CN112831200A - Coating for chromium-free oriented electromagnetic steel sheet, preparation method thereof and preparation method of chromium-free oriented electromagnetic steel sheet with coating - Google Patents
Coating for chromium-free oriented electromagnetic steel sheet, preparation method thereof and preparation method of chromium-free oriented electromagnetic steel sheet with coating Download PDFInfo
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING 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
- C09D1/00—Coating compositions, e.g. paints, varnishes or lacquers, based on inorganic substances
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- C—CHEMISTRY; METALLURGY
- C09—DYES; PAINTS; POLISHES; NATURAL RESINS; ADHESIVES; COMPOSITIONS NOT OTHERWISE PROVIDED FOR; APPLICATIONS OF MATERIALS NOT OTHERWISE PROVIDED FOR
- C09D—COATING 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
- C09D7/00—Features of coating compositions, not provided for in group C09D5/00; Processes for incorporating ingredients in coating compositions
- C09D7/40—Additives
- C09D7/60—Additives non-macromolecular
- C09D7/61—Additives non-macromolecular inorganic
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D1/00—General methods or devices for heat treatment, e.g. annealing, hardening, quenching or tempering
- C21D1/26—Methods of annealing
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/005—Heat treatment of ferrous alloys containing Mn
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- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D6/00—Heat treatment of ferrous alloys
- C21D6/008—Heat treatment of ferrous alloys containing Si
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D8/00—Modifying the physical properties by deformation combined with, or followed by, heat treatment
- C21D8/02—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips
- C21D8/0221—Modifying the physical properties by deformation combined with, or followed by, heat treatment during manufacturing of plates or strips characterised by the working steps
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21D—MODIFYING THE PHYSICAL STRUCTURE OF FERROUS METALS; GENERAL DEVICES FOR HEAT TREATMENT OF FERROUS OR NON-FERROUS METALS OR ALLOYS; MAKING METAL MALLEABLE, e.g. BY DECARBURISATION OR TEMPERING
- C21D9/00—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor
- C21D9/0081—Heat treatment, e.g. annealing, hardening, quenching or tempering, adapted for particular articles; Furnaces therefor for slabs; for billets
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/001—Ferrous alloys, e.g. steel alloys containing N
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/002—Ferrous alloys, e.g. steel alloys containing In, Mg, or other elements not provided for in one single group C22C38/001 - C22C38/60
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/02—Ferrous alloys, e.g. steel alloys containing silicon
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/04—Ferrous alloys, e.g. steel alloys containing manganese
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- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22C—ALLOYS
- C22C38/00—Ferrous alloys, e.g. steel alloys
- C22C38/06—Ferrous alloys, e.g. steel alloys containing aluminium
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- C—CHEMISTRY; METALLURGY
- C23—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; CHEMICAL SURFACE TREATMENT; DIFFUSION TREATMENT OF METALLIC MATERIAL; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL; INHIBITING CORROSION OF METALLIC MATERIAL OR INCRUSTATION IN GENERAL
- C23C—COATING METALLIC MATERIAL; COATING MATERIAL WITH METALLIC MATERIAL; SURFACE TREATMENT OF METALLIC MATERIAL BY DIFFUSION INTO THE SURFACE, BY CHEMICAL CONVERSION OR SUBSTITUTION; COATING BY VACUUM EVAPORATION, BY SPUTTERING, BY ION IMPLANTATION OR BY CHEMICAL VAPOUR DEPOSITION, IN GENERAL
- C23C8/00—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals
- C23C8/06—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases
- C23C8/08—Solid state diffusion of only non-metal elements into metallic material surfaces; Chemical surface treatment of metallic material by reaction of the surface with a reactive gas, leaving reaction products of surface material in the coating, e.g. conversion coatings, passivation of metals using gases only one element being applied
- C23C8/24—Nitriding
- C23C8/26—Nitriding of ferrous surfaces
Abstract
A coating for a chromium-free oriented electromagnetic steel sheet, a preparation method thereof and a preparation method of the chromium-free oriented electromagnetic steel sheet with the coating belong to the technical field of oriented electromagnetic steel sheets. The coating comprises the following components in parts by mass: 100 parts of phosphate, 60-120 parts of silica sol, 5-50 parts of tin oxide sol, 2-40 parts of boric acid and 0.5-10 parts of silica powder. The preparation method is environment-friendly, can meet the requirement of large-scale production, and the prepared coating does not contain chromium and has good stability and coating property, and the coating of the invention can ensure that the surface coating of the grain-oriented electromagnetic steel plate has good moisture absorption resistance, corrosion resistance, heat resistance, tension effect and sheet sticking resistance.
Description
Technical Field
The invention belongs to the technical field of oriented electromagnetic steel plates, and particularly relates to a coating for a chromium-free oriented electromagnetic steel plate, a preparation method of the coating and a preparation method of the chromium-free oriented electromagnetic steel plate with a coating.
Background
The phosphate inorganic paint has good film forming property, high temperature resistance, low price and excellent corrosion resistance and electrical insulation property, and is widely used for manufacturing insulating coatings on the surfaces of steel plates. The phosphate inorganic paint mainly comprises phosphate, filler and curing agent. Phosphates are film-forming substances by forming a network structure during heating. The filler mainly comprises silicon dioxide, aluminum oxide, chromium oxide, titanium dioxide and the like, and plays a role in improving the heat resistance of the coating and improving cracks. The curing agent can lower the film forming temperature of the phosphate coating and improve the water resistance of the coating. The commonly used curing agent comprises metal oxide, silicate, boric acid and the like, wherein the metal oxide curing agent forms insoluble phosphate in the heating film forming process and plays a role in fixing free phosphate.
Japanese examined patent publication No. 56-52117 discloses a coating material comprising magnesium dihydrogen phosphate, colloidal silica and chromic acid. Japanese patent publication No. 53-28375 discloses a coating material comprising aluminum dihydrogen phosphate, colloidal silica and chromic acid. Magnesium dihydrogen phosphate and aluminum dihydrogen phosphate are used as film-forming substances, silicon dioxide is used as a filler, and chromic acid is used as a curing agent. The coating is applied to the surface of grain-oriented electrical steel, and the coating formed at high temperature has a low thermal expansion rate and a high elastic modulus. The difference in thermal expansion between the steel sheet and the coating when cooled to room temperature can produce tensile stress on the steel sheet. The tensile stress (σ) of the coating to the steel sheet is expressed as: σ ═ E (α)Fe-αCoating layer) Delta T (2D/D), E is the modulus of elasticity of the coating, alphaFeIs the coefficient of thermal expansion of the steel plate,αcoating layerThe thermal expansion coefficient of the coating, the difference between the film forming temperature delta T and the room temperature, D is the thickness of the coating, and D is the thickness of the steel plate. The tensile stress applied to the grain-oriented electrical steel sheet by the coating layer can reduce the iron loss and the amount of hysteresis expansion and contraction. The coating has excellent corrosion resistance, moisture absorption resistance, heat resistance and high insulation.
The free phosphate remaining and decomposed in the phosphate coating has hygroscopic properties. The chromium in the coating forms a stable compound with the phosphate radical to fix the phosphate radical in the coating, and the moisture absorption resistance and the heat resistance of the coating during annealing are improved. However, hexavalent chromium in the paint causes serious harm to the environment and human body, and it is necessary to develop a paint containing no hexavalent chromium.
Chinese patent publication No. CN 101223300 a entitled "grain-oriented electrical steel sheet having insulating coating film not containing chromium and insulating coating film thereof" published as 16.7.2008 "discloses an insulating coating film for grain-oriented electrical steel sheet not containing chromium, which mainly contains phosphate, colloidal silica and colloidal substance of hydroxide of Fe, Ni, Co, Cu, Sr, Mo having particle size of 15nm or less. However, the colloidal substance of hydroxide of Fe, Ni, Co, Cu, Sr, Mo is difficult to be stabilized in a phosphate solution.
Chinese patent publication No. CN 101790599 a, published as 28/7/2010, entitled "insulating coating treatment liquid for grain-oriented electrical steel sheet and method for producing grain-oriented electrical steel sheet having insulating coating" discloses a chromium-free insulating coating treatment liquid for grain-oriented electrical steel sheet containing at least one of phosphates of Mg, Ca, Ba, Sr, Zn, Al and Mn, and a chelate of colloidal silica and titanium. However, the proposed technique uses titanium chelates that leave organic residues in the coating and may result in poor coating tension and thermal stability.
Chinese patent publication No. CN 102119239 a, published as 7/6/2011 entitled "chromium-free coating agent for oriented electrical steel sheet, method for preparing same, electrical steel sheet using same, and method for preparing same" discloses a chromium-free coating agent for oriented electrical steel sheet, which contains phosphate, colloidal silica, and hematite sol. However, the use of the tridymite sol also has a problem that the phosphate solution is difficult to stabilize for a long time.
Chinese patent publication No. CN 101778964 a, published as 2010, 7 and 14, entitled "insulating coating treatment liquid for grain-oriented electrical steel sheet and method for producing grain-oriented electrical steel sheet having insulating coating" uses water-soluble vanadium compound instead of hexavalent chromium. However, the proposed technique uses a water-soluble vanadium compound and thus phosphate radicals and the like remain. Also, decomposition of sulfate radicals and the like during heat treatment causes deterioration of coating properties and environmental pollution.
Chinese patent publication No. CN 103709796 a, published as 2014, 4, 9, and entitled "chromium-free stress coating capable of improving surface tension of oriented silicon steel and preparation method thereof", discloses a chromium-free coating containing at least one of phosphates of Zn, Ni, and Co, at least one of silicates of Na, K, Bi, and Li, borate, colloidal silica, nitrate, and Ce. However, the nitrate used therein remains in the coating layer to deteriorate the coating properties, and also decomposes upon heat treatment to cause environmental pollution.
Chinese patent publication No. CN 106189459 a, published as 2016, 12, 7, entitled "a chromium-free environment-friendly insulating coating for oriented silicon steel", discloses a chromium-free environment-friendly insulating coating for oriented silicon steel, which comprises tungstate, titanyl sulfate, dihydrogen phosphate and silica sol. However, the sulfate group of titanyl sulfate used therein causes problems such as discoloration during annealing, insulation, corrosion resistance and the like.
Chinese patent publication No. CN 104024443 a, published as 2014, 9, 3, entitled "coated grain-oriented steel", discloses a chromium-free coating mixture comprising metal phosphate, silicon oxide particles and organosilane. Chinese patent publication No. CN 105086778A, published as 2015, 11, 25 and titled "a chromium-free insulating coating for oriented silicon steel and method for preparing same", discloses a method for preparing a chromium-free insulating coating for oriented silicon steel, wherein the insulating coating is composed of organic mixed resin, silica sol, aluminum dihydrogen phosphate, inorganic buffer, silane coupling agent, auxiliary agent and silanol polyvinyl ether. The techniques proposed in these two patent documents use organic substances that reduce the heat resistance of the coating.
These techniques solve the problem of moisture absorption of chromium-free coatings for grain-oriented electrical steel to some extent. It is difficult to say that the performance of the chromium-containing coating is similar to that of the chromium-containing coating or the practical productivity of the chromium-free coating is sufficiently solved. Therefore, it is desired to obtain a hexavalent chromium-free coating material for surface coating production of grain-oriented electrical steel, which further solves the problems of coating properties and productivity.
Disclosure of Invention
The technical problem to be solved is as follows: aiming at the technical problems that hexavalent chromium in the existing coating can cause serious harm to the environment and human bodies, and moisture absorption resistance, heat resistance, corrosion resistance, poor tension and the like exist when the phosphate-silicon dioxide system coating without hexavalent chromium forms a coating, the invention provides the coating for the chromium-free oriented electrical steel plate, the preparation method thereof and the preparation method of the chromium-free oriented electrical steel plate with the coating.
The technical scheme is as follows: the chromium-free coating for the grain-oriented electrical steel plate comprises the following components in parts by mass: 100 parts of phosphate, 60-120 parts of silica sol (silica sol for short), 5-50 parts of tin oxide sol (tin sol for short), 2-40 parts of boric acid and 0.5-10 parts of silica powder, wherein the mass of the phosphate is phosphate radical PO4The mass of the silica sol is converted to SiO2The mass of the tin oxide sol is calculated as the mass of SnO.
Preferably, the phosphate is at least one of phosphates of Mg, Ca, Zn, Al and Mn.
Preferably, the colloidal silica in the silica sol has a size of 5 to 50nm, which enables a coating to have a better tensile effect and surface characteristics.
Preferably, the silicon dioxide powder has a particle size of 5-100nm, when the size is less than 5nm, the anti-sticking performance of the coating is poor, and when the size is more than 100nm, the surface roughness of the coating is large, so that the lamination performance of the steel plate is poor.
Based on the preparation method of the chromium-free coating for the grain-oriented electrical steel plate, silicon dioxide powder is dispersed in all or part of colloidal silicon dioxide through mechanical dispersion or ultrasonic dispersion to form stable suspension, then boric acid is added into silica sol or the suspension and stirred to completely dissolve the boric acid, and then tin sol is added and stirred to be fully mixed to form stable mixed solution A; and mixing the mixed solution A with the rest silica sol and phosphate and stirring to form the coating for later use.
A method for producing a coated chromium-free grain-oriented electrical steel sheet, said coating being produced from the above-mentioned coating material for chromium-free grain-oriented electrical steel sheet, comprising the steps of: coating the coating on the surface of a grain-oriented electrical steel plate, drying, and performing heat treatment at 880 ℃ of 800 ℃ for more than 10s, wherein the amount of a single-sided dry film is 2-8g/m2。
Has the advantages that: (1) the chromium-free coating for the grain-oriented electromagnetic steel plate does not contain hexavalent chromium, has small pollution to the surrounding environment, good environmental protection benefit and good stability and coating property, can realize industrial production and use, and the prepared coating has good moisture absorption resistance, corrosion resistance, heat resistance, tension effect and adhesion resistance.
(2) The coating comprises phosphate, silica sol, tin sol, boric acid and silicon dioxide powder, is coated on the surface of an oriented electrical steel plate, is dried and then is subjected to heat treatment at the temperature of 800-880 ℃ for more than 10 seconds, and the phosphate can form a network structure on the surface of the steel plate when being subjected to sintering heat treatment. The silica sol and the above-mentioned phosphate are subjected to a sintering heat treatment to form a coating layer having a low thermal expansion coefficient. The phosphate contains a certain amount of free phosphate radical which is easy to absorb water to dissolve and damage the integrity of the coating, and the addition of the tin oxide sol can form insoluble Sn2P2O7Plays a role in fixing phosphate radicals and improving the water resistance of the coating. The added boric acid can promote sintering, improve heat resistance and Sn during film-forming heat treatment2P2O7Is performed. The added silicon dioxide powder can enable the coating to have better tension effect, surface characteristic and anti-sticking performance.
(3) According to the coating, the raw materials are scientifically proportioned, 100 parts of phosphate correspond to 60-120 parts of silica sol, 5-50 parts of tin sol, 2-40 parts of boric acid and 0.5-10 parts of silicon dioxide powder, and when the silica sol is lower than 60 parts, the coating performance of the coating is reduced, and the coating tension is reduced; above 120 parts, the coating cracks and the tension and corrosion resistance are reduced. When the tin sol is less than 5 parts, the moisture resistance is lowered, and when it is more than 50 parts, the sintering property of the coating is affected to cause a decrease in tension. When the boric acid is less than 2 parts, the coating is compact and has low tension cracking; above 40 parts, the coating is unstable, and the coating has low tension and poor heat resistance. When the silica powder is less than 0.5 part, the coating is poor in blocking resistance; above 10 parts the coating tension becomes worse.
Detailed Description
The present invention will be further explained and illustrated with reference to specific examples, which, however, should not be construed to unduly limit the technical scope of the present invention.
Examples and comparative examples
The invention relates to a chromium-free coating for grain-oriented electrical steel plates, which comprises the following raw materials: 100 parts of phosphate, 60-120 parts of silica sol, 5-50 parts of tin oxide sol, 2-40 parts of boric acid and 0.5-10 parts of silica powder.
The preparation method comprises the following steps: dispersing silicon dioxide powder in all or part of colloidal silicon dioxide (wherein the dispersing is convenient for actual storage and transportation, and the actual addition amount has little influence on the performance of a final coating) by mechanical dispersion or ultrasonic dispersion to form stable suspension, then adding boric acid into silica sol or the suspension and stirring to completely dissolve the boric acid, and then adding tin sol and stirring to fully mix to form stable mixed solution A; and mixing the mixed solution A with silica sol and phosphate and stirring to form the coating for later use.
The raw materials and preparation methods of the coatings of examples 1 to 15 and comparative examples 1 to 4 are the same as above, except that the coatings for grain-oriented electrical steel sheets not containing chromium in examples 1 to 15 and comparative examples 1 to 4 are different in the parts by mass and the sizes of some components, as shown in table 1 below.
TABLE 1
It should be noted that, in examples 1 to 15 and comparative examples 1 to 4 according to the present invention, the phosphate may be a dihydrogen phosphate containing Al and a dihydrogen phosphate containing Mg. In some other embodiments, other phosphates may be used, such as: contains dihydric phosphate of Ca, Sr, Ba, Mn and Zn.
In the raw material proportion of the coating, phosphate radical PO is used as the mass of phosphate radical4The mass of the silica sol is converted to SiO2The mass of the tin oxide sol is calculated as the mass of SnO.
It should be noted that, the coating materials of examples 1-15 and comparative examples 1-4 of the present invention can be added with solvent water in a proper amount, the amount of water does not affect the performance of the final coating, and the addition amount have no specific requirements.
It should be noted that the silica sol in the examples of the present invention is a general commercially available product. The tin oxide sol is self-made, and the specific preparation method comprises the following steps: 100mL of 1mol/L tin sulfate or stannous chloride is added with 100mL of 2mol/L sodium hydroxide solution dropwise at 90 ℃, and the temperature is kept at 90 ℃ for 2h to form a large amount of white precipitate. And naturally cooling to room temperature after the heat preservation is finished, pouring out the product, and repeatedly washing with deionized water to obtain the gel solid. 60 g of the solid (6 g in terms of tin dioxide) is weighed and placed in a beaker, 100mL of hydrogen peroxide with the concentration of 0.5mol/L is weighed and added into the beaker filled with the gel solid, and the mixture is stirred and ultrasonically dispersed and kept for 24 hours to obtain transparent sol.
The coatings of examples 1 to 15 and the comparative coatings of comparative examples 1 to 4 were applied to substrates of grain-oriented electrical steel sheets to produce coated, chromium-free grain-oriented electrical steel sheets according to the present invention.
In each example and comparative grain-oriented electrical steel slab substrate, the mass percentages of the chemical elements are the same, and are unified as follows: c: 0.048%, Si: 3.35%, S: 0.006%, Als: 0.031%, N: 0.006%, Mn: 0.012%, and the balance of Fe and other unavoidable impurities. Of course, in some other embodiments, grain-oriented electrical steel sheets having other chemical compositions may be used, and the content of Si in the steel may be controlled to be 2 to 4% by mass. In the present invention, the composition of the grain-oriented electrical steel sheet is not particularly limited, and any conventional composition system capable of achieving the technical effects of the present invention can be used.
Grain-oriented electrical steels of examples 1 to 15 and comparative examples 1 to 4 were each produced by the following procedure:
(1) and smelting and casting according to the mass percent of the chemical elements to obtain the billet.
(2) The slab was heated at 1150 ℃ and then hot-rolled into a hot-rolled sheet having a thickness of 2.8 mm.
(3) And pickling and cold-rolling the hot-rolled plate into a cold-rolled plate with the thickness of 0.15-0.50 mm. The cold rolling may be performed 1 time or 2 or more times with intermediate annealing interposed therebetween.
(4) After decarburization annealing treatment, continuous nitriding treatment is carried out on the cold-rolled sheet in the atmosphere of wet ammonia-introduced nitrogen and hydrogen protection.
(5) The nitrided steel sheet is coated with a release agent mainly composed of magnesium oxide.
(6) And (3) performing secondary recrystallization annealing in a dry nitrogen and hydrogen protective atmosphere after coiling, controlling the annealing temperature at 1200 ℃, and keeping the temperature for 25 hours to obtain a substrate with a Gaussian texture, the surface of which is covered with the forsterite ceramic membrane, wherein the thickness of the substrate is 0.15-0.50 mm.
(7) A coating liquid is applied to the surface of a substrate.
(8) Sintering at 800-880 deg.c for over 10 sec to obtain oriented electromagnetic steel plate with coating layer of one-side dry film in 2-8g/m2。
In the above-described production method, the forsterite ceramic film may not be formed on the surface of the steel sheet by controlling the decarburization annealing and the release agent. The coating of the present invention can be effectively applied regardless of the presence or absence of a forsterite ceramic film.
Table 2 below shows the relevant process parameters of the manufacturing methods of grain-oriented electrical steel sheets of examples 1 to 15 and comparative examples 1 to 4.
TABLE 2
The coating performance test method is as follows, and the test results are listed in table 3.
(1) Tension σ of single-sided coating: an oriented (grain-oriented) electrical steel sheet was cut into a template having a length of 300mm × a width of 30mm with the rolling direction as the longitudinal direction, and the single-side coating was removed. The amount of bending of the sample was measured and the tension σ of the single-sided coating was calculated by the following formula.
In the above formula, σ represents the coating tension in units of MPa; e represents the Young's modulus of the steel plate, and the unit of the Young's modulus is GPa; t represents the thickness of the steel plate in mm; h represents the warping amount, and the unit is mm; l represents the length of the steel sheet and is in mm.
(2) Evaluation of moisture resistance: the coated grain-oriented electrical steel sheet was boiled in pure water at 100 ℃ to evaluate the change in the appearance of the coating and the content of dissolved phosphorus.
(3) Evaluation of corrosion resistance: the corrosion resistance of the coating was evaluated by a salt spray test, which was a 5 wt.% NaCl solution, with a test temperature of 35 ℃ and a test time of 10 h.
(4) Evaluation of Heat resistance: the degree of tensile deterioration and the degree of insulation deterioration of the insulating coating after stress relief annealing treatment of the coated grain-oriented electrical steel sheet were tested, wherein the process conditions of the stress relief annealing treatment were 850 ℃ and 100 vol.% N2Keeping the temperature in the air for 4 hours.
(5) Evaluation of anti-blocking property: laminated steel plate is subjected to 850 ℃ x 100 vol.% N under a certain pressure2After the stress relief annealing treatment was performed for 4 hours, the sheet resistance was evaluated by comparing the magnitude of the peeling force between the steel plates, and the smaller the peeling force, the better the sheet resistance.
Table 3 shows the results of the performance test concerning the grain-oriented electrical steel sheets of examples 1 to 15 and comparative examples 1 to 4.
Table 3.
Note: coating performance evaluation ∈: the quality is excellent; o: good; o: generally; gamma rays: and (4) poor.
As is apparent from Table 3, in examples 1 to 15, when the coating material satisfying the design control requirements of the present invention was used, a low iron loss grain-oriented electrical steel sheet having very excellent properties could be obtained. Correspondingly, in the comparative examples 1 to 4, the comparative examples 1 to 4 have poor performance of the surface coating of the oriented silicon steel formed by coating the comparative coatings because the comparative coatings of the comparative examples 1 to 4 have parameters which do not meet the design control requirements of the invention during design.
It should be noted that the combination of the features in the present application is not limited to the combination described in the claims of the present application or the combination described in the embodiments, and all the features described in the present application may be freely combined or combined in any manner unless contradicted by each other.
It should also be noted that the above-mentioned embodiments are only specific embodiments of the present invention. It is apparent that the present invention is not limited to the above embodiments and similar changes or modifications can be easily made by those skilled in the art from the disclosure of the present invention and shall fall within the scope of the present invention.
Claims (6)
1. The chromium-free coating for the grain-oriented electrical steel plate is characterized by comprising the following components in parts by mass: 100 parts of phosphate, 60-120 parts of silica sol, 5-50 parts of tin oxide sol, 2-40 parts of boric acid and 0.5-10 parts of silica powder, wherein the mass of the phosphate is phosphate radical PO4The mass of the silica sol is converted to SiO2The mass of the tin oxide sol is calculated as the mass of SnO.
2. The coating material for grain-oriented electrical steel sheet according to claim 1, wherein said phosphate is at least one of phosphate of Mg, Ca, Zn, Al and Mn.
3. The coating material for a chromium-free grain-oriented electrical steel sheet according to claim 1, wherein the colloidal silica in said silica sol has a size of 5 to 50 nm.
4. The chromium-free coating material for grain-oriented electrical steel sheets according to claim 1, wherein the silica powder has a particle size of 5 to 100 nm.
5. The method of claim 1, wherein the silica powder is dispersed mechanically or ultrasonically in all or part of the silica sol to form a stable suspension, boric acid is added to the silica sol or the suspension and stirred to completely dissolve the boric acid, and then the tin sol is added and stirred to be mixed thoroughly to form a stable mixture A; and mixing the mixed solution A with the rest silica sol and phosphate and stirring to form the coating for later use.
6. A process for producing a coated chromium-free grain-oriented electrical steel sheet, characterized in that the coating is prepared from the coating material for a chromium-free grain-oriented electrical steel sheet according to claim 1 by the following steps: coating the coating on the surface of a grain-oriented electrical steel plate, drying, and performing heat treatment at 880 ℃ of 800 ℃ for more than 10s, wherein the amount of a single-sided dry film is 2-8g/m2。
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| Application Number | Priority Date | Filing Date | Title |
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| CN202011605469.XA CN112831200A (en) | 2020-12-30 | 2020-12-30 | Coating for chromium-free oriented electromagnetic steel sheet, preparation method thereof and preparation method of chromium-free oriented electromagnetic steel sheet with coating |
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| CN202011605469.XA CN112831200A (en) | 2020-12-30 | 2020-12-30 | Coating for chromium-free oriented electromagnetic steel sheet, preparation method thereof and preparation method of chromium-free oriented electromagnetic steel sheet with coating |
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| CN202011605469.XA Pending CN112831200A (en) | 2020-12-30 | 2020-12-30 | Coating for chromium-free oriented electromagnetic steel sheet, preparation method thereof and preparation method of chromium-free oriented electromagnetic steel sheet with coating |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN116478562A (en) * | 2022-01-14 | 2023-07-25 | 宝山钢铁股份有限公司 | Paint for oriented silicon steel coating, oriented silicon steel plate and manufacturing method thereof |
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| JP2005240157A (en) * | 2004-02-27 | 2005-09-08 | Jfe Steel Kk | Grain-oriented electromagnetic steel sheet with phosphate-based insulating layer having superior hygroscopicity resistance without containing chromium, and method for forming phosphate-based insulating layer having superior hygroscopicity resistance without containing chromium |
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| CN111171609A (en) * | 2020-01-22 | 2020-05-19 | 上海迪升防腐新材料科技有限公司 | Environment-friendly insulating masking liquid and preparation method and application thereof |
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| JP2005240157A (en) * | 2004-02-27 | 2005-09-08 | Jfe Steel Kk | Grain-oriented electromagnetic steel sheet with phosphate-based insulating layer having superior hygroscopicity resistance without containing chromium, and method for forming phosphate-based insulating layer having superior hygroscopicity resistance without containing chromium |
| CN104341808A (en) * | 2014-11-05 | 2015-02-11 | 海南大学 | Room-temperature self-curing inorganic phosphate anti-corrosion paint as well as preparing method and use method of paint |
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Cited By (1)
| Publication number | Priority date | Publication date | Assignee | Title |
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| CN116478562A (en) * | 2022-01-14 | 2023-07-25 | 宝山钢铁股份有限公司 | Paint for oriented silicon steel coating, oriented silicon steel plate and manufacturing method thereof |
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