermal insulation composite material, its preparation method, and its application. The fiber-reinforced structural thermal insulation composite material provided by the present invention has the characteristics of low thermal conductivity and high strength.

[0006] To achieve the above-mentioned objectives, the present invention provides the following technical solution:

[0007] A fiber-reinforced structural thermal insulation composite material comprises the following raw materials in the indicated mass fractions: 25-30% silica sol, 10-60% zirconium-containing silica micropowder, 5-50% fused silica glass powder, 5-10% glass fiber, 0.5-2% active antifoaming agent, 0.5-2% interface modifier, and 0.1-1% fiber impregnating agent; wherein the active antifoaming agent is N,N-diethylethanolamine; and the interface modifier is ethylene bis-stearamide.

[0008] Preferably, the mass fraction of SiO2 in the silica sol is 10-30%; the mass fraction of SiO2 in the zirconium-containing silicon micropowder is 76-96%; and the mass fraction of SiO2 in the fused silica glass powder is 89.8-99.2%.

[0009] Preferably, the silica sol has the following composition by mass fraction: SiO2 10-30%, Na2O ≤0.3%, and the balance being water;

[0010] The zirconium-containing silicon micropowder, by mass fraction, comprises: SiO2 86-96%, ZrO2+HfO2 4-6%, Al2O3 0.2-0.4%, Fe2O3 0.3-0.7%, TiO2 0-0.1%, with the remainder being impurities.

[0011] Preferably, the mass fraction of SiO2 in the glass fiber is 89.8-99.2%; the diameter of the glass fiber monofilament is 7-8 μm and the length is 0.9-1 mm.

[0012] Preferably, the fiber impregnating agent is a silane coupling agent.

[0013] Preferably, the bulk density of the fiber-reinforced structural thermal insulation composite material is greater than or equal to 1.3 g / cm³. 3 The compressive strength is greater than or equal to 10 MPa, and the thermal conductivity is less than or equal to 0.496 W / m·K.

[0014] This invention also provides a method for preparing the fiber-reinforced structural thermal insulation composite material described above, comprising the following steps:

[0015] Modified glass fibers are obtained by impregnating and modifying glass fibers in a fiber sizing agent.

[0016] A mixed slurry is obtained by mixing silica sol, zirconium-containing silica micro powder, fused silica glass powder, modified glass fiber, active antifoaming agent and interface modifier;

[0017] The mixed slurry is poured into a mold, and after defoaming, it is dried and sintered in sequence to obtain a fiber-reinforced structural thermal insulation composite material.

[0018] Preferably, the sintering temperature is 400–1000°C and the time is 100–200 min.

[0019] Preferably, the defoaming includes vacuum defoaming and vibration defoaming; one vacuum defoaming and one vibration defoaming are performed sequentially as one defoaming cycle, and the number of defoaming cycles is 2 to 3.

[0020] The present invention also provides the application of the fiber-reinforced structural thermal insulation composite material described in the above-described scheme or the fiber-reinforced structural thermal insulation composite material prepared by the preparation method described in the above-described scheme in thermal equipment.

[0021] This invention provides a fiber-reinforced structural thermal insulation composite material, comprising the following raw materials by mass fraction: 25-30% silica sol, 10-60% zirconium-containing silica micropowder, 5-50% fused silica glass powder, 5-10% glass fiber, 0.5-2% active antifoaming agent, 0.5-2% interface modifier, and 0.1-1% fiber impregnating agent; wherein the active antifoaming agent is N,N-diethylethanolamine; and the interface modifier is ethylene bis-stearamide. The thermal insulation composite material provided by this invention comprises four raw materials (silica sol, zirconium-containing silicon micropowder, fused silica glass powder, and glass fiber) and three additives (active antifoaming agent, interface modifier, and fiber wetting agent). The resulting thermal insulation composite material exhibits excellent mechanical and thermal insulation properties. The zirconium-containing silicon micropowder, due to its small particle size, is used to fill pores. The addition of fused silica glass powder facilitates the bonding between matrices and between the matrix and fibers, thereby improving the mechanical properties of the thermal insulation composite material. Glass fiber and matrix powder play a synergistic role within the thermal insulation composite material. The presence of micropores and microcracks in the stacking of zirconium-containing silicon micropowder and fused silica powder of different particle sizes further enhances the thermal insulation properties. The resulting thermal insulation composite material exhibits improved mechanical properties by making crack propagation more difficult under load and generating microcracks for toughening. Interface modifiers enable the slurry to achieve a suitable pH value (9.5–10) and viscosity, allowing for better and more uniform fiber dispersion, thus enhancing the thermal insulation and mechanical properties of the composite material. Active antifoaming agents utilize solvents to carry N,N-diethylethanolamine; when added to a solution containing bubbles, the N,N-diethylethanolamine gradually condenses into microdroplets, carrying away the bubbles and helping to expel bubbles generated during slurry stirring, further reducing internal defects and improving various performance indicators of the material.

[0022] This invention also provides a method for preparing the fiber-reinforced structural thermal insulation composite material described above. First, glass fibers are modified with a fiber impregnating agent. Then, the modified glass fibers are mixed with other raw materials to obtain a mixed slurry. The mixed slurry is then poured, defoamed, dried, and sintered to obtain the fiber-reinforced structural thermal insulation composite material. The preparation method is simple and low-cost. Furthermore, this invention allows for the selection of appropriate molds based on different application locations, thereby obtaining thermal insulation composite materials of the required size, which helps to further reduce costs. Moreover, this invention directly mixes the raw materials, resulting in an anisotropic arrangement of glass fibers in the mixed slurry. This anisotropic fiber structure provides toughness to the material during fracture in different directions, thereby improving the mechanical properties of the thermal insulation composite material. Attached Figure Description

[0023] Figure 1 Scanning electron microscope (SEM) images of the fiber-reinforced structural thermal insulation composite materials prepared in Examples 1-5. Detailed Implementation

[0024] This invention provides a fiber-reinforced structural thermal insulation composite material, comprising the following raw materials by mass fraction: 25-30% silica sol, 10-60% zirconium-containing silica micropowder, 5-50% fused silica glass powder, 5-10% glass fiber, 0.5-2% active antifoaming agent, 0.5-2% interface modifier, and 0.1-1% fiber impregnating agent; wherein the active antifoaming agent is N,N-diethylethanolamine; and the interface modifier is ethylene bis-stearamide.

[0025] Unless otherwise specified, all raw materials used in this invention are commercially available.

[0026] The raw materials for preparing the fiber-reinforced structural thermal insulation composite material provided by the present invention, by mass fraction, include 25-30% silica sol, preferably 26-28%. In the present invention, the mass fraction of SiO2 in the silica sol is preferably 10-30%, more preferably 15-25%, and even more preferably 19-21%. Specifically, the composition of the silica sol is preferably: 10-30% SiO2, ≤0.3% Na2O, and the balance being water; more preferably: 19-21% SiO2, ≤0.3% Na2O, and the balance being water.

[0027] The raw materials for preparing the fiber-reinforced structural thermal insulation composite material provided by the present invention, by mass fraction, include 10-60% zirconium-containing silicon micropowder, preferably 20-50%. In the present invention, the zirconium-containing silicon micropowder has a D... 50The particle size is preferably 1.5-2 μm, more preferably 1.8 μm; the mass fraction of SiO2 in the zirconium-containing silicon micropowder is preferably 86-96%, more preferably 88-94%, and even more preferably 91%; specifically, the composition of the zirconium-containing silicon micropowder is preferably: SiO2 86-96%, ZrO2+HfO2 4-6%, Al2O3 0.2-0.4%, Fe2O3 0.3-0.7%, TiO2 0.04%, with the balance being impurities, more preferably: SiO2 91%, ZrO2+HfO2 5%, Al2O3 0.3%, Fe2O3 0.5%, TiO2 0.04%, with the balance being impurities.

[0028] The raw materials for preparing the fiber-reinforced structural thermal insulation composite material provided by this invention, by mass fraction, include 5-50% fused silica glass powder, preferably 10-40%. In this invention, the melting point of the fused silica glass powder is preferably 1713℃; the D of the fused silica glass powder... 50 The particle size is preferably 50-60 μm; the mass fraction of SiO2 in the fused silica glass powder is preferably 98.8-99.2%, more preferably 99%, with the remainder being impurities; the present invention uses zirconium-containing silicon micro powder and fused silica glass powder in combination, and the two have different particle sizes, making it easier to disperse evenly during the dispersion process.

[0029] The raw materials for preparing the fiber-reinforced structural thermal insulation composite material provided by the present invention, by mass fraction, include 5-10% glass fiber, preferably 6-8%. In the present invention, the mass fraction of SiO2 in the glass fiber is preferably 98.8-99.2%, more preferably 99%, with the remainder being impurities; the diameter of the single filament of the glass fiber is preferably 7-8 μm, and the length is preferably 0.9-1 mm.

[0030] The raw materials for preparing the fiber-reinforced structural thermal insulation composite material provided by the present invention, by mass fraction, include 0.5-2% active antifoaming agent, preferably 1-1.5%; in the present invention, the active antifoaming agent is N,N-diethylethanolamine; in a specific embodiment of the present invention, commercially available N,N-diethylethanolamine is preferably used directly, and the purity of the N,N-diethylethanolamine is preferably 90-98%, more preferably 95%, with the balance being water.

[0031] The raw materials for preparing the fiber-reinforced structural thermal insulation composite material provided by the present invention, by mass fraction, include 0.5-2% interface modifier, preferably 1-1.5%. In the present invention, the interface modifier is ethylene bis-stearamide; in specific embodiments of the present invention, commercially available ethylene bis-stearamide is preferably used directly, and the purity of the ethylene bis-stearamide is preferably 85-90%, more preferably 90%, with the balance being water; the interface modifier can control the pH value of the mixed slurry at 9.5-10, and reduce the viscosity of the mixture, improve the interface between the fiber and the matrix powder, thereby improving the performance of the thermal insulation composite material.

[0032] The raw materials for preparing the fiber-reinforced structural thermal insulation composite material provided by the present invention, by mass fraction, include 0.1-1% fiber sizing agent, preferably 0.3-0.6%. In the present invention, the fiber sizing agent is preferably a silane coupling agent, which preferably includes 3-mercaptopropyltrimethoxysilane and γ-glycidyl etherpropyltrimethoxysilane; the mass ratio of 3-mercaptopropyltrimethoxysilane to γ-glycidyl etherpropyltrimethoxysilane is preferably 1:0.4-0.8, more preferably 1:0.6.

[0033] In this invention, the bulk density of the fiber-reinforced structural thermal insulation composite material is preferably greater than or equal to 1.3 g / cm³. 3 More preferably, it is 1.3–1.5 g / cm³. 3 The compressive strength of the fiber-reinforced structural thermal insulation composite material is preferably greater than or equal to 10 MPa, more preferably 10 to 20 MPa; the thermal conductivity of the fiber-reinforced structural thermal insulation composite material is preferably less than or equal to 0.496 W / m·K, more preferably 0.300 to 0.500 W / m·K.

[0034] This invention also provides a method for preparing the fiber-reinforced structural thermal insulation composite material of the above-mentioned scheme, comprising the following steps:

[0035] Modified glass fibers are obtained by impregnating and modifying glass fibers in a fiber sizing agent.

[0036] A mixed slurry is obtained by mixing silica sol, zirconium-containing silica micro powder, fused silica glass powder, modified glass fiber, active antifoaming agent and interface modifier;

[0037] The mixed slurry is poured into a mold, and after defoaming, it is dried and sintered in sequence to obtain a fiber-reinforced structural thermal insulation composite material.

[0038] This invention modifies glass fibers by impregnating them in a fiber sizing agent to obtain modified glass fibers. In this invention, the impregnation and modification time is preferably 1 to 12 hours, and more preferably 1 to 5 hours. This invention uses a sizing agent to modify glass fibers, which makes the fibers easier to disperse during casting and enhances their interfacial bonding with the composite matrix.

[0039] After obtaining the modified glass fibers, the present invention mixes silica sol, zirconium-containing silica micropowder, fused silica glass powder, modified glass fibers, active antifoaming agent, and interface modifier to obtain a mixed slurry; the fiber arrangement direction in the mixed slurry is anisotropic. In the present invention, the mixing is preferably carried out under stirring conditions, and the stirring time is preferably 30 min; in the present invention, the modified glass fibers in the mixed slurry are arranged in anisotropic directions; the viscosity of the mixed slurry at room temperature is preferably less than 6000 Pa·s, preferably 3000-4000 Pa·s, and the pH value of the mixed slurry is preferably 9-10.

[0040] After obtaining the mixed slurry, the present invention pours the mixed slurry into a mold, removes bubbles, and then dries and sintersects it sequentially to obtain a fiber-reinforced structural thermal insulation composite material. In the present invention, the mold is preferably made of acrylic sheet; the present invention has no special requirements for the shape of the mold, which can be selected according to the needs of the target thermal insulation composite material; the mixed slurry is preferably poured into the mold in three stages. In a specific embodiment of the present invention, it is preferable to first add the first part of the slurry into the mold, place the mold on a vibration table for vibration, and stir the slurry in the mold during the vibration until no more bubbles are released. Then, the second part of the slurry is added, and the same operation is performed until no more bubbles are released, and then the third part of the slurry is added.

[0041] In this invention, the defoaming includes vacuum defoaming and vibration defoaming; one vacuum defoaming and one vibration defoaming are performed sequentially as one defoaming cycle, and the number of defoaming cycles is preferably 2 to 3. In this invention, the vacuum defoaming method is preferably: placing the mold containing the slurry in a vacuum-capable container and evacuating it to -0.1 MPa, holding it for 5 seconds, and then slowly releasing the pressure to atmospheric pressure; the vibration defoaming method is preferably: placing the mold containing the slurry on a vibration table and vibrating it, while stirring the slurry in the mold during the vibration process until no more bubbles are discharged.

[0042] In this invention, the drying temperature is preferably 80-100°C, and the drying time is preferably 12-24 hours.

[0043] In this invention, the sintering temperature is preferably 400-1000℃, more preferably 500-900℃, and the sintering time is preferably 100-200 min, more preferably 120-150 min. After sintering, the obtained thermal insulation composite material is preferably cooled and then demolded.

[0044] This invention also provides the application of the fiber-reinforced structural thermal insulation composite material described in the above-described scheme or the fiber-reinforced structural thermal insulation composite material prepared by the preparation method described in the above-described scheme in thermal equipment. The fiber-reinforced structural thermal insulation composite material provided by this invention has high thermal conductivity and good mechanical properties, and has broad application prospects. This invention does not have special requirements for the application method; methods well known to those skilled in the art can be used.

[0045] The technical solutions of this invention will be clearly and completely described below with reference to the embodiments thereof. Obviously, the described embodiments are only a part of the embodiments of this invention, and not all of them. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0046] The composition of each component used in the following examples is as follows, by mass fraction:

[0047] The composition of silica sol is as follows: SiO2 20±1%, Na2O≤0.3%, and the balance is water;

[0048] The composition of the zirconium-containing silicon micropowder is as follows: SiO2 91%, ZrO2+HfO2 5%, Al2O3 0.3%, Fe2O3 0.5%, TiO2 0.04%, with the balance being impurities;

[0049] The composition of the silicon fused silica glass powder is as follows: SiO2 99%, with the balance being impurities;

[0050] The glass fiber composition is as follows: 99% SiO2, with the balance being impurities; the glass fiber diameter is 7-8 μm and the length is 0.9-1 mm;

[0051] The active antifoaming agent consists of the following components: 95% N,N-diethylethanolamine, with the remainder being water;

[0052] The interface modifier consists of the following components: 90% ethylene bis-stearamide (EBS) and the remainder is water;

[0053] The fiber impregnating agent is 3-mercaptopropyltrimethoxysilane and γ-glycidyl etherpropyltrimethoxysilane; the mass ratio of 3-mercaptopropyltrimethoxysilane and γ-glycidyl etherpropyltrimethoxysilane is 1:0.6.

[0054] Example 1

[0055] Weigh each component according to the following mass percentages:

[0056] The composition consists of 30% silica sol, 56% zirconium-containing silica micropowder, 5.2% fused silica glass powder, 7% glass fiber, 1.0% active antifoaming agent, 0.5% interface modifier, and 0.3% fiber wetting agent; the total amount of all components is 1000g.

[0057] The above components were stirred and mixed, and the mass fraction of SiO2, the main component in the resulting mixture, was 69.15%.

[0058] The preparation steps of fiber-reinforced structural thermal insulation composite materials are as follows:

[0059] 1) Modify glass fibers by using an impregnating agent for 1 hour to obtain modified glass fibers;

[0060] 2) The silica sol, zirconium-containing silica micro powder, fused silica glass powder, modified glass fiber, active antifoaming agent and interface modifier are stirred and mixed for 30 minutes under the action of a mixer to obtain a mixed slurry with a viscosity of 3000-5000 Pa·s and a pH value of 9.5.

[0061] 3) Add the mixed slurry obtained in step 1) into the mold in three batches. After each addition, place the mold on the vibration table and stir it with a vibrating rod during the vibration of the vibration table until no more air bubbles are released. Then add the next batch of mixed slurry.

[0062] 4) Place the mold containing the slurry obtained in step 2) into a vacuum-capable container and vacuum it to -0.1MPa. After waiting for 5 seconds, slowly release the pressure to atmospheric pressure. Place the mold on a vibration table and stir it with a vibrating rod during the vibration process until no more air bubbles are released.

[0063] 5) Repeat step 4) twice;

[0064] 6) After drying the mold containing the slurry obtained in step 5) at 80°C for 24 hours, place it in a medium-temperature furnace and sinter at 900°C for 2 hours. After cooling, the fiber-reinforced structural thermal insulation composite material is obtained.

[0065] Example 2

[0066] Weigh each component according to the following mass percentages:

[0067] The composition includes 30% silica sol, 50% zirconium-containing silica micropowder, 11.2% fused silica glass powder, 7% glass fiber, 1.0% active antifoaming agent, 0.5% interface modifier, and 0.3% fiber sizing agent.

[0068] The above components were stirred and mixed, and the mass fraction of SiO2, the main component in the resulting mixture, was 69.69%.

[0069] The preparation method of the fiber-reinforced structural thermal insulation composite material is the same as that in Example 1. The viscosity of the mixed slurry obtained during the preparation process is 3000-5000 Pa·s, and the pH value is 9.5.

[0070] Example 3

[0071] Weigh each component according to the following mass percentages:

[0072] The composition includes 30% silica sol, 45% zirconium-containing silica micropowder, 16.2% fused silica glass powder, 7% glass fiber, 1.0% active antifoaming agent, 0.5% interface modifier, and 0.3% fiber sizing agent.

[0073] The above components were stirred and mixed, and the mass fraction of SiO2, the main component in the resulting mixture, was 70.14%.

[0074] The preparation method of the fiber-reinforced structural thermal insulation composite material is the same as that in Example 1. The viscosity of the mixed slurry obtained during the preparation process is 3000-5000 Pa·s, and the pH value is 9.6.

[0075] Example 4

[0076] Weigh each component according to the following mass percentages:

[0077] The composition includes 30% silica sol, 40% zirconium-containing silica micropowder, 21.2% fused silica glass powder, 7% glass fiber, 1.0% active antifoaming agent, 0.5% interface modifier, and 0.3% fiber sizing agent.

[0078] The above components were stirred and mixed. The mass fraction of the main component SiO2 in the resulting mixture was 70.59%, with the remainder being water and impurities.

[0079] The preparation method of the fiber-reinforced structural thermal insulation composite material is the same as that in Example 1. The viscosity of the mixed slurry obtained during the preparation process is 3000-5000 Pa·s, and the pH value is 9.7.

[0080] Example 5

[0081] Weigh each component according to the following mass percentages:

[0082] The composition includes 30% silica sol, 35% zirconium-containing silica micropowder, 26.2% fused silica glass powder, 7% glass fiber, 1.0% active antifoaming agent, 0.5% interface modifier, and 0.3% fiber sizing agent.

[0083] The above components were stirred and mixed, and the mass fraction of SiO2, the main component in the resulting mixture, was 71.04%.

[0084] The preparation method of the fiber-reinforced structural thermal insulation composite material is the same as that in Example 1. The viscosity of the mixed slurry obtained during the preparation process is 3000-5000 Pa·s, and the pH value is 9.9.

[0085] Comparative Example 1

[0086] The only difference from Example 1 is that glass fiber and fiber sizing agent were not added in Comparative Example 1, while the percentages of the remaining raw materials and the preparation process were the same as in Example 1. Specifically, omitting glass fiber and fiber sizing agent resulted in a total reduction of 73g compared to Example 1, with the total amount of the remaining six components being 927g. Based on this total amount of 927g, the specific dosage of each component was calculated according to the following formula: 30% silica sol, 56% zirconium-containing silicon micropowder, 5.2% fused silica glass powder, 1.0% active antifoaming agent, and 0.5% interface modifier. For example, the dosage of silica sol was 278.1g. The dosage of other components after omitting a certain component in subsequent comparative examples will be calculated in the same way, and will not be repeated hereafter.

[0087] Comparative Example 2

[0088] The difference from Example 1 is that no fused silica glass powder was added in Comparative Example 2, while the percentages of the remaining raw materials and the preparation process were the same as in Example 1.

[0089] Comparative Example 3

[0090] The difference from Example 1 is that no active antifoaming agent was added in Comparative Example 3, while the percentages of the remaining raw materials and the preparation process were the same as in Example 1.

[0091] Comparative Example 4

[0092] The difference between Comparative Example 4 and Example 1 is that no interface modifier was added in Comparative Example 4, and the percentage of the remaining raw materials and the preparation process were the same as in Example 1. The viscosity of the mixed slurry obtained during the preparation process was 9000 Pa·s, and the pH value was 10.

[0093] Comparative Example 5

[0094] Thermal insulation composite materials were prepared using a semi-dry pressing method; the specific steps are as follows:

[0095] After adding deionized water to a beaker, place it in an ultrasonic cleaner. Slowly add glass fiber (10 wt.%) and vibrate in the ultrasonic cleaner for 10 minutes at an ultrasonic frequency of 40 kHz. Then, add zirconium silicate powder (57 wt.%) and fused silica glass powder (32 wt.%) in sequence, and stir evenly with a glass rod. Stir with an electronic stirrer for 15 minutes at a speed of 400 r / min. Then, place it in an oven and dry at 100℃ until the moisture content is 5%. After removal, grind and sieve with an 18-mesh sieve. After sieving, spray 1% of the total powder mass of silica sol as a binder. Then, use a press to press and shape it with a mold with a diameter of 20 mm. After shaping, break it and repeat the grinding, sieving, and secondary pressure shaping. The pressure for both shaping is 9.42 kN, the pressurization rate is 0.1 kN / s, and the demolding rate is 5 mm / min.

[0096] Comparative Example 6

[0097] The difference from Example 1 is that in Comparative Example 6, the zirconium-containing silicon micro powder was replaced with ordinary silicon micro powder (silica content of 60 wt%), while the percentages of the remaining raw materials and the preparation process were the same as in Example 1.

[0098] Comparative Example 7

[0099] Based on existing technology: Ding Donghai, Li Runan, Zhang Li, Peng Kai, Xiao Guoqing, Duan Feng, Deng Peilin, Li Jie. Effect of heat treatment temperature on SiO2 2f The composite material prepared in the paper "Influence of SiO2 Composite Material Properties on the Performance of SiO2 Composite Material" [J], Chinese Journal of the Chinese Ceramic Society, 2022, 50(7):10, is Comparative Example 7. The specific preparation method of the composite material in this paper is as follows:

[0100] SiO2 was prepared by precursor impregnation heat treatment method 2f / SiO2 composite material: First, place the quartz fiber needle-punched felt in a vacuum impregnation device, turn on the vacuum pump, and when the pressure gauge reading stabilizes at -0.098MPa, open the liquid injection switch to inject silica sol and then close the switch. After the pressure gauge reading reaches -0.098MPa again, allow the fiber needle-punched felt to be fully impregnated, then turn off the vacuum pump and remove the sample; place it in an oven at 50℃ for 4 hours, then at 80℃ for 10 hours to form a gel, and finally dry at 110℃ for 2 hours; then place the material in a muffle furnace for heat treatment at 400℃ for 0.5 hours. This process is repeated 4 times. In the 4th cycle, the final heat treatment temperature of the material is 900℃, the holding time is 1 hour, and it is cooled with the furnace.

[0101] Test case

[0102] 1. Performance parameter testing

[0103] The fiber-reinforced structural thermal insulation composites prepared in Examples 1-5 and Comparative Examples 1-7 were tested for bulk density, apparent porosity, flexural strength, compressive strength, coefficient of thermal expansion, and thermal conductivity. The testing was conducted strictly in accordance with the performance testing methods of GB / T 2998-2015, JCT2405-2017, JCT2406-2017, GB / T7320-2018, and GB / T 22588-2008. The test results are shown in Tables 1-2.

[0104] Table 1. Performance test results of the thermal insulation composite materials obtained in Examples 1-5

[0105] Test content Example 1 Example 2 Example 3 Example 4 Example 5 Firing temperature (°C) 900 900 900 900 900 <![CDATA[Apparent density (g / cm 3 )]]> 1.34 1.41 1.45 1.46 1.51 Apparent porosity (%) 22.04 25.64 23.06 26.55 21.93 Flexural strength (MPa) 5.07 5.87 7.01 13.89 14.17 Pressure resistance (MPa) 10.93 12.00 13.57 19.63 23.88 Average coefficient of thermal expansion ( / ℃) <![CDATA[1.213×10 -6 ]]> <![CDATA[1.065×10 -6 ]]> <![CDATA[0.972×10 -6 ]]> <![CDATA[0.711×10 -6 ]]> <![CDATA[0.567×10 -6 ]]> Thermal conductivity (W / m·K) (400℃) 0.366 0.378 0.496 0.451 0.427

[0106] Table 2 shows the test results of the thermal insulation composite materials obtained in Comparative Examples 1-7.

[0107]

[0108] As can be seen from the data in Tables 1-2, the fiber-reinforced structural thermal insulation composite materials obtained in Examples 1-5 of the present invention have the characteristics of high strength and low coefficient of thermal expansion.

[0109] Compared with Example 1, without the addition of glass fiber, the flexural strength and compressive strength of the resulting thermal insulation composite material were significantly reduced, indicating that the glass fiber used in this invention can improve the strength of the thermal insulation composite material.

[0110] Compared with Example 1, Comparative Example 2 did not add fused silica glass powder. The addition of a small amount of fused silica glass powder is beneficial to the bonding between matrices and between matrices and fibers. The structural thermal insulation composite material obtained in Comparative Example 2 has lower strength and higher average coefficient of thermal expansion.

[0111] Compared with Example 1, Comparative Examples 3 and 4 each had one less additive added. The resulting thermal insulation composite material had increased apparent porosity, worse mechanical properties, and a higher average coefficient of thermal expansion compared with Example 1. The performance data show that the additive has a positive effect on the performance of the thermal insulation composite material.

[0112] Comparative Example 5 uses a semi-dry pressing method to prepare thermal insulation composite material. After changing the molding method, the strength is improved, but it is lower than that of Example 1.

[0113] Compared with Example 1, Comparative Example 6 changed the type of silicon powder used, replacing zirconium-containing silicon powder with ordinary silicon powder, resulting in a significant decrease in the strength of the resulting thermal insulation composite material.

[0114] Comparative Example 7 is a prior art method. It uses a precursor impregnation heat treatment method to prepare the thermal insulation composite material, resulting in isotropic fiber orientation in the final material. Although the thermal insulation composite material obtained in Comparative Example 7 has good mechanical and thermal insulation properties, it uses a completely different method than the present invention. This method uses quartz fiber felt prepared by impregnation, which is costly and results in a high quartz fiber content (around 30%) in the final thermal insulation composite material. The present invention, however, uses injection molding, which is simple to operate, low in cost, and uses only 5-10% glass fiber. Furthermore, the glass fiber orientation in the resulting thermal insulation composite material is anisotropic. This anisotropic fiber structure provides toughness during fracture in different directions, thereby improving the mechanical properties of the thermal insulation composite material. Data from Tables 1-2 shows that the mechanical properties of the thermal insulation composite materials obtained in Examples 4-5 are superior to those in Comparative Example 7. This indicates that the present invention, through a simple molding method and with less glass fiber, obtains thermal insulation composite materials with excellent mechanical and thermal insulation properties, and significantly reduces costs compared to the precursor impregnation heat treatment method.

[0115] 2. Scanning electron microscopy test

[0116] Scanning electron microscopy (SEM) was performed on the fiber-reinforced structural thermal insulation composite material after flexural strength testing. The results are as follows: Figure 1 As shown, Figure 1 (a) to (e) in the text correspond to Examples 1 to 5, respectively.

[0117] according to Figure 1 As can be seen in the figure, there are broken and failed fibers, unbroken fibers that are toughening the material, and grooves left by fibers that have fallen off. There are a large number of particles attached to the fiber surface, which indicates that the fibers debonded from the matrix during the pulling process. During the debonding process, friction occurred between the fibers and the matrix, which caused the material to bear a large load during the fracture process.

[0118] In summary, the fiber-reinforced thermal insulation composite material obtained by sintering the four raw materials and three additives used in this invention has the characteristics of high strength, low average coefficient of thermal expansion, and low thermal conductivity, and has low preparation cost and broad application prospects.

[0119] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A fiber-reinforced structural intumescent composite material, characterized by, The raw materials include the following mass fractions: silica sol 25-30%, zirconium-containing silicon micro powder 10-60%, fused quartz glass powder 5-50%, glass fiber 5-10%, active antifoaming agent 0.5-2%, interface modifier 0.5-2%, and fiber wetting agent 0.1-1%; the active antifoaming agent is N,N-diethylethanolamine; and the interface modifier is ethylene bis-stearamide.

2. The fiber reinforced structural thermal insulation composite material of claim 1, wherein, The mass fraction of SiO2 in the silica sol is 10-30%; the mass fraction of SiO2 in the zirconium-containing silicon micro powder is 76-96%; and the mass fraction of SiO2 in the fused quartz glass powder is 89.8-99.2%.

3. The fiber reinforced structural thermal insulation composite material of claim 1, wherein, The silica sol contains, by mass fraction, 10-30% of SiO2, 0.3% or less of Na2O, and the balance of water.

4. The fiber reinforced structural thermal insulation composite material of claim 1, wherein, The mass fraction of SiO2 in the glass fiber is 89.8-99.2%; the single-fiber diameter of the glass fiber is 7-8 μm; and the length of the glass fiber is 0.9-1 mm.

5. The fiber reinforced structural thermal insulation composite material of claim 1, wherein, The fiber wetting agent is a silane coupling agent.

6. The fiber reinforced structural thermal insulation composite material of claim 1, wherein, The fiber-reinforced structural thermal insulation composite material has a bulk density greater than or equal to 1.3 g / cm 3 , a compressive strength greater than or equal to 10 MPa, and a thermal conductivity less than or equal to 0.496 W / m·K.

7. A process for the production of the fibre-reinforced structural thermal insulation composite material according to any one of claims 1 to 6, characterized in that The method comprises the following steps: glass fiber is modified by being immersed in a fiber wetting agent to obtain modified glass fiber; the silica sol, the zirconium-containing silicon micro powder, the fused quartz glass powder, the modified glass fiber, the active antifoaming agent, and the interface modifier are mixed to obtain a mixed slurry; the mixed slurry is cast into a mold, and after defoaming, drying and sintering are sequentially performed to obtain a fiber-reinforced structural thermal insulation composite material.

8. The preparation method according to claim 7, characterized in that, The sintering temperature is 400-1000 °C, and the sintering time is 100-200 min.

9. The preparation method according to claim 7, characterized in that, The defoaming includes vacuum defoaming and vibration defoaming; one vacuum defoaming and one vibration defoaming are sequentially performed as one defoaming, and the number of defoaming is 2-3 times.

10. Use of the fiber-reinforced structural thermal insulation composite material of any one of claims 1-6 or the fiber-reinforced structural thermal insulation composite material prepared by the method of any one of claims 7-9 in a thermal equipment.

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