CN116496647B - Insulation coating liquid for surface modification of oriented silicon steel and preparation method thereof - Google Patents

Insulation coating liquid for surface modification of oriented silicon steel and preparation method thereof Download PDF

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CN116496647B
CN116496647B CN202211414320.2A CN202211414320A CN116496647B CN 116496647 B CN116496647 B CN 116496647B CN 202211414320 A CN202211414320 A CN 202211414320A CN 116496647 B CN116496647 B CN 116496647B
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silicon steel
coating liquid
silica sol
coating
dihydrogen phosphate
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CN116496647A (en
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王佳伟
王�琦
王强明
杨猛
叶明辉
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Anqing Xinpu Electric Equipment Co ltd
Wuxi Putian Iron Core Co Ltd
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Anqing Xinpu Electric Equipment Co ltd
Wuxi Putian Iron Core Co Ltd
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    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09DCOATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D1/00Coating compositions, e.g. paints, varnishes or lacquers, based on inorganic substances
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    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09DCOATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • CCHEMISTRY; METALLURGY
    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09DCOATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/08Anti-corrosive paints
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    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
    • C09DCOATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR
    • C09D5/00Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced; Filling pastes
    • C09D5/18Fireproof paints including high temperature resistant paints
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    • C09DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
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    • C09D7/00Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40Additives
    • C09D7/60Additives non-macromolecular
    • C09D7/61Additives non-macromolecular inorganic
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    • C09D7/00Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
    • C09D7/40Additives
    • C09D7/60Additives non-macromolecular
    • C09D7/61Additives non-macromolecular inorganic
    • C09D7/62Additives non-macromolecular inorganic modified by treatment with other compounds

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Abstract

The invention relates to an insulating coating liquid for surface modification of oriented silicon steel and a preparation method thereof, wherein the insulating coating liquid comprises the following components in percentage by mass based on the total mass of a coating solution: 20-40% of aluminum dihydrogen phosphate, 5-15% of magnesium dihydrogen phosphate, 1-5% of chromic anhydride, 30-60% of modified silica sol and the balance of water. The invention has the advantages that: after the working procedures of coating the oriented silicon steel and the like, the formed coating can improve the insulativity of the silicon steel sheet, increase the interlayer resistance of the silicon steel sheet, reduce the iron loss, prolong the service life of the iron core, reduce the energy consumption of the iron core, improve the toughness and the sheet punching performance of the silicon steel sheet and improve the adhesiveness, and the coating has the advantages of high-temperature sintering crack resistance, reduced crack quantity and size, good appearance and excellent corrosion resistance.

Description

Insulation coating liquid for surface modification of oriented silicon steel and preparation method thereof
Technical Field
The invention relates to an insulating coating liquid for surface modification of oriented silicon steel and a preparation method thereof, belonging to the technical field of insulating coatings.
Background
Oriented silicon steel is used as a magnetic material and is widely applied to manufacturing transformers, large motors and transformers in the power transmission and transformation industry, and belongs to the power industry. In recent years, the requirements for energy conservation and emission reduction are increasingly urgent, and electric energy is taken as a widely used green energy source and also provides energy conservation and synergy requirements. The insulating coating is coated on the surface of the silicon steel, so that the resistance between the silicon steel sheets is improved, the eddy current loss can be reduced, the iron loss can be reduced, and the silicon steel can be protected from being corroded in the processes of processing, transportation and long-term use.
In general, a magnesium silicate bottom layer, commonly known as a glass substrate, is formed in the high-temperature secondary recrystallization process in the production process of oriented silicon steel, and the interlayer resistance of the magnesium silicate bottom layer can reach 5 Ω cm 2 The requirement of the rolled iron core can be met, but the laminated iron core is far from enough, and the silicon steel sheet still needs to be coated with an insulating coating with the thickness of 2-3 mu m, so that the interlayer resistance of the oriented silicon steel reaches 30-50Ω & cm 2 However, the requirements of the iron core of the transformer with higher performance still cannot be met, the voltage class of the transformer with higher performance is 220KV, and the transformer is exposed to an ultra-high current environment for a long time, so that the requirements on the interlayer resistance are higher. And the lamination coefficient of the silicon steel sheet is reduced a little when each surface is coated with an insulating coating with the thickness of 2-3 mu m, and thinner and more efficient coatings are the future trend.
Because the temperature of the oriented silicon steel production and processing link is extremely high, the conventional organic coating cannot be tolerated, and the oriented silicon steel insulating coating liquid applied in the prior art is basically an inorganic component, mainly comprises phosphate inorganic matters, and is matched with silica sol, chromic anhydride and a small amount of additives. The silica sol can be uniformly coated on the surface of the glued component, so that the film forming property of the coating liquid is improved. Meanwhile, due to the body-type cross-linked structure of the silica sol, the binding force inside the coating is greatly enhanced, and the overall strength of the coating is improved, but the side effect is that cracks are easy to generate when the coating is sintered at high temperature. Not only the appearance is affected, but also the corrosion resistance of the whole silicon steel is reduced.
After the silicon steel sheet is coiled, certain curling tension exists inside the silicon steel sheet, and the local deformation of the coating can be caused. The extremely important is, silicon steel sheet has received huge shearing pressure in the section course of working, very easily causes the peeling off of coating, causes the local crystal emergence, influences product performance. In addition, in the process of arranging and laminating silicon steel sheets, the coating is extremely easy to damage due to manual carrying and overturning. These problems all put higher demands on the adhesion of the coating to the substrate, the higher the adhesion of the coating, the better the workability of the silicon steel sheet. However, most methods of improving adhesion in the prior art require the addition of heavy metal compounds, which increases environmental pollution.
CN114381584a discloses an insulating coating liquid for oriented silicon steel surface, oriented silicon steel plate and its manufacturing method, which comprises: magnesium dihydrogen phosphate, colloidal silica, chromic anhydride, zinc dihydrogen phosphate and zirconium oxychloride. The insulating coating produced by the formula can endow the oriented silicon steel plate with higher tension and more excellent high-temperature crack resistance, but has no effect of improving interlayer resistance, coating adhesion and corrosion resistance.
CN101812683a discloses an insulating coating liquid for oriented silicon steel of an anti-sticking sheet and a coating process thereof, wherein the coating liquid comprises: dihydrogen phosphate, soluble molybdates and tungstates, chromic anhydride, silica sol or aluminium sol. The obtained insulating coating has good adhesiveness and corrosion resistance, but the formula is relatively complex, contains various heavy metals, and has interlayer resistance of only 30-50Ω cm 2
CN111171608A discloses an insulating coating liquid, its preparation method and use, the insulating coating liquid comprises: aluminum dihydrogen phosphate aqueous solution, chromic anhydride, silica sol, organic silicon resin aqueous solution, cerium compound, sodium tungstate and polyether modified silicone oil. The coating obtained by the invention can improve the punching performance, adhesiveness and corrosion resistance of the silicon steel sheet. However, the formulation components are up to 7 items, and the interlayer resistance is only 30-50Ω cm 2
CN106243791a discloses a high hiding insulating paint for oriented silicon steel, which comprises inorganic salt colorant, chromic anhydride, monobasic phosphate aqueous solution, silica sol and deionized water, wherein the components are disclosed, the surface is hidden by adding colorant, the insulating property only reaches basic standard, and the interlayer resistance is only more than 30Ω·cm 2
Disclosure of Invention
The invention provides an insulating coating liquid for surface modification of oriented silicon steel and a preparation method thereof, and aims to overcome the defects in the prior art, effectively improve interlayer resistance, avoid high-temperature sintering cracks of a phosphate insulating coating, improve coating adhesiveness and improve slicing processability on the premise of not improving processing difficulty.
The technical solution of the invention is as follows: the insulating coating liquid for the surface modification of the oriented silicon steel comprises the following components in percentage by mass based on the total mass of the coating solution:
the other part is water.
Wherein,
aluminum dihydrogen phosphate is Al (H) 2 PO 4 ) 3 In the aqueous solution of Al (H) 2 PO 4 ) 3 The mass fraction of (2) is 40% -60%;
the magnesium dihydrogen phosphate is white solid powder with density of 1.56g/cm 3 The purity is more than or equal to 98 percent;
chromic anhydride is purple red flake with density of 2.70g/cm 3 The purity is more than or equal to 99.5%;
the modified silica sol contains a template, the silica is uniformly wrapped on the surface of the template to form a closed shell, the template is an organic compound, and hollow silica can be formed in the coating after high-temperature sintering.
Specifically, the preparation method of the modified silica sol comprises the following steps: and (3) controlling the reaction temperature at 10 ℃, slowly dropwise adding TEOS or TMOS into the polyacrylic emulsion for 2-4h, returning to room temperature after the dropwise adding is finished, continuously reacting for 3-6h, and finally filtering by using a filter screen with at least 400 meshes to obtain the modified silica sol.
In addition to polyacrylic acid, the polymer may be organic polymer such as polyacrylate, polyurethane, polyester, polyvinyl alcohol, polyether, polyamide, etc. or modified product thereof, or surfactant such as sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, tetraethylammonium chloride, long chain fatty alcohol polyoxyethylene ether, etc.
The particle size of the template is 10-50nm, the particle size of the modified silica sol is 20-70nm, and the mass percentage of the particles in the modified silica sol is 10-20%.
The aluminum dihydrogen phosphate is a novel inorganic synthetic material, can be solidified at normal temperature, has strong liquid and solid chemical binding force, and has the characteristics of high temperature resistance, shock resistance, spalling resistance and good insulating property. The aluminum has smaller atomic radius, so the insulating coating taking aluminum dihydrogen phosphate as a main body has better adhesion to silicon steel, is easy to obtain unordered solidified bodies, and is easier to absorb stress and strain so as to improve the performance of the coating. The inorganic coating is mainly used for electric industry, heat treatment resistance furnaces and electric insulation, and can be used as an inorganic coating and an organic coating in a matching way. The invention adopts the aluminum dihydrogen phosphate to play a film forming role, is favorable for tightly combining the coating and the matrix, and improves the insulativity between the insulating layer and the glass film bottom layer.
The magnesium dihydrogen phosphate is used as an auxiliary film forming material, the valence state of the magnesium is divalent, and the aluminum dihydrogen phosphate (trivalent) has weak effect at some sites in the insulating coating, so that the magnesium dihydrogen phosphate can supplement the aluminum dihydrogen phosphate, and the performances of the coating such as water resistance, adhesive force, coating strength and the like can be further improved.
Chromic acid has the effects of improving the dispersibility of the coating liquid, promoting the wettability to the substrate, improving the heat resistance of the insulating film and improving the glossiness of the surface of the coating. Cr can capture free P, so that free phosphoric acid in phosphate is more stable, the problems of rust and stickiness caused by hygroscopicity of free phosphorus after the coating is sintered are prevented, and Cr forms chemical bonds with Si, O and P to make the insulating film stronger, free of defects and good in corrosion resistance and magnetism. Chromic acid is used as an acidic corrosion inhibitor, and can inhibit the erosion of the coating on the matrix.
The modified silica sol is sintered at high temperature to form hollow silica, and the hollow silica has much higher insulativity than the conventional silica due to pores in the hollow silica, and the pores are nanoscale and closed, so that the bonding fastness of the coating is not affected; when the coating is sintered at high temperature to generate cracks, the cracks are broken when being conducted to the pores, so that the number and the length of the cracks are reduced; after nanoscale pores exist in the coating, the toughness and slicing processability of the coating are improved, and the adhesion effect is improved. In a word, the modified silica sol in the invention improves the insulation performance, high-temperature sintering crack resistance and adhesiveness of the whole coating.
The surface property of the modified silica sol is reserved, the specific surface area is large, a large amount of hydroxyl groups exist on the surface and hydrate a large amount of water molecules, the hydrophilicity is shown, the modified silica sol can be uniformly coated on the surfaces of other coating liquid components, and the self-drying film forming is carried out, so that the crosslinking density is high, the bonding strength and the wear resistance of the coating are improved, and the like.
The preparation method of the insulating coating liquid for surface modification of oriented silicon steel comprises the following process steps:
(1) Weighing the components in the coating liquid according to the proportion;
(2) Adding aluminum dihydrogen phosphate, magnesium dihydrogen phosphate and 40% of water into a stirrer, and stirring (0.5 h) until the solid is completely dissolved;
(3) Slowly adding chromic anhydride into the solution obtained in the step (2), adding 30% of water, and fully stirring until the solid is fully dissolved;
(4) Adding the modified silica sol and the rest of water into the solution obtained in the step (3), and fully stirring for 2 hours to obtain white uniform emulsion;
(5) And filtering by adopting a filter screen with at least 1000 meshes to finally obtain the insulating coating liquid for surface modification of the oriented silicon steel, wherein the shelf life is 24 hours.
When the insulating coating liquid for surface modification of the oriented silicon steel is applied to an oriented silicon steel insulating coating, the coating liquid is coated on a magnesium silicate bottom layer of the oriented silicon steel by adopting a method of roller coating after spraying, and then the insulating coating layer with high interlayer resistance, high-temperature sintering crack resistance and high adhesiveness can be finally formed on the surface of the oriented silicon steel through the procedures of heating, drying (300-400 ℃) and sintering (700-900 ℃), and the thickness of the coating layer is 1.7-2.5 mu m.
The invention has the advantages that: 1) The aluminum dihydrogen phosphate and the magnesium dihydrogen phosphate are adopted to act synergistically, the free phosphoric acid in the chromic anhydride stabilizing system can improve the appearance and corrosion resistance of the coating, and the modified silica sol prepared by the template method can improve the interlayer resistance, high-temperature sintering crack resistance and adhesiveness of the coating;
2) The oriented silicon steel is coated, and the insulating property of the silicon steel sheet can be improved, the interlayer resistance of the silicon steel sheet is increased, the iron loss is reduced, the service life of an iron core is prolonged, the energy consumption of the iron core is reduced, the toughness and the sheet punching performance of the silicon steel sheet are improved, the adhesiveness is improved, and the coating resists high-temperature sintering cracks, the number and the size of cracks are reduced, and the coating has good appearance and excellent corrosion resistance;
3) The free P can be captured by adding chromium anhydride Cr into the coating, so that the free phosphoric acid in the phosphate is more stable, the problems of rust and stickiness caused by the hygroscopicity of the free phosphoric acid when the coating is sintered at high temperature and annealed at eliminated stress are prevented, and the insulating film is firmer, free of defects, high in corrosion resistance and high in glossiness due to the fact that Cr forms chemical bonds with Si, O and P. Chromic acid is used as an acidic corrosion inhibitor, and can inhibit the erosion of the coating on the matrix. Particularly importantly, the modified silica sol adopted in the invention forms hollow silica after high-temperature sintering, and the hollow silica has much higher insulativity than the conventional silica due to pores in the hollow silica, and the pores are nanoscale and closed, so that the bonding fastness of the coating is not affected; when the coating is sintered at high temperature to generate cracks, the cracks are broken when being conducted to the pores, so that the number and the size of the cracks are reduced, and the corrosion resistance is improved; after nanoscale pores exist in the coating, the toughness and slicing processability of the coating are improved, and the adhesion effect is improved. In a word, the modified silica sol in the invention improves the insulation performance, high-temperature sintering crack resistance and adhesiveness of the whole coating;
4) The surface property of the modified silica sol is reserved, the specific surface area is large, a large amount of hydroxyl groups exist on the surface and hydrate a large amount of water molecules, the hydrophilicity is shown, the modified silica sol can be uniformly coated on the surfaces of other coating liquid components, and the self-drying film forming is carried out, so that the crosslinking density is high, and the bonding strength, the wear resistance, the corrosion resistance and the like of the coating are improved.
Detailed Description
The present invention will be described in further detail with reference to examples and embodiments.
Example 1
The insulating coating liquid comprises the following components in percentage by mass: 30% of aluminum dihydrogen phosphate, 10% of magnesium dihydrogen phosphate, 3% of chromic anhydride, 30% of modified silica sol and the balance of water.
Wherein the aluminum dihydrogen phosphate is Al (H) 2 PO 4 ) 3 In the aqueous solution of Al (H) 2 PO 4 ) 3 Is 50% by mass.
The magnesium dihydrogen phosphate is white solid powder with density of 1.56g/cm 3 The purity was 98%.
Chromic anhydride is purple red flake with density of 2.70g/cm 3 The purity was 99.5%.
The modified silica sol contains a template, and the template is polyacrylate. The silicon dioxide is uniformly distributed on the surface of the polyacrylate to form a closed shell. The particle size of the template is 30-50nm, the particle size of the modified silica sol is 40-70nm, and the mass percentage of the particles in the modified silica sol is 15%.
The coating liquid is prepared according to the following steps:
(1) Weighing the components in the coating liquid according to the proportion;
(2) Aluminum dihydrogen phosphate, magnesium dihydrogen phosphate and part of water (about 40%) are added into a stirrer and stirred fully (0.5 h) until the solid is completely dissolved;
(3) Slowly adding chromic anhydride into the solution obtained in the step (2), adding part of water (about 30%), and fully stirring until the solid is completely dissolved;
(4) Adding the modified silica sol and the rest of water into the solution obtained in the step (3), and fully stirring for 2 hours to obtain white uniform emulsion;
(5) And filtering by adopting a 1000-mesh filter screen to finally obtain the applicable insulating coating liquid, wherein the shelf life is 24 hours.
Then, the coating liquid is coated on the magnesium silicate bottom layer of the oriented silicon steel by adopting a method of roller coating after spraying, and then the insulating coating is subjected to the procedures of heating, drying at 400 ℃ and sintering at 900 ℃, wherein the thickness of the insulating coating is 2.0 mu m.
Example 2
The insulating coating liquid comprises 40 mass percent of modified silica sol and the characteristics of the rest components are the same as those of the embodiment 1.
The preparation method and the coating conditions of the coating liquid were the same as in example 1.
Example 3
The insulating coating liquid comprises 45 mass percent of modified silica sol and the rest components have the same characteristics as those of the embodiment 1.
The preparation method and the coating conditions of the coating liquid were the same as in example 1.
Example 4
The insulating coating liquid comprises the following components in percentage by mass, except that the modified silica sol is 50%, and the characteristics of the other components are the same as those of the embodiment 1.
The preparation method and the coating conditions of the coating liquid were the same as in example 1.
Example 5
The insulating coating liquid comprises 5 mass percent of magnesium dihydrogen phosphate, 45 mass percent of modified silica sol and the rest of components with the same characteristics as those of the example 1.
The preparation method and the coating conditions of the coating liquid were the same as in example 1.
Example 6
The insulating coating liquid comprises 15 mass percent of magnesium dihydrogen phosphate, 45 mass percent of modified silica sol and the rest of components with the same characteristics as those of the example 1.
The preparation method and the coating conditions of the coating liquid were the same as in example 1.
Example 7
The insulating coating liquid comprises 1% by mass of chromic anhydride, 45% by mass of modified silica sol and the rest of components with the same characteristics as those of the embodiment 1.
The preparation method and the coating conditions of the coating liquid were the same as in example 1.
Example 8
The insulating coating liquid comprises 5 mass percent of chromic anhydride, 45 mass percent of modified silica sol and the rest of components with the same characteristics as those of the example 1.
The preparation method and the coating conditions of the coating liquid were the same as in example 1.
Example 9
The insulating coating liquid comprises 45 mass percent of modified silica sol and the rest components have the same characteristics as those of the embodiment 1.
The preparation method and the coating conditions of the coating liquid were the same as in example 1.
Example 10
The insulating coating liquid comprises the following components in percentage by mass, except that the modified silica sol is 50%, and the characteristics of the other components are the same as those of the embodiment 1.
The preparation method and the coating conditions of the coating liquid were the same as in example 1.
Comparative example 1
The insulating coating liquid comprises 10 mass percent of modified silica sol and the characteristics of the rest components are the same as those of the embodiment 1.
The preparation method and the coating conditions of the coating liquid were the same as in example 1.
Comparative example 2
The insulating coating liquid comprises the following components in percentage by mass, except that the modified silica sol is 20%, and the characteristics of the other components are the same as those of the embodiment 1.
The preparation method and the coating conditions of the coating liquid were the same as in example 1.
Comparative example 3
The insulating coating liquid comprises the following components in percentage by mass: 30% of aluminum dihydrogen phosphate, 3% of chromic anhydride, 40% of modified silica sol and the balance of water.
Wherein the aluminum dihydrogen phosphate is Al (H) 2 PO4) 3 In the aqueous solution of Al (H) 2 PO 4 ) 3 Is 50% by mass.
Chromic anhydride is purple red flake with density of 2.70g/cm 3 The purity was 99.5%.
The modified silica sol contains a template, and the template is polyacrylate. The silicon dioxide is uniformly distributed on the surface of the polyacrylate to form a closed shell. The particle size of the template is 30-50nm, the particle size of the modified silica sol is 40-70nm, and the mass percentage of the particles in the modified silica sol is 15%.
The coating liquid is prepared according to the following steps:
(1) Weighing the components in the coating liquid according to the proportion;
(2) Adding aluminum dihydrogen phosphate and part of water into a stirrer, and fully stirring (0.5 h) until the solid is fully dissolved;
(3) Slowly adding chromic anhydride into the solution obtained in the step (2), adding part of water, and fully stirring until the solid is fully dissolved;
(4) Adding the modified silica sol and the rest of water into the solution obtained in the step (3), and fully stirring for 2 hours to obtain white uniform emulsion;
(5) And filtering by adopting a 1000-mesh filter screen to finally obtain the applicable insulating coating liquid, wherein the shelf life is 24 hours.
Then, the coating liquid is coated on the magnesium silicate bottom layer of the oriented silicon steel by adopting a method of roller coating after spraying, and then the insulating coating is subjected to the procedures of heating, drying at 400 ℃ and sintering at 900 ℃, wherein the thickness of the insulating coating is 2.0 mu m.
Comparative example 4
The insulating coating liquid comprises the following components in percentage by mass: 30% of aluminum dihydrogen phosphate, 10% of magnesium dihydrogen phosphate, 3% of chromic anhydride, 40% of silica sol and the balance of water.
Wherein the aluminum dihydrogen phosphate is Al (H) 2 PO 4 ) 3 In the aqueous solution of Al (H) 2 PO 4 ) 3 Is 50% by mass.
The magnesium dihydrogen phosphate is white solid powder with density of 1.56g/cm 3 The purity was 98%.
Chromic anhydride is purple red flake with density of 2.70g/cm 3 The purity was 99.5%.
The silica sol is an emulsion of nano-scale silicon dioxide ultrafine particles dispersed in water, the average particle size is 20nm, and the mass percentage of the silicon dioxide in the silica sol is 20%.
The coating liquid is prepared according to the following steps:
(1) Weighing the components in the coating liquid according to the proportion;
(2) Adding aluminum dihydrogen phosphate, magnesium dihydrogen phosphate and part of water into a stirrer, and stirring (0.5 h) until the solid is completely dissolved;
(3) Slowly adding chromic anhydride into the solution obtained in the step (2), adding part of water, and fully stirring until the solid is fully dissolved;
(4) Adding the silica sol and the rest of water into the solution obtained in the step (3), and fully stirring for 2 hours to obtain white uniform emulsion;
(5) And filtering by adopting a 1000-mesh filter screen to finally obtain the applicable insulating coating liquid, wherein the shelf life is 24 hours.
Then, the coating liquid is coated on the magnesium silicate bottom layer of the oriented silicon steel by adopting a method of roller coating after spraying, and then the insulating coating is subjected to the procedures of heating, drying at 400 ℃ and sintering at 900 ℃, wherein the thickness of the insulating coating is 2.0 mu m.
Comparative example 5
The insulating coating liquid comprises the following components in percentage by mass: 30% of aluminum dihydrogen phosphate, 3% of chromic anhydride, 40% of silica sol and the balance of water.
Wherein the aluminum dihydrogen phosphate is Al (H) 2 PO 4 ) 3 In the aqueous solution of Al (H) 2 PO 4 ) 3 Is 50% by mass.
The magnesium dihydrogen phosphate is white solid powder with density of 1.56g/cm 3 The purity was 98%.
Chromic anhydride is purple red flake with density of 2.70g/cm 3 The purity was 99.5%.
The silica sol is an emulsion of nano-scale silicon dioxide ultrafine particles dispersed in water, the average particle size is 20nm, and the mass percentage of the silicon dioxide in the silica sol is 20%.
The coating liquid is prepared according to the following steps:
(1) Weighing the components in the coating liquid according to the proportion;
(2) Adding aluminum dihydrogen phosphate and part of water into a stirrer, and fully stirring (0.5 h) until the solid is fully dissolved;
(3) Slowly adding chromic anhydride into the solution obtained in the step (2), adding part of water, and fully stirring until the solid is fully dissolved;
(4) Adding the silica sol and the rest of water into the solution obtained in the step (3), and fully stirring for 2 hours to obtain white uniform emulsion;
(5) And filtering by adopting a 1000-mesh filter screen to finally obtain the applicable insulating coating liquid, wherein the shelf life is 24 hours.
Then, the coating liquid is coated on the magnesium silicate bottom layer of the oriented silicon steel by adopting a method of roller coating after spraying, and then the insulating coating is subjected to the procedures of heating, drying at 400 ℃ and sintering at 900 ℃, wherein the thickness of the insulating coating is 2.0 mu m.
The insulating coatings obtained in each example and comparative example were subjected to performance test, and the results are shown in table 1.
Wherein,
the interlayer resistance is measured by an insulation resistance tester.
The appearance of the coating was determined by observing the number and size of cracks in the coating using a scanning resistance microscope.
Adhesion was graded according to the procedure specified in GB 2522-2017.
The corrosion resistance test was performed in a cyclic corrosion box. Corrosion conditions: and continuously spraying with 5% sodium chloride aqueous solution for 5 hours at 35 ℃, taking out, and observing the surface of the sample. The corrosion resistance evaluation criteria were: the rust area is better than 5%, the rust area is better than 5% -29%, the rust area is common, and the rust area is worse than 30% -59%.
TABLE 1 coating performance results for examples 1-10 and comparative examples 1-5
The foregoing is merely a preferred embodiment of the present invention, and it should be noted that modifications and improvements could be made by those skilled in the art without departing from the inventive concept, which falls within the scope of the present invention.

Claims (3)

1. The insulating coating liquid for surface modification of oriented silicon steel is characterized by comprising the following components in percentage by mass based on the total mass of a coating solution:
20 to 40 percent of aluminum dihydrogen phosphate
5 to 15 percent of magnesium dihydrogen phosphate
1 to 5 percent of chromic anhydride
30 to 60 percent of modified silica sol
The rest is water, and the water is water,
wherein the aluminum dihydrogen phosphate is Al (H) with the mass fraction of 40-60 percent 2 PO 43 Is used as a solvent in the preparation of the aqueous solution,
the magnesium dihydrogen phosphate is white solid powder with density of 1.56g/cm 3 The purity is more than or equal to 98 percent,
chromic anhydride is purple red flake with density of 2.70g/cm 3 The purity is more than or equal to 99.5 percent,
the modified silica sol internally contains an organic compound template, and silicon dioxide is uniformly wrapped on the surface of the template to form a closed shell;
the preparation method of the modified silica sol comprises the following steps: slowly dripping TEOS or TMOS into organic polymer and its modified substance or surfactant for 2-4 hr, cooling to room temperature after dripping, reacting for 3-6 hr, and filtering with at least 400 mesh sieve to obtain modified silica sol;
the organic polymer and the modified substance thereof are polyacrylic acid, polyacrylate, polyurethane, polyester, polyvinyl alcohol, polyether or polyamide, and the surfactant is sodium dodecyl benzene sulfonate, sodium dodecyl sulfate, tetraethylammonium chloride or long-chain fatty alcohol polyoxyethylene ether;
the particle size of the template is 10-50nm, the particle size of the modified silica sol is 20-70nm, and the mass percentage of particles in the modified silica sol is 10% -20%.
2. The method for preparing the insulating coating liquid for surface modification of oriented silicon steel as claimed in claim 1, which is characterized by comprising the following process steps:
(1) Weighing the components according to the proportion;
(2) Adding aluminum dihydrogen phosphate, magnesium dihydrogen phosphate and 40% of water into a stirrer, and stirring for 0.5h until the solid is completely dissolved;
(3) Slowly adding chromic anhydride into the solution obtained in the step (2), adding 30% of water, and fully stirring until the solid is fully dissolved;
(4) Adding the modified silica sol and the rest of water into the solution obtained in the step (3), and fully stirring for 2 hours to obtain white uniform emulsion;
(5) Filtering by a filter screen with at least 1000 meshes to obtain the insulating coating liquid for modifying the surface of the oriented silicon steel.
3. The method for using the insulating coating liquid for surface modification of oriented silicon steel according to claim 1, wherein the insulating coating liquid is coated on a magnesium silicate bottom layer of the oriented silicon steel, and then the oriented silicon steel insulating coating with the thickness of 1.7-2.5 μm is formed on the surface of the oriented silicon steel after heating, drying at 300-400 ℃ and sintering at 700-900 ℃.
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