High-temperature-resistant and erosion-resistant composite material for plasma gasification furnace and preparation method thereof

Abstract

The invention discloses a high-temperature-resistant and erosion-resistant composite material for a plasma gasifier and a preparation method thereof, belongs to the technical field of high-temperature-resistant composite materials, and aims to solve the technical problem that the high-temperature-resistant and erosion-resistant performance of a ramming composite material for the plasma gasifier in the prior art needs to be further improved. The silicon nitride reinforced silicon carbide composite material comprises the following components in parts by weight: 50-70 parts of aggregate, 25-45 parts of powder and 5-8 parts of a binding agent, the component of the aggregate is a silicon binding material, and the aggregate is composed of coarse aggregate, medium aggregate and fine aggregate according to the weight ratio of (30-40): (40-50): (30-50). The particle size distribution of the aggregate and the composition of the powder and the binding agent are optimized, so that the high-temperature erosion resistance and the volume density of the composite material are effectively improved, and the heat-conducting property of the composite material is also reduced.

Description

Technical Field

[0001] The invention relates to the technical field of high temperature resistant composite materials, and in particular to a high temperature resistant and corrosion resistant composite material for a plasma gasification furnace and a preparation method thereof. Background Art

[0002] As a new type of hazardous waste treatment technology, plasma gasification furnace has been greatly developed and applied in recent years, especially in the treatment of hazardous wastes generated by garbage incineration and waste oil sludge. Under the high temperature treatment of the plasma furnace, organic hazardous waste is rapidly dehydrated, pyrolyzed, cracked and burned, and inorganic matter is melted into tailings under the action of high temperature. After treatment, high-risk waste is finally transformed into harmless.

[0003] However, due to the high temperature of plasma, the corrosiveness of materials and the erosion of slag, it is difficult to guarantee the life of the refractory materials of plasma furnaces. At present, in addition to refractory bricks, a layer of amorphous refractory materials is generally laid at the bottom of the pool of plasma gasification furnaces to extend the service life of the furnace. These amorphous materials are mainly silicon carbide ramming materials.

[0004] In the prior art, a Chinese invention patent with publication number CN106747460A discloses a silicon carbide ramming material for a gasifier, comprising a main material, an auxiliary material, and a binder doped in the main material and the auxiliary material. The mass percentage content of the raw material components of the main material is as follows: silicon carbide, α-type silicon nitride, zirconium corundum, brown corundum fine powder, plate-shaped corundum fine powder, silicon carbide particles, alumina micropowder, and silicon dioxide micropowder. The mass percentage content of the raw material components of the auxiliary material is as follows: coagulant, inhibitor iodine oxytannate bismuth, explosion-proof fiber, silicon carbide fine powder, silicon fine powder, and aluminum fine powder. The binder accounts for 5 to 10% of the total amount of the main material and the auxiliary material. The binder is industrial aluminum phosphate solution and thermosetting phenolic resin, which reduces resource allocation, saves production costs, and ensures product quality. The antioxidant and slag erosion resistance of the ramming material are improved to a certain extent, meeting the needs of gasifier application.

[0005] However, the volume density of the ramming layer of the furnace bottom of the plasma gasification furnace in the prior art is low, and the life is difficult to guarantee due to oxidation at high temperature, erosion of slag and penetration of melt, and high chromium, chrome corundum and magnesium chromium ramming materials also face the same problem. 6+ The risk of pollution and the high temperature corrosion resistance of the ramming composite material need to be further improved.

[0006] In view of the technical defects in this aspect, a solution is now proposed. Summary of the invention

[0007] The purpose of the present invention is to provide a high temperature resistant and corrosion resistant composite material for a plasma gasifier and a preparation method thereof, so as to solve the technical problem in the prior art that the high temperature corrosion resistance of the ramming composite material for a plasma gasifier needs to be further improved.

[0008] The object of the present invention can be achieved by the following technical scheme: a high temperature resistant and corrosion resistant composite material for a plasma gasification furnace, comprising the following components in parts by weight: 50-70 parts of aggregate, 25-45 parts of powder and 5-8 parts of binder;

[0009] The aggregate component is a silicon binder, and the aggregate is composed of coarse aggregate, medium aggregate and fine aggregate in a weight ratio of 30-40:40-50:30-50;

[0010] The powder material is composed of silicon carbide powder, silicon nitride powder, zirconium oxide and α-aluminum oxide in a weight ratio of 40-50:40-50:5-10:5-10;

[0011] The binder consists of mixed gel, humic acid, lignin and methyl cellulose in a weight ratio of 10:3:3:4.

[0012] Furthermore, the particle size of the coarse aggregate is 3-5 mm, the particle size of the medium aggregate is 1-3 mm, the particle size of the fine aggregate is 0-1 mm, the particle sizes of the silicon carbide powder and the silicon nitride powder are both 0-0.88 mm, the particle size of the zirconium oxide is 0-45 μm, and the d50 of α-alumina is 2 μm.

[0013] Further, the silicon binder is processed by the following steps:

[0014] A1. Add silicon carbide, silicon powder, ammonium chloride and carbon powder into a ball mill. After ball milling, pass through an 80-mesh sieve to obtain a mixture.

[0015] A2. Place the mixed material in a vacuum self-propagating combustion high-temperature synthesis furnace to carry out a self-propagating combustion reaction to obtain a silicon binder.

[0016] The synthetic reaction mechanism of silicon binder is:

[0017] Silicon carbide, silicon powder, ammonium chloride and carbon powder are selected as raw materials, and ball milling is used to promote uniform mixing of the raw materials. In a nitrogen environment, the temperature of a vacuum self-propagating combustion high-temperature synthesis furnace is gradually increased. In the process of increasing the temperature from 300-400°C to 600-800°C, ammonium chloride is decomposed to produce ammonia and hydrogen chloride gas. These gases act as reaction media at high temperatures to promote the formation of silicon nitride. In the process of increasing the temperature from 600-800°C to 1200-1450°C, silicon powder reacts with ammonia or nitrogen to form silicon nitride, and the temperature for the reaction of carbon powder with silicon to form silicon carbide needs to reach above 1500°C. By controlling the reaction temperature, a binder of carbon powder-doped silicon carbide and silicon nitride is prepared. In an air environment, the carbon powder in the binder is carbonized to generate carbon dioxide to prepare a silicon binder with a porous structure.

[0018] Furthermore, in step A1, the weight ratio of the silicon carbide, silicon powder, ammonium chloride and carbon powder is 70-75:12-15:10-13:4-6; in step A2, the self-propagating combustion reaction is: the vacuum self-propagating combustion high temperature synthesis furnace is evacuated to a vacuum degree of 10-20Pa, nitrogen is introduced into the vacuum self-propagating combustion high temperature synthesis furnace to a pressure of 1-2MPa, the temperature of the vacuum self-propagating combustion high temperature synthesis furnace is increased to 300-400°C at a heating rate of 8-10°C / min, then increased to 600-800°C at a heating rate of 2-4°C / min, and then increased to 1200-1450°C at a heating rate of 6-8°C / min, and heat-insulated for 30-50min, air is introduced into the vacuum self-propagating combustion high temperature synthesis furnace, heat-insulated for 50-70min, naturally cooled to room temperature, discharged, and crushed to obtain a silicon binder.

[0019] Further, the mixed gel is processed by the following steps;

[0020] B1. Add silica sol, N-methylpyrrolidone and deionized water into a reactor and stir. Add hydrochloric acid into the reactor to adjust the pH of the system to 2-3. Increase the temperature of the reactor to 55-65° C., add ethyl orthosilicate into the reactor, keep warm and stir for 3-5 hours, and perform post-treatment to obtain silica gel.

[0021] The synthetic reaction mechanism of silicone gel is:

[0022] Under acidic conditions, ethyl orthosilicate is hydrolyzed to form silanol groups and ethanol. The silanol groups generated by hydrolysis can directly undergo condensation reaction with silanol groups or silica sol to form silicon-oxygen bonds, thereby constructing a three-dimensional network structure of silica gel. Silica gel is prepared by post-treatment with reduced pressure evaporation to remove low-boiling point solvents such as ionized water and ethanol.

[0023] B2, adding modified polyimide and N-methylpyrrolidone into a reaction kettle and stirring, raising the temperature of the reaction kettle to 70-80° C., stirring until the system is dissolved, and obtaining a modified polyimide solution;

[0024] B3. Add the silica gel and modified polyimide solution into the reaction kettle and stir at room temperature for 20-30 minutes to obtain a mixed gel.

[0025] Furthermore, in step B1, the amount ratio of the silica sol, N-methylpyrrolidone, deionized water and tetraethyl orthosilicate is 10g:30mL:15mL:8g, and the post-treatment includes: after the reaction is completed, the temperature of the reactor is increased to 75-85°C, and the solvent is evaporated under reduced pressure to obtain silica gel; in step B2, the amount ratio of the modified polyimide and N-methylpyrrolidone is 2g:3mL; in step B3, the weight ratio of the silica gel and the modified polyimide solution is 3:5.

[0026] Furthermore, the preparation method of the modified polyimide is as follows: 4,4'-diaminodiphenyl ether and N,N-dimethylformamide are added to a nitrogen-protected reactor and stirred, and stirred at room temperature until the system is dissolved, the temperature of the reactor is lowered to 5-8°C, and pyromellitic dianhydride is added to the reactor in batches. After the addition is completed, the mixture is stirred for 30-50 minutes at a temperature maintained at room temperature, the reactor is heated to room temperature, stirred for 6-8 hours at a temperature maintained ...

[0027] The synthetic reaction formula of modified polyimide is:

[0028]

[0029] The synthetic reaction mechanism of modified polyimide is:

[0030] Under nitrogen protection, the amino group on 4,4'-diaminodiphenyl ether acts as a nucleophilic reagent to attack the carbonyl carbon of the anhydride group of the pyromellitic dianhydride molecule, and a nucleophilic addition reaction occurs to form an imide bond of an intermediate. As the reaction proceeds, the polymer chain continues to grow, and a modified polyimide solution is prepared. The solubility of the modified polyimide in the N,N-dimethylformamide solution is changed by a dispersion liquid, and the modified polyimide is promoted to precipitate from the solution. Sodium dodecyl sulfate is a surfactant, and its long-chain alkyl part is hydrophobic in water, while the sulfate part is hydrophilic. The sodium dodecyl sulfate molecules are attached to the surface of the polyimide particles by physical adsorption, which improves its dispersibility in the DMF / water mixed solution, is conducive to the precipitation of the modified polyimide from the solution, and the modified polyimide is prepared.

[0031] Furthermore, the dosage ratio of the 4,4'-diaminodiphenyl ether and pyromellitic anhydride is 1 mol:1.02 mol, and the dosage ratio of the 4,4'-diaminodiphenyl ether and N,N-dimethylformamide is 1 g:6 mL. The post-treatment includes: after the reaction is completed, adding the dispersion to the reactor at room temperature, stirring for 20-30 minutes at a temperature of 60-70°C, filtering, transferring the filter cake to a drying oven at a temperature of 60-70°C, constant weight during vacuum drying, crushing, and passing through an 80-mesh sieve to obtain a modified polyimide.

[0032] The present invention also provides a method for preparing a high temperature resistant and corrosion resistant composite material for a plasma gasification furnace, comprising the following steps:

[0033] S1. The silicon binder is screened and graded, and the particles with a diameter greater than 5 mm are returned for re-crushing, and the rest are graded into coarse aggregate, medium aggregate and fine aggregate according to the particle sizes of 3-5 mm, 1-3 mm and 0-1 mm;

[0034] S2, mixing the coarse aggregate, the medium aggregate and the fine aggregate uniformly to obtain aggregate;

[0035] S3, mixing silicon carbide powder, silicon nitride powder, zirconium oxide and α-aluminum oxide uniformly to obtain a powder;

[0036] S4, mixing the mixed gel, humic acid, lignin and methyl cellulose uniformly to obtain a binder;

[0037] S5. Add aggregate and powder into a mixer, premix for 10-15 minutes, add a binder into the mixer, and continue mixing for 30-50 minutes to obtain a composite material.

[0038] The present invention has the following beneficial effects:

[0039] 1. The high temperature resistant and corrosion resistant composite material for a plasma gasifier of the present invention is prepared by reinforcing silicon carbide with silicon nitride to prepare a silicon binder as an aggregate of the composite material, optimize the particle size distribution of the aggregate, form a tightly stacked structure in the composite material, and improve the volume density and mechanical properties of the material. Both silicon nitride and silicon carbide are materials with excellent chemical stability and can resist corrosion by a variety of acids, alkalis and organic solvents. Silicon nitride is combined with silicon carbide to prepare a porous binder combining silicon nitride and silicon carbide, which can further improve the chemical stability of the material, especially in high temperature, high pressure or corrosive environments, thereby improving the high temperature resistance and corrosion resistance of the composite material. In addition, the thermal expansion coefficients of silicon nitride and silicon carbide are relatively low, and the difference in thermal expansion coefficients between the two is not large, which helps to reduce material cracking or deformation caused by thermal stress at high temperatures and improve the high temperature resistance of the composite material.

[0040] 2. The high temperature resistant and corrosion resistant composite material for the plasma gasifier of the present invention is composed of silicon carbide powder, silicon nitride powder, zirconium oxide and α-alumina powder. The materials constituting the powder have excellent high temperature stability and chemical stability. The chemical properties of silicon nitride, silicon carbide and α-alumina are stable and they all have extremely high melting points and excellent oxidation resistance. Under high temperature, silicon nitride can form a dense silicon oxide protective film to effectively prevent further erosion by oxygen, thereby protecting the inside of the material from damage. Zirconia will undergo a phase change at high temperature, from a monoclinic system to a tetragonal system. This process is accompanied by a change in volume, which can absorb energy, thereby significantly improving the toughness of the material, further enhancing the high temperature resistance and corrosion resistance of the composite material, and enabling the composite material to maintain the integrity and performance of the material under extreme environments.

[0041] 3. The high temperature resistant and corrosion resistant composite material for plasma gasification furnace of the present invention is prepared by blending silica gel with modified polyimide and then mixing with humic acid, lignin and methyl cellulose to form a binder. During the mixing process, the molecules of silica gel and modified polyimide will interact with each other, such as hydrogen bonds and van der Waals forces. The polar groups such as amide groups and carboxyl groups introduced into the modified polyimide can form hydrogen bonds with the water molecule layer on the surface of inorganic powder, thereby enhancing the affinity with the surface of inorganic substances and promoting the penetration and diffusion of gel between powder particles. Such wetting and penetration effects help to form a more uniform and dense bonding structure, thereby improving the bonding strength of the ramming material. Silica gel and modified polyimide each have good thermal stability. Qualitative, which is the basis for them to be used as high-temperature materials. The high-temperature resistance of silicone gel combined with the heat-oxidation resistance of modified polyimide makes the mixed gel less likely to undergo thermal decomposition or thermal oxidation in a high-temperature environment, thereby maintaining its adhesion and mechanical properties. In the mixed gel, the thermal insulation performance of silicone gel and the thermal conductivity of modified polyimide complement each other, forming a balance between thermal insulation and thermal conductivity. The thermal insulation performance of silicone gel helps to slow down the transfer of heat to the inside of the ramming material, reduce the internal temperature gradient, and reduce the generation of thermal stress. The thermal conductivity of modified polyimide, aggregate, and powder helps to quickly disperse the heat to the surrounding environment, avoid heat accumulation in the local area of ​​the ramming material, and further improve its thermal stability.

[0042] Humic acid has natural colloidal properties, which can increase the viscosity of the binder during the mixing process, thereby improving its fluidity and making it easier to mix the ramming material evenly during the preparation process. In addition, humic acid can form a stable carbon layer at high temperatures, which can isolate oxygen and slow down the oxidation rate of the ramming material at high temperatures, thereby improving its high temperature resistance. Lignin is a natural polymer compound, and its molecular structure contains a large number of functional groups such as hydroxyl and carboxyl groups. These functional groups can form hydrogen bonds or ionic bonds with other components in the mixed gel, thereby enhancing the internal binding force of the ramming material. Lignin can undergo pyrolysis reaction at high temperatures to generate some compounds with cross-linking effects, which can promote the curing process of the ramming material and enable it to reach the designed strength faster.

[0043] Methyl cellulose is a commonly used thickener and stabilizer. Its addition can adjust the viscosity of the binder. Appropriate viscosity helps to evenly spread and compact the ramming material during construction, reduce the generation of bubbles and defects, and make the ramming material have better processability during the preparation process; humic acid, lignin and methyl cellulose, these three additives, synergistically complement each other in the ramming material, so that the ramming material can still maintain the stability of its structure and performance under harsh environments such as high temperature and high pressure. BRIEF DESCRIPTION OF THE DRAWINGS

[0044] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0045] Figure 1 The synthetic process flow chart of the composite material of the present invention is shown in FIG. DETAILED DESCRIPTION

[0046] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are only part of the embodiments of the present invention, rather than all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0047] The content of silicon carbide powder in this application is higher than 97% and the particle size is lower than 0.88mm;

[0048] The content of silicon nitride powder is higher than 98% and the particle size is lower than 0.88mm;

[0049] The content of zirconium oxide is higher than 98% and the particle size is lower than 45μm;

[0050] The content of α-alumina is higher than 99%, d50 = 2 μm;

[0051] The silica sol has a silicon dioxide content of 25±1% and is selected from Shanghai Yingcheng New Materials Co., Ltd., with a model of YC-SI15S-2.

[0052] Example 1

[0053] This embodiment provides a method for preparing a high temperature resistant and corrosion resistant composite material for a plasma gasification furnace, comprising the following steps:

[0054] S1. Preparation of silicon binder

[0055] Weigh 70 parts of silicon carbide, 12 parts of silicon powder, 10 parts of ammonium chloride and 4 parts of carbon powder by weight and add them into a ball mill. After ball milling, pass through an 80-mesh sieve to obtain a mixture.

[0056] The mixture is placed in a vacuum self-propagating combustion high temperature synthesis furnace, the vacuum self-propagating combustion high temperature synthesis furnace is evacuated to a vacuum degree of 10Pa, nitrogen is introduced into the vacuum self-propagating combustion high temperature synthesis furnace to a pressure of 1MPa, the temperature of the vacuum self-propagating combustion high temperature synthesis furnace is increased to 300°C at a heating rate of 8°C / min, then increased to 600°C at a heating rate of 2°C / min, and then increased to 1200°C at a heating rate of 6°C / min, and heat-insulated for 30min, air is introduced into the vacuum self-propagating combustion high temperature synthesis furnace, heat-insulated for 50min, naturally cooled to room temperature, discharged, and a silicon binder is obtained.

[0057] S2. Preparation of aggregate

[0058] The silicon binder is crushed and then screened and graded. The particles larger than 5 mm are returned for re-crushing, and the rest are graded into coarse aggregate, medium aggregate and fine aggregate according to the particle sizes of 3-5 mm, 1-3 mm and 0-1 mm. The coarse aggregate, medium aggregate and fine aggregate are evenly mixed in a weight ratio of 30:40:30 to obtain aggregate.

[0059] S3. Preparation of powder

[0060] Weigh by weight: 40 parts of silicon carbide powder, 40 parts of silicon nitride powder, 5 parts of zirconium oxide and 5 parts of α-aluminum oxide, mix evenly to obtain powder.

[0061] S4. Preparation of modified polyimide

[0062] Sodium dodecyl sulfate and purified water were mixed uniformly at a ratio of 1 g:20 mL to obtain a dispersion;

[0063] Weigh: 200 g of 4,4'-diaminodiphenyl ether and 1200 mL of N,N-dimethylformamide, add them to a nitrogen-protected reactor and stir, stir at room temperature until the system is dissolved, lower the temperature of the reactor to 5°C, add 222 g of pyromellitic dianhydride to the reactor in batches, and after the addition is completed, stir for 30 minutes at this temperature. Heat the reactor to room temperature and stir for 6 hours. At room temperature, add 3600 mL of the dispersion to the reactor, stir for 20 minutes at this temperature, filter, transfer the filter cake to a drying oven at 60°C, keep constant weight during vacuum drying, crush, and pass through an 80-mesh sieve to obtain a modified polyimide.

[0064] S5. Preparation of mixed gel

[0065] Weigh: 200 g of silica sol, 600 mL of N-methylpyrrolidone, and 300 mL of deionized water, add them into a reactor and stir, add hydrochloric acid into the reactor to adjust the pH of the system to 2, raise the temperature of the reactor to 55°C, add 160 g of ethyl orthosilicate into the reactor, keep warm and stir for 3 hours, raise the temperature of the reactor to 75°C, and evaporate the solvent under reduced pressure to obtain silica gel;

[0066] Add modified polyimide and N-methylpyrrolidone in a ratio of 2 g:3 mL into a reactor, raise the temperature of the reactor to 70° C., and stir until the system is dissolved to obtain a modified polyimide solution;

[0067] The silica gel and the modified polyimide solution were added into the reaction kettle at a weight ratio of 3:5, and stirred at room temperature for 20 minutes to obtain a mixed gel.

[0068] S6. Preparation of binding agent

[0069] The mixed gel, humic acid, lignin and methyl cellulose were uniformly mixed in a weight ratio of 10:3:3:4 to obtain a binder.

[0070] S7. Preparation of composite materials

[0071] Weigh by weight: 50 parts of aggregate and 25 parts of powder are added into a mixer, pre-mixed for 10 minutes, 5 parts of binder are added into the mixer, and mixing is continued for 30 minutes to obtain a composite material.

[0072] Example 2

[0073] This embodiment provides a method for preparing a high temperature resistant and corrosion resistant composite material for a plasma gasification furnace, comprising the following steps:

[0074] S1. Preparation of silicon binder

[0075] Weigh 73 parts of silicon carbide, 13 parts of silicon powder, 12 parts of ammonium chloride and 5 parts of carbon powder by weight and add them into a ball mill. After ball milling, pass through an 80-mesh sieve to obtain a mixed material.

[0076] The mixture is placed in a vacuum self-propagating combustion high temperature synthesis furnace, the vacuum self-propagating combustion high temperature synthesis furnace is evacuated to a vacuum degree of 15Pa, nitrogen is introduced into the vacuum self-propagating combustion high temperature synthesis furnace to a pressure of 1.5MPa, the temperature of the vacuum self-propagating combustion high temperature synthesis furnace is increased to 350°C at a heating rate of 9°C / min, then increased to 700°C at a heating rate of 3°C / min, and then increased to 1325°C at a heating rate of 7°C / min, and heat-insulated for 40min, air is introduced into the vacuum self-propagating combustion high temperature synthesis furnace, heat-insulated for 60min, naturally cooled to room temperature, discharged, and a silicon binder is obtained.

[0077] S2. Preparation of aggregate

[0078] The silicon binder is crushed and then screened and graded. The particles with a diameter greater than 5 mm are returned for re-crushing, and the rest are graded into coarse aggregate, medium aggregate and fine aggregate according to the particle diameters of 3-5 mm, 1-3 mm and 0-1 mm. The coarse aggregate, medium aggregate and fine aggregate are evenly mixed in a weight ratio of 35:45:40 to obtain aggregate.

[0079] S3. Preparation of powder

[0080] Weigh by weight: 45 parts of silicon carbide powder, 45 parts of silicon nitride powder, 7.5 parts of zirconium oxide and 7.5 parts of α-aluminum oxide, mix well to obtain powder.

[0081] S4. Preparation of modified polyimide

[0082] Sodium dodecyl sulfate and purified water were mixed uniformly at a ratio of 1 g:20 mL to obtain a dispersion;

[0083] Weigh: 200 g of 4,4'-diaminodiphenyl ether and 1200 mL of N,N-dimethylformamide are added to a nitrogen-protected reactor and stirred. Stir at room temperature until the system is dissolved. The temperature of the reactor is lowered to 7°C. 222 g of pyromellitic dianhydride is added to the reactor in batches. After the addition is completed, stir at this temperature for 40 minutes. The reactor is heated to room temperature and stirred at this temperature for 7 hours. At room temperature, 3600 mL of the dispersion is added to the reactor, stirred at this temperature for 25 minutes, filtered, and the filter cake is transferred to a drying oven at a temperature of 65°C. Constant weight is obtained during vacuum drying, crushed, and passed through an 80-mesh sieve to obtain a modified polyimide.

[0084] S5. Preparation of mixed gel

[0085] Weigh: 200 g of silica sol, 600 mL of N-methylpyrrolidone, and 300 mL of deionized water, add them into a reactor and stir, add hydrochloric acid into the reactor, adjust the pH of the system to 2.5, raise the temperature of the reactor to 60°C, add 160 g of ethyl orthosilicate into the reactor, keep warm and stir for 4 hours, raise the temperature of the reactor to 80°C, and evaporate the solvent under reduced pressure to obtain silica gel;

[0086] Add modified polyimide and N-methylpyrrolidone in a ratio of 2 g:3 mL into a reactor, raise the temperature of the reactor to 75° C., and stir until the system is dissolved to obtain a modified polyimide solution;

[0087] The silica gel and the modified polyimide solution were added into the reaction kettle at a weight ratio of 3:5, and stirred at room temperature for 25 minutes to obtain a mixed gel.

[0088] S6. Preparation of binding agent

[0089] The mixed gel, humic acid, lignin and methyl cellulose were uniformly mixed in a weight ratio of 10:3:3:4 to obtain a binder.

[0090] S7. Preparation of composite materials

[0091] Weigh by weight: 60 parts of aggregate and 35 parts of powder are added to a mixer and premixed for 13 minutes. Add 6.5 parts of binder to the mixer and continue mixing for 40 minutes to obtain a composite material.

[0092] Example 3

[0093] This embodiment provides a method for preparing a high temperature resistant and corrosion resistant composite material for a plasma gasification furnace, comprising the following steps:

[0094] S1. Preparation of silicon binder

[0095] Weigh 75 parts of silicon carbide, 15 parts of silicon powder, 13 parts of ammonium chloride and 6 parts of carbon powder by weight and add them into a ball mill. After ball milling, pass through an 80-mesh sieve to obtain a mixed material.

[0096] The mixture is placed in a vacuum self-propagating combustion high temperature synthesis furnace, the vacuum self-propagating combustion high temperature synthesis furnace is evacuated to a vacuum degree of 20Pa, nitrogen is introduced into the vacuum self-propagating combustion high temperature synthesis furnace to a pressure of 2MPa, the temperature of the vacuum self-propagating combustion high temperature synthesis furnace is increased to 400°C at a heating rate of 10°C / min, then increased to 800°C at a heating rate of 4°C / min, and then increased to 1450°C at a heating rate of 8°C / min, and heat-insulated for 50min, air is introduced into the vacuum self-propagating combustion high temperature synthesis furnace, heat-insulated for 70min, naturally cooled to room temperature, discharged, and a silicon binder is obtained.

[0097] S2. Preparation of aggregate

[0098] The silicon binder is crushed and then screened and graded. The particles with a diameter greater than 5 mm are returned for re-crushing, and the rest are graded into coarse aggregate, medium aggregate and fine aggregate according to the particle diameters of 3-5 mm, 1-3 mm and 0-1 mm. The coarse aggregate, medium aggregate and fine aggregate are evenly mixed in a weight ratio of 40:50:50 to obtain aggregate.

[0099] S3. Preparation of powder

[0100] Weigh by weight: 50 parts of silicon carbide powder, 50 parts of silicon nitride powder, 10 parts of zirconium oxide and 10 parts of α-aluminum oxide, mix well to obtain powder.

[0101] S4. Preparation of modified polyimide

[0102] Sodium dodecyl sulfate and purified water were mixed uniformly at a ratio of 1 g:20 mL to obtain a dispersion;

[0103] Weigh: 200 g of 4,4'-diaminodiphenyl ether and 1200 mL of N,N-dimethylformamide are added to a nitrogen-protected reactor and stirred. Stir at room temperature until the system is dissolved. The temperature of the reactor is lowered to 8°C. 222 g of pyromellitic dianhydride is added to the reactor in batches. After the addition is completed, stir for 50 minutes at this temperature. The reactor is heated to room temperature and stirred for 8 hours at this temperature. At room temperature, 3600 mL of the dispersion is added to the reactor, stirred for 30 minutes at this temperature, filtered, and the filter cake is transferred to a drying oven at a temperature of 70°C. The weight is constant during vacuum drying, crushed, and passed through an 80-mesh sieve to obtain a modified polyimide.

[0104] S5. Preparation of mixed gel

[0105] Weigh: 200 g of silica sol, 600 mL of N-methylpyrrolidone, and 300 mL of deionized water, add them into a reactor and stir, add hydrochloric acid into the reactor, adjust the pH of the system to 3, raise the temperature of the reactor to 65°C, add 160 g of ethyl orthosilicate into the reactor, keep warm and stir for 5 hours, raise the temperature of the reactor to 85°C, and evaporate the solvent under reduced pressure to obtain silica gel;

[0106] Add modified polyimide and N-methylpyrrolidone in a ratio of 2 g:3 mL into a reactor, raise the temperature of the reactor to 80° C., and stir until the system is dissolved to obtain a modified polyimide solution;

[0107] The silica gel and the modified polyimide solution were added into the reaction kettle at a weight ratio of 3:5, and stirred at room temperature for 30 minutes to obtain a mixed gel.

[0108] S6. Preparation of binding agent

[0109] The mixed gel, humic acid, lignin and methyl cellulose were uniformly mixed in a weight ratio of 10:3:3:4 to obtain a binder.

[0110] S7. Preparation of composite materials

[0111] Weigh by weight: 70 parts of aggregate and 45 parts of powder are added to a mixer, pre-mixed for 15 minutes, 8 parts of binder are added to the mixer, and mixing is continued for 50 minutes to obtain a composite material.

[0112] Comparative Example 1

[0113] The difference between this comparative example and Example 3 is that in step S1, no carbon powder is added.

[0114] Comparative Example 2

[0115] The difference between this comparative example and Example 3 is that in step S3, zirconium oxide is not added.

[0116] Comparative Example 3

[0117] The difference between this comparative example and Example 3 is that step S4 is eliminated, and the mixed gel in step S6 is replaced by the silicone gel in step S5.

[0118] Comparative Example 4

[0119] The difference between this comparative example and Example 3 is that humic acid and lignin are not added in step S6.

[0120] Performance Test:

[0121] The bulk density and thermal conductivity of the composite materials prepared in Examples 1-3 and Comparative Examples 1-4 were tested with reference to the standard YB / T 4349-2013 "Silicon carbide-carbonaceous ramming material for blast furnace";

[0122] With reference to the standard GB / T 3002-2017 “Test method for high temperature flexural strength of refractory materials”, the high temperature flexural strength of the composite materials prepared in Examples 1-3 and Comparative Examples 1-4 at 200°C and 1200°C was tested. The specific test results are shown in Table 1 below.

[0123] Table 1-Testing and analysis data of samples

[0124]

[0125]

[0126] Data Analysis:

[0127] Comparing and analyzing the data in Table 1 above, the volume density of the composite material prepared by the present invention reaches 2.89 g / cm 3 The thermal conductivity reaches 1.623W / (m·k), the flexural strength at 200℃ reaches 19.42MPa, and the flexural strength at 1200℃ reaches 25.31MPa. All performance parameters are better than those of the comparative example.

[0128] It is explained that the present invention optimizes the particle size distribution of the aggregate and the composition of the powder by combining a binder composed of silicone gel, modified polyimide, humic acid, lignin, and methyl cellulose with aggregates and powders reinforced with silicon nitride and silicon carbide, which not only effectively improves the high temperature resistance and corrosion resistance of the composite material, but also increases the volume density of the composite material and reduces its thermal conductivity.

[0129] The above contents are merely examples and explanations of the structure of the present invention. The technicians in this technical field may make various modifications or additions to the specific embodiments described or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they should all fall within the protection scope of the present invention.

[0130] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0131] The preferred embodiments of the present invention disclosed above are only used to help explain the present invention. The preferred embodiments do not describe all the details in detail, nor do they limit the invention to only specific implementation methods. Obviously, many modifications and changes can be made according to the content of this specification. This specification selects and specifically describes these embodiments in order to better explain the principles and practical applications of the present invention, so that those skilled in the art can understand and use the present invention well. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A high temperature resistant and corrosion resistant composite material for a plasma gasification furnace, characterized in that: The invention comprises the following components in parts by weight: 50-70 parts of aggregate, 25-45 parts of powder and 5-8 parts of binder; The aggregate component is a silicon binder, and the aggregate is composed of coarse aggregate, medium aggregate and fine aggregate in a weight ratio of 30-40:40-50:30-50; The powder material is composed of silicon carbide powder, silicon nitride powder, zirconium oxide and α-aluminum oxide in a weight ratio of 40-50:40-50:5-10:5-10; The binder consists of mixed gel, humic acid, lignin and methyl cellulose in a weight ratio of 10:3:3:

4.

2. The high temperature and corrosion resistant composite material for a plasma gasification furnace according to claim 1, characterized in that: The particle size of the coarse aggregate is 3-5 mm, the particle size of the medium aggregate is 1-3 mm, the particle size of the fine aggregate is 0-1 mm, the particle sizes of the silicon carbide powder and the silicon nitride powder are both 0-0.88 mm, the particle size of the zirconium oxide is 0-45 μm, and the d50 of α-alumina is 2 μm.

3. The high temperature and corrosion resistant composite material for a plasma gasification furnace according to claim 1, characterized in that: The silicon binder is processed by the following steps: A1. Add silicon carbide, silicon powder, ammonium chloride and carbon powder into a ball mill. After ball milling, pass through an 80-mesh sieve to obtain a mixture. A2. Place the mixed material in a vacuum self-propagating combustion high-temperature synthesis furnace to carry out a self-propagating combustion reaction to obtain a silicon binder.

4. The high temperature and corrosion resistant composite material for a plasma gasification furnace according to claim 3, characterized in that: In step A1, the weight ratio of silicon carbide, silicon powder, ammonium chloride and carbon powder is 70-75:12-15:10-13:4-6; in step A2, the self-propagating combustion reaction is: the vacuum self-propagating combustion high temperature synthesis furnace is evacuated to a vacuum degree of 10-20Pa, nitrogen is introduced into the vacuum self-propagating combustion high temperature synthesis furnace to a pressure of 1-2MPa, the temperature of the vacuum self-propagating combustion high temperature synthesis furnace is increased to 300-400°C at a heating rate of 8-10°C / min, then increased to 600-800°C at a heating rate of 2-4°C / min, and then increased to 1200-1450°C at a heating rate of 6-8°C / min, and heat-insulated for 30-50min, air is introduced into the vacuum self-propagating combustion high temperature synthesis furnace, heat-insulated for 50-70min, naturally cooled to room temperature, discharged, crushed, and a silicon binder is obtained.

5. The high temperature and corrosion resistant composite material for a plasma gasification furnace according to claim 1, characterized in that: The mixed gel is processed by the following steps; B1. Add silica sol, N-methylpyrrolidone and deionized water into a reactor and stir. Add hydrochloric acid into the reactor to adjust the pH of the system to 2-3. Increase the temperature of the reactor to 55-65° C., add ethyl orthosilicate into the reactor, keep warm and stir for 3-5 hours, and perform post-treatment to obtain silica gel. B2, adding modified polyimide and N-methylpyrrolidone into a reaction kettle and stirring, raising the temperature of the reaction kettle to 70-80° C., stirring until the system is dissolved, and obtaining a modified polyimide solution; B3. Add the silica gel and modified polyimide solution into the reaction kettle and stir at room temperature for 20-30 minutes to obtain a mixed gel.

6. The high temperature and corrosion resistant composite material for a plasma gasification furnace according to claim 5, characterized in that: In step B1, the amount ratio of the silica sol, N-methylpyrrolidone, deionized water and tetraethyl orthosilicate is 10g:30mL:15mL:8g; in step B2, the amount ratio of the modified polyimide and N-methylpyrrolidone is 2g:3mL; in step B3, the weight ratio of the silica gel and the modified polyimide solution is 3:

5.

7. The high temperature and corrosion resistant composite material for a plasma gasification furnace according to claim 5, characterized in that: The preparation method of the modified polyimide is as follows: 4,4'-diaminodiphenyl ether and N,N-dimethylformamide are added to a nitrogen-protected reactor and stirred, and the system is stirred at room temperature until the system is dissolved, the temperature of the reactor is lowered to 5-8°C, and pyromellitic dianhydride is added to the reactor in batches. After the addition is completed, the reaction is stirred for 30-50 minutes at a temperature maintained, the reactor is heated to room temperature, stirred for 6-8 hours at a temperature maintained, and post-treated to obtain the modified polyimide.

8. The high temperature and corrosion resistant composite material for a plasma gasification furnace according to claim 7, characterized in that: The usage ratio of the 4,4'-diaminodiphenyl ether and pyromellitic acid dianhydride is 1 mol: 1.02 mol, the usage ratio of 4,4'-diaminodiphenyl ether and N,N-dimethylformamide is 1 g:6 mL.

9. The method for preparing the high temperature resistant and corrosion resistant composite material for a plasma gasification furnace according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1. The silicon binder is screened and graded, and the particles with a diameter greater than 5 mm are returned for re-crushing, and the rest are graded into coarse aggregate, medium aggregate and fine aggregate according to the particle sizes of 3-5 mm, 1-3 mm and 0-1 mm; S2, mixing the coarse aggregate, the medium aggregate and the fine aggregate uniformly to obtain aggregate; S3, mixing silicon carbide powder, silicon nitride powder, zirconium oxide and α-aluminum oxide uniformly to obtain a powder; S4, mixing the mixed gel, humic acid, lignin and methyl cellulose uniformly to obtain a binder; S5. Add aggregate and powder into a mixer, premix for 10-15 minutes, add a binder into the mixer, and continue mixing for 30-50 minutes to obtain a composite material.

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