Insulating coating liquid, insulating coating, and oriented silicon steel

Abstract

The application relates to an insulating coating liquid, an insulating coating and oriented silicon steel, components of the insulating coating liquid comprising: a dihydrogen phosphate, a silica sol, phosphoric acid, a zirconium oxide dispersion liquid and chromic anhydride; wherein the content of the zirconium oxide dispersion liquid is 1-5% in mass fraction. The zirconium oxide dispersion liquid can be dissolved into the phosphate coating liquid, and zirconium phosphate generated after heat treatment can reduce the coating expansion coefficient and thus improve the coating tension. The phosphoric acid and the zirconium oxide dispersion liquid can be dissolved in the water-based coating, and zirconium phosphate can be generated after heat treatment. The low expansion coefficient of the zirconium phosphate can improve the coating tension, so that the technical problem of low coating tension existing in the prior art phosphate insulating coating is solved.

Description

Technical Field

[0001] This application relates to the field of insulating coating technology for grain-oriented silicon steel, and more particularly to an insulating coating liquid, an insulating coating, and grain-oriented silicon steel. Background Technology

[0002] A layer of insulating coating is required on the surface of grain-oriented silicon steel. Iron losses in grain-oriented silicon steel are mainly caused by hysteresis loss, eddy current loss, and abnormal losses. The insulating coating can apply a certain tension to the grain-oriented silicon steel substrate, hence it is also called a tension coating, which can reduce iron losses, refine the magnetic flux, and improve magnetic properties. The insulating coating also provides grain-oriented silicon steel with good insulation properties, good corrosion resistance, good heat resistance and high-temperature resistance, good adhesion properties, and good hardness. Phosphate insulating coatings, which have excellent heat resistance and high-temperature resistance, are commonly used.

[0003] However, existing phosphate insulating coatings suffer from the technical problem of low coating tension. Summary of the Invention

[0004] This application provides an insulating coating liquid, an insulating coating, and oriented silicon steel to solve the technical problem of low coating tension in existing phosphate insulating coatings.

[0005] In a first aspect, this application provides an insulating coating liquid, the components of which include:

[0006] Dihydrogen phosphate, silica sol, phosphoric acid, zirconium oxide dispersion, and chromium anhydride; wherein, by mass fraction,

[0007] The content of the zirconium oxide dispersion is 1-5%.

[0008] Optionally, the weight concentration of the zirconium oxide dispersion is 15-18%.

[0009] Optionally, the dihydrogen phosphate, by mass fraction,

[0010] The content is 20-40%, the content of the silica sol is 20-40%, the content of the phosphoric acid is 1-5%, and the content of the chromic anhydride is 1-5%.

[0011] Optionally, the dihydrogen phosphate salt includes at least one of the following: aluminum dihydrogen phosphate, magnesium dihydrogen phosphate, calcium dihydrogen phosphate, and sodium dihydrogen phosphate.

[0012] Optionally, the process parameters of the silica sol include: SiO2 content of 29-31%, pH value of 8.5-10.5, and...

[0013] The average particle size is 10–20 nm.

[0014] Optionally, the phosphoric acid has a weight concentration of 85-88%.

[0015] Optionally, the purity of the chromic anhydride is ≥99.5%.

[0016] Optionally, the insulating coating liquid may also include deionized water.

[0017] Secondly, this application provides an insulating coating formed from the insulating coating liquid described in any embodiment of the first aspect.

[0018] Thirdly, this application provides a grain-oriented silicon steel, which includes a steel matrix and a substrate attached to the steel matrix.

[0019] The insulating coating described in any one of the second aspects of the embodiment of the body, at least a portion of its surface.

[0020] The technical solutions provided in this application have the following advantages compared with the prior art:

[0021] The insulating coating liquid provided in this application embodiment can dissolve zirconium oxide dispersion in phosphate coating liquid. The zirconium phosphate generated after heat treatment can reduce the coating expansion coefficient and thus increase the coating tension. Phosphoric acid and zirconium oxide dispersion can be dissolved in water-based coatings. After heat treatment, zirconium phosphate can be generated. The low expansion coefficient of zirconium phosphate can increase the coating tension. Attached Figure Description

[0022] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this application and, together with the description, serve to explain the principles of this application.

[0023] To more clearly illustrate the technical solutions in the embodiments of this application or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, for those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0024] Figure 1 A scanning electron microscope image of an insulating layer provided in an embodiment of this application;

[0025] Figure 2 An X-ray diffraction test pattern of an insulating layer provided in an embodiment of this application. Detailed Implementation

[0026] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, not all embodiments. Based on the embodiments of this application, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this application.

[0027] Various embodiments of this application may exist in the form of a range; it should be understood that the description in the form of a range is merely for convenience and brevity and should not be construed as a hard limitation on the scope of this application; therefore, it should be considered that the range description has specifically disclosed all possible sub-ranges and single numerical values ​​within that range. For example, it should be considered that the range description from 1 to 6 has specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 6, from 3 to 6, etc., and single numbers within the range, such as 1, 2, 3, 4, 5, and 6, regardless of the range. Furthermore, whenever a numerical range is referred to herein, it means including any referenced number (fraction or integer) within the referred range.

[0028] In this application, unless otherwise stated, directional terms such as "upper" and "lower" specifically refer to the drawing directions in the accompanying drawings. Furthermore, in the description of this application, terms such as "comprising" and "including" mean "including but not limited to." In this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. In this document, "and / or" describes the relationship between related objects, indicating that three relationships can exist; for example, A and / or B can represent: A alone, A and B simultaneously, or B alone. A and B can be singular or plural. In this document, "at least one" means one or more, and "more than one" means two or more. "At least one," "at least one of the following," or similar expressions refer to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b, and c" can both mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can be a single or multiple.

[0029] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this application can be purchased from the market or prepared by existing methods.

[0030] In a first aspect, this application provides an insulating coating liquid, the components of which include:

[0031] Dihydrogen phosphate, silica sol, phosphoric acid, zirconium oxide dispersion, and chromium anhydride; wherein, by mass fraction,

[0032] The content of the zirconium oxide dispersion is 1-5%.

[0033] In this embodiment, the zirconium oxide dispersion can be dissolved in the phosphate coating solution. The zirconium phosphate generated after heat treatment can reduce the coating expansion coefficient and thus increase the coating tension. Phosphoric acid and zirconium oxide dispersion can be dissolved in water-based coatings. After heat treatment, zirconium phosphate can be generated. The low expansion coefficient of zirconium phosphate can increase the coating tension and effectively reduce the loss of oriented silicon steel.

[0034] If the content of the zirconia dispersion is too high, it will shorten the gelation time of the phosphate coating and reduce the stability of the coating to some extent; if the content of the zirconia dispersion is too low, the corrosion resistance will not change much, the coating tension will not increase significantly, and the iron loss will not decrease significantly. Specifically, the content of the zirconia dispersion can be 1%, 2%, 3%, 4%, 5%, etc.

[0035] In some embodiments, the zirconium oxide dispersion has a weight concentration of 15-18%.

[0036] In this embodiment, the weight concentration of the zirconia dispersion is controlled to make the zirconia dispersion more stable. This is achieved by shortening the mixing time between the zirconia sol and the phosphate solution, ensuring thorough mixing. If the weight concentration of the zirconia dispersion is too high, it will increase the mixing time between the phosphate solution and the zirconia dispersion, reducing stability. Conversely, if the weight concentration is too low, it will increase the amount of zirconia dispersion used, reducing the solid content of the solution. Specifically, the weight concentration of the zirconia dispersion can be 15%, 16%, 17%, 18%, etc.

[0037] In some embodiments, the content of the dihydrogen phosphate is 20-40% by mass fraction, and the silica sol...

[0038] The content of the chromium trioxide is 20-40%, the content of the phosphoric acid is 1-5%, and the content of the chromium trioxide is 1-5%.

[0039] In this embodiment, dihydrogen phosphate is colorless, odorless, and viscous, commonly used as an adhesive or inorganic coating for refractory materials. After curing, it exhibits high bonding strength and possesses excellent high-temperature resistance, shock resistance, peeling resistance, and insulation properties. Controlling the content of dihydrogen phosphate facilitates a tighter bond between the coating and the substrate and increases the coating tension, significantly improving the adhesion between the high-tension coating of oriented silicon steel and the magnesium silicate underlayer. Specifically, the content of dihydrogen phosphate can be 20%, 25%, 30%, 35%, 40%, etc.

[0040] Silica sol is a milky white colloidal solution composed of nano-sized ultrafine silica particles dispersed in water. The silica surface has numerous active groups such as water and hydroxyl groups, which can cross-link with phosphates through these active hydroxyl groups, promoting the formation of a network structure in the coating. However, silica sol experiences significant volume shrinkage during film formation, making the coating prone to cracking. Therefore, it must be used in conjunction with a phosphate binder. The silica sol used in this application's embodiments effectively improves the adhesion and wear resistance of high-tensile coatings for grain-oriented silicon steel. By controlling the silica sol content, a low coefficient of thermal expansion is achieved, effectively improving the tension, adhesion, and wear resistance of the high-tensile coating on grain-oriented silicon steel. Specifically, the silica sol content can be 20%, 25%, 30%, 35%, 40%, etc.

[0041] Chromium anhydride can improve the leveling properties of the coating solution and stabilize free phosphate ions in phosphate. The chromium anhydride used in this invention can prevent moisture absorption in the oriented silicon steel phosphate insulating coating and improve the coating appearance. Controlling the chromium anhydride content improves the wettability of the coating solution, stabilizes free phosphoric acid in the phosphate, enhances the stability and moisture resistance of the high-tension coating of oriented silicon steel, and improves the coating appearance. Specifically, the chromium anhydride content can be 1%, 2%, 3%, 4%, 5%, etc.

[0042] Phosphoric acid and zirconium oxide dispersions are soluble in aqueous coatings. After heat treatment, zirconium phosphate is formed. The low coefficient of thermal expansion of zirconium phosphate can increase coating tension and reduce steel loss in oriented silicon steel. The phosphoric acid content can be controlled to make the zirconium oxide dispersion easier to mix with the coating solution, thus increasing the amount of zirconium oxide added. Specifically, the phosphoric acid content can be 1%, 2%, 3%, 4%, 5%, etc.

[0043] In some embodiments, the dihydrogen phosphate salt includes at least one of the following: aluminum dihydrogen phosphate, magnesium dihydrogen phosphate, calcium dihydrogen phosphate, and sodium dihydrogen phosphate.

[0044] In the embodiments of this application, the positive effects of selecting aluminum dihydrogen phosphate, magnesium dihydrogen phosphate, calcium dihydrogen phosphate, and sodium dihydrogen phosphate as dihydrogen phosphate salts are as follows: aluminum dihydrogen phosphate and magnesium dihydrogen phosphate have high strength and adhesion, calcium dihydrogen phosphate has high water resistance, and sodium dihydrogen phosphate easily forms a smooth coating. Furthermore, the mass fraction of this dihydrogen phosphate salt is 50%.

[0045] In some embodiments, the process parameters of the silica sol include: SiO2 content of 29-31%, pH value of 8.5-

[0046] 10.5 and an average particle size of 10–20 nm.

[0047] In this embodiment, the SiO2 content of the silica sol is controlled to effectively improve the tension, adhesion, and wear resistance of the high-tension coating on oriented silicon steel. Controlling the pH value of the silica sol stabilizes the metal cations in the insulating coating solution, protecting the stability of these cations. Controlling the average particle size of the silica sol increases the reaction contact area of ​​silica, improves system permeability, and gives the coating stronger adhesion, increasing film strength and coatability. Specifically, the SiO2 content can be 29%, 30%, 31%, etc., the pH value can be 8.5, 9, 10, 10.5, etc., and the average particle size can be 10nm, 12nm, 14nm, 16nm, 18nm, 20nm, etc.

[0048] In some embodiments, the phosphoric acid has a weight concentration of 85-88%.

[0049] In the embodiments of this application, the weight concentration of phosphoric acid is controlled to ensure the mass fraction of dihydrogen phosphate. Specifically...

[0050] The weight concentration of this phosphoric acid can be 85%, 86%, 87%, 88%, etc.

[0051] In some embodiments, the purity of the chromic anhydride is ≥99.5%.

[0052] In this embodiment, the purity of chromic anhydride is controlled to improve the wettability of the coating solution and stabilize free phosphorus in the phosphate.

[0053] The high-tensile coating on acid-oriented silicon steel improves stability and moisture resistance, and enhances the coating's appearance. Specifically, the purity of the chromic anhydride can be 99.5%, 99.6%, 99.8%, etc.

[0054] In some embodiments, the insulating coating liquid also includes deionized water.

[0055] In this embodiment, the deionized water is used as a diluent, and the deionized water content is 20-30 wt% to ensure...

[0056] The solid content of the coating liquid is around 30%.

[0057] Preparation of the above insulating coating liquid: According to the components and contents of the above insulating coating liquid, the dihydrogen phosphate, silica sol, phosphoric acid, zirconium oxide dispersion and chromic anhydride are added to the reaction vessel and mixed evenly to obtain the insulating coating liquid.

[0058] Secondly, this application provides an insulating coating formed from the insulating coating liquid described in any embodiment of the first aspect.

[0059] The insulating coating provided in this application exhibits significantly superior water resistance and heat resistance compared to organic coatings. The coating film is dense and hard, does not generate static electricity, and makes it difficult for various dust particles in the air to adhere. It also boasts good gloss and high film quality. Please refer to [link / reference]. Figure 1 The image shows a scanning electron microscope (SEM) image of the insulating layer. The high-tension coating on the grain-oriented silicon steel exhibits good adhesion and high interlayer resistivity, meeting not only the insulation performance requirements but also demonstrating good corrosion resistance. Please refer to [link to relevant documentation]. Figure 2 The X-ray diffraction pattern of the insulating layer shown indicates that the coating generates a zirconium phosphate material with a negative coefficient of thermal expansion during the heat treatment process.

[0060] The insulating coating is based on the above-mentioned insulating coating liquid. The specific components of the insulating coating liquid can be referred to in the above embodiments. Since the insulating coating adopts some or all of the technical solutions of the above embodiments, it has at least all the beneficial effects brought about by the technical solutions of the above embodiments, which will not be elaborated here.

[0061] Thirdly, this application provides a grain-oriented silicon steel, which includes a steel matrix and a substrate attached to the steel matrix.

[0062] The insulating coating described in any one of the second aspects of the embodiment of the body, at least a portion of its surface.

[0063] Preparation of the above-mentioned oriented silicon steel coating: The above-mentioned insulating coating liquid is applied to at least part of the surface of the oriented silicon steel, then dried at 300-500°C for 20-40 seconds, and then heat-treated at 750-850°C for 100-200 seconds to obtain the oriented silicon steel coating.

[0064] The preparation process is simple, does not require PVD or CVD methods, is easy to industrialize, and is low in cost.

[0065] The present application is further illustrated below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the application. Experimental methods in the following embodiments that do not specify specific conditions are generally determined according to national standards. If there is no corresponding national standard, then general international standards, conventional conditions, or conditions recommended by the manufacturer are followed.

[0066] The components of the insulating coating liquid provided in Examples 1-4 of this application are shown in Table 1, the process parameters of the components of the insulating coating liquid are shown in Table 2, and the preparation process parameters of the insulating coating are shown in Table 3.

[0067] Table 1. Composition of the insulating coating liquid (wt%)

[0068]

[0069] Table 2 Process parameters of the components of the insulating coating liquid

[0070]

[0071] Table 3. Preparation process parameters of the insulating coating

[0072]

[0073] Comparative Examples: The components of the insulating coating liquid provided in Comparative Examples 1 and 2 are shown in Table 4, the process parameters of the components of the insulating coating liquid are shown in Table 5, and the preparation process parameters of the insulating coating are shown in Table 6.

[0074] Table 4. Composition of the insulating coating liquid (wt%)

[0075]

[0076] Table 5 Process parameters of the components of the insulating coating liquid

[0077]

[0078] Table 6. Preparation process parameters of insulating coating

[0079]

[0080] The properties of the oriented silicon steel prepared in this specific embodiment were judged or measured according to the following methods or standards: the surface quality of the coating was evaluated by SEM; adhesion was measured according to GB2522-88; and iron loss was measured using an iron loss tester. The properties of the insulating coatings of Examples 1-4 and Comparative Examples 1-2 are detailed in Table 7.

[0081] Table 7 Performance of Insulating Coatings

[0082]

[0083] The insulating coating in this embodiment has good coating tension, and therefore has low iron loss. In contrast, Comparative Examples 1 and 2, which did not adopt the scheme of this embodiment, have insulating coatings with relatively high iron loss.

[0084] The above description is merely a specific embodiment of this application, enabling those skilled in the art to understand or implement this application. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of this application. Therefore, this application is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features claimed herein.

Claims

1. An insulating coating liquid, characterized in that, The insulating coating liquid is composed of the following components: The mixture comprises dihydrogen phosphate, silica sol, phosphoric acid, zirconium oxide dispersion, chromium anhydride, and deionized water; wherein, by mass fraction, the content of the zirconium oxide dispersion is 1-5%, the content of the dihydrogen phosphate is 20-40%, the content of the silica sol is 20-40%, the content of the phosphoric acid is 1-5%, the content of the chromium anhydride is 1-5%, and the content of the deionized water is 20-30%. The zirconium oxide dispersion has a weight concentration of 15-18%; The dihydrogen phosphate includes at least one of the following: aluminum dihydrogen phosphate, magnesium dihydrogen phosphate, calcium dihydrogen phosphate, and sodium dihydrogen phosphate. The process parameters of the silica sol include: SiO2 content of 29-31%, pH value of 8.5-10.5, and average particle size of 10-20 nm; The phosphoric acid has a weight concentration of 85-88%.

2. The insulating coating liquid according to claim 1, characterized in that, The purity of the chromic anhydride is ≥99.5%.

3. An insulating coating, characterized in that, The insulating coating is formed from the insulating coating liquid according to claim 1 or 2.

4. A type of grain-oriented silicon steel, characterized in that, The oriented silicon steel comprises a steel substrate and an insulating coating of claim 3 attached to at least a portion of the surface of the steel substrate.

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