Preparation method of ultrahigh-temperature refractory material based on carbon-based nano-composite structure

Abstract

The invention relates to a preparation method of an ultrahigh-temperature refractory material based on a carbon-based nano composite structure, which comprises the following steps: carrying out graft copolymerization reaction on a controllable carbonized starch-based material and brominated silicon resin colloid in raw materials to form a three-dimensional network precursor; co-grinding the three-dimensional network precursor and other remaining raw materials by a wet method until D50 is less than or equal to 5 microns; carrying out compression molding on the materials subjected to wet co-grinding, then carrying out gradient curing, and sequentially and continuously drying at 30 DEG C for 18-24 hours, 80 DEG C for 5-7 hours and 150 DEG C for 1-3 hours; and finally, carbonizing for 1-2 hours at 600-800 DEG C under the protection of a nitrogen atmosphere, and naturally cooling. The obtained material has supernormal fire resistance, and the fire endurance reaches 3100 DEG C or above; the carbon-based material is gasified to form a nano gas chamber, so that excellent heat insulation performance is obtained. CO2 / N2 mixed gas in the gas chamber realizes heat shielding, a continuous protection layer is formed in an inorganic framework, a synergistic protection effect is formed, and stable heat insulation and ablation resistance at ultrahigh temperature are obtained.

Description

Technical Field

[0001] The present invention belongs to the field of inorganic non-metallic materials, and particularly relates to a preparation method of ultra-high temperature refractory materials based on a carbon-based nano composite structure, which is particularly suitable for heat insulation and protection in extreme thermal environments above 3000°C. Background Art

[0002] Although traditional refractory materials (such as alumina, silicon carbide, etc.) have certain high-temperature resistance, their temperature resistance limit is usually lower than 2500°C, and they are prone to structural collapse or increased heat conduction at extremely high temperatures, making it difficult to meet the requirements of heat insulation and protection for ultra-high temperatures (≥3000°C) in fields such as aerospace and nuclear energy. In the prior art, although some carbon-based composite materials can improve the temperature resistance, they have problems such as low porosity and insufficient heat insulation efficiency, and the defect of rapid oxidation failure of the carbon component at high temperatures has not been solved.

[0003] Although existing aerogel-based thermal insulation materials have low thermal conductivity, their thermal insulation performance drops sharply due to structural collapse at high temperatures; while graphite-based materials have high temperature resistance, they have poor oxidation resistance and high preparation costs.

[0004] Therefore, there is an urgent need to develop a new type of refractory material to achieve stable heat insulation and ablation resistance at ultra-high temperatures through structural innovation. Summary of the Invention

[0005] The object of the present invention is to propose a preparation method of ultra-high temperature refractory materials based on a carbon-based nano composite structure, which realizes stable heat insulation and ablation resistance at ultra-high temperatures through structural innovation.

[0006] To achieve the above object, the present invention provides a preparation method of ultra-high temperature refractory materials based on a carbon-based nano composite structure, and the raw materials include:

[0007] Carbon precursor: 15-28 wt% of a controllable carbonized starch-based material, and the controllable carbonized starch-based material is made from high amylose corn starch through gelatinization cross-linking and ammonium dihydrogen phosphate esterification;

[0008] Inorganic binder phase: 45-55 wt% of an aluminosilicate-sulfoaluminate cement composite system, wherein the aluminosilicate-sulfoaluminate cement composite system includes 70-80 wt% of rapid hardening sulfoaluminate cement accounting for the total inorganic phase of the aluminosilicate-sulfoaluminate cement composite system and 20-30 wt% of an auxiliary cementitious material, and the auxiliary cementitious material is calcined kaolin, and SiO2 / Al2O3 = 2.1 in the calcined kaolin;

[0009] Nano air chamber forming agent: 12-18 wt% of a silicon bromide resin colloid, and the silicon bromide resin colloid is a methylphenyl silicone resin and brominated propylene oxide with a mass ratio of 4:1, and the methylphenyl silicone resin and brominated propylene oxide are reacted at 80°C for 4 h under nitrogen protection;

[0010] High-temperature stabilizer: 8-12 wt% of alkali metal-rare earth composite ore powder, and the alkali metal-rare earth composite ore powder is made by ball-milling and high-temperature calcination of potassium feldspar powder accounting for 60 wt% of the total amount of the alkali metal-rare earth composite ore powder, 12-18 wt% of yttrium oxide, and 22-28 wt% of zirconium silicate;

[0011] Processing aids: 2-5 wt%, and the processing aids include 0.3-0.8 wt% of dispersant, 0.05-0.15 wt% of foaming agent, 1.2-2.0 wt% of mineralizer, and 0.5-1.5 wt% of antioxidant;

[0012] Graft copolymerization reaction is carried out between the controllable carbonized starch-based material and the silicon bromide resin colloid in the raw materials to form a three-dimensional network precursor; the three-dimensional network precursor and the remaining other raw materials are wet-ground together until D50≤5 μm; the wet-ground material is molded by compression and then gradient-cured, successively baked at 30°C for 18-24 h, 80°C for 5-7 h, and 150°C for 1-3 h; finally, carbonized at 600-800°C for 1-2 h under the protection of nitrogen atmosphere and then cooled naturally.

[0013] Preferably, the steps of gelatinization cross-linking and ammonium dihydrogen phosphate esterification include:

[0014] Mix high-amylose corn starch and 0.1 mol / L NaOH solution according to a solid-liquid volume ratio of 1:5, and stir at 60°C for 1 h to form a gelatinized liquid;

[0015] Add ammonium dihydrogen phosphate, and react at pH 5.5 and a temperature of 120°C for 30 min to obtain a controllable carbonized starch-based material.

[0016] Preferably, the grading design in the aluminosilicate-sulfoaluminate cement composite system is: the volume ratio of cement clinker with coarse particles of 10-30 μm accounts for 60%, and the volume ratio of calcined kaolin with fine particles of 1-5 μm accounts for 40%.

[0017] Preferably, the aluminosilicate-sulfoaluminate cement composite system also includes 0.5-1.2 wt% of borax as a retarder and 0.3-0.8 wt% of Li2CO3 as an early strength agent.

[0018] Preferably, the phenyl content in the methylphenyl silicone resin is 40-50 wt% and the viscosity is 5000 cP; the Br content in the brominated propylene oxide is 28-32 wt%.

[0019] Preferably, the steps of nodular mixing and high-temperature calcination include: wet-milling in an ethanol medium for 12 h to uniformly coat yttrium oxide and zirconium silicate on potassium feldspar powder, and then calcining at 1150°C for 2 h.

[0020] The dispersant is polycarboxylate, and the viscosity of the slurry is < 200 cP; the foaming agent is sodium dodecyl sulfate; the mineralizer is CaF2 nanopowder; the antioxidant is 200-mesh metallic silicon powder.

[0021] Based on the above technical solutions, the advantages of the present invention are as follows:

[0022] The material obtained by the preparation method of the ultra-high temperature refractory material of the present invention has extraordinary refractory properties, and the fire resistance limit reaches above 3100 °C; due to the gasification of the carbon-based material to form nano gas chambers, excellent heat insulation performance is obtained. The CO2 / N2 mixed gas in the gas chamber realizes thermal shielding, and a continuous protective layer is formed in the inorganic framework, forming a synergistic protection effect, and obtaining stable heat insulation and ablation resistance performance at ultra-high temperatures. Detailed implementation manners

[0023] Next, through examples, the technical solutions of the present invention will be further described in detail.

[0024] The present invention provides a preparation method of an ultra-high temperature refractory material based on a carbon-based nano composite structure, and the raw materials include:

[0025] Carbon precursor: 15-28 wt% of a controllable carbonized starch-based material, and the controllable carbonized starch-based material is prepared by gelatinization cross-linking and ammonium dihydrogen phosphate esterification of high amylose corn starch.

[0026] Raw material specifications:

[0027] Main material: High amylose corn starch, with a straight-chain content ≥ 70%, and a particle size D50 = 10-15 μm.

[0028] Modifier: Ammonium dihydrogen phosphate, analytical pure, and the addition amount accounts for 3-5% of the starch mass.

[0029] Treatment process:

[0030] Cross-linking treatment: Mix starch with 0.1 mol / L NaOH solution according to a solid-liquid volume ratio of 1:5, and stir at 60 °C for 1 h to form a gelatinized solution

[0031] Phosphoric acid esterification: Add ammonium dihydrogen phosphate, and react at pH = 5.5 and 120 °C for 30 min to generate phosphate ester starch.

[0032] After modification, the carbon residue rate is increased from 25% to 48%, and the phosphate group promotes the formation of 3-5 nm micropores during carbonization, so that the BET specific surface area can reach 620 m 2 / g or more.

[0033] Inorganic bonding phase: 45 - 55 wt% of aluminosilicate - sulfoaluminate cement composite system, where the aluminosilicate - sulfoaluminate cement composite system includes 70 - 80 wt% of rapid - hardening sulfoaluminate cement ( with Al2O3 content of 38 ± 2%) and 20 - 30 wt% of auxiliary cementitious material. The auxiliary cementitious material is calcined kaolin, and in the calcined kaolin, SiO2 / Al2O3 = 2.1, which is the product calcined at 800℃.

[0034] Preferably, the grading design in the aluminosilicate - sulfoaluminate cement composite system is: the volume ratio of coarse cement clinker with a particle size of 10 - 30 μm accounts for 60%, and the volume ratio of fine calcined kaolin with a particle size of 1 - 5 μm accounts for 40%. More preferably, the aluminosilicate - sulfoaluminate cement composite system also includes 0.5 - 1.2 wt% of borax Na2B4O7·10H2O as a setting retarder and 0.3 - 0.8 wt% of Li2CO3 as an early - strength agent.

[0035] Nano - gas - chamber forming agent: 12 - 18 wt% of silicon bromide resin colloid. The silicon bromide resin colloid is a methylphenyl silicone resin and brominated propylene oxide with a mass ratio of 4:1, which is prepared by reacting methylphenyl silicone resin and brominated propylene oxide at 80℃ for 4 h under nitrogen protection. Preferably, the phenyl content in the methylphenyl silicone resin is 40 - 50 wt% and the viscosity is 5000 cP; the Br content in the brominated propylene oxide is 28 - 32 wt%.

[0036] Grafting process: Under nitrogen protection, silicon resin and brominated propylene oxide are reacted at 80℃ for 4 h to generate a flame - retardant silica gel with a bromine content of 8 - 12% (the Br3d peak detected by XPS is located at 70.2 eV).

[0037] The nano - gas - chamber forming agent releases HBr gas at high temperature, decomposes and releases it at 300 - 500℃ to form an initial gas - chamber nucleus. At the same time, the silicon - oxygen skeleton carbonizes to generate a SiO2 / C composite wall, enhancing the structural stability of the gas chamber.

[0038] High - temperature stabilizer: 8 - 12 wt% of alkali metal - rare earth composite ore powder. The alkali metal - rare earth composite ore powder is composed of 60 wt% of potassium feldspar powder (KAlSi3O8, particle size D90 ≤ 5 μm), 12 - 18 wt% of yttrium oxide (Y2O3, purity 99.9%, 50 nm), and 22 - 28 wt% of zirconium silicate (ZrSiO4, ultrafine powder), which is prepared by ball - milling and high - temperature calcination.

[0039] During preparation, it is wet - milled in an ethanol medium for 12 h to uniformly coat the feldspar particles with Y2O3 and ZrSiO4, and then calcined at 1150℃ for 2 h to generate a K - Al - Si - O - Y glass phase. At this time, Y3 The +ions fill the lattice defects, and through DSC testing, the refractoriness is increased to 1760 °C. ZrSiO4 decomposes into ZrO2 and SiO2 at 1300 °C, forming a high-temperature stable phase.

[0040] Specifically, the preparation of the high-temperature stabilizer includes:

[0041] Raw material pretreatment stage: Mixing is carried out at the initial stage of preparing the composite ore powder. Weigh potassium feldspar powder (KAlSi3O4), yttrium oxide (Y2O3), and ZrSiO4 according to a mass ratio of 6:1.5:2.5, and put the three into a wet ball mill in an ethanol medium for co-blending. The ball milling parameters are as follows:

[0042]

[0043] High-temperature activation stage: The wet-milled mixed powder needs to be pre-sintered at 1150 °C. Load the dried powder after ball milling into a corundum crucible, place it in a box furnace, heat it to the target temperature at a rate of 5 °C / min, keep it warm for 2 h, and then cool it with the furnace. The phase change control parameters are as follows:

[0044]

[0045] When the material is exposed to an environment above 1300 °C, ZrSiO4 begins to decompose: ZrSiO4 → ZrO2 (monoclinic phase) + SiO2 (cristobalite phase); the newly formed phase reacts with Y2O3: Y2O3 + SiO2 → Y-Si-O glass phase; the phase transformation toughening of ZrO2: t-ZrO2 (tetragonal phase) → m-ZrO2 (monoclinic phase), absorbing the energy of crack propagation. From the above principles, it can be seen that ZrSiO4 has an important influence on the material properties, specifically as follows:

[0046]

[0047]

[0048] In the material of the present invention, the nano-ZrSiO4 particles are pinned at the potassium feldspar grain boundaries, inhibiting the abnormal growth of grains at high temperatures. The phase transformation of t-ZrO2 absorbs thermal stress, enhancing the fracture toughness of the material. The Y-Si-O glass phase flows and fills the microcracks above 1500 °C. This component and process design achieve the synergistic improvement of the structural stability and functional responsiveness of the refractory material at extreme temperatures.

[0049] Processing aids: 2 - 5 wt%, and the processing aids include 0.3 - 0.8 wt% of dispersant, 0.05 - 0.15 wt% of foaming agent, 1.2 - 2.0 wt% of mineralizer, and 0.5 - 1.5 wt% of antioxidant. Further, the dispersant is polycarboxylate (PCE type), and the slurry viscosity < 200 cP; the foaming agent is sodium dodecyl sulfate (SDS), which is used to regulate the gas chamber size distribution; the mineralizer is CaF2 nanopowder, which is used to promote the formation of mullite phase; the antioxidant is 200 - mesh silicon powder, which is used to inhibit the high - temperature oxidation of carbon precursor.

[0050] During the preparation, first obtain the raw materials; then carry out graft copolymerization reaction on the controllable carbonized starch - based material and brominated silicone resin colloid in the raw materials to form a three - dimensional network precursor; wet - grind the three - dimensional network precursor and the remaining other raw materials together to D50 ≤ 5 μm; after the wet - grinding, mold and press the material and then cure it gradiently, successively drying it continuously at 30 °C for 18 - 24 h, at 80 °C for 5 - 7 h, and at 150 °C for 1 - 3 h; finally, carbonize it at 600 - 800 °C for 1 - 2 h under the protection of nitrogen atmosphere and then cool it naturally.

[0051] Further, the mechanism of the graft copolymerization reaction to generate a three - dimensional network precursor in the present invention is as follows:

[0052] (1) The Si - OH of the silicone resin undergoes a ring - opening graft reaction with bromopropylene oxide to form Si - O - C bonds and introduce bromine atoms. The specific process parameters are as follows:

[0053] Catalyst: tetrabutylammonium bromide (TBAB), addition amount 1.2 wt%;

[0054] Reaction temperature: 80 ± 2 °C;

[0055] Reaction time: 4 hours (under nitrogen protection);

[0056] Material ratio: silicone resin: bromopropylene oxide = 4:1 (w / w).

[0057] (2) The phosphate group (-OPO3 2- ) of starch undergoes a condensation reaction with the hydroxyl group (-OH) of silica gel, and at the same time, the epoxy group of silica gel undergoes a nucleophilic ring - opening reaction with the starch hydroxyl group to form a three - dimensional network. The specific process parameters are as follows:

[0058] Solvent: DMSO (dimethyl sulfoxide), which dissolves starch and promotes compatibility;

[0059] Reaction temperature: 75 °C, balancing the reaction rate and suppressing side reactions;

[0060] Reaction time: 6 h, and the grafting rate can reach 65 - 75%;

[0061] pH control: 8.5, using a sodium carbonate buffer system to promote the condensation reaction.

[0062] (3) Post-treatment process

[0063] Terminate the reaction: Quench with 0.5% glacial acetic acid;

[0064] Purification: Remove unreacted monomers by ethanol precipitation, ethanol:reaction solution = 3:1;

[0065] Dialysis treatment (cut-off molecular weight 8000 Da) to remove small molecule impurities;

[0066] Drying: Freeze-dry (-50°C, 10 Pa) to maintain the porous structure;

[0067] The final product is a white porous solid with pore sizes of 50 - 200 nm.

[0068] The graft copolymerization reaction of the present invention generates a three-dimensional network precursor. By precisely controlling the grafting sites and crosslinking density, efficient synergy between the carbon precursor and the inorganic phase is achieved, forming a "starch-silica hybrid network" that decomposes directionally at high temperatures to form a gradient pore structure, namely an outer layer of nano gas chambers / inner layer of micropores, obtaining excellent fire resistance and heat insulation properties.

[0069] The material obtained by the method for preparing an ultra-high temperature refractory material of the present invention has extraordinary fire resistance, with a fire resistance limit of over 3100°C; due to the gasification of the carbon-based material to form nano gas chambers, excellent heat insulation properties are obtained. The CO2 / N2 mixed gas in the gas chambers achieves thermal shielding, and a continuous protective layer is formed in the inorganic framework, forming a synergistic protection effect, obtaining stable heat insulation and ablation resistance properties at ultra-high temperatures.

[0070] Example 1

[0071] Raw material composition (wt%):

[0072]

[0073]

[0074] Preparation process:

[0075] Graft copolymerization: The starch-based material and halogenated silica gel react in DMSO at 75°C for 6 h, followed by dialysis and drying;

[0076] Wet grinding: All raw materials are ball-milled with deionized water (water-binder ratio 0.3) to D50 = 4.2 μm;

[0077] Gradient curing: 30°C × 20 h → 80°C × 6 h → 150°C × 2 h;

[0078] Carbonization treatment: Heat up to 750 °C at a rate of 5 °C / min under N2 protection and hold for 1.5 h;

[0079] Performance indicators:

[0080] Fire resistance limit: 3260 °C (tested by oxyacetylene flame);

[0081] Thermal conductivity at 800 °C: 0.029 W / (m·K);

[0082] Thermal shock resistance ( water cooling): Strength retention rate is 89% after 48 cycles;

[0083] Bulk density: 0.71 g / cm 3 .

[0084] Example 2

[0085] Raw material composition (wt%):

[0086]

[0087]

[0088] Preparation process:

[0089] Graft copolymerization: React the starch-based material with halogenated silica gel in DMSO at 75 °C for 6 h, then dialyze and dry;

[0090] Wet grinding together: Grind all raw materials with deionized water (water-to-binder ratio 0.3) in a ball mill until D50 = 4.2 μm;

[0091] Gradient curing: 30 °C × 20 h → 80 °C × 6 h → 150 °C × 2 h;

[0092] Carbonization treatment: Heat up to 750 °C at a rate of 5 °C / min under N2 protection and hold for 1.5 h;

[0093] Performance indicators:

[0094] Fire resistance limit: 3180 °C (tested by oxyacetylene flame);

[0095] Thermal conductivity at 800 °C: 0.035 W / (m·K).

[0096] Example 3

[0097] Raw material composition (wt%):

[0098]

[0099]

[0100] Preparation process:

[0101] Graft copolymerization: The starch-based material and the halogenated silica gel react in DMSO at 75°C for 6 hours, followed by dialysis and drying;

[0102] Wet grinding: All raw materials are added with deionized water (water-to-resin ratio of 0.3) and ball-milled to D50 = 4.2 μm;

[0103] Gradient curing: 30°C × 20 h → 80°C × 6 h → 150°C × 2 h;

[0104] Carbonization treatment: Under N2 protection, the temperature is raised to 750°C at a rate of 5°C / min and held for 1.5 h;

[0105] Performance indicators:

[0106] Fire resistance limit: 3320°C (oxyacetylene flame test);

[0107] Thermal conductivity at 800°C: 0.023 W / (m·K).

[0108] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them; although the present invention has been described in detail with reference to the preferred embodiments, those of ordinary skill in the art should understand that it is still possible to modify the specific implementation manners of the present invention or perform equivalent replacements for some technical features; without departing from the spirit of the technical solutions of the present invention, they should all be covered within the scope of the technical solutions claimed by the present invention.

Claims

1. A method for preparing a ultra-high temperature refractory based on a carbon-based nanocomposite structure, characterized in that: The raw materials include: Carbon precursor: 15 - 28 wt% of a controllable carbonized starch-based material, which is made from high amylose corn starch through gelatinization cross-linking and ammonium dihydrogen phosphate esterification; Inorganic binder phase: 45 - 55 wt% of an aluminosilicate-sulfoaluminate cement composite system, where the aluminosilicate-sulfoaluminate cement composite system includes 70 - 80 wt% of rapid hardening sulfoaluminate cement accounting for the total inorganic phase of the aluminosilicate-sulfoaluminate cement composite system and 20 - 30 wt% of an auxiliary cementitious material, and the auxiliary cementitious material is calcined kaolin with SiO2 / Al2O3 = 2.1 in the calcined kaolin; Nano gas chamber former: 12 - 18 wt% of a silicon bromide resin colloid, which is a methylphenyl silicone resin and brominated propylene oxide with a mass ratio of 4:1, and is prepared by reacting methylphenyl silicone resin and brominated propylene oxide at 80 °C for 4 h under nitrogen protection; High-temperature stabilizer: 8 - 12 wt% of an alkali metal-rare earth composite ore powder, which is made from 60 wt% of potassium feldspar powder, 12 - 18 wt% of yttrium oxide, and 22 - 28 wt% of zirconium silicate in the alkali metal-rare earth composite ore powder through nodular mixing and high-temperature calcination; Process aids 2 - 5 wt%, and the process aids include 0.3 - 0.8 wt% of a dispersant, 0.05 - 0.15 wt% of a foaming agent, 1.2 - 2.0 wt% of a mineralizer, and 0.5 - 1.5 wt% of an antioxidant; Perform a graft copolymerization reaction on the controllable carbonized starch-based material and the silicon bromide resin colloid in the raw materials to form a three-dimensional network precursor; wet-grind the three-dimensional network precursor and the remaining other raw materials together until D50 ≤ 5 μm; after molding the wet-ground material by molding, cure it gradiently, successively bake at 30 °C for 18 - 24 h, 80 °C for 5 - 7 h, and 150 °C for 1 - 3 h; finally, carbonize at 600 - 800 °C for 1 - 2 h under nitrogen atmosphere protection and cool naturally.

2. The method for preparing the ultra-high temperature refractory material according to claim 1, characterized in that: The steps of gelatinization cross-linking and ammonium dihydrogen phosphate esterification include: Mix high amylose corn starch with 0.1 mol / L NaOH solution at a solid-liquid volume ratio of 1:5, and stir at 60 °C for 1 h to form a gelatinized solution; Add ammonium dihydrogen phosphate, and react at pH 5.5 and a temperature of 120 °C for 30 min to obtain the controllable carbonized starch-based material.

3. The method for preparing the ultra-high temperature refractory material according to claim 1, wherein: The grading design in the aluminosilicate-sulfoaluminate cement composite system is: the volume ratio of cement clinker with 10 - 30 μm coarse particles accounts for 60%, and the volume ratio of calcined kaolin with 1 - 5 μm fine particles accounts for 40%.

4. The method for preparing the ultra-high temperature refractory material according to claim 3, characterized in that: The aluminosilicate-sulfoaluminate cement composite system also includes 0.5 - 1.2 wt% of borax as a retarder and 0.3 - 0.8 wt% of Li2CO3 as an early strength agent.

5. The method for preparing the ultra-high temperature refractory material according to claim 1, wherein: The phenyl content in the methylphenyl silicone resin is 40 - 50 wt%, and the viscosity is 5000 cP; the Br content in the brominated propylene oxide is 28 - 32 wt%.

6. The method for preparing the ultra-high temperature refractory material according to claim 1, characterized in that: The steps of nodular mixing and high-temperature calcination include: wet-grind in an ethanol medium for 12 h to uniformly coat yttrium oxide and zirconium silicate on potassium feldspar powder, and then calcine at 1150 °C for 2 h.

7. The method for preparing the ultra-high temperature refractory material according to claim 1, wherein: The dispersant is polycarboxylate, and the viscosity of the slurry is <200 cP; the foaming agent is sodium dodecyl sulfate; the mineralizer is CaF2 nanoflour; the antioxidant is 200-mesh metallic silicon powder.

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