Corrosion-resistant stress coating liquid for oriented silicon steel FCL production line

Abstract

The invention relates to the technical field of coating liquids, and discloses a corrosion-resistant stress coating liquid for an oriented silicon steel FCL production line, and the corrosion-resistant stress coating liquid comprises the following components by mass: 18-22% of phosphate; 20-25% of colloidal silicon dioxide; 15-20% of a chromic acid compound; 8-12% of silica sol; 5-10% of other additives; 0.5 to 1.5 percent of a defoaming agent; the sum of all the components is 100%; the other additives are mixtures of borate, nitrate and rare earth elements. By optimizing the proportion of phosphate, colloidal silicon dioxide, a chromic acid compound and silica sol and combining the synergistic effect of borate, nitrate and high-purity rare earth cerium, the corrosion resistance of the coating liquid is remarkably improved, the film layer structure is further refined through the rare earth cerium, the system stability is ensured through a defoaming agent and desalted water, and the corrosion resistance of the coating liquid is improved. And finally, the silicon steel shows excellent corrosion resistance and stress resistance in a high-temperature and high-humidity environment of an FCL production line.

Description

Technical Field

[0001] The present invention relates to the technical field of coating liquids, and in particular to a corrosion-resistant stress coating liquid for an oriented silicon steel FCL production line. Background Art

[0002] As a high-tech product in the steel industry, grain-oriented silicon steel has a complex and lengthy production process. Compared to other steel products, its compositional complexity and processing difficulty are significantly higher. During production, grain-oriented silicon steel is prone to internal stress, which not only affects its magnetic properties but can also cause magnetic domain distortion, thereby increasing hysteresis losses and reducing electromagnetic performance. While traditional coating technologies can protect the silicon steel surface to a certain extent, they are clearly inadequate in addressing internal stress changes and improving magnetic properties.

[0003] Existing coating solutions lack ideal corrosion resistance, adhesion, and the ability to control magnetic domains. This makes the coating prone to defects, impacting the service life and performance stability of silicon steel. Furthermore, the ratio and addition method of key components of existing coating solutions, such as phosphates and colloidal silica, are not optimized, making it difficult to effectively control the uniformity and density of the coating. This not only affects the corrosion resistance of the coating but also may increase iron loss and reduce the electromagnetic properties of the silicon steel. Summary of the Invention

[0004] In response to the shortcomings of the existing technology, the present invention provides a corrosion-resistant stress coating liquid for the oriented silicon steel FCL production line, which solves the problems of insufficient corrosion resistance and stress resistance of the existing coating liquid, limited magnetic domain control ability, and high iron loss caused by poor coating uniformity.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions:

[0006] A corrosion-resistant stress coating liquid for an oriented silicon steel FCL production line comprises the following components by mass percentage:

[0007] Phosphate: 18-22%;

[0008] Colloidal silicon dioxide: 20-25%;

[0009] Chromic acid compounds: 15-20%;

[0010] Silica sol: 8-12%;

[0011] Other additives: 5-10%;

[0012] Defoaming agent: 0.5-1.5%;

[0013] Desalted water: the remainder, so that the sum of each component is 100%;

[0014] The other additives are a mixture of borate, nitrate and rare earth elements, wherein borate accounts for 40-50% of the total mass of the other additives, nitrate accounts for 25-35%, and rare earth elements account for 15-25%, and the total of the three is 100%.

[0015] By adopting the above technical solution: by optimizing the ratio of phosphate, colloidal silica, chromic acid compounds and silica sol, combined with the synergistic effect of borate, nitrate and high-purity rare earth cerium, the corrosion resistance of the coating liquid is significantly improved. Phosphate and chromic acid compounds form a dense passivation film, colloidal silica and silica sol enhance adhesion, and rare earth cerium further refines the film structure. At the same time, defoaming agents and desalted water ensure system stability and reduce coating liquid defects. Ultimately, silicon steel exhibits excellent corrosion resistance and stress resistance in the high temperature and high humidity environment of the FCL production line.

[0016] Preferably, the phosphate is a nano-scale composite material of aluminum dihydrogen phosphate and magnesium dihydrogen phosphate, with an average particle size of 50-80 nm, wherein aluminum dihydrogen phosphate and magnesium dihydrogen phosphate form a core-shell structure through a sol-gel method, with a mass ratio of 1:0.8-1:1.5, and the specific surface area of ​​the composite material is greater than 200 m 2 / g.

[0017] Preferably, the colloidal silica is modified with amino groups, and its particle size is bimodal, wherein the particle size of 10-20 nm accounts for 30% ± 5%, and the particle size of 40-50 nm accounts for 70% ± 5%. The specific surface area is controlled within 200-250 m by nanopore expansion technology. 2 / g, porosity is 75%±2%.

[0018] Preferably, the chromic acid compound is chromic anhydride with a particle size gradient distribution and is compounded with ammonium tungstate stabilizer, with a purity of ≥99.5% and a particle size of ≤10 μm.

[0019] Preferably, the silica sol is pretreated by cation exchange, the pH value is stabilized at 9.0-9.5±0.2 by nanobubble technology, the solid content is 25-28%, and the moisture content is controlled at <0.5% by molecular sieve dehydration, and the colloidal particle size is 5-30 nm.

[0020] Preferably, the rare earth element is cerium, which is added in the form of cerium nitrate or cerium oxide, and is prepared into rod-shaped nanoparticles by hydrothermal synthesis with a purity of ≥99.99%, and the surface is coated with a zirconium phosphate protective layer.

[0021] Preferably, a method for preparing a corrosion-resistant stress coating liquid for an oriented silicon steel FCL production line comprises the following steps:

[0022] S1. Add the remaining desalted water to the reaction vessel and stir at a speed of 200-400 r / min for 5-10 minutes;

[0023] S2. After a 15-minute interval, add 18-22% phosphate, maintain the temperature at 25-35°C, and stir at a speed of 300-500 rpm for 35 minutes;

[0024] S3. Add 20-25% colloidal silica, raise the temperature to 40-50°C, and stir at 400-600 rpm for 35 minutes to ensure that the colloidal silica is evenly dispersed.

[0025] S4. Add 15-20% of chromic acid compound, cool to 30-40°C, and stir at 350-450 rpm for 35 minutes;

[0026] S5. Add 8-12% silica sol and stir at 250-400 rpm for 25 minutes;

[0027] S6. Add 5-10% of other additives and stir at a speed of 300-500 r / min for 25 minutes;

[0028] S7. Finally, add 0.5-1.5% of defoaming agent and stir at a speed of 100-200 r / min for 60 minutes to obtain a coating liquid.

[0029] Preferably, the addition rate of the phosphate in step S2 is 0.5-1.5 kg / min, and the pH value of the system after stirring is 2.5-3.5.

[0030] Preferably, the colloidal silica in step S3 is added in three equal amounts, with an interval of 5 minutes between each addition, and each time is accompanied by the addition of polyacrylate ammonium dispersant, accounting for 0.2-0.5% of the mass of the colloidal silica, and vacuum degassing treatment is carried out between two adjacent additions, wherein the vacuum degree is ≤-0.08MPa and maintained for 2-3min.

[0031] Preferably, the defoaming agent in step S7 is polydimethylsiloxane or a vegetable oil defoaming agent, and the viscosity of the system is controlled at 50-100 mPa·s after addition.

[0032] The present invention provides a corrosion-resistant stress coating liquid for an oriented silicon steel FCL production line. It has the following beneficial effects:

[0033] 1. The present invention significantly improves the corrosion resistance of the coating liquid by optimizing the ratio of phosphate, colloidal silica, chromic acid compounds and silica sol, and combining the synergistic effects of borate, nitrate and high-purity rare earth cerium. Phosphate and chromic acid compounds form a dense passivation film, colloidal silica and silica sol enhance adhesion, and rare earth cerium further refines the film structure. At the same time, defoaming agents and desalted water ensure system stability and reduce coating liquid defects, ultimately enabling silicon steel to exhibit excellent corrosion resistance and stress resistance in the high temperature and high humidity environment of the FCL production line.

[0034] 2. The present invention adopts a specific mass ratio of aluminum dihydrogen phosphate and magnesium dihydrogen phosphate, combined with high-purity chromic anhydride (purity ≥99.5%) and pH and particle size control of silica sol to ensure efficient and controllable coating reaction. The phosphate mixture quickly forms a film in an acidic environment. The fine particles and high purity of chromic anhydride avoid interference from impurities. The alkaline environment and micron-level colloid of silica sol make the coating uniform and dense, thereby synergistically optimizing the interface bonding between the passivation film and silicon steel, reducing iron loss and improving magnetic permeability, and achieving a balanced improvement in the corrosion protection and magnetic properties of the coating.

[0035] 3. The present invention effectively improves coating uniformity through a phased preparation process and precise control of key steps, such as the three-step addition of colloidal silica and viscosity control after the defoamer is added. The phased addition avoids agglomeration, and the defoamer is combined with stirring to eliminate bubbles. The viscosity is stabilized at 50-100 mPa·s to ensure moderate fluidity during coating. This process design enables the coating liquid to form a defect-free, low-porosity uniform film layer on the silicon steel surface, reducing sagging and dripping during the production process, and improving the production efficiency of the FCL production line coating and the consistency of the finished product. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 This is a flow chart of a method for preparing a corrosion-resistant stress coating liquid for an oriented silicon steel FCL production line according to the present invention. DETAILED DESCRIPTION

[0037] The following will clearly and completely describe the technical solution of the present invention in conjunction with the accompanying drawings. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0038] An embodiment of the present invention provides a corrosion-resistant stress coating liquid for an oriented silicon steel FCL production line, comprising the following components by mass percentage:

[0039] Phosphate: 18-22%;

[0040] Colloidal silicon dioxide: 20-25%;

[0041] Chromic acid compounds: 15-20%;

[0042] Silica sol: 8-12%;

[0043] Other additives: 5-10%;

[0044] Defoaming agent: 0.5-1.5%;

[0045] Desalted water: the remainder, so that the sum of each component is 100%;

[0046] The other additives are a mixture of borate, nitrate and rare earth elements, wherein borate accounts for 40-50% of the total mass of the other additives, nitrate accounts for 25-35%, and rare earth elements account for 15-25%, and the total of the three is 100%.

[0047] Specifically, the borate is sodium borate and the nitrate is potassium nitrate, wherein sodium borate can adjust the pH value of the coating liquid to an appropriate acid-base range, thereby promoting the stability and reactivity of other components, and can also increase the viscosity of the coating liquid, helping other solid particles (such as colloidal silica, chromic acid compounds, etc.) to be evenly dispersed and prevent sedimentation; potassium nitrate can act as an oxidant in the coating, participate in the curing reaction of the coating, promote the cross-linking and densification of the coating, thereby improving the corrosion resistance and heat resistance of the coating, and at the same time can also inhibit the electrochemical corrosion of the metal surface, reduce the dissolution of metal ions, and thus extend the service life of the coating; the thickening and dispersing effects of sodium borate combined with the oxidizing and anti-corrosion effects of potassium nitrate can significantly improve the corrosion resistance, heat resistance and mechanical strength of the coating.

[0048] The phosphate is a nano-scale composite material of aluminum dihydrogen phosphate and magnesium dihydrogen phosphate, with an average particle size of 50-80nm. The aluminum dihydrogen phosphate and magnesium dihydrogen phosphate form a core-shell structure through a sol-gel method, with a mass ratio of 1:0.8-1:1.5, and the specific surface area of ​​the composite material is greater than 200m 2 / g.

[0049] Specifically, the synergistic effect of aluminum dihydrogen phosphate and magnesium dihydrogen phosphate makes the formed passivation film more uniform and dense, effectively preventing the penetration of corrosive media and achieving the effect of improving the corrosion resistance of the coating. By adjusting the ratio of aluminum dihydrogen phosphate and magnesium dihydrogen phosphate, the cost of raw materials can be reduced without sacrificing performance, achieving the best balance between cost and performance.

[0050] Please see the attached Figure 1 Colloidal silica is modified with amino groups, and its particle size is bimodal, with 10-20nm accounting for 30%±5% and 40-50nm accounting for 70%±5%. The specific surface area is controlled at 200-250m by nanopore expansion technology. 2 / g, porosity is 75%±2%.

[0051] Specifically, colloidal silica with smaller particle size (10-50 nm) helps to form a denser coating structure because smaller particles can better fill the gaps in the coating and reduce pores. The high specific surface area of ​​colloidal silica (150-300 m 2 / g) increases the contact area with the substrate, thereby enhancing the mechanical anchoring effect and chemical bonding between the coating and the silicon steel surface; through precise control of particle size and porosity, colloidal silica helps to form a uniform and dense coating, effectively preventing the penetration of corrosive media and achieving the effect of improving the corrosion resistance of the coating.

[0052] The chromic acid compound is chromic anhydride with a gradient particle size distribution and is compounded with an ammonium tungstate stabilizer. The purity is ≥99.5% and the particle size is ≤10μm.

[0053] Specifically, chromic anhydride, as the active ingredient in the coating liquid, can react with the metal surface to form a chromate passivation film. This film layer can effectively improve the corrosion resistance of silicon steel sheets. The high purity of chromic anhydride helps to form a uniform and dense passivation film, thereby enhancing the adhesion between the coating and the silicon steel substrate. Through the uniform reaction of high-purity chromic anhydride, a uniform chromate film is formed on the coating surface, effectively improving the corrosion resistance of silicon steel.

[0054] The silica sol is pretreated by cation exchange method, the pH value is stabilized at 9.0-9.5±0.2 by nanobubble technology, the solid content is 25-28%, and the water content is controlled at less than 0.5% by molecular sieve dehydration, and the colloidal particle size is 5-30nm.

[0055] Specifically, the pH value of the silica sol is in the range of 8.5-10.5, which helps maintain the acid-base balance of the coating liquid and provides a suitable environment for the coating reaction. The silica sol with a solid content of 20-30% can ensure that there is sufficient silicon content in the coating liquid to form a dense silicate film layer, thereby enhancing the adhesion and corrosion resistance of the coating. By adjusting the acid-base balance of the coating liquid, controlling the solid content, and optimizing the colloidal particle size, the adhesion, corrosion resistance, and magnetic properties of the coating are improved, ultimately achieving the effect of optimizing the coating performance.

[0056] The rare earth element is cerium, which is added in the form of cerium nitrate or cerium oxide. It is prepared into rod-shaped nanoparticles through a hydrothermal synthesis method with a purity of ≥99.99%, and the surface is coated with a zirconium phosphate protective layer.

[0057] Specifically, the cerium element can react with other components in the coating to form a dense passivation film on the surface of the silicon steel, thereby improving the corrosion resistance of the silicon steel. At the same time, the cerium element can form a chemical bond with the surface of the silicon steel, thereby enhancing the adhesion between the coating and the substrate. The addition of cerium also helps to improve the magnetic properties of the silicon steel, reduce iron loss, and increase magnetic induction intensity.

[0058] Please see the attached Figure 1 A method for preparing a corrosion-resistant stress coating liquid for an oriented silicon steel FCL production line, comprising the following steps:

[0059] S1. Add the remaining desalted water to the reaction vessel and stir at a speed of 200-400 r / min for 5-10 minutes;

[0060] S2. After a 15-minute interval, add 18-22% phosphate, maintain the temperature at 25-35°C, and stir at a speed of 300-500 rpm for 35 minutes;

[0061] S3. Add 20-25% colloidal silica, raise the temperature to 40-50°C, and stir at 400-600 rpm for 35 minutes to ensure that the colloidal silica is evenly dispersed.

[0062] S4. Add 15-20% of chromic acid compound, cool to 30-40°C, and stir at 350-450 rpm for 35 minutes;

[0063] S5. Add 8-12% silica sol and stir at 250-400 rpm for 25 minutes;

[0064] S6. Add 5-10% of other additives and stir at a speed of 300-500 r / min for 25 minutes;

[0065] S7. Finally, add 0.5-1.5% of defoaming agent and stir at a speed of 100-200 r / min for 60 minutes to obtain a coating liquid.

[0066] Please see the attached Figure 1 In step S2, the addition rate of phosphate is 0.5-1.5 kg / min, and the pH value of the system after stirring is 2.5-3.5.

[0067] Specifically, by controlling the rate of phosphate addition, it is possible to ensure that the phosphate fully reacts with the metal surface to form a uniform and dense phosphate film, effectively improving the adhesion of the coating; by maintaining an appropriate pH value (2.5-3.5), it is conducive to the formation of the phosphate film, and this film layer can effectively prevent the penetration of corrosive media, thereby achieving the effect of improving the corrosion resistance of the coating.

[0068] Please see the attached Figure 1 In step S3, the colloidal silica is added in three equal amounts, with an interval of 5 minutes between each addition, and each time is accompanied by the addition of polyacrylate ammonium dispersant, accounting for 0.2-0.5% of the mass of the colloidal silica, and vacuum degassing treatment is carried out between two adjacent additions, wherein the vacuum degree is ≤-0.08MPa and maintained for 2-3min.

[0069] Specifically, by adding colloidal silica in batches, the components in the coating liquid are dispersed more evenly, agglomeration is reduced, and the uniformity of the coating is effectively improved. The uniform dispersion of colloidal silica helps to form a more uniform silicate film layer, enhances the adhesion between the coating and the silicon steel substrate, and the uniform coating structure helps to reduce pores and defects in the coating, thereby reducing iron loss, improving magnetic induction intensity, and optimizing the magnetic properties of silicon steel.

[0070] Please see the attached Figure 1 In step S7, the defoaming agent is polydimethylsiloxane or a vegetable oil defoaming agent, and the viscosity of the system is controlled at 50-100 mPa·s after addition.

[0071] Specifically, by using a defoaming agent, bubbles in the coating process can be reduced, thereby improving the uniformity and adhesion of the coating and reducing coating defects. The use of a defoaming agent and the control of viscosity help to form a more uniform and denser coating, thereby enhancing the corrosion resistance and magnetic properties of the coating. By controlling foam and adjusting viscosity, the coating quality is improved, the coating process is optimized, and the coating performance is enhanced, ultimately achieving the effect of improving the overall performance of the coating.

[0072] Example 1

[0073] 1. Technical Solution

[0074] 1. Coating liquid component ratio (mass percentage):

[0075] Phosphate (aluminum dihydrogen phosphate and magnesium dihydrogen phosphate mass ratio 1:1): 20%;

[0076] Colloidal silica (particle size 30nm, specific surface area 200m 2 / g, porosity 70%): 22%;

[0077] Chromic acid compound (chromic anhydride, purity 99.5%, particle size 8 μm): 18%;

[0078] Silica sol (pH 9.5, solid content 25%, colloidal particle size 20 nm): 10%;

[0079] Other additives (borate 45%, nitrate 30%, cerium nitrate 25%): 8%;

[0080] Defoaming agent (polydimethylsiloxane): 1%;

[0081] Desalted water balance: 21%.

[0082] 2. Preparation method:

[0083] S1: Add 21% desalted water into the reactor and stir at 300 r / min for 8 minutes.

[0084] S2: After an interval of 15 minutes, phosphate was added at a rate of 1.0 kg / min, the temperature was maintained at 30°C, and stirring was carried out at 400 r / min for 35 minutes (system pH 3.0).

[0085] S3: Colloidal silica was added in three equal portions (5 minutes apart), the temperature was raised to 45°C, and the mixture was stirred at 500 rpm for 35 minutes.

[0086] S4: Add chromic acid compound, cool to 35°C, and stir at 400 r / min for 35 minutes.

[0087] S5: Add silica sol and stir at 300 r / min for 25 minutes.

[0088] S6: Add other additives and stir at 400 r / min for 25 minutes.

[0089] S7: Finally, add the defoamer and stir at 150 r / min for 60 minutes (viscosity 80 mPa·s).

[0090] 2. Technical Effect

[0091] Iron loss (P1.7 / 50): 0.85W / kg (GB / T13789-2021);

[0092] Magnetic induction intensity (B8000): 1.92T (GB / T3656-2008);

[0093] Salt spray resistance (500h): no rust (GB / T10125-2021);

[0094] Coating adhesion: Grade 1 (cross-hatch method ASTM D3359).

[0095] Example 2

[0096] 1. Technical Solution

[0097] 1. Coating liquid component ratio (mass percentage):

[0098] Phosphate (mass ratio of aluminum dihydrogen phosphate to magnesium dihydrogen phosphate 1:0.8): 22%;

[0099] Colloidal silica (particle size 50nm, specific surface area 250m 2 / g, porosity 80%): 25%;

[0100] Chromic acid compound (chromic anhydride, purity 99.8%, particle size 5 μm): 20%;

[0101] Silica sol (pH 10.0, solid content 28%, colloidal particle size 15 nm): 12%;

[0102] Other additives (borate 50%, nitrate 25%, cerium oxide 25%): 10%;

[0103] Defoaming agent (vegetable oil defoaming agent): 1.5%;

[0104] Desalted water balance: 9.5%.

[0105] 2. Preparation method:

[0106] S1: Add 9.5% desalted water and stir at 400 r / min for 5 minutes.

[0107] S2: Phosphate was added at a rate of 0.8 kg / min, maintained at 25°C, and stirred at 500 r / min for 35 minutes (pH 2.8).

[0108] S3: Colloidal silica was added in three portions, the temperature was raised to 50°C, and stirred at 600 rpm for 35 minutes.

[0109] S4: Add chromic acid compound, cool to 40°C, and stir at 450 r / min for 35 minutes.

[0110] S5: The silica sol was stirred at 400 r / min for 25 minutes.

[0111] S6: Stir other additives at 500 r / min for 25 minutes.

[0112] S7: The defoamer was stirred at 200 r / min for 60 minutes (viscosity 100 mPa·s).

[0113] 2. Technical Effect

[0114] Iron loss (P1.7 / 50): 0.78W / kg;

[0115] Magnetic induction intensity (B8000): 1.95T;

[0116] Salt spray resistance (500h): single point rust area ≤ 1% (Grade A);

[0117] Coating porosity: ≤0.5% (GB / T1771-2007).

[0118] Example 3

[0119] 1. Technical Solution

[0120] 1. Coating liquid component ratio (mass percentage):

[0121] Phosphate (mainly magnesium dihydrogen phosphate, mass ratio 1:2): 18%;

[0122] Colloidal silica (particle size 10nm, specific surface area 300m 2 / g, porosity 60%): 20%;

[0123] Chromic acid compound (chromic anhydride, purity 99.5%, particle size 10μm): 15%;

[0124] Silica sol (pH 8.5, solid content 20%, colloidal particle size 30nm): 8%;

[0125] Other additives (borate 40%, nitrate 35%, cerium nitrate 25%): 5%;

[0126] Defoamer (polydimethylsiloxane): 0.5%;

[0127] Deionized water balance: 33.5%.

[0128] 2. Preparation method:

[0129] S1: Add 33.5% deionized water and stir at 200 r / min for 10 minutes.

[0130] S2: Add phosphate at a rate of 1.5 kg / min, maintain at 35°C, and stir at 300 r / min for 35 minutes (pH 3.2).

[0131] S3: Add colloidal silica in three portions, heat up to 40°C, and stir at 400 r / min for 35 minutes.

[0132] S4: Cool the chromic acid compound to 30°C and stir at 350 r / min for 35 minutes.

[0133] S5: Stir the silica sol at 250 r / min for 25 minutes.

[0134] S6: Stir other additives at 300 r / min for 25 minutes.

[0135] S7: Stir the defoamer at 100 r / min for 60 minutes (viscosity 50 mPa·s).

[0136] II. Technical effects

[0137] Iron loss (P1.7 / 50): 0.90 W / kg;

[0138] Magnetic induction intensity (B8000): 1.88 T;

[0139] Moisture and heat resistance (1000h): The coating does not fall off (GB / T1740-2007);

[0140] Cost comparison: The cost of raw materials is reduced by 15% compared with Example 1.

[0141] Comparative Example 1

[0142] 1. Technical solution:

[0143] 1. Component ratio (mass percentage):

[0144] Phosphate (aluminum dihydrogen phosphate and magnesium dihydrogen phosphate mass ratio 1:1): 20%;

[0145] Colloidal silica (particle size 30nm, specific surface area 200m 2 / g, porosity 70%): 25%;

[0146] Chromic acid compound (chromic anhydride, purity 99.5%, particle size 8 μm): 20%;

[0147] Silica sol (pH 9.5, solid content 25%, colloidal particle size 20 nm): 10%;

[0148] Other additives (borates and nitrates only, ratio 60%:40%): 8%;

[0149] Defoaming agent (polydimethylsiloxane): 1%;

[0150] Desalted water balance: 16%.

[0151] 2. Preparation method: Same as Example 1, but omitting the rare earth element and using only borates and nitrates as additives.

[0152] 3. Test standards and items:

[0153] Iron loss (P1.7 / 50): Based on "GB / T13789-2021 Electrical steel sheet (strip) iron loss determination method".

[0154] Magnetic induction intensity (B8000): Based on "GB / T3656-2008 Determination of magnetic properties of electrical steel sheets (strips)".

[0155] Salt spray resistance: According to GB / T10125-2021 Artificial atmosphere corrosion test salt spray test, the rust spot area is tested after 500 hours.

[0156] Experimental results:

[0157] Test items Comparative Example 1 Example 1 Iron loss (W / kg) 1.12 0.85 Magnetic induction intensity (T) 1.83 1.92 Salt spray rust area 15％ No rust spots

[0158] Summary: After omitting the rare earth element in Comparative Example 1, the iron loss increased by 32%, the magnetic induction intensity decreased by 4.7%, and the salt spray resistance deteriorated significantly, indicating that the rare earth element regulates the density of the oxide film (such as the passivation effect of cerium).

[0159] Comparative Example 2

[0160] 1. Technical solution:

[0161] The component ratio was the same as that in Example 2, but the colloidal silicon dioxide was added all at once and the stirring speed was reduced to 200 r / min.

[0162] 2. Preparation method:

[0163] In step S3, the colloidal silica is added all at once, not in batches;

[0164] The stirring speed was reduced to 200 r / min (600 r / min in Example 2).

[0165] 3. Test standards and items:

[0166] Coating uniformity: According to GB / T1720-2020 Determination of paint film uniformity, visually observe particle agglomeration.

[0167] Adhesion grade: According to ASTM D3359 cross-cut method, 0-5 (0 means no peeling, 5 means complete peeling).

[0168] Porosity: Calculate the percentage of micropore area in the coating based on GB / T1771-2007 Paints and varnishes - Determination of resistance to neutral salt spray.

[0169] 4. Experimental results:

[0170] Test items Comparative Example 2 Example 2 Coating uniformity Local agglomeration Uniform without lumps Iron loss (W / kg) 0.95 0.78 Adhesion grade Level 3 (partial detachment) Level 1 (no shedding) Porosity 2.1％ ≤0.5％

[0171] In summary, Comparative Example 2 used a traditional single, low-speed stirring process, resulting in uneven dispersion of the colloidal silica, increased porosity, and a 21.8% increase in iron loss. In contrast, Example 2 significantly improved dispersibility by adding the colloidal silica in batches (5-minute intervals) and stirring at a high speed (400-600 rpm).

[0172] Comparative Example 3

[0173] 1. Technical solution:

[0174] 1. Component ratio (mass percentage):

[0175] Phosphate (aluminum dihydrogen phosphate and magnesium dihydrogen phosphate mass ratio 1:1): 20%;

[0176] Colloidal silica (particle size 30nm, specific surface area 200m 2 / g, porosity 70%): 25%;

[0177] Chromic acid compound (chromic anhydride, purity 99.5%, particle size 8 μm): 20%;

[0178] Silica sol (pH 9.5, solid content 25%, colloidal particle size 20 nm): 10%;

[0179] Other additives: only nitrates and rare earth elements (nitrate 70%, cerium nitrate 30%), excluding borates, which account for 8%;

[0180] Defoaming agent (polydimethylsiloxane): 1%;

[0181] Desalted water balance: 16%.

[0182] 2. Preparation method:

[0183] S1: Add 16% desalted water and stir at 300 r / min for 8 minutes.

[0184] S2: After an interval of 15 minutes, phosphate was added at a rate of 1.0 kg / min, and the mixture was maintained at 30°C and stirred at 400 rpm for 35 minutes (system pH 3.0).

[0185] S3: Add colloidal silica all at once (not in batches), heat to 45°C, and stir at 400 rpm for 35 minutes.

[0186] S4: Add chromic acid compound, cool to 35°C, and stir at 400 r / min for 35 minutes.

[0187] S5: Add silica sol and stir at 300 r / min for 25 minutes.

[0188] S6: Add other additives (nitrate 70% and cerium nitrate 30%, no borate), and stir at 400 r / min for 25 minutes.

[0189] S7: Add defoaming agent and stir at 150 r / min for 60 minutes (viscosity 80 mPa·s).

[0190] 2. Test Standards and Items

[0191] Iron loss (P1.7 / 50): GB / T13789-2021.

[0192] Magnetic induction intensity (B8000): GB / T3656-2008.

[0193] Salt spray resistance: GB / T10125-2021, rust spot area after 500h.

[0194] Coating adhesion: ASTM D3359 cross-cut method (grade 0-5).

[0195] Porosity: GB / T1771-2007 coating cross-section microscopic analysis.

[0196] 3. Experimental Results and Comparison

[0197] Test items Control group 3 Example 3 Iron loss (W / kg) 1.18 0.85 Magnetic induction intensity (T) 1.78 1.92 Salt spray rust area 25％ No rust spots Adhesion grade Level 4 (large area shedding) Level 1 (no shedding) Porosity 3.2％ ≤0.5％

[0198] Conclusion: In the present invention, borate significantly improves the density and adhesion of the coating through the synergistic effect with rare earth elements (such as forming a cerium borate complex).

[0199] While embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions, and variations may be made to these embodiments without departing from the principles and spirit of the invention, and that the scope of the invention is defined by the appended claims and their equivalents.

Claims

1. A corrosion-resistant stress coating liquid for an oriented silicon steel FCL production line, characterized in that: The following components are included by mass percentage: Phosphate: 18-22%; Colloidal silicon dioxide: 20-25%; Chromic acid compounds: 15-20%; Silica sol: 8-12%; Other additives: 5-10%; Defoaming agent: 0.5-1.5%; Desalted water: the remainder, so that the sum of each component is 100%; The other additives are a mixture of borate, nitrate and rare earth elements, wherein borate accounts for 40-50% of the total mass of the other additives, nitrate accounts for 25-35%, and rare earth elements account for 15-25%, and the total of the three is 100%.

2. The corrosion-resistant stress coating liquid for an oriented silicon steel FCL production line according to claim 1, characterized in that: The phosphate is a nano-scale composite material of aluminum dihydrogen phosphate and magnesium dihydrogen phosphate, with an average particle size of 50-80 nm, wherein the aluminum dihydrogen phosphate and magnesium dihydrogen phosphate form a core-shell structure through a sol-gel method, with a mass ratio of 1:0.8-1:1.5, and the specific surface area of ​​the composite material is greater than 200 m 2 / g.

3. The corrosion-resistant stress coating liquid for an oriented silicon steel FCL production line according to claim 1, characterized in that: The colloidal silica is modified with amino groups, and its particle size is bimodal, wherein the particle size of 10-20 nm accounts for 30% ± 5%, and the particle size of 40-50 nm accounts for 70% ± 5%. The specific surface area is controlled within 200-250 m by nanopore expansion technology. 2 / g, porosity is 75%±2%.

4. The corrosion-resistant stress coating liquid for an oriented silicon steel FCL production line according to claim 1, characterized in that: The chromic acid compound is chromic anhydride with a gradient particle size distribution and is compounded with an ammonium tungstate stabilizer. The purity of the chromic acid compound is ≥99.5% and the particle size is ≤10 μm.

5. The corrosion-resistant stress coating liquid for an oriented silicon steel FCL production line according to claim 1, characterized in that: The silica sol is pretreated by cation exchange method, the pH value is stabilized at 9.0-9.5±0.2 by nanobubble technology, the solid content is 25-28%, and the water content is controlled at <0.5% by molecular sieve dehydration, and the colloidal particle size is 5-30nm.

6. The corrosion-resistant stress coating liquid for an oriented silicon steel FCL production line according to claim 1, characterized in that: The rare earth element is cerium, which is added in the form of cerium nitrate or cerium oxide. It is prepared into rod-shaped nanoparticles by a hydrothermal synthesis method with a purity of ≥99.99%, and the surface is coated with a zirconium phosphate protective layer.

7. A method for preparing a corrosion-resistant stress coating liquid for an oriented silicon steel FCL production line, characterized in that: The method for preparing the coating liquid according to any one of claims 1 to 6 comprises the following steps: S1. Add the remaining desalted water to the reaction vessel and stir at a speed of 200-400 r / min for 5-10 minutes; S2. After a 15-minute interval, add 18-22% phosphate, maintain the temperature at 25-35°C, and stir at a speed of 300-500 rpm for 35 minutes; S3. Add 20-25% colloidal silica, raise the temperature to 40-50°C, and stir at 400-600 rpm for 35 minutes to ensure that the colloidal silica is evenly dispersed. S4. Add 15-20% of chromic acid compound, cool to 30-40°C, and stir at 350-450 rpm for 35 minutes; S5. Add 8-12% silica sol and stir at 250-400 rpm for 25 minutes; S6. Add 5-10% of other additives and stir at a speed of 300-500 r / min for 25 minutes; S7. Finally, add 0.5-1.5% of defoaming agent and stir at a speed of 100-200 r / min for 60 minutes to obtain a coating liquid.

8. The method for preparing a corrosion-resistant stress coating liquid for an oriented silicon steel FCL production line according to claim 7, characterized in that: The phosphate is added at a rate of 0.5-1.5 kg / min in step S2, and the pH value of the system after stirring is 2.5-3.

5.

9. The method for preparing a corrosion-resistant stress coating liquid for an oriented silicon steel FCL production line according to claim 7, characterized in that: The colloidal silica in step S3 is added in three equal amounts, with an interval of 5 minutes between each addition, and each addition is accompanied by the addition of ammonium polyacrylate dispersant, accounting for 0.2-0.5% of the mass of the colloidal silica, and vacuum degassing treatment is performed between two adjacent additions, wherein the vacuum degree is ≤-0.08MPa and maintained for 2-3min.

10. The method for preparing a corrosion-resistant stress coating liquid for an oriented silicon steel FCL production line according to claim 7, characterized in that: The defoaming agent in step S7 is polydimethylsiloxane or a vegetable oil defoaming agent, and the viscosity of the system is controlled at 50-100 mPa·s after addition.

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