High thermal shock resistant material for a return valve and method of making the same

Abstract

The application belongs to the technical field of ceramic materials, and particularly relates to a high thermal shock resistance material for a return valve and a preparation method thereof. The main component of the thermal shock resistance material, mullite, is modified, and the cordierite-titanium dioxide composite material and modified silicon dioxide are introduced, so that the components synergistically act to achieve good thermal shock resistance, significantly improve the bending strength, and increase the fracture toughness.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of ceramic materials, and particularly relates to a high thermal shock resistance material for a return valve and a preparation method thereof. BACKGROUND

[0002] The return valve is one of the key components in the circulating fluidized bed boiler, and its main function is to collect the solid particles in the separator and return them to the furnace to maintain the stability and efficiency of the combustion process. Since the return valve works under extreme conditions such as high temperature, thermal cycling (frequent temperature changes), corrosive media (such as acidic gases, particle erosion), etc., it has very high requirements for the thermal shock resistance (resistance to rapid cooling and heating), high temperature resistance, corrosion resistance and mechanical strength of the material. Thermal shock resistant materials are materials that can maintain structural integrity and functionality in rapidly changing temperature environments. Such materials typically have low thermal expansion coefficients, high fracture toughness, and good thermal conductivity, thereby effectively resisting thermal stress caused by rapid temperature changes and are widely used in high-temperature industries (such as metallurgy, chemical industry, energy), aerospace, electronic devices, etc.

[0003] A thermal shock resistant composite ceramic material is disclosed in Chinese patent (publication number CN113956024B). This invention adds zirconium oxide to the alumina ceramic material to alleviate the thermal stress caused by thermal shock through the volume effect caused by phase transition, thereby improving the bending strength and fracture toughness of the composite material. The introduction of mullite into the composite ceramic improves the thermal shock resistance of the composite ceramic by reducing its thermal expansion. The material has high strength, good thermal shock resistance, etc., is simple to prepare, easy to operate, and low in cost. However, the existing anti-thermal shock material for return valves still has problems such as poor thermal shock resistance, low bending strength, and low fracture toughness, which seriously affects its actual use.

[0004] Therefore, there is an urgent need for a high thermal shock resistance material for return valves, which can achieve good thermal shock resistance by modifying the material components, significantly improve the bending strength, and increase the fracture toughness. SUMMARY

[0005] The purpose of the present application is to provide a high thermal shock resistance material for return valves and a preparation method thereof. By modifying the main component of the thermal shock resistance material, mullite, and introducing cordierite-titanium dioxide composite material and modified silicon dioxide, the components work together to achieve good thermal shock resistance, significantly improve the bending strength, and increase the fracture toughness.

[0006] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0007] The first aspect of the present application provides a high thermal shock resistance material for return valves,

[0008] The modified mullite is prepared by the following method: 6-8 parts of ferrous chloride is added into 900-1000 parts of deionized water to be dissolved thoroughly, then 20-30 parts of commercial mullite is soaked for 2-4 hours, and dried to obtain iron-containing mullite; 3-5 parts of potassium permanganate is dissolved in 200-300 parts of deionized water, 20-30 parts of the iron-containing mullite is added, and 90-100 parts of 3-5% ammonium oxalate aqueous solution is added to modify the mullite.

[0009] The modified mullite is prepared by the following method: 6-8 parts of ferrous chloride is added into 900-1000 parts of deionized water to be dissolved thoroughly, then 20-30 parts of commercial mullite is soaked for 2-4 hours, and dried to obtain iron-containing mullite; 3-5 parts of potassium permanganate is dissolved in 200-300 parts of deionized water, 20-30 parts of the iron-containing mullite is added, and 90-100 parts of 3-5% ammonium oxalate aqueous solution is added to modify the mullite.

[0010] As a preferred solution, the modification conditions include adjusting the pH to 7.2-7.4, oscillating at 160-200 r / min for 8-10 hours at 80-90℃, and drying.

[0011] The manganese-iron oxide introduced by the modified mullite forms new composite phases such as spinel phase with the mullite matrix, the new phases are dispersedly distributed between the mullite grains, effectively inhibiting crack propagation, changing the lattice constant and bonding strength, finely controlling the thermal expansion coefficient, and improving the thermal shock resistance of the material.

[0012] As a preferred solution, the epi-dodecahedron is an epi-dodecahedron-titanium dioxide composite material.

[0013] The epi-dodecahedron-titanium dioxide composite material is prepared by the following method: 6-10 parts of commercial epi-dodecahedron is surface treated to obtain pretreated epi-dodecahedron; the pH of 200-300 parts of 15% titanyl sulfate solution is adjusted to 7.2-7.6 with ammonia water, filtered, washed with water, and then the precipitate is added into 900-1000 parts of deionized water for aging treatment to obtain titanium dioxide sol; 6-10 parts of the pretreated epi-dodecahedron is immersed in 200-300 parts of the titanium dioxide sol for surface coating to obtain the epi-dodecahedron-titanium dioxide composite material.

[0014] As a preferred solution, the surface treatment conditions include: 6-10 parts of epi-dodecahedron is added into 80-100 parts of 10-20% oxalic acid solution, heated at 80-90℃ for 1-3 hours, filtered, dried, and calcined at 500-540℃ for 6-8 hours, and cooled to room temperature.

[0015] As a preferred solution, the conditions of the aging treatment include: heating to 70-80℃, then adjusting the pH to 1.8-2.2 with a nitric acid solution with a mass concentration fraction of 8-10%, and aging for 10-12h, and adjusting the pH to 5.8-6.2 with ammonia water.

[0016] As a preferred solution, the conditions of the surface coating include: stirring for 30-40min at room temperature, then aging for 10-12h, drying, and calcining at 580-600℃ for 3-5h.

[0017] The titanium dioxide coating layer on the surface of the coestite-titanium dioxide composite material can form a strong bonding interface between the coestite particles and the matrix, reduce the interface defects and stress concentration, and help to more evenly transmit the load to the coestite particles by improving the interface bonding strength, thereby improving the bending strength of the overall material.

[0018] As a preferred solution, the silicon dioxide is modified silicon dioxide.

[0019] The preparation method of the modified silicon dioxide includes: uniformly mixing 100-200 parts of deionized water and 400-500 parts of anhydrous ethanol by weight, then uniformly stirring 10-16 parts of quaternary ammonium alkali lignin and 0.2-0.4 parts of sodium dodecyl benzene sulfonate, and then adding 10-16 parts of commercially available silicon dioxide for hydrothermal reaction to obtain modified silicon dioxide.

[0020] As a preferred solution, the particle size of the commercially available silicon dioxide is 10-50nm.

[0021] As a preferred solution, the preparation method of the quaternary ammonium alkali lignin includes: uniformly mixing 10-16 parts of alkali lignin into 90-100 parts of a (3-chloro-2-hydroxypropyl) trimethylammonium chloride solution with a mass concentration fraction of 60%, then adding 30-40 parts of a sodium hydroxide solution with a mass concentration fraction of 16-20%, and reacting at 80-90℃ for 3-5h, dialysis purification, rotary evaporation, freeze-drying to obtain quaternary ammonium alkali lignin.

[0022] As a preferred solution, the conditions of the hydrothermal reaction include: hydrothermal reaction at 156-160℃ for 60-80min, cooling to room temperature, centrifugation, and drying.

[0023] The quaternary ammonium alkali lignin in the modified silicon dioxide will be carbonized during high-temperature sintering, and the formed carbon skeleton can form a stable carbon-silicon composite structure with the silicon dioxide, the interface bonding force of the carbon-silicon composite structure is strong, can pin the crack tip, prevent the rapid expansion of the crack, and thereby improve the fracture toughness of the material.

[0024] As a preferred scheme, the binder is polyvinyl alcohol and carboxymethyl cellulose; the mass ratio of polyvinyl alcohol and carboxymethyl cellulose in the binder is (1-2):1.

[0025] The second aspect of the present application provides a preparation method of a high thermal shock resistance material for a return valve,

[0026] The method comprises the following steps:

[0027] Step S1: 85-95 parts of modified mullite, 6-10 parts of epidote, 2-4 parts of silicon carbide, 4-8 parts of silicon dioxide, 1-3 parts of zirconium oxide, 8-12 parts of a binder and 0.2-0.6 parts of polyethylene glycol are mixed, and then deionized water is added for wet grinding for 30-40 hours to obtain a mixed slurry;

[0028] Step S2: the mixed slurry is subjected to spray drying, sintering at 1200-1300 DEG C, and furnace cooling to obtain the high thermal shock resistance material for the return valve.

[0029] In order to achieve the above-mentioned purpose, the present application provides the following technical scheme:

[0030] Compared with the prior art, the present application has the following advantages and beneficial effects:

[0031] 1、The modified mullite contains manganese-iron metal oxides, and manganese ions and iron ions have high diffusion capacity under high temperature conditions, which can diffuse from the surface of the manganese-iron oxide particles to the surface of the epidote-titanium dioxide composite material, and part of the manganese ions and iron ions enter the titanium dioxide lattice to replace the positions of titanium ions to form a solid solution, which effectively enhances the uniformity and stability of the material; in addition, the porous carbon skeleton formed by the decomposition of the modified silica quaternary ammonium alkali lignin at high temperature can form an interfacial composite structure with the surface of the manganese-iron oxide; through the comprehensive action of multiple components, the material obtains good thermal shock resistance, and the bending strength and fracture toughness are also improved.

[0032] 2、The modified mullite introduces manganese-iron oxides to form new composite phases such as spinel phases with the mullite matrix, and the new phases can be dispersedly distributed between the mullite grains, effectively inhibiting crack propagation, changing the lattice constant and bond strength, finely controlling the thermal expansion coefficient, and improving the thermal shock resistance of the material.

[0033] 3、The titanium dioxide coating layer on the surface of the epidote-titanium dioxide composite material can form a strong bonding interface between the epidote particles and the matrix, reduce the interface defects and stress concentration, and improve the interface bonding strength, which helps to more uniformly transmit the load to the epidote particles, thereby improving the bending strength of the overall material.

[0034] 4. The quaternized alkali lignin in the modified silica of this invention will carbonize during high-temperature sintering. The resulting carbon skeleton can form a stable carbon-silicon composite structure with silica. The carbon-silicon composite structure has strong interfacial bonding force, which can hold the crack tip and prevent the crack from propagating rapidly, thereby improving the fracture toughness of the material. Detailed Implementation

[0035] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0036] The sources of some components in the examples and comparative examples are as follows:

[0037] Commercially available mullite, CAS No. 37287-16-4, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0038] Commercially available iolite, model CO2200, purchased from Kyocera, Japan;

[0039] Silicon carbide, CAS No. 409-21-2, purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0040] Commercially available silica I, product number S433693, with a particle size of 20nm, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0041] Commercially available silica II, product number S433669, with a particle size of 500 nm, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0042] Zirconia, CAS No. 1314-23-4, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0043] Polyvinyl alcohol, product number P139540, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0044] Carboxymethyl cellulose, CAS No. 9004-32-4, was purchased from Shanghai Maclean Biochemical Technology Co., Ltd.

[0045] Polyethylene glycol, product number P103728, was purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.

[0046] Ferrous chloride, CAS No. 7758-94-3, was purchased from Sinopharm Chemical Reagent Co., Ltd.

[0047] Potassium permanganate, CAS No. 7722-64-7, purchased from Sinopharm Chemical Reagent Co., Ltd.

[0048] Ammonium oxalate, CAS No. 6009-70-7, purchased from Shanghai Macklin Biochemical Technology Co., Ltd.;

[0049] Titanium sulfate solution, product No. T432017, mass concentration fraction 15%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0050] Alkaline lignin, CAS No. 8068-05-1, purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0051] (3-chloro-2-hydroxypropyl) trimethylammonium chloride solution, product No. C120679, mass concentration fraction 60%, purchased from Shanghai Aladdin Biochemical Technology Co., Ltd.;

[0052] Sodium dodecylbenzenesulfonate, CAS No. 25155-30-0, purchased from Sinopharm Chemical Reagent Co., Ltd.;

[0053] Example 1

[0054] The embodiment provides a preparation method of a high thermal shock resistance material for a return valve,

[0055] comprising the following steps:

[0056] Step S1: 95 parts of modified mullite, 10 parts of cordierite-titanium dioxide composite material, 4 parts of silicon carbide, 8 parts of modified silicon dioxide, 3 parts of zirconium oxide, 12 parts of binder (8 parts of polyvinyl alcohol and 4 parts of carboxymethyl cellulose) and 0.6 parts of polyethylene glycol are mixed, and then deionized water is added for wet grinding for 40h to obtain a mixed slurry;

[0057] Step S2: the mixed slurry is subjected to spray drying, sintering at 1300℃, and furnace cooling to obtain the high thermal shock resistance material for the return valve.

[0058] Preparation of the modified mullite: 8 parts of ferrous chloride are added to 1000 parts of deionized water for complete dissolution, then 30 parts of commercially available mullite is impregnated for 4h, and dried to obtain iron-containing mullite; 5 parts of potassium permanganate is dissolved in 300 parts of deionized water, 30 parts of the iron-containing mullite is added, and then 100 parts of 5% ammonium oxalate aqueous solution is added for modification treatment, the pH is adjusted to 7.4, and the oscillation is performed at 90℃ and at a speed of 200r / min for 10h, and then dried to obtain the modified mullite.

[0059] Preparation of the cordierite-titanium dioxide composite material: 10 parts of cordierite was added to 100 parts of 20% oxalic acid solution in mass concentration fraction, heated at 90℃ for 1h, filtered, dried, calcined at 540℃ for 6h, cooled to room temperature to obtain pretreated cordierite; the pH of 300 parts of 15% titanyl sulfate solution in mass concentration fraction was adjusted to 7.6 with ammonia water, filtered, washed with water, and then the precipitate was added to 1000 parts of deionized water for aging treatment, heated to 80℃, and then the pH was adjusted to 2.2 with 10% nitric acid solution in mass concentration fraction, aged for 12h, and the pH was adjusted to 6.2 with ammonia water to obtain a titanium dioxide sol; 10 parts of the pretreated cordierite was immersed in 300 parts of the titanium dioxide sol for surface coating, stirred at room temperature for 40min, and then aged for 12h, dried, and calcined at 600℃ for 3h to obtain the cordierite-titanium dioxide composite material.

[0060] Preparation of the modified silica: (1) 16 parts of alkali lignin was added to 100 parts of 60% (3-chloro-2-hydroxypropyl) trimethylammonium chloride solution in mass concentration fraction, mixed well, and then 40 parts of 20% sodium hydroxide solution in mass concentration fraction was added, reacted at 90℃ for 3h, dialyzed and purified, rotary evaporated, and freeze-dried to obtain quaternary ammonium alkali lignin; 200 parts of deionized water and 500 parts of anhydrous ethanol were mixed uniformly, and then 16 parts of quaternary ammonium alkali lignin and 0.4 parts of sodium dodecyl benzene sulfonate were stirred uniformly, and 16 parts of commercially available silica I (item number S433693, particle size 20nm) was added for hydrothermal reaction, hydrothermal reaction was carried out at 160℃ for 60min, cooled to room temperature, centrifuged, and dried to obtain modified silica.

[0061] Example 2

[0062] The present embodiment provides a preparation method of a high thermal shock resistance material for a return valve,

[0063] comprising the following steps:

[0064] Step S1: 85 parts of modified mullite, 6 parts of cordierite-titanium dioxide composite material, 2 parts of silicon carbide, 4 parts of modified silica, 1 part of zirconia, 8 parts of binder (4 parts of polyvinyl alcohol and 4 parts of carboxymethyl cellulose), and 0.2 parts of polyethylene glycol were mixed, and then deionized water was added for wet grinding for 30h to obtain a mixed slurry;

[0065] Step S2: the mixed slurry was spray dried, sintered at 1200℃, and cooled in the furnace to obtain a high thermal shock resistance material for a return valve.

[0066] The preparation of the modified mullite: 6 parts of ferrous chloride is added into 900 parts of deionized water to be dissolved thoroughly, then 20 parts of commercially available mullite is added to be impregnated for 2 hours, and dried to obtain iron-containing mullite; 3 parts of potassium permanganate is dissolved in 200 parts of deionized water, 20 parts of the iron-containing mullite is added, and 90 parts of 3% ammonium oxalate aqueous solution is added to be modified, the pH is adjusted to 7.2, and the oscillation is carried out at 80℃ and at a speed of 160r / min for 10 hours, and dried to obtain the modified mullite.

[0067] The preparation of the cordierite-titanium dioxide composite material: 6 parts of cordierite is added into 80 parts of 10% oxalic acid solution, heated at 80℃ for 3 hours, filtered, dried, calcined at 500℃ for 8 hours, and cooled to room temperature to obtain pretreated cordierite; the pH of 200 parts of 15% titanyl sulfate solution is adjusted to 7.2 with ammonia water, filtered, washed with water, and then the precipitate is added into 900 parts of deionized water to be aged, heated to 70℃, and then the pH is adjusted to 1.8 with 8% nitric acid solution, aged for 12 hours, and adjusted to pH 5.8 with ammonia water to obtain titanium dioxide sol; 6 parts of the pretreated cordierite is immersed in 200 parts of the titanium dioxide sol to be coated, stirred at room temperature for 30 minutes, and then aged for 10 hours, dried, and calcined at 580℃ for 5 hours to obtain the cordierite-titanium dioxide composite material.

[0068] The preparation of the modified silica: (1) 10 parts of alkali lignin is added into 90 parts of 60% (3-chloro-2-hydroxypropyl) trimethylammonium chloride solution to be mixed thoroughly, and then 30 parts of 16% sodium hydroxide solution is added to react at 80℃ for 5 hours, purified by dialysis, rotary evaporated, and freeze-dried to obtain quaternary ammonium alkali lignin; 100 parts of deionized water and 400 parts of anhydrous ethanol are mixed uniformly, and then 10 parts of the quaternary ammonium alkali lignin and 0.2 parts of sodium dodecyl benzene sulfonate are added to be stirred uniformly, and then 10 parts of commercially available silica I (item number S433693, particle size of 20nm) is added to be hydrothermally reacted at 156℃ for 80 minutes, cooled to room temperature, centrifuged, and dried to obtain the modified silica.

[0069] Example 3

[0070] The present embodiment provides a preparation method of a high-thermal-shock-resistant material for a return valve,

[0071] comprising the following steps:

[0072] Step S1: 90 parts of modified mullite, 8 parts of zoisite-titanium dioxide composite material, 3 parts of silicon carbide, 6 parts of modified silicon dioxide, 2 parts of zirconia, 10 parts of binder (6 parts of polyvinyl alcohol and 4 parts of carboxymethyl cellulose) and 0.4 parts of polyethylene glycol were mixed, and then deionized water was added for wet grinding for 35 h to obtain a mixed slurry;

[0073] Step S2: The mixed slurry was subjected to spray drying, sintering at 1250°C, and furnace cooling to obtain a high thermal shock resistant material for a return valve.

[0074] Preparation of the modified mullite: 7 parts of ferrous chloride was added to 950 parts of deionized water to dissolve completely, and then 25 parts of commercially available mullite was immersed for 3 h, and dried to obtain iron-containing mullite; 4 parts of potassium permanganate was dissolved in 250 parts of deionized water, 25 parts of the iron-containing mullite was added, and then 95 parts of 4% ammonium oxalate aqueous solution was added for modification treatment, the pH was adjusted to 7.3, and the mixture was oscillated at 85°C and 180 r / min for 9 h, and then dried to obtain the modified mullite.

[0075] Preparation of the zoisite-titanium dioxide composite material: 8 parts of zoisite was added to 90 parts of 15% oxalic acid solution, heated at 85°C for 2 h, filtered, dried, and calcined at 520°C for 7 h to obtain pretreated zoisite; the pH of 250 parts of 15% titanyl sulfate solution was adjusted to 7.4 with ammonia water, filtered, washed with water, and then the precipitate was added to 950 parts of deionized water for aging treatment, the temperature was increased to 75°C, and then the pH was adjusted to 1.9 with 9% nitric acid solution, and aged for 11 h, and then the pH was adjusted to 5.9 with ammonia water to obtain a titanium dioxide sol; 8 parts of the pretreated zoisite was immersed in 250 parts of the titanium dioxide sol for surface coating, stirred at room temperature for 35 min, and then aged for 11 h, dried, and calcined at 590°C for 4 h to obtain the zoisite-titanium dioxide composite material.

[0076] Preparation of the modified silica: (1) 12 parts of alkali lignin was added into 95 parts of (3-chloro-2-hydroxypropyl) trimethylammonium chloride solution with a mass concentration fraction of 60% and mixed well, then 35 parts of sodium hydroxide solution with a mass concentration fraction of 18% was added, and the mixture was reacted at 85°C for 4h, purified by dialysis, rotary evaporation, and freeze-drying to obtain quaternary ammonium alkali lignin; 150 parts of deionized water and 450 parts of anhydrous ethanol were mixed uniformly, then 12 parts of quaternary ammonium alkali lignin and 0.3 parts of sodium dodecyl benzene sulfonate were added and stirred uniformly, and 12 parts of commercially available silica I (item number S433693, particle size of 20nm) was added for hydrothermal reaction, and the mixture was hydrothermally reacted at 158°C for 70min, cooled to room temperature, centrifuged, and dried to obtain modified silica.

[0077] Comparative Example 1

[0078] The difference between this comparative example and Example 1 is that commercially available mullite (CAS No. 37287-16-4) is used instead of modified mullite.

[0079] Comparative Example 2

[0080] The difference between this comparative example and Example 1 is that the amount of polyvinyl alcohol in the binder is changed to 10 parts, and the amount of carboxymethyl cellulose is changed to 2 parts.

[0081] Comparative Example 3

[0082] The difference between this comparative example and Example 1 is that the amount of polyvinyl alcohol in the binder is changed to 4 parts, and the amount of carboxymethyl cellulose is changed to 8 parts.

[0083] Comparative Example 4

[0084] The difference between this comparative example and Example 1 is that commercially available coptite (model CO2200) is used instead of coptite-titanium dioxide composite material.

[0085] Comparative Example 5

[0086] The difference between this comparative example and Example 1 is that commercially available silica I is used instead of modified silica.

[0087] Comparative Example 6

[0088] The difference between this comparative example and Example 1 is that commercially available silica II is used instead of commercially available silica I to prepare modified silica.

[0089] Performance test

[0090] The return valve of the above examples and comparative examples was tested with high heat shock resistance material as follows:

[0091] (1) Thermal shock resistance test: tested according to the requirements of GB / T 30873-2014 Test Method of Thermal Shock Resistance of Refractory Materials.

[0092] (2) Bending strength test: tested according to the requirements of GB / T 6569-2006 Test Method of Bending Strength of Fine Ceramics.

[0093] (3) Fracture toughness test: tested according to the requirements of GB / T 23806-2009 Test Method of Fracture Toughness of Fine Ceramics Single Edge Pre-cracked Beam (SEPB) Method.

[0094] Table 1 Performance test results

[0095]

[0096] From the above performance test results, it can be seen that the high thermal shock resistance material for return valve of Examples 1-3 has the best comprehensive performance, the thermal shock resistance is 46-49 times, the bending strength is 559-564 MPa, and the fracture toughness is 6.4-6.8 MPa.m 1 / 2 ; this is mainly because the main component of the thermal shock resistance material, mullite, is modified, and cordierite-titanium dioxide composite material and modified silicon dioxide are introduced, and the various components synergistically act to achieve good thermal shock resistance, significantly improve the bending strength, and increase the fracture toughness.

[0097] Compared with Example 1, Comparative Example 1 uses commercially available mullite (CAS No. 37287-16-4) instead of modified mullite, the thermal shock resistance is poor, the bending strength is reduced, and the fracture toughness is reduced; compared with Example 1, Comparative Example 2 changes the amount of polyvinyl alcohol in the binder to 10 parts and the amount of carboxymethyl cellulose to 2 parts, the amount of polyvinyl alcohol is too much, the compounding effect is not good, the thermal shock resistance is poor, the bending strength is reduced, and the fracture toughness is reduced; compared with Example 1, Comparative Example 3 changes the amount of polyvinyl alcohol in the binder to 4 parts and the amount of carboxymethyl cellulose to 8 parts, the amount of polyvinyl alcohol is too little, the compounding effect is not good, the thermal shock resistance is poor, the bending strength is reduced, and the fracture toughness is reduced; compared with Example 1, Comparative Example 4 uses commercially available cordierite (model CO2200) instead of cordierite-titanium dioxide composite material, the thermal shock resistance is poor, the bending strength is reduced, and the fracture toughness is reduced; compared with Example 1, Comparative Example 5 uses commercially available silicon dioxide I instead of modified silicon dioxide, the thermal shock resistance is poor, the bending strength is reduced, and the fracture toughness is reduced; compared with Example 1, Comparative Example 6 uses commercially available silicon dioxide II instead of commercially available silicon dioxide I to prepare modified silicon dioxide, because the particle size of commercially available silicon dioxide II is too large, the modification effect is not good, the thermal shock resistance is poor, the bending strength is reduced, and the fracture toughness is reduced.

Claims

1. A high thermal shock resistance material for a return valve, characterized in that, comprising the following components in parts by weight: 85-95 parts of modified mullite, 6-10 parts of cordierite, 2-4 parts of silicon carbide, 4-8 parts of silicon dioxide, 1-3 parts of zirconium oxide, 8-12 parts of a binder, and 0.2-0.6 parts of polyethylene glycol. The preparation method of the modified mullite comprises: adding 6-8 parts of ferrous chloride into 900-1000 parts of deionized water to dissolve thoroughly, then adding 20-30 parts of commercially available mullite to soak for 2-4 hours, and drying to obtain iron-containing mullite; dissolving 3-5 parts of potassium permanganate in 200-300 parts of deionized water, adding 20-30 parts of the iron-containing mullite, and adding 90-100 parts of an ammonium oxalate aqueous solution with a mass concentration fraction of 3-5% to perform a modification treatment, to obtain the modified mullite. 2.The high thermal shock resistance material for a return valve according to claim 1, characterized in that, the modification treatment conditions comprise: adjusting the pH to 7.2-7.4, oscillating at a speed of 160-200 r / min for 8-10 hours at 80-90 ℃, and drying. 3.The high thermal shock resistance material for a return valve according to claim 1, characterized in that, the cordierite is a cordierite-titanium dioxide composite material. The preparation method of the cordierite-titanium dioxide composite material comprises: treating 6-10 parts of commercially available cordierite to obtain pretreated cordierite; adjusting the pH of 200-300 parts of a titanium dioxide sulfate solution with a mass concentration fraction of 15% to 7.2-7.6 with ammonia water, filtering, washing with water, then adding the precipitate to 900-1000 parts of deionized water to perform an aging treatment, to obtain a titanium dioxide sol; immersing 6-10 parts of the pretreated cordierite in 200-300 parts of the titanium dioxide sol to perform surface coating, to obtain the cordierite-titanium dioxide composite material. 4.The high thermal shock resistance material for a return valve according to claim 3, characterized in that, the surface treatment conditions comprise: adding 6-10 parts of cordierite to 80-100 parts of oxalic acid solution with a mass concentration fraction of 10-20%, heating at 80-90 ℃ for 1-3 hours, filtering, drying, and calcining at 500-540 ℃ for 6-8 hours, and cooling to room temperature. 5.The high thermal shock resistance material for a return valve according to claim 3, characterized in that, the aging treatment conditions comprise: warming to 70-80 ℃, then adjusting the pH to 1.8-2.2 with a nitric acid solution with a mass concentration fraction of 8-10%, and aging for 10-12 hours, and adjusting the pH to 5.8-6.2 with ammonia water. 6.The high thermal shock resistance material for a return valve according to claim 3, characterized in that, the surface coating conditions comprise: stirring at room temperature for 30-40 minutes, then aging and coating for 10-12 hours, drying, and calcining at 580-600 ℃ for 3-5 hours. 7.The high thermal shock resistance material for a return valve according to claim 1, characterized in that, the silicon dioxide is modified silicon dioxide. ​ ​ ​ ​ ​ ​ ​ The preparation method of the modified silicon dioxide comprises the following steps: uniformly mixing 100-200 parts of deionized water and 400-500 parts of anhydrous ethanol by weight, then uniformly stirring 10-16 parts of quaternary ammonium alkali lignin and 0.2-0.4 parts of sodium dodecyl benzene sulfonate, then adding 10-16 parts of commercially available silicon dioxide to perform hydrothermal reaction, and obtaining modified silicon dioxide. The particle size of the commercially available silicon dioxide is 10-50 nm.

8. The high thermal shock resistance material for a return valve according to claim 7, characterized in that, The preparation method of the quaternary ammonium alkali lignin comprises the following steps: adding 10-16 parts of alkali lignin to 90-100 parts of a (3-chloro-2-hydroxypropyl) trimethylammonium chloride solution with a mass concentration of 60%, then adding 30-40 parts of a sodium hydroxide solution with a mass concentration of 16-20%, and reacting at 80-90 DEG C for 3-5 h, and then performing dialysis purification, rotary evaporation, and freeze drying to obtain the quaternary ammonium alkali lignin.

9. The high thermal shock resistance material for a return valve according to claim 1, characterized in that, The binder is polyvinyl alcohol and carboxymethyl cellulose, and the mass ratio of polyvinyl alcohol to carboxymethyl cellulose in the binder is (1-2):

1.

10. A preparation method of the high thermal shock resistance material for a return valve according to any one of claims 1-9, characterized in that, The preparation method comprises the following steps: Step S1: uniformly mixing 85-95 parts of modified mullite, 6-10 parts of cordierite, 2-4 parts of silicon carbide, 4-8 parts of silicon dioxide, 1-3 parts of zirconia, 8-12 parts of a binder, and 0.2-0.6 parts of polyethylene glycol by weight, then adding deionized water to perform wet grinding for 30-40 h to obtain a mixed slurry; Step S2: performing spray drying on the mixed slurry, sintering at 1200-1300 DEG C, and cooling in the furnace to obtain the high thermal shock resistance material for a return valve.

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