A composite troweling material for a clean steel tundish and a preparation method thereof

Abstract

The present application relates to the technical field of refractory material, and proposes a tundish composite coating material for clean steel and a preparation method thereof.The tundish composite coating material comprises the following components by weight: 30-70 parts of forsterite, 5-15 parts of magnesia, 3-10 parts of silicon carbide, 3-5 parts of mixed additives, 0.8-2.5 parts of binding agent, 0.1-0.3 parts of flaky graphite, 0.5-1 part of bentonite, 0.5-1 part of vermiculite, 0.6-1.5 parts of organic fiber, and 0.2-0.6 parts of water reducing agent, wherein the raw materials of the mixed additives comprise silicon powder, magnesium oxide powder, polyvinyl acetate and 2-aminoisonicotinic acid ethyl ester.The above technical solution solves the problem of insufficient strength of the tundish coating material for clean steel at high temperature in the related art.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of refractory materials, in particular to a tundish composite coating material for clean steel and a preparation method thereof. BACKGROUND

[0002] Clean steel is a general term for steel with low impurities and high purity, and the production process puts high requirements on the cleanliness control of molten steel at the continuous casting stage. The tundish, as a key transition container for molten steel from ladle to mold during continuous casting, the high-temperature mechanical properties of the working layer of the tundish lining composed of coating material are directly related to the temperature maintenance, purity control of molten steel, and the smoothness and efficiency of continuous casting production.

[0003] At present, the tundish coating material is mainly based on sintered magnesia, which has the advantage of strong resistance to alkaline slag erosion, but the thermal expansion coefficient of magnesia is high, and microcracks are easily generated due to thermal stress under temperature cycling conditions. These cracks not only cause the penetration of molten steel into the deep layer of the lining, increasing the risk of lining spalling, but also become the attachment and growth carrier of non-metallic inclusions in steel, directly affecting the requirement of clean steel on inclusion content.

[0004] Therefore, clean steel production usually turns to using coating material based on forsterite. The thermal expansion coefficient of forsterite is only about 8*10 -6 / ℃, and it has excellent thermal shock resistance, which can effectively reduce the structural damage caused by temperature cycling, however, the forsterite-based coating material itself has obvious shortcomings, its refractoriness is relatively low, and it is easy to soften under long-term high temperature, causing insufficient strength, resulting in reduced resistance to molten steel erosion and shortened service life. Therefore, it is necessary to prepare a tundish composite coating material for clean steel with high high-temperature mechanical properties to ensure the stability of clean steel quality. SUMMARY

[0005] The present application provides a tundish composite coating material for clean steel and a preparation method thereof, which solves the problem of insufficient mechanical properties of the tundish coating material for clean steel at high temperature in the related art.

[0006] The technical scheme of the present application is as follows:

[0007] The present application provides a tundish composite coating material for clean steel, which comprises the following components by weight: forsterite 30-70 parts, magnesia 5-15 parts, silicon carbide 3-10 parts, mixed additives 3-5 parts, binder 0.8-2.5 parts, flaky graphite 0.1-0.3 parts, bentonite 0.5-1 part, vermiculite 0.5-1 part, organic fiber 0.6-1.5 parts, and water reducing agent 0.2-0.6 parts. The raw materials of the mixed additives include silicon powder, magnesium oxide powder, polyvinyl acetate, and 2-aminoisonicotinic acid ethyl ester.

[0008] The water reducing agent added in the intermediate ladle composite coating material for clean steel can effectively reduce the mixing water consumption of the slurry, significantly improve the fluidity and construction spreading property of the slurry, and make the slurry more easily and uniformly coated. In addition, the reduction of water consumption can also reduce the shrinkage stress in the drying process, and the anti-cracking effect of the organic fiber can further inhibit the generation of cracks, thereby improving the construction quality and structural stability of the coating material.

[0009] As a further technical solution, the mass ratio of the silicon powder, magnesium oxide powder, polyvinyl acetate and 2-aminoethyl isonicotinate is 35:25:4:1~3, for example, it can be 35:25:4:1, 35:25:4:1.5, 35:25:4:2, 35:25:4:3, and preferably 35:25:4:2.

[0010] The intermediate ladle composite coating material for clean steel limits the mass ratio of the silicon powder, magnesium oxide powder, polyvinyl acetate and 2-aminoethyl isonicotinate to 35:25:4:1~3, which can further improve the high-temperature mechanical properties of the intermediate ladle composite coating material. The addition of silicon powder and magnesium oxide powder can synergistically fill the interstitial gaps to improve the density, while the introduction of polyvinyl acetate and 2-aminoethyl isonicotinate can improve the dispersibility of silicon powder and magnesium oxide powder. When the amount of 2-aminoethyl isonicotinate is insufficient, the polar groups in its molecule cannot fully act on the hydroxyl groups on the surface of silicon powder and magnesium oxide powder, resulting in agglomeration and uneven dispersion of the two, which cannot effectively improve the mechanical properties of the coating material. If the amount of 2-aminoethyl isonicotinate is too much, excessive 2-aminoethyl isonicotinate will be introduced, and during the use of the coating material, excessive gas will be generated during the high-temperature carbonization process, resulting in the formation of many pores inside the material, destroying the structural density, and weakening the high-temperature performance, thereby reducing the high-temperature mechanical properties of the coating material.

[0011] As a further technical solution, the preparation method of the mixing aid includes the following steps: adding polyvinyl acetate and 2-aminoethyl isonicotinate into a solvent and dispersing uniformly, then adding silicon powder and magnesium oxide powder and mixing, and drying to obtain the mixing aid.

[0012] As a further technical solution, the solvent is anhydrous ethanol.

[0013] As a further technical solution, the mixing temperature is 40℃, and the mixing time is 2h.

[0014] As a further technical solution, the forsterite is composed of 1mm<particle size≤3mm forsterite, 0.088mm<particle size≤1mm forsterite and 0<particle size≤0.088mm forsterite with a mass ratio of 3:2:1~2.

[0015] The magnesia is composed of 0.088mm < particle size <= 1mm magnesia and 0 < particle size <= 0.074mm magnesia with a mass ratio of 2:1.

[0016] As a further technical solution, the particle size of the bentonite is 0.02mm~0.064mm.

[0017] The particle size of the vermiculite is 0.9um~3um.

[0018] As a further technical solution, the organic fiber includes one or more of hemp fiber, polyethylene fiber and wood fiber.

[0019] As a further technical solution, the organic fiber is composed of hemp fiber and polyethylene fiber with a mass ratio of 1:2.

[0020] As a further technical solution, the binding agent includes asphalt, magnesium chloride, phenolic resin and 2-acetylamino-5-amino pyridine.

[0021] The present application adds asphalt, magnesium chloride, phenolic resin and 2-acetylamino-5-amino pyridine in the tundish composite coating material for clean steel, and the high temperature mechanical properties of the coating material are improved through the synergy between the components, wherein the magnesium chloride acts as an inorganic binding agent, and forms a gel body with water molecules at room temperature during use to provide initial strength, and the asphalt and the phenolic resin are carbonized at high temperature to jointly build a stable and dense high-temperature carbon skeleton, greatly enhancing the bending strength and thermal stability of the material; in addition, the 2-acetylamino-5-amino pyridine effectively improves the dispersity and compatibility of the binding agent through its polar groups, ensures the uniform distribution of the binding agent, reduces stress concentration at high temperature, and inhibits crack generation, thereby further improving the high temperature mechanical properties of the coating material.

[0022] As a further technical solution, the mass ratio of the asphalt, magnesium chloride, phenolic resin and 2-acetylamino-5-amino pyridine is 35:30:4:3~5.

[0023] As a further technical solution, the water reducing agent includes one or both of sodium tripolyphosphate and sodium hexametaphosphate.

[0024] As a further technical solution, the water reducing agent is composed of sodium tripolyphosphate and sodium hexametaphosphate with a mass ratio of 1:1.

[0025] The present application also proposes a preparation method of a tundish composite coating material for clean steel, for preparing the above-mentioned tundish composite coating material for clean steel, including the following steps: uniformly mixing the raw materials to obtain the tundish composite coating material for clean steel.

[0026] The working principle and beneficial effects of the present application are as follows:

[0027] In the intermediate ladle composite coating material for clean steel, the addition of the mixed additive effectively improves the high-temperature mechanical properties of the coating material. In the prior art, in order to improve the high-temperature mechanical properties of the forsterite-based coating material, silicon powder and magnesium oxide powder are added. However, the silicon powder and the magnesium oxide powder are prone to agglomeration, which limits the effect of improving the high-temperature mechanical properties and stability of the material. In the present application, the raw materials of the mixed additive include silicon powder, magnesium oxide powder, polyvinyl acetate and 2-aminoethyl isonicotinate. The polyvinyl acetate can effectively improve the dispersibility between the silicon powder and the magnesium oxide powder. At the same time, the polar groups in the molecular structure of 2-aminoethyl isonicotinate can form hydrogen bonding force with the hydroxyl groups on the surface of the silicon powder and the magnesium oxide powder, further promoting the uniform dispersion of the inorganic powder in the coating material system. Moreover, the aromatic ring structure can participate in the carbonization reaction in the high-temperature environment during use, further improving the mechanical properties of the coating material at high temperature. DETAILED DESCRIPTION

[0028] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present application.

[0029] In the following examples and comparative examples:

[0030] The forsterite is composed of 1mm≤particle size≤3mm forsterite, 0.088mm≤particle size≤1mm forsterite and 0≤particle size≤0.088mm forsterite with a mass ratio of 3:2:2;

[0031] The magnesia is sintered magnesia composed of 0.088mm≤particle size≤1mm sintered magnesia and 0≤particle size≤0.074mm sintered magnesia with a mass ratio of 2:1;

[0032] The average particle size of the silicon carbide is 45μm;

[0033] The average particle size of the silicon powder is 2000 mesh;

[0034] The average particle size of the magnesium oxide powder is 2000 mesh;

[0035] The average particle size of the bentonite is 0.035mm;

[0036] The average particle size of the vermiculite is 3μm;

[0037] The diameter of the hemp fiber is 20μm and the length is 6mm;

[0038] The diameter of the polyethylene fiber is 12μm and the length is 4mm;

[0039] The average particle size of the flaky graphite is 2000 mesh;

[0040] Asphalt, model: No. 70, manufacturer: Foshan Nanhai Hongxian Municipal Engineering Co., Ltd.;

[0041] Polyvinyl acetate, model: DH5405, manufacturer: Donghao Chemical (Shandong) Co., Ltd.

[0042] Example 1

[0043] A kind of intermediate ladle composite coating material for clean steel, including the following weight parts components raw materials: peridot 30 parts, magnesite 5 parts, silicon carbide 3 parts, mixed additive 3 parts, binder 0.8 parts, flaky graphite 0.1 parts, bentonite 0.5 parts, vermiculite 0.5 parts, hemp fiber 0.2 parts, polyethylene fiber 0.4 parts, sodium tripolyphosphate 0.1 parts, sodium hexametaphosphate 0.1 parts, wherein the binder is composed of asphalt and magnesium chloride with mass ratio of 35:30;

[0044] The preparation method of the mixed additive comprises the following steps: polyvinyl acetate and 2-aminoisonicotinic acid ethyl ester are uniformly dispersed in anhydrous ethanol, then silicon powder and magnesium oxide powder are mixed at 40 DEG C for 2h, and then dried to obtain the mixed additive, wherein the mass ratio of the silicon powder, the magnesium oxide powder, the polyvinyl acetate and the 2-aminoisonicotinic acid ethyl ester is 35:25:4:1, and the volume ratio of the silicon powder and the magnesium oxide powder to the anhydrous ethanol is 1g:8ml;

[0045] A preparation method of an intermediate ladle composite coating material for clean steel, comprising the following steps:

[0046] After the above raw material components are uniformly mixed, the intermediate ladle composite coating material for clean steel is obtained.

[0047] Example 2

[0048] A kind of intermediate ladle composite coating material for clean steel, including the following weight parts components raw materials: peridot 30 parts, magnesite 5 parts, silicon carbide 3 parts, mixed additive 3 parts, binder 0.8 parts, flaky graphite 0.1 parts, bentonite 0.5 parts, vermiculite 0.5 parts, hemp fiber 0.2 parts, polyethylene fiber 0.4 parts, sodium tripolyphosphate 0.1 parts, sodium hexametaphosphate 0.1 parts, wherein the binder is composed of asphalt and magnesium chloride with mass ratio of 35:30;

[0049] The preparation method of the mixing aid comprises the following steps: uniformly dispersing polyvinyl acetate and ethyl 2-aminoisonicotinate in anhydrous ethanol, adding silicon powder and magnesium oxide powder, mixing at 40 DEG C for 2 hours, and drying to obtain the mixing aid, wherein the mass ratio of the silicon powder, the magnesium oxide powder, the polyvinyl acetate and the ethyl 2-aminoisonicotinate is 35:25:4:1, and the volume ratio of the mass of the silicon powder and the magnesium oxide powder to the volume of the anhydrous ethanol is 1g:8ml.

[0050] The preparation method of the intermediate ladle composite coating material for clean steel comprises the following steps:

[0051] After the above raw materials are uniformly mixed, the intermediate ladle composite coating material for clean steel is obtained.

[0052] Example 3

[0053] The intermediate ladle composite coating material for clean steel comprises the following raw materials in parts by weight: forsterite 70 parts, magnesia 15 parts, silicon carbide 10 parts, mixing aid 5 parts, binding agent 2.5 parts, flaky graphite 0.3 parts, bentonite 1 part, vermiculite 1 part, hemp fiber 0.5 parts, polyethylene fiber 1.0 part, sodium tripolyphosphate 0.3 part, and sodium hexametaphosphate 0.3 part, wherein the binding agent is composed of pitch and magnesium chloride with a mass ratio of 35:30.

[0054] The preparation method of the mixing aid comprises the following steps: uniformly dispersing polyvinyl acetate and ethyl 2-aminoisonicotinate in anhydrous ethanol, adding silicon powder and magnesium oxide powder, mixing at 40 DEG C for 2 hours, and drying to obtain the mixing aid, wherein the mass ratio of the silicon powder, the magnesium oxide powder, the polyvinyl acetate and the ethyl 2-aminoisonicotinate is 35:25:4:1, and the volume ratio of the mass of the silicon powder and the magnesium oxide powder to the volume of the anhydrous ethanol is 1g:8ml.

[0055] The preparation method of the intermediate ladle composite coating material for clean steel comprises the following steps:

[0056] After the above raw materials are uniformly mixed, the intermediate ladle composite coating material for clean steel is obtained.

[0057] Example 4

[0058] The difference between the present example and example 2 is that the mass ratio of the silicon powder, the magnesium oxide powder, the polyvinyl acetate and the ethyl 2-aminoisonicotinate in the present example is 35:25:4:2.

[0059] Example 5

[0060] The difference between the present example and example 2 is that the mass ratio of the silicon powder, the magnesium oxide powder, the polyvinyl acetate and the ethyl 2-aminoisonicotinate in the present example is 35:25:4:3.

[0061] Example 6

[0062] The difference between this example and Example 4 is that the binder in this example is composed of asphalt, magnesium chloride, and phenolic resin in a mass ratio of 35:30:4.

[0063] Example 7

[0064] The difference between this example and Example 4 is that the binder in this example is composed of asphalt, magnesium chloride, phenolic resin, and 2-acetylamino-5- aminopyridine in a mass ratio of 35:30:4:3.

[0065] Example 8

[0066] The difference between this example and Example 4 is that the binder in this example is composed of asphalt, magnesium chloride, phenolic resin, and 2-acetylamino-5- aminopyridine in a mass ratio of 35:30:4:4.

[0067] Example 9

[0068] The difference between this example and Example 4 is that the binder in this example is composed of asphalt, magnesium chloride, phenolic resin, and 2-acetylamino-5- aminopyridine in a mass ratio of 35:30:4:5.

[0069] Comparative Example 1

[0070] The difference between this comparative example and Example 2 is that the silicon powder, magnesium oxide powder, polyvinyl acetate, and 2-aminoethyl isonicotinate in a mass ratio of 35:25:4:1 in this comparative example are replaced with an equal amount of silicon powder, magnesium oxide powder, and polyvinyl acetate in a mass ratio of 35:25:5.

[0071] Comparative Example 2

[0072] The difference between this comparative example and Example 2 is that the silicon powder, magnesium oxide powder, polyvinyl acetate, and 2-aminoethyl isonicotinate in a mass ratio of 35:25:4:1 in this comparative example are replaced with an equal amount of silicon powder, magnesium oxide powder, and 2-aminoethyl isonicotinate in a mass ratio of 35:25:5.

[0073] Comparative Example 3

[0074] The difference between this comparative example and Example 2 is that the silicon powder, magnesium oxide powder, polyvinyl acetate, and 2-aminoethyl isonicotinate in a mass ratio of 35:25:4:1 in this comparative example are replaced with an equal amount of silicon powder and magnesium oxide powder in a mass ratio of 35:25.

[0075] Experimental Example 1

[0076] The intermediate ladle composite coating paste obtained from Examples 1-9 and Comparative Examples 1-3 was respectively added into 15% water by total mass, stirred uniformly, shaped, cured, and baked at 200℃ for 2.5h, and then the performance was determined according to the following test method;

[0077] Compressive strength: The 110℃x24h compressive strength was tested according to the method 3 of GB / T 5072-2023 "Refractory materials - Test method for cold compressive strength", and the 1500℃x3h compressive strength was tested according to the method of GB / T 34218-2017 "Refractory materials - Test method for hot compressive strength", and the heating rate during the test was 10℃ / min; the test results were recorded in Table 1;

[0078] Table 1 Performance test results of Examples 1-9 and Comparative Examples 1-3

[0079]

[0080] The compressive strength of the intermediate ladle coating paste obtained from Examples 1-5 is higher than that of Comparative Examples 1-3, which shows that the mixed additive composed of silicon powder, magnesium oxide powder, polyvinyl acetate and 2-aminoisonicotinic acid ethyl ester added in the present application can improve the high-temperature mechanical properties of the intermediate ladle composite coating paste.

[0081] The compressive strength of the intermediate ladle coating paste obtained from Examples 7-9 is higher than that of Examples 4 and 6, which shows that the asphalt, magnesium chloride, phenolic resin and 2-acetylamino-5-aminopyridine added as a binding agent in the present application can improve the high-temperature mechanical properties of the intermediate ladle composite coating paste.

[0082] The above only describes the preferred embodiments of the present application and should not be used to limit the present application, and any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included in the protection scope of the present application.

Claims

1. A composite coating material for intermediate ladles used in clean steel, characterized in that, The raw materials include the following components by weight: 30-70 parts of magnesium olivine, 5-15 parts of magnesia, 3-10 parts of silicon carbide, 3-5 parts of mixed additives, 0.8-2.5 parts of binder, 0.1-0.3 parts of flake graphite, 0.5-1 part of bentonite, 0.5-1 part of vernix caseosa, 0.6-1.5 parts of organic fiber, and 0.2-0.6 parts of water-reducing agent. The raw materials of the mixed additives include silica powder, magnesium oxide powder, polyvinyl acetate, and ethyl 2-aminoisonicotinic acid. The mass ratio of the silicon micro powder, magnesium oxide micro powder, polyvinyl acetate and ethyl 2-aminoisonicotinic acid is 35:25:4:1~3; The preparation method of the mixed additive includes the following steps: polyvinyl acetate and ethyl 2-aminoisonicotinic acid are added to a solvent and dispersed evenly, then silica powder and magnesium oxide powder are added and mixed, and then dried to obtain the mixed additive.

2. The composite coating material for tundishes used in clean steel according to claim 1, characterized in that, The forsterite is composed of forsterite with a mass ratio of 3:2:1~2, consisting of forsterite with a particle size of 1 mm < ≤ 3 mm, forsterite with a particle size of 0.088 mm < ≤ 1 mm, and forsterite with a particle size of 0 < ≤ 0.088 mm. The magnesia is composed of magnesia with a particle size of 0.088 mm < ≤ 1 mm and magnesia with a particle size of 0 < ≤ 0.074 mm in a mass ratio of 2:

1.

3. The composite coating material for tundishes used in clean steel according to claim 1, characterized in that, The bentonite has a particle size of 0.02 mm to 0.064 mm; The particle size of the Vero white clay is 0.9μm~3μm.

4. The composite coating material for tundishes used in clean steel according to claim 1, characterized in that, The organic fibers include one or more of hemp fibers, polyethylene fibers, and wood fibers.

5. The composite coating material for tundishes used in clean steel according to claim 1, characterized in that, The binder includes asphalt, magnesium chloride, phenolic resin, and 2-acetamido-5-aminopyridine.

6. The composite coating material for tundishes used in clean steel according to claim 5, characterized in that, The mass ratio of the asphalt, magnesium chloride, phenolic resin and 2-acetamido-5-aminopyridine is 35:30:4:3~5.

7. The composite coating material for tundishes used in clean steel according to claim 1, characterized in that, The water-reducing agent includes one or both of sodium tripolyphosphate and sodium hexametaphosphate.

8. A method for preparing a composite coating for tundishes used in clean steel, used to prepare the composite coating for tundishes according to any one of claims 1 to 7, characterized in that, Includes the following steps: After the raw materials are mixed evenly, a composite coating material for intermediate ladle of clean steel is obtained.

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