Silicon steel annealing separator and preparation method thereof

Abstract

The present invention relates to a silicon steel annealing separator and a preparation method thereof, comprising: magnesium oxide, titanium dioxide, silica sol, Ca(OH)2 and additives, and water; wherein the mass ratio of water to other substances except water is 1:7.5; the additives include B2O3, FeCl2·4H2O, Sb2(SO4)3, MgF2 and hydroxides whose anions ionized in aqueous solution are all hydroxide ions; the total amount of other substances except water is 100wt%, the content of magnesium oxide is 70-90wt%, the content of B2O3 is 0.3-0.65wt%, and the content of MgF2 is 0.1-0.5wt%. The present invention can increase the contact area and adhesion between MgO and steel plate, reduce the risk of damaging the bottom layer and performance, and make the bottom layer uniform and glossy.

Description

Technical Field

[0001] The invention relates to the technical field of silicon steel production, in particular to a silicon steel annealing separator and a preparation method thereof. Background Art

[0002] After the decarburization process, the surface of the silicon steel strip needs to be coated with magnesium oxide. The coating of magnesium oxide plays three key roles in high-temperature annealing. First, it prevents the steel strip from sticking during the annealing process. Second, magnesium oxide forms an insulating bottom layer of magnesium silicate with silicon dioxide in the steel strip. Third, it generates a desulfurization reaction at high temperature to purify the steel strip. For these three aspects, the formation of the bottom layer is crucial. Not only the particle size and activity of magnesium oxide should be considered, but also the drainage capacity of the bell furnace should be considered. If the combined water in the magnesium oxide cannot be quickly removed, the bottom layer defects of watermark blackening and crystal leakage will appear, and the silicon steel surface with good bottom layer uniformity, glossiness and adhesion cannot be formed, which reduces the qualified rate of finished products.

[0003] In the existing technology, there is a technical solution of adding rare earth elements to the annealing separator, but in the actual production of enterprises, the cost is relatively high; there is a technical solution of adding nitrogen elements to the annealing separator, which has the risk of deteriorating the underlying layer from the perspective of supplementing inhibitors; there is a technical solution of adding strontium and antimony elements to the annealing separator, which will improve some of the magnetic properties but will deteriorate the underlying layer. Summary of the invention

[0004] The object of the present invention is to provide a silicon steel annealing separator and a preparation method thereof, so as to increase the contact area and adhesion between MgO and steel plate, reduce the risk of damaging the bottom layer and performance, and make the bottom layer uniform and glossy.

[0005] To achieve the above object, the present invention provides a silicon steel annealing separator and a preparation method thereof, comprising: magnesium oxide, titanium dioxide, silica sol, Ca(OH)2 and additives, and water; wherein the mass ratio of water to other substances except water is 1:7.5;

[0006] The additives include B2O3, FeCl2·4H2O, Sb2(SO4)3, MgF2 and hydroxides whose anions ionized in aqueous solution are all hydroxide ions;

[0007] The total amount of other substances except water is 100wt%, the content of magnesium oxide is 70~90wt%, the content of B2O3 is 0.3~0.65wt%, and the content of MgF2 is 0.1~0.5wt%.

[0008] According to a technical solution of the present invention, the total amount of other substances except water is 100wt%, and the content of silica sol is 0.2-0.7wt%.

[0009] According to a technical solution of the present invention, the total amount of other substances except water is 100wt%, and the titanium dioxide content is 5-8wt%.

[0010] According to a technical solution of the present invention, the total amount of other substances except water is 100wt%, and the content of FeCl2·4H2O is 0.5~2.5wt%.

[0011] According to a technical solution of the present invention, the total amount of other substances except water is 100wt%, and the content of Sb2(SO4)3 is 0.5~3.5wt%.

[0012] According to a technical solution of the present invention, the total amount of other substances except water is 100wt%, and the content of hydroxide is 0.5-3.5wt%;

[0013] The hydroxide is one or more of NaOH, KOH, and Mg(OH)2.

[0014] According to a technical solution of the present invention, the total amount of other substances except water is 100wt%, and the content of Ca(OH)2 is 0.3~1.5wt%.

[0015] According to one aspect of the present invention, a method for preparing a silicon steel annealing separator as described in any one of the above technical solutions is proposed, comprising the following steps:

[0016] Step S1, stabilizing the rotation frequency of the agitators of the liquid preparation cylinder and the circulation cylinder at 30-50 Hz;

[0017] Step S2, adding water into the liquid preparation tank and starting to cool down;

[0018] Step S3, when the water temperature drops to between 0 and 5°C, add silica sol and Ca(OH)2 and stir for 30 minutes; then add additives and stir for 30 minutes;

[0019] Step S4: Keep the liquid temperature between 0 and 5°C, slowly add MgO powder, and stir for 60 minutes to evenly disperse and mix it.

[0020] According to one aspect of the present invention, a method for producing silicon steel with a bottom layer is proposed. After the decarburization process, the silicon steel is coated with a silicon steel annealing separator as described in any one of the above technical solutions on the surface of the silicon steel and then annealed. The coating process is roller coating, and the coating amount of the silicon steel annealing separator on the upper and lower surfaces of the silicon steel is 15-18 g / m 2 .

[0021] According to one aspect of the present invention, a silicon steel with a bottom layer produced based on the production method described in the above technical solution is proposed.

[0022] Compared with the prior art, the present invention has the following beneficial effects:

[0023] The silicon steel annealing separator and preparation method thereof can increase the contact area and adhesion between MgO and steel plate by introducing additives into the existing annealing separator, and can also reduce the crystallization temperature of the bottom layer and promote the crystallization reaction.

[0024] Compared with rare earth, the additive of the present invention has the advantage of lower price and will not damage the bottom layer and performance. At the same time, it can make the bottom layer uniform and glossy, with good adhesion and strong pinning force, enhance surface tension and improve magnetism. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematically showing the surface quality of silicon steel produced using the annealing separator prepared in Example 1 of the present invention;

[0026] Figure 2 Schematically showing the surface quality of silicon steel produced using the annealing separator prepared in Example 2 of the present invention;

[0027] Figure 3 Schematically showing the surface quality of silicon steel produced using the annealing separator prepared in Example 3 of the present invention;

[0028] Figure 4 Schematically showing the surface quality of silicon steel produced using the annealing separator prepared in Example 4 of the present invention;

[0029] Figure 5 Schematically showing the surface quality of silicon steel produced using the annealing separator prepared in Comparative Example 1 of the present invention;

[0030] Figure 6 Schematically showing the surface quality of silicon steel produced using the annealing separator prepared in Comparative Example 2 of the present invention;

[0031] Figure 7 Schematically showing the surface quality of silicon steel produced using the annealing separator prepared in Comparative Example 3 of the present invention;

[0032] Figure 8 Schematically showing the surface quality of silicon steel produced using the annealing separator prepared in Comparative Example 4 of the present invention;

[0033] Fig. 9 Schematically showing the surface quality of silicon steel produced using the annealing separator prepared in Comparative Example 5 of the present invention;

[0034] Fig.10 Schematically showing the surface quality of silicon steel produced using the annealing separator prepared in Comparative Example 6 of the present invention;

[0035] Fig.11 Schematically showing the surface quality of silicon steel produced using the annealing separator prepared in Comparative Example 7 of the present invention;

[0036] Fig.12 Schematically showing the surface quality of silicon steel produced using the annealing separator prepared in Comparative Example 8 of the present invention;

[0037] Fig.13 Schematically showing the surface quality of silicon steel produced using the annealing separator prepared in Comparative Example 9 of the present invention;

[0038] Fig.14 Schematically showing the surface quality of silicon steel produced using the annealing separator prepared in Comparative Example 10 of the present invention;

[0039] Fig.15 The surface quality diagram of silicon steel produced using the annealing separator prepared in Comparative Example 11 of the present invention is schematically shown. DETAILED DESCRIPTION

[0040] 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 are briefly introduced below.

[0041] The present invention discloses a silicon steel annealing separator, comprising magnesium oxide, titanium dioxide, silica sol, Ca(OH)2 and additives, and water; wherein the mass ratio of water to other substances except water is 1:7.5;

[0042] The additives include B2O3, FeCl2·4H2O, Sb2(SO4)3, MgF2 and hydroxides whose anions ionized in aqueous solution are all hydroxide ions;

[0043] The total amount of other substances except water is 100wt%, the content of magnesium oxide is 70~90wt%, the content of B2O3 is 0.3~0.65wt%, and the content of MgF2 is 0.1~0.5wt%.

[0044] During high-temperature annealing of silicon steel, adding a small amount of B2O3 and antimony compounds can reduce the reaction temperature of magnesium oxide and SiO2 in the steel plate, and also reduce the degree of oxidation of the steel strip; chlorides and fluorides can corrode the amorphous silicon dioxide on the outermost side of the steel strip and reduce the bottom layer formation temperature. However, too little fluoride will lead to poor results, while too much will erode the boundary, damage the surface, affect the growth direction of the grains, deteriorate the grade rate, and cause poor bottom layer phenomena.

[0045] The total amount of other substances except water is 100 wt %. In some embodiments of the present invention, the content of silica sol is 0.2-0.7 wt %.

[0046] Adding a small amount of silica sol can increase adhesion, but adding a large amount will react with part of the MgO, resulting in poor formation of the magnesium silicate base layer.

[0047] In some embodiments of the present invention, the titanium dioxide content is 5-8 wt %.

[0048] In some embodiments of the present invention, the content of FeCl2·4H2O is 0.5-2.5 wt%.

[0049] In some embodiments of the present invention, the content of Sb2(SO4)3 is 0.5~3.5wt%.

[0050] In some embodiments of the present invention, the content of hydroxide is 0.5~3.5wt%; the hydroxide is one or more of NaOH, KOH, and Mg(OH)2.

[0051] Hydroxide increases the viscosity of magnesium oxide, and at the same time increases the adhesion with the contact surface of the steel strip and increases the reaction capacity; too much hydroxide enters with the magnesium oxide, and as the temperature rises, a large amount of crystal water is formed, which will cause watermarks on the surface to turn black, and is accompanied by defects such as poor edge adhesion and gold exposure on the edges, and it will not be washed off during the stretching annealing flattening.

[0052] In some embodiments of the present invention, the content of Ca(OH)2 is 0.3~1.5wt%.

[0053] According to one aspect of the present invention, a method for preparing a silicon steel annealing separator as described in any one of the above technical solutions is proposed, comprising the following steps:

[0054] Step S1, stabilizing the rotation frequency of the agitators of the liquid preparation cylinder and the circulation cylinder at 30-50 Hz;

[0055] Step S2, adding water into the liquid preparation tank and starting to cool down;

[0056] Step S3, when the water temperature drops to between 0 and 5°C, add silica sol and Ca(OH)2 and stir for 30 minutes; then add additives and stir for 30 minutes;

[0057] Step S4: Keep the liquid temperature between 0 and 5°C, slowly add MgO powder, and stir for 60 minutes to evenly disperse and mix it.

[0058] According to one aspect of the present invention, a method for producing silicon steel with a bottom layer is proposed. After the decarburization process, the silicon steel is coated with a silicon steel annealing separator as described in any one of the above technical solutions on the surface of the silicon steel and then annealed. The coating process is roller coating, and the coating amount of the silicon steel annealing separator on the upper and lower surfaces of the silicon steel is 15-18 g / m 2 .

[0059] According to one aspect of the present invention, a silicon steel with a bottom layer produced based on the production method described in the above technical solution is proposed.

[0060] The technical solution of the annealing isolation agent of the present invention is further described below in conjunction with specific embodiments.

[0061] The silicon steel annealing separators (the mass ratio of water to other substances is 1:7.5) of the embodiments and comparative examples are prepared by the above method, and their compositions (the total amount of other substances except water is 100wt%) are shown in Table 1. KOH represents hydroxide.

[0062]

[0063] As shown in Table 1, the silica sol in the embodiments of the present invention ranges from 0.3 to 0.6 wt%, B2O3 ranges from 0.4 to 0.6 wt%, FeCl2·4H2O ranges from 1 to 2 wt%, Sb2(SO4)3 ranges from 1 to 3 wt%, Ca(OH)2 ranges from 0.7 to 1 wt%, KOH ranges from 1 to 3 wt%, and MgF2 ranges from 0.2 to 0.4 wt%.

[0064] Comparative Examples 1 and 2 are silica sol and OH - The compounds were within the experimental range, and the B2O3, antimony compounds, chlorides and fluorides in Comparative Example 1 were all higher than the ranges of the embodiments, and those in Comparative Example 2 were all lower than the ranges of the embodiments of the present invention.

[0065] Comparative Examples 3 and 4 are B2O3, antimony compounds, chlorides and fluorides, and silica sol within the experimental range. - It is higher than the range of the embodiments, while that in Comparative Example 4 is lower than the range of the embodiments of the present invention.

[0066] Comparative Examples 5 and 6 are B2O3, antimony compounds, chlorides and fluorides, silica sol, OH - In the experimental range, the silica sol in Comparative Example 5 is higher than the range of the embodiments, and the silica sol in Comparative Example 4 is lower than the range of the embodiments of the present invention.

[0067] Comparative Examples 7 and 8 are silica sol, B2O3, antimony compound, OH -In the experimental range, the chloride and fluoride in Comparative Example 7 are higher than the range of the embodiment, and the chloride and fluoride in Comparative Example 8 are lower than the range of the embodiment of the present invention.

[0068] Comparative Examples 9 and 10 are silica sol, chloride, fluoride, OH - Within the experimental range, B2O3 and antimony compounds in Comparative Example 9 are higher than the range of the embodiment, and those in Comparative Example 10 are lower than the range of the embodiment of the present invention.

[0069] After the decarburization process, the silicon steel strip surface is coated with the above-mentioned silicon steel annealing isolation agent and then annealed. The coating process is roller coating to ensure that the coating amount of the isolation agent on the upper and lower surfaces of the steel strip is 15~18g / m 2 The results after annealing of Examples 1 to 4 and Comparative Examples 1 to 11 are as follows Figures 1 to 15 As shown, the surface quality and coating adhesion were statistically analyzed as shown in Table 2.

[0070] Table 2 Results after annealing of various embodiments and comparative examples

[0071]

[0072] based on Figures 1 to 15 As can be seen from Table 2, the surface corresponding to Example 2 is the best, followed by Example 4, Example 3, and Example 1, while the comparative examples all have problems with surface quality and / or coating adhesion.

[0073] The surface of Comparative Example 1 has invisible exposed crystals and the coating has fallen off; the surface of Comparative Example 2 has blackened watermarks and the coating has slightly fallen off.

[0074] The surface of Comparative Example 3 has point-shaped gold exposure that cannot be washed off and the coating has fallen off; the surface of Comparative Example 4 has watermarks and blackening and the coating has slightly fallen off.

[0075] Comparative Example 5 has invisible exposed crystals on the surface and the coating has fallen off; Comparative Example 6 has blackened watermarks on the surface and the coating has slightly fallen off.

[0076] Comparative Example 7 has invisible exposed crystals on the surface and the coating has fallen off; Comparative Example 8 has blackened watermarks on the surface and the coating has slightly fallen off.

[0077] Comparative Example 9 has invisible exposed crystals on the surface and the coating has fallen off; Comparative Examples 10 and 11 have blackened watermarks on the surface and the coating has slightly fallen off.

[0078] Based on the above embodiments and comparative examples, it can be seen that the invention introduces additives into the existing annealing separator, which can not only increase the contact area and adhesion between MgO and the steel plate, but also reduce the crystallization temperature of the bottom layer and promote the crystallization reaction. Compared with rare earth, this additive is cheaper and will not damage the bottom layer and performance, but also make the bottom layer uniform and shiny, with good adhesion and strong pinning force, enhance surface tension and improve magnetism.

[0079] Although the preferred embodiments of the present invention have been described, those skilled in the art may make additional changes and modifications to these embodiments once they have learned the basic creative concept. Therefore, the appended claims are intended to be interpreted as including the preferred embodiments and all changes and modifications that fall within the scope of the present invention.

[0080] Obviously, those skilled in the art can make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if these modifications and variations of the present invention fall within the scope of the claims of the present invention and their equivalents, the present invention is also intended to include these modifications and variations.

Claims

1. A silicon steel annealing separator, characterized in that: include: Magnesium oxide, titanium dioxide, silica sol, Ca(OH)2 and additives, and water; wherein the mass ratio of water to other substances except water is 1:7.5; The additives include B2O3, FeCl2·4H2O, Sb2(SO4)3, MgF2 and hydroxides whose anions ionized in aqueous solution are all hydroxide ions; Based on the total amount of other substances except water being 100wt%, the content of magnesium oxide is 70~90wt%, the content of B2O3 is 0.3~0.65wt%, the content of MgF2 is 0.1~0.5wt%, the content of silica sol is 0.2~0.7wt%, the content of FeCl2·4H2O is 0.5~2.5wt%, the content of Sb2(SO4)3 is 0.5~3.5wt%, the content of hydroxide is 0.5~3.5wt%, and the hydroxide is one or more of NaOH, KOH, and Mg(OH)2. The content of titanium dioxide is 5~8wt%, and the content of Ca(OH)2 is 0.3~1.5wt%.

2. A method for producing silicon steel with a bottom layer, characterized in that: After the decarburization process, the silicon steel is coated with the silicon steel annealing isolation agent as claimed in claim 1 on the surface of the silicon steel and then annealed. The coating process is roller coating, and the coating amount of the silicon steel annealing isolation agent on the upper and lower surfaces of the silicon steel is 15-18 g / m 2 .

3. Silicon steel with a bottom layer produced based on the method for producing silicon steel with a bottom layer as claimed in claim 2.

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