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

Abstract

The application relates to a preparation method of a super-high-temperature refractory material based on a carbon-based nano-composite structure. Controllable carbonized starch-based materials in raw materials are subjected to graft copolymerization reaction with a brominated silicone resin colloid to form a three-dimensional network precursor; the three-dimensional network precursor is wet-ground with the remaining other raw materials to D50<=5 mu m; the wet-ground material is molded and gradiently solidified, and is sequentially and continuously baked at 30 DEG C for 18-24 h, baked at 80 DEG C for 5-7 h, and baked at 150 DEG C for 1-3 h; finally, the material is carbonized at 600-800 DEG C for 1-2 h under the protection of a nitrogen atmosphere, and is naturally cooled. The obtained material has super-normal refractory performance, and the refractory limit reaches above 3100 DEG C; due to the gasification of the carbon-based material to form a nano-air chamber, excellent heat insulation performance is obtained. The CO2 / N2 mixed gas in the air chamber realizes heat shielding, a continuous protection layer is formed in the inorganic skeleton, a synergistic protection effect is formed, and stable heat insulation and ablation resistance performance under super-high temperature are obtained.

Description

TECHNICAL FIELD

[0001] The application belongs to the field of inorganic non-metallic materials, and particularly relates to a preparation method of an ultra-high-temperature refractory material based on a carbon-based nano-composite structure, which is particularly suitable for heat insulation and protection in an extreme thermal environment above 3000 DEG C. BACKGROUND

[0002] Although traditional refractory materials (such as alumina and silicon carbide) have certain high-temperature resistance, their temperature resistance limit is usually lower than 2500 DEG C, and they are prone to structural collapse or aggravated heat conduction at an extreme high temperature, which is difficult to meet the needs of aerospace, nuclear energy and other fields for ultra-high-temperature (≥3000 DEG C) heat insulation and protection. 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 a high temperature has not been solved.

[0003] Although the existing aerogel type heat insulation materials have low thermal conductivity, the structure collapses at a high temperature, resulting in a sharp drop in heat insulation performance; and although graphite materials are resistant to high temperature, they have poor oxidation resistance and high preparation cost.

[0004] Therefore, it is urgent to develop a new type of refractory material to realize stable heat insulation and ablation resistance at an ultra-high temperature through structural innovation. SUMMARY

[0005] The application aims to provide a preparation method of an ultra-high-temperature refractory material based on a carbon-based nano-composite structure, which realizes stable heat insulation and ablation resistance at an ultra-high temperature through structural innovation.

[0006] To achieve the above-mentioned purpose, the application provides a preparation method of an ultra-high-temperature refractory material based on a carbon-based nano-composite structure, and the raw materials include:

[0007] Carbon precursor: 15-28wt% of controllable carbonized starch-based material, wherein the controllable carbonized starch-based material is prepared by gelatinization and crosslinking of high amylose corn starch and ammonium dihydrogen phosphate esterification;

[0008] Inorganic bonding phase: 45-55wt% of an aluminosilicate-sulphoaluminate cement composite system, wherein the aluminosilicate-sulphoaluminate cement composite system includes 70-80wt% of fast-hardening sulphoaluminate cement and 20-30wt% of auxiliary cementitious material, the auxiliary cementitious material is calcined kaolin, and SiO2 / Al2O3 in the calcined kaolin is 2.1;

[0009] Nanocavity forming agent: 12-18wt% of brominated silicone resin colloid, wherein the brominated silicone resin colloid is prepared by reacting methylphenyl silicone resin and brominated propylene oxide at 80 DEG C for 4h under nitrogen protection, and the mass ratio of the methylphenyl silicone resin to the brominated propylene oxide is 4:1;

[0010] High-temperature stabilizer: 8-12 wt% of alkali metal-rare earth composite ore powder, wherein the alkali metal-rare earth composite ore powder is prepared by mixing 60 wt% of potassium feldspar powder, 12-18 wt% of yttrium oxide, and 22-28 wt% of zirconium silicate with spheroidal graphite and calcining at high temperature;

[0011] 2-5 wt% of process aids, wherein 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;

[0012] The controllable carbonized starch-based material in the raw materials is grafted and copolymerized with the brominated silicone resin colloid to form a three-dimensional network precursor; the three-dimensional network precursor and the remaining other raw materials are wet-grinded to D50≤5μm; the wet-grinded material is compression-molded and gradient-cured, and is successively baked at 30°C for 18-24 hours, 80°C for 5-7 hours, and 150°C for 1-3 hours; finally, it is carbonized at 600-800°C for 1-2 hours under nitrogen atmosphere protection and naturally cooled.

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

[0014] High-amylose corn starch was mixed with 0.1 mol / L NaOH solution at a solid-liquid volume ratio of 1:5 and stirred at 60°C for 1 h to form a gelatinized solution;

[0015] Ammonium dihydrogen phosphate was added and reacted at a pH of 5.5 and a temperature of 120° C. for 30 min to obtain a controllable carbonized starch-based material.

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

[0017] Preferably, the aluminosilicate-sulfur-aluminum cement composite system further comprises 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 methylphenyl silicone resin has a phenyl content of 40 to 50 wt% and a viscosity of 5000 cP; and the Br content of the brominated propylene oxide is 28 to 32 wt%.

[0019] Preferably, the steps of mixing spheroidal graphite and calcining at high temperature include: wet grinding in an ethanol medium for 12 hours to uniformly coat the potassium feldspar powder with yttrium oxide and zirconium silicate, and then calcining at 1150° C. for 2 hours.

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

[0021] Based on the above technical solution, the advantages of the present application are:

[0022] The super-high-temperature refractory material prepared by the method has super-normal refractory performance, and the refractory limit is above 3100 DEG C; due to the gasification of the carbon-based material to form a nano gas chamber, excellent heat insulation performance is obtained. The CO2 / N2 mixed gas in the gas chamber realizes heat shielding, a continuous protective layer is formed in the inorganic skeleton, a synergistic protection effect is formed, and stable heat insulation and ablation resistance performance under super-high temperature are obtained. DETAILED DESCRIPTION

[0023] The technical solution of the present application is described in further detail below through examples.

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

[0025] Carbon precursor: controllable carbonized starch-based material 15-28wt%, the controllable carbonized starch-based material is made of high amylose corn starch through gelatinization crosslinking and ammonium dihydrogen phosphate esterification.

[0026] Raw material specifications:

[0027] Main material: high amylose corn starch, amylose content ≥ 70%, particle size D50 = 10-15 um.

[0028] Modifier: ammonium dihydrogen phosphate, analytical pure, the addition amount is 3-5% of the mass of the starch.

[0029] Processing technology:

[0030] Crosslinking treatment: mix the starch with 0.1 mol / L NaOH solution at a solid-liquid volume ratio of 1:5, stir at 60 DEG C for 1h to form a gelatinized liquid

[0031] Phosphate esterification: add ammonium dihydrogen phosphate, react at pH = 5.5 and 120 DEG C for 30 min to generate phosphate ester starch.

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

[0033] Inorganic binder phase: 45-55wt% of aluminosilicate-sulphoaluminate cement composite system, wherein the aluminosilicate-sulphoaluminate cement composite system comprises 70-80wt% of fast-hardening sulphoaluminate cement (Al2O3 content 38±2%) and 20-30wt% of auxiliary cementitious material, which is calcined kaolin with SiO2 / Al2O3=2.1, 800℃ calcined product. Al2O3 content 38±2%) and 20-30wt% of auxiliary cementitious material, which is calcined kaolin with SiO2 / Al2O3=2.1, 800℃ calcined product.

[0034] Preferably, the aluminosilicate-sulphoaluminate cement composite system is designed with 60% of cement clinker of 10-30μm coarse particles and 40% of calcined kaolin of 1-5μm fine particles. More preferably, the aluminosilicate-sulphoaluminate cement composite system further comprises 0.5-1.2wt% of borax Na2B4O7·10H2O as retarder and 0.3-0.8wt% of Li2CO3 as early strength agent.

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

[0036] Grafting process: under nitrogen protection, the silicone resin is reacted with bromo-propylene oxide at 80℃ for 4h to generate flame-retardant silicone glue (XPS detects Br3d peak at 70.2eV) with 8-12% of Br content.

[0037] The nano-cell forming agent releases HBr gas at high temperature, which is decomposed and released at 300-500℃ to form initial cell nucleus. At the same time, the silicon-oxygen skeleton is carbonized to generate SiO2 / C composite wall, which enhances the stability of cell structure.

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

[0039] During preparation, Y2O3 and ZrSiO4 are uniformly coated on feldspar particles by wet milling in ethanol medium for 12h, and then calcined at 1150℃ for 2h to generate K-Al-Si-O-Y glass phase. At this time, Y3 + ion filling lattice defects, through DSC test, the refractoriness is improved to 1760℃. And ZrSiO4 is decomposed into ZrO2 and SiO2 at 1300℃, forming a high-temperature stable phase.

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

[0041] Raw material pretreatment stage: in the initial stage of composite ore powder preparation, the potassium feldspar powder (KAlSi3O4), yttrium oxide (Y2O3) and ZrSiO4 are weighed according to the mass ratio of 6:1.5:2.5, and are simultaneously put into an ethanol medium wet ball mill for blending. The ball milling parameters are as follows:

[0042]

[0043] High-temperature activation stage: the mixed powder after wet milling needs to be pre-fired at 1150℃. The dried powder after ball milling is loaded into a corundum crucible and placed in a box furnace to heat up to the target temperature at a rate of 5℃ / min, and then cooled with the furnace after holding for 2h. The phase change control parameters are as follows:

[0044]

[0045] When the material is exposed to an environment above 1300℃, ZrSiO4 begins to decompose: ZrSiO4→ZrO2(monoclinic phase)+SiO2(cristobalite phase); the new phase reacts with Y2O3: Y2O3+SiO2→Y-Si-O glass phase; ZrO2 phase transition toughening: t-ZrO2(tetragonal phase)→m-ZrO2(monoclinic phase), absorbing crack propagation energy. From the above principles, ZrSiO4 has an important influence on material performance, as follows:

[0046]

[0047] In the material of the application, nano ZrSiO4 particles are pinned at the potassium feldspar grain boundaries, inhibiting abnormal grain growth at high temperatures, t-ZrO2 phase transition absorbs thermal stress, enhancing material fracture toughness, and Y-Si-O glass phase flows to fill microcracks above 1500℃. The component and process design realize the synergistic improvement of structural stability and functional responsiveness of refractory materials at extreme temperatures.

[0048] Process aids 2-5wt%, the process aids include 0.3-0.8wt% dispersant, 0.05-0.15wt% foaming agent, 1.2-2.0wt% mineralizer, 0.5-1.5wt% antioxidant. Further, the dispersant is polycarboxylate (PCE type), slurry viscosity <200cP; the foaming agent is sodium dodecyl sulfate (SDS), used to regulate the size distribution of the air chamber; the mineralizer is CaF2 nano powder, used to promote the generation of mullite phase; the antioxidant is 200 mesh metal silicon powder, used to inhibit the high temperature oxidation of carbon precursor.

[0049] In preparation, first obtain raw materials; then the controllable carbonized starch-based material in the raw materials is subjected to graft copolymerization reaction with silicon resin colloidal bromide to form a three-dimensional network precursor; the three-dimensional network precursor is wet ground with the remaining other raw materials to D50≤5μm; the wet ground material is molded and gradient solidified, sequentially and continuously baked at 30℃ for 18-24h, 80℃ for 5-7h, and 150℃ for 1-3h; finally, carbonized at 600-800℃ for 1-2h under the protection of nitrogen atmosphere, and naturally cooled.

[0050] Further, the mechanism of the graft copolymerization reaction of the present application to generate a three-dimensional network precursor is as follows:

[0051] (1) The Si-OH of silicon resin undergoes ring-opening grafting reaction with bromine propylene oxide to form Si-O-C bond and introduce bromine atom, and the specific process parameters are as follows:

[0052] Catalyst: tetrabutylammonium bromide (TBAB), addition amount 1.2wt%;

[0053] Reaction temperature: 80±2℃;

[0054] Reaction time: 4 hours (under nitrogen protection);

[0055] Material ratio: silicon resin: bromine propylene oxide = 4:1 (w / w).

[0056] (2) The phosphate ester group (-OPO3 2- ) of starch undergoes condensation reaction with the hydroxyl group (-OH) of silica gel, and the nucleophilic ring-opening reaction of the epoxy group of silica gel with the hydroxyl group of starch to form a three-dimensional network, and the specific process parameters are as follows:

[0057] Solvent: DMSO (dimethyl sulfoxide), dissolves starch and promotes phase solubility;

[0058] Reaction temperature: 75℃, balanced reaction rate and side reaction inhibition;

[0059] Reaction time: 6h, grafting rate up to 65-75%;

[0060] pH control: 8.5, using sodium carbonate buffer system to promote condensation reaction.

[0061] (3) Post-treatment process

[0062] Reaction termination: quenching by adding 0.5% glacial acetic acid;

[0063] Purification: ethanol precipitation to remove unreacted monomers, ethanol: reaction liquid = 3:1;

[0064] Dialysis treatment (molecular weight cut-off 8000 Da) to remove small molecular impurities;

[0065] Drying: freeze-drying (-50℃, 10Pa) to maintain porous structure;

[0066] The final product is a white porous solid with a pore size of 50-200 nm.

[0067] The graft copolymerization of the present application generates a three-dimensional network precursor. By precisely controlling the grafting site and crosslinking density, efficient synergy between the carbon precursor and the inorganic phase is achieved, forming a "starch-silica gel hybrid network". This network is directionally decomposed at high temperatures to form a gradient pore structure, i.e., an outer layer of nano-chambers and an inner layer of micropores, achieving excellent fire resistance and thermal insulation performance.

[0068] The super-high-temperature refractory material prepared by the method of the present application has super-normal fire resistance, with a fire resistance limit of above 3100℃. Due to the gasification of the carbon-based material to form nano-chambers, excellent thermal insulation performance is achieved. The CO2 / N2 mixed gas in the chambers achieves thermal shielding, and a continuous protective layer is formed in the inorganic framework, forming a synergistic protection effect, achieving stable thermal insulation and ablation resistance at super-high temperatures.

[0069] Example 1

[0070] Raw material composition (wt%):

[0071]

[0072] Preparation process:

[0073] Graft copolymerization: starch-based material and halogenated silica gel are reacted in DMSO at 75℃ for 6h, and dialysis drying is performed;

[0074] Wet co-milling: all raw materials are ball milled with deionized water (water to glue ratio 0.3) to D50 = 4.2μm;

[0075] Gradient curing: 30℃×20h→80℃×6h→150℃×2h;

[0076] Carbonization treatment: heating to 750℃ at 5℃ / min under N2 protection for 1.5h;

[0077] Performance index:

[0078] Fire resistance limit: 3260℃ (oxyacetylene flame test);

[0079] Thermal conductivity at 800℃: 0.029 W / (m·K);

[0080] Thermal shock resistance (water cooling): 89% strength retention after 48 cycles; Bulk density: 0.71 g / cm 3 .

[0081] Example 2

[0082] Raw material composition (wt%):

[0083]

[0084] Preparation process:

[0085] Graft copolymerization: starch-based material and halogenated silica gel were reacted in DMSO at 75℃ for 6h, dialysis and drying;

[0086] Wet co-milling: all raw materials were ball milled with deionized water (water-binder ratio 0.3) to D50=4.2μm;

[0087] Gradient curing: 30℃×20h→80℃×6h→150℃×2h;

[0088] Carbonization treatment: under N2 protection, temperature was raised to 750℃ at 5℃ / min and kept for 1.5h;

[0089] Performance index:

[0090] Fire resistance limit: 3180℃ (oxyacetylene flame test);

[0091] Thermal conductivity at 800℃: 0.035 W / (m·K).

[0092] Example 3

[0093] Raw material composition (wt%):

[0094]

[0095] Preparation process:

[0096] Graft copolymerization: starch-based material and halogenated silica gel were reacted in DMSO at 75℃ for 6h, dialysis and drying;

[0097] Wet co-milling: all raw materials were ball milled with deionized water (water-binder ratio 0.3) to D50=4.2μm;

[0098]

[0099] ​Gradient curing: 30℃ x 20h→80℃ x 6h→150℃ x 2h;

[0100] Carbonization treatment: under N2 protection, temperature raised to 750℃ at 5℃ / min, and kept for 1.5h;

[0101] Performance index:

[0102] Fire resistance limit: 3320℃ (oxygen-ethyne flame test);

[0103] 800℃ thermal conductivity: 0.023 W / (m·K).

[0104] Finally, it should be noted that: the above examples are used to illustrate the technical solutions of the present application rather than limit them; although the present application has been described in detail with reference to the preferred embodiments, those skilled in the art should understand that: the specific embodiments of the present application can still be modified or some technical features can be replaced by equivalents; without departing from the spirit of the technical solutions of the present application, they should be covered in the technical solution range of the present application claimed.

Claims

1. A method for preparing an ultra-high temperature refractory material based on a carbon-based nanocomposite structure, characterized by: Raw materials include: Carbon precursor: 15-28 wt% of a controllable carbonized starch-based material, wherein the controllable carbonized starch-based material is made from high-amylose corn starch through gelatinization, cross-linking, and esterification with diammonium dihydrogen phosphate; Inorganic binder phase: 45-55 wt% of an aluminosilicate-sulfoaluminum cement composite system, wherein the aluminosilicate-sulfoaluminum cement composite system comprises 70-80 wt% of a fast-hardening sulfoaluminate cement and 20-30 wt% of an auxiliary cementitious material, wherein the auxiliary cementitious material is calcined kaolin, and the SiO2 / Al2O3 ratio of the calcined kaolin is 2.1; Nano-gas cell forming agent: 12-18 wt% brominated silicone resin colloid, wherein the brominated silicone resin colloid is prepared by reacting methylphenyl silicone resin and bromopropylene oxide in a mass ratio of 4:1 at 80°C for 4 hours under nitrogen protection; High-temperature stabilizer: 8-12 wt% of alkali metal-rare earth composite ore powder, which is made by ball-milling and high-temperature calcination of potassium feldspar powder (60 wt% of the total alkali metal-rare earth composite ore powder), 12-18 wt% of yttrium oxide, and 22-28 wt% of zirconium silicate; 2-5 wt% of process aids, wherein 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; The controllable carbonized starch-based material in the raw materials is grafted and copolymerized with the brominated silicone resin colloid to form a three-dimensional network precursor; the three-dimensional network precursor and the remaining other raw materials are wet-grinded to D50≤5μm; the wet-grinded material is compression-molded and gradient-cured, and is successively baked at 30°C for 18-24 hours, 80°C for 5-7 hours, and 150°C for 1-3 hours; finally, it is carbonized at 600-800°C for 1-2 hours under nitrogen atmosphere protection and naturally cooled.

2. The method for preparing ultrahigh temperature refractory material according to claim 1, characterized in that: The steps of gelatinization, cross-linking and diammonium phosphate esterification include: High-amylose corn starch was mixed with 0.1 mol / L NaOH solution at a solid-liquid volume ratio of 1:5 and stirred at 60°C for 1 h to form a gelatinized solution; Ammonium dihydrogen phosphate was added and reacted at a pH of 5.5 and a temperature of 120° C. for 30 min to obtain a controllable carbonized starch-based material.

3. The method for preparing ultrahigh temperature refractory material according to claim 1, characterized in that: The gradation design of the aluminosilicate-sulfoaluminum cement composite system is as follows: the volume of cement clinker with coarse particles of 10 to 30 μm accounts for 60%, and the volume of calcined kaolin with fine particles of 1 to 5 μm accounts for 40%.

4. The method for preparing ultrahigh temperature refractory material according to claim 3, characterized in that: The aluminosilicate-sulfur-aluminum cement composite system further 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 ultrahigh temperature refractory material according to claim 1, characterized in that: The methylphenyl silicone resin has a phenyl content of 40 to 50 wt% and a viscosity of 5000 cP; the brominated propylene oxide has a Br content of 28 to 32 wt%.

6. The method for preparing ultrahigh temperature refractory material according to claim 1, characterized in that: The ball milling and high-temperature calcination steps include: wet milling in an ethanol medium for 12 hours to uniformly coat the potassium feldspar powder with yttrium oxide and zirconium silicate, and then calcining at 1150° C. for 2 hours.

7. The method for preparing ultrahigh temperature refractory material according to claim 1, characterized in that: The dispersant is polycarboxylate, and the slurry viscosity is less than 200 cP; the foaming agent is sodium lauryl sulfate; the mineralizer is CaF2 nanopowder; and the antioxidant is 200 mesh metallic silicon powder.

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