High-performance corundum-based repair material and method for producing same

Abstract

The application discloses high-performance corundum-based repairing material and a preparation method thereof, and belongs to the technical field of furnace lining repairing material, and comprises the following preparation raw materials in mass parts: 60-80 parts of aggregate, 10-30 parts of powder, 8-20 parts of binder and 0.5-2 parts of additive; the aggregate comprises fused white corundum and fused magnesium-aluminum spinel; the powder comprises white corundum powder, rare earth modified alumina powder and boride. The preparation method of the high-performance corundum-based repairing material comprises the following steps: uniformly adding the powder into the aggregate, adding the organic binder, then adding the silica sol, and finally adding the additive. The high-performance corundum-based repairing material has high early strength and still has a long working life under a high-temperature environment.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of furnace lining repair material, and particularly relates to a high-performance corundum-based repair material and a preparation method thereof. BACKGROUND

[0002] In the high-temperature industrial field of metallurgy, non-ferrous metals and the like, the kiln lining is subjected to the combined damage of high temperature, thermal shock and strong corrosion for a long time, and the repair material is required to have the performance requirements of "fast hardening, early strength, medium-high temperature strength and long-term service" which are coherent and contradictory. However, the existing corundum-based repair material has three defects which are difficult to reconcile, resulting in that it is difficult to meet the above requirements: (1) structural defect: the thermal expansion coefficient of corundum is high, stress is concentrated in the heating-cooling cycle, and cracks and peeling are easily caused; (2) protection defect: there is a lack of stable and dispersed anti-corrosion phase in the system, and once the repair layer contacts with slag or alloy melt, the repair layer is rapidly penetrated and eroded, and the service life is short and the maintenance is frequent; (3) strength evolution defect: if the early strength is emphasized, the organic binder or high-reactivity fine powder is mainly used, although the mold can be removed within a few hours, but the high-temperature carbonization of the organic matter causes large shrinkage, resulting in cracking in the later period; if the medium-high temperature strength is emphasized, the dense corundum-mullite structure is tended, but the sintering shrinkage and abnormal grain growth cause low early strength, the repair material cannot be used immediately after repair, and the strength is suddenly reduced after the deterioration of the crystal phase, so that the long-term service is difficult.

[0003] The traditional improvement idea is to introduce rigid fibers or high-strength inorganic particles into the matrix, hoping to simultaneously improve the toughness and corrosion resistance. However, the difference between these reinforcing phases and the corundum matrix in thermal expansion coefficient causes additional stress due to the thermal mismatch at the interface, which becomes a crack source; the chemical compatibility of the two is poor at high temperature, and the interface reaction generates a brittle phase, which cannot play the role of grain refinement or strengthening; the organic complex system can improve the low-temperature workability, but it aggravates the high-temperature carbonization shrinkage, and the volume change of the reinforcing phase is superimposed, further increasing the cracking risk. SUMMARY

[0004] The present application is to overcome the above technical problems, and therefore provides a high-performance corundum-based repair material and a preparation method thereof. The high-performance corundum-based repair material has high early strength and still has a long working life in a high-temperature environment.

[0005] The present application solves the above technical problems through the following technical solutions.

[0006] The present application discloses a high-performance corundum-based repair material, which comprises the following preparation raw materials in mass fraction: 60-80 parts of aggregate, 10-30 parts of powder, 8-20 parts of binder and 0.5-2 parts of additive.

[0007] Preferably, the high-performance corundum-based repair material comprises the following preparation raw materials in mass fraction: 60-75 parts of aggregate, 15-25 parts of powder, 8-15 parts of binder and 0.5-1.5 parts of additive.

[0008] The aggregate comprises electrically fused white corundum and electrically fused magnesium aluminate spinel;

[0009] The powder comprises white corundum powder, rare earth modified alumina powder and boride;

[0010] The binder is silica sol and organic binder; the organic binder is phenolic resin and polyethylene glycol;

[0011] The additive is 0.2-0.8 parts of water reducing agent, 0.2-0.7 parts of dispersant and 0-0.5 parts of plasticizer.

[0012] According to some embodiments of the present application, the aggregate is 10-30 wt% electrically fused magnesium aluminate spinel and the balance electrically fused white corundum; preferably, the aggregate is 15-28 wt% electrically fused magnesium aluminate spinel and the balance electrically fused white corundum.

[0013] According to some embodiments of the present application, the powder is 15-30 wt% rare earth modified alumina powder, 3-18 wt% boride and the balance white corundum powder; preferably, the powder is 15-23 wt% rare earth modified alumina powder, 6-15 wt% boride and the balance white corundum powder.

[0014] According to some embodiments of the present application, the chemical composition of the electrically fused white corundum, by mass fraction, is: Al2O3≥98.5%, Fe2O3≤0.08%, Na2O≤0.40%, SiO2≤0.08%.

[0015] According to some embodiments of the present application, the bulk density of the electrically fused white corundum is 3.6-3.88 g / cm 3 .

[0016] The chemical composition of the electrically fused magnesium aluminate spinel, by mass fraction, is: 70-77% Al2O3, 22-28% MgO, SiO2≤0.6%, Fe2O3≤0.4%.

[0017] According to some embodiments of the present application, the bulk density of the electrically fused magnesium aluminate spinel is ≥3.2 g / cm 3 .

[0018] According to some embodiments of the present application, the D50 of the white corundum powder is 20-50 μm, preferably 28-45 μm.

[0019] According to some embodiments of the present application, the rare earth modified alumina powder is lanthanum oxide modified alumina powder, and the rare earth modified alumina powder contains 3-5 wt% La2O3 and the balance alumina.

[0020] According to some embodiments of the present application, the D50 of the rare earth modified alumina powder is 3-6 μm.

[0021] According to some embodiments of the present application, the boride is titanium boride or tungsten boride.

[0022] According to some embodiments of the present application, the particle size of the boride is 0.8-10 μm.

[0023] According to some embodiments of the present application, the binder is 5-12 parts of silica sol and 3-7 parts of organic binder.

[0024] According to some embodiments of the present application, the silica sol is a colloid formed by uniform diffusion of silica nanoparticles in water.

[0025] According to some embodiments of the present application, the pH of the silica sol is 9-11, preferably 9-10.

[0026] According to some embodiments of the present application, in the silica sol, SiO2 is 20-40 wt%, and Na2O is ≤0.5 wt%; preferably, in the silica sol, SiO2 is 25-35 wt%, and Na2O is ≤0.3 wt%.

[0027] According to some embodiments of the present application, the D50 of the silica nanoparticles in the silica sol is 10-20 nm.

[0028] According to some embodiments of the present application, the water reducing agent is a polycarboxylic acid type water reducing agent.

[0029] According to some embodiments of the present application, the plasticizer is dibutyl phthalate, dioctyl sebacate or epoxy soybean oil.

[0030] According to some embodiments of the present application, the dispersant is sodium hexametaphosphate, sodium tripolyphosphate or sodium pyrophosphate.

[0031] According to some embodiments of the present application, the maximum working temperature of the high-performance corundum-based repair material is 1700-1750 °C.

[0032] According to some embodiments of the present application, the compressive strength of the high-performance corundum-based repair material is 60-100 MPa, preferably 80-100 MPa.

[0033] According to some embodiments of the present application, the bulk density of the high-performance corundum-based repair material is 2.70-2.85 g / cm 3 ; preferably, the bulk density of the high-performance corundum-based repair material is 2.75-2.85 g / cm 3 .

[0034] According to some embodiments of the present application, the high-performance corundum-based repair material has a compressive strength of 35-50 MPa after 20-40 cycles at a maximum temperature of 1600-1750 DEG C.

[0035] According to some embodiments of the present application, the high-performance corundum-based repair material has a bulk density of 2.4-2.6 g / cm after 20-40 cycles at a maximum temperature of 1700-1750 DEG C. 3 .

[0036] The application discloses a preparation method of high-performance corundum-based repair material, which comprises the following steps: uniformly mixing dry powders with aggregates, adding an organic binder, then adding silica sol, and finally adding additives.

[0037] The raw materials of the aggregates and the powders need to be pretreated, and the qualified pretreatment step can ensure the consistency and quality of the high-performance corundum-based repair material product.

[0038] The pretreatment is to remove impurities from the raw materials of the aggregates and the powders, respectively, and then screen the raw materials 2-3 times through a 300-400 mesh sieve, and dry the raw materials at 80-100 DEG C to control the water content to be less than or equal to 0.5%; the raw materials of the aggregates are dry-mixed in a mixer for 3-5 min to obtain the aggregates, and the raw materials of the powders are dry-mixed in a mixer for 5-8 min to obtain the powders.

[0039] The silica sol is added dropwise, and the dropping speed is 5-10 mL / min.

[0040] The application further discloses a construction process of the high-performance corundum-based repair material, which comprises daubing construction, pouring construction and spraying construction.

[0041] The application further discloses an application of the high-performance corundum-based repair material in lining repair of a medium-frequency furnace, a metallurgical furnace, a vacuum furnace or a casting transfer ladle, in particular, in lining repair of a medium-frequency induction furnace.

[0042] On the basis of common knowledge in the art, the above-mentioned preferred conditions can be combined at will to obtain various preferred examples of the present application.

[0043] Compared with the prior art, the present application has the following beneficial effects:

[0044] 1. The aggregates of the present application are electrically fused magnesium-aluminum spinel and electrically fused white corundum, the spinel and the corundum form a magnesium-aluminum spinel solid solution at high temperature to relieve thermal stress, and the microporous structure of the spinel blocks the penetration of molten slag; the electrically fused white corundum provides a high-strength framework, so that the repair material still has high strength after working under high-temperature conditions; the rare earth modified alumina powder in the powders can refine the corundum and inhibit the migration of the grain boundary; and the boride forms a glass phase covering layer at high temperature to strengthen the interfacial bonding.

[0045] 2. The binder system of the present application is a combination of alkaline silica sol and organic binder. The organic binder has good adhesion at room temperature, and the processing performance of the repair material is good. At high temperature, the binder forms a Si-O-C crosslinking network, thus avoiding the situation of "debinding at room temperature and cracking at high temperature".

[0046] 3. The high-performance corundum-based repair material of the present application is used for high-temperature resistance with high compressive strength, and even after 20-40 high-temperature cycles, it can still maintain high compressive strength. For example, after 30 cycles at 1750°C, the compressive strength of the repair material sample is 35-50 MPa, according to some embodiments of the present application, 36-47 MPa, and in some preferred embodiments, 40-47 MPa. After 30 cycles at 1750°C, the bulk density of the repair material sample is 2.40-2.60 g / cm 3 , according to some embodiments of the present application, 2.43-2.59 g / cm 3 , and in some preferred embodiments, 2.50-2.59 g / cm 3 . DETAILED DESCRIPTION

[0047] In order to facilitate the understanding of the present application, the following will make a more comprehensive and detailed description of the present application in combination with the preferred embodiments, but the protection scope of the present application is not limited to the following specific embodiments.

[0048] Unless otherwise defined, all the professional terms used in the following have the same meaning as generally understood by those skilled in the art. The professional terms used in the present application are only for the purpose of describing the specific embodiments, and are not intended to limit the protection scope of the present application.

[0049] The ranges disclosed herein are intended to be "open" ranges, unless expressly specified otherwise. For example, a range of "1 to 10" is intended to include all whole numbers and fractions within this range, e.g., 1, 1.1, 1.2.,..., 10. Similarly, a range of "5-10" is intended to include, 5, 5.1, 5.2,..., 10. Also, the ranges disclosed herein are intended to be "inclusive" of the minimum and maximum values, unless specifically indicated otherwise. For example, a range of "between 1 and 10" is intended to include the values of 1 and 10. Also, when referring to a parameter as being an integer, it is understood that the parameter can be, for example, an integer of 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, etc.

[0050] All embodiments and optional embodiments of the present application can be combined with each other to form new technical solutions, unless otherwise specified.

[0051] All technical features and optional technical features of the present application can be combined with each other to form new technical solutions, unless otherwise specified.

[0052] All steps of the present application can be performed in sequence or randomly, preferably in sequence, unless otherwise specified. For example, the method comprises steps (a) and (b), which means that the method can comprise steps (a) and (b) in sequence, or steps (b) and (a) in sequence. For example, the method can further comprise step (c), which means that step (c) can be added to the method in any order, for example, the method can comprise steps (a), (b) and (c), or steps (a), (c) and (b), or steps (c), (a) and (b), etc.

[0053] Unless otherwise specified, "including" and "comprising" mentioned in the present application means open-ended, and can also be closed-ended. For example, "including" and "comprising" can mean that other components not listed can also be included or contained, or only the listed components can be included or contained.

[0054] If not otherwise specifically defined, the term "or" in the present invention is inclusive. For example, the phrase "A or B" means "A, B, or both A and B." More specifically, any of the following satisfy the condition "A or B": A is true (or present) and B is false (or not present); A is false (or not present) and B is true (or present); or both A and B are true (or present).

[0055] The raw material information used in the following examples is as follows:

[0056] The electrofused white corundum (fine powder) was purchased from Zhengzhou Haixu Abrasive Co., Ltd., and its chemical composition was: Al2O3≥98.5%, Fe2O3≤0.08%, Na2O≤0.40%, SiO2≤0.08%; and its bulk density was 3.6 g / cm 3 ;

[0057] The electrofused magnesium aluminate spinel was purchased from Sanmenxia Shuntai Electrofused Corundum Co., Ltd., and its chemical composition was: 70-77% Al2O3, 22-28% MgO, SiO2≤0.6%, Fe2O3≤0.4%; and its bulk density was 3.2 g / cm 3 ;

[0058] The white corundum powder was purchased from Henan Sicheng Abrasive Technology Co., Ltd. F240, and its D50=44.5±2.0 μm;

[0059] The rare earth modified alumina powder was purchased from Suzhou Zhengde Rare Earth Materials Co., Ltd., and its chemical composition was 4% La2O3 and 95% Al2O3, and its D50=3-6 μm;

[0060] The tungsten diboride was purchased from Jinzhou Haixin Metal Material Co., Ltd., and its D50=8.3 μm;

[0061] The titanium diboride was purchased from Jiamai New Material Co., Ltd., and its D50=8.4 μm;

[0062] The silica sol was purchased from Qingdao Jiyida Silicon Sol Reagent Co., Ltd. JN25 alkaline silica sol, which contained 25-26% SiO2, Na2O≤0.3%, and its pH was 9-10, and its density was 1.15-1.17 g / cm 3 , and the average particle size of the nanosilica was 10-20 nm;

[0063] The phenolic resin was purchased from Hebei Zetian Chemical Co., Ltd. PF900B, and its viscosity (25°C) was 1500-3000 cp, its free phenol was 9-12%, its solid content was 76-81%, and its residual carbon≥35%;

[0064] including but not limited to the above manufacturers and models.

[0065] Example 1

[0066] 1. The high-performance corundum-based repair material of this embodiment has the following composition: 70 parts of aggregate, 20.5 parts of powder, 12.5 parts of binder, and 1.1 parts of additive;

[0067] In this embodiment, the aggregate is 18 wt% of fused magnesio-alumina spinel and the balance is fused white corundum;

[0068] In this embodiment, the powder is 20.8 wt% of rare earth modified alumina powder, 11.3 wt% of boride (titanium diboride), and the balance is white corundum powder;

[0069] In this embodiment, the binder is 8.2 parts of silica sol and 4.3 parts of organic binder; the organic binder is phenolic resin and polyethylene glycol (PEG400), and the mass ratio of phenolic resin to polyethylene glycol is 4:1;

[0070] In this embodiment, the additive is 0.4 parts of polycarboxylic acid water reducer (Jiangsu Subote New Material Co., Ltd. PCA-I), 0.4 parts of plasticizer (dibutyl phthalate), and 0.3 parts of dispersant (sodium hexametaphosphate);

[0071] 2. The preparation method of the high-performance corundum-based repair material of this embodiment is as follows:

[0072] Pre-treatment: remove impurities from the raw materials of the aggregate and the powder, then sieve twice with a 400-mesh sieve, and dry at 100°C to control the water content to 0.2%; dry mix the preparation raw materials of the aggregate in a blender for 3 min to obtain the aggregate, and then dry mix the preparation raw materials of the powder in a blender for 5 min to obtain the powder;

[0073] Add the powder to the aggregate and stir for 5 min at 300 rpm for dry mixing; add the organic binder and continue stirring for 3 min; then add the silica sol at a drop rate of 5 mL / min, keep stirring during the process, stir for another 10 min after the drop is completed, and finally add the additive and stir for 8 min to obtain the high-performance corundum-based repair material.

[0074] Example 2

[0075] The difference between this embodiment and Example 1 is that:

[0076] The aggregate is 26.4 wt% of fused magnesio-alumina spinel and the balance is fused white corundum;

[0077] The other raw materials, steps, and parameters are the same as in Example 1.

[0078] Example 3

[0079] The difference between this embodiment and Example 1 is that:

[0080] The powder is 15.7% of rare earth modified alumina powder, 8.6% of boride, and the balance is white corundum powder;

[0081] Other raw materials, steps and parameters are the same as in Example 1.

[0082] Example 4

[0083] The difference between this example and Example 1 is that:

[0084] The powder is 10.7 wt% rare earth modified alumina powder, 18.1 wt% boride and the balance white corundum powder;

[0085] Other raw materials, steps and parameters are the same as in Example 1.

[0086] Example 5

[0087] The difference between this example and Example 1 is that:

[0088] The diboride in this example is tungsten diboride;

[0089] Other raw materials, steps and parameters are the same as in Example 1.

[0090] Example 6

[0091] The difference between this example and Example 1 is that:

[0092] The binder in this example is 3.8 parts of silica sol and 8.7 parts of organic binder;

[0093] Other raw materials, steps and parameters are the same as in Example 1.

[0094] Example 7

[0095] The difference between this example and Example 1 is that:

[0096] The binder in this example is only organic binder, without silica sol;

[0097] Other raw materials, steps and parameters are the same as in Example 1.

[0098] Comparative Example 1

[0099] The difference between this example and Example 1 is that:

[0100] The powder in the aggregate of this example is 25 wt% rare earth modified alumina powder and the balance white corundum powder;

[0101] Other raw materials, steps and parameters are the same as in Example 1.

[0102] Comparative Example 2

[0103] The difference between this example and Example 1 is that:

[0104] The powder is 10.4wt% boride (titanium diboride) and the balance white corundum powder, i.e. the powder does not contain rare earth modified alumina powder;

[0105] The other raw materials, steps and parameters are the same as in Example 1.

[0106] Test example - high temperature cycle test

[0107] (1) Sample preparation: The high-performance corundum-based repair material prepared in the above examples and comparative examples was used to prepare a cylindrical sample with a diameter of 50 mm and a height of 50 mm on a pressure testing machine at a pressure of 80 MPa. After demolding, the sample was dried at 100°C for 24 h;

[0108] (2) Heat treatment test: heating to 1750°C for 3 h, then cooling to room temperature in the furnace, and repeating this heat treatment step 30 times. The performance of the sample was tested after the first heat treatment and the tenth heat treatment, and the performance change before and after the highest temperature (1750°C) cycle was recorded. The test results are shown in Table 1;

[0109] (3) Performance test items

[0110] Bulk density: the test method refers to GB / T2997-2015;

[0111] Compressive strength: the test method refers to GB / T5072-2008.

[0112]

[0113] According to the foregoing results, it can be seen that:

[0114] Compared with Example 1, the amount of electrically fused magnesium aluminate spinel in the aggregate is increased in Example 2, which generates a solid solution with corundum at high temperature to release thermal stress and block molten slag, thereby improving the overall performance.

[0115] In Examples 3 and 4, the proportion of rare earth modified alumina and titanium diboride in the powder is adjusted. In Example 3, the grain refinement and interface strengthening effect are weakened, and the strength before and after the cycle is lower than that of Example 1. In Example 4, the amount of rare earth modified alumina is insufficient, and the grain coarsening leads to a decrease in density and strength.

[0116] In Example 5, titanium diboride is replaced by tungsten diboride. The interface bonding of titanium diboride at room temperature is slightly reduced, but the high-temperature stability is better, and the strength decreases less after the cycle.

[0117] In Example 6, the organic binder in the binder is more, and the strength and density after high-temperature cycle are poorer. In Example 7, there is no silica sol, only organic binder. The adhesion is acceptable at room temperature, but the carbonization shrinkage is obvious at high temperature, and the compressive strength decreases significantly.

[0118] Comparative Example 1 lacks boride, no high-temperature glass phase sealing, weakens the grain boundary, the volume density and strength retention rate significantly decrease after high-temperature cycle.

[0119] Comparative Example 2 does not contain rare earth modified alumina, the grain cannot be refined, the initial densification is poor, the grain further grows after high-temperature cycle, the crack expands, and the strength and density continuously decrease.

[0120] Unless otherwise specifically indicated, various materials, reagents, instruments and equipment and the like used in the present application can be purchased from the market or can be prepared by the existing method. The above specific examples further illustrate the purpose, technical solutions and beneficial effects of the present application. It should be understood that the above description is only a specific embodiment of the present application and is not intended to limit the present application. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. High-performance corundum-based repair material, characterized in that The preparation raw materials include the following quality parts: 60-80 parts of aggregate, 10-30 parts of powder, 8-20 parts of binder and 0.5-2 parts of additive; The aggregate is 10-30wt% of fused magnesio-alumina spinel and the balance of fused white corundum; The powder is 15-30wt% of rare earth modified alumina powder, 3-18wt% of boride and the balance of white corundum powder; the rare earth modified alumina powder is lanthanum modified alumina powder, the rare earth modified alumina powder contains 3-5wt% of La2O3 and the balance of alumina; the boride is titanium boride or tungsten boride; The binder is silica sol and organic binder, the organic binder is phenolic resin and polyethylene glycol; The additive is 0.2-0.8 parts of water reducing agent, 0.2-0.7 parts of dispersant and 0-0.5 parts of plasticizer.

2. The high-performance corundum-based repair material according to claim 1, characterized in that The volume density of the electrically fused white corundum is 3.6-3.88 g / cm 3 ; and / or the electrically conductive magnesium aluminate spinel has a bulk density of > 3.2 g / cm3 3 .

3. The high-performance corundum-based repair material according to claim 1, characterized in that The D50 of the rare earth modified alumina powder is 3-6μm.

4. The high-performance corundum-based repair material according to claim 1, characterized in that The particle size of the boride is 0.8-10μm.

5. The high-performance corundum-based repair material according to claim 4, characterized in that At least one of the following conditions a-c is met: a. the pH of the silica sol is 9-11; b. the SiO2 in the silica sol is 20-40wt%, Na2O≤0.5wt%; c. the D50 of the silica nanoparticles in the silica sol is 10-20nm.

6. The high-performance corundum-based repair material according to claim 4, characterized in that At least one of the following conditions a-c is met: a. the water reducing agent is polycarboxylic acid type water reducing agent; b. the plasticizer is dibutyl phthalate, dioctyl sebacate or epoxy soybean oil; c. the dispersant is sodium hexametaphosphate, sodium tripolyphosphate or sodium pyrophosphate.

7. A high-performance corundum-based repair material according to any one of claims 1 to 6, characterized in that At least one of the following conditions a-e is met: a. the maximum working temperature of the high-performance corundum-based repair material is 1700-1750℃; b. the compressive strength of the high-performance corundum-based repair material after sintering at the maximum temperature of 1600-1750℃ is 60-100MPa; d. The high-performance corundum-based repair material has a bulk density of 2.70-2.85 g / cm 3 ; c. the compressive strength of the high-performance corundum-based repair material after 20-40 cycles at the maximum temperature of 1600-1750℃ is 35-55MPa; e. The high-performance corundum-based repair material has a bulk density of 2.4-2.6 g / cm after 20-40 cycles at a maximum temperature of 1700-1750 °C 3 .

8. The high-performance corundum-based repair material according to any one of claims 1 to 6, characterized in that At least one of the following conditions a-b is met: a. the high-performance corundum-based repair material has a bulk density of 2.75 to 2.85 g / cm 3 ; b. the compressive strength of the high-performance corundum-based repair material after 20-40 cycles at the maximum temperature of 1600-1750℃ is 40-55MPa.

9. The method of producing a high-performance corundum-based repair material according to any one of claims 1 to 6, characterized in that, The following steps are included: The powder is added to the aggregate and mixed evenly, the organic binder is added, then the silica sol is added, and finally the additive is added.

10. The method of producing a high-performance corundum-based repair material according to claim 9, characterized in that The raw materials of the aggregate and the powder need to be pretreated, the pretreatment is to remove impurities from the raw materials of the aggregate and the powder, then sieved 2-3 times with a 300-400 mesh sieve, and dried at 80-100℃ to control the water content≤0.5%; the preparation raw materials of the aggregate are dry mixed in a blender for 3-5min to obtain the aggregate, and the preparation raw materials of the powder are dry mixed in a blender for 5-8min to obtain the powder; And / or, the silica sol is added by dripping, and the dripping speed is 5-10mL / min.

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