Cooling roller for plane flow casting production of non-oriented silicon steel ultra-thin strip and preparation method

Abstract

A cooling roller for producing a non-oriented silicon steel ultra-thin strip through plane flow casting is composed of a cooling copper roller and is characterized in that a nickel-plated layer is arranged on the surface of the cooling copper roller, and the thickness of the nickel-plated layer is controlled to be 30-60 microns; the preparation method comprises the following steps: removing oil; pickling; alkali washing; chemical nickel plating; washing is conducted; performing drying; and reserving. Under the conditions that B50 is larger than or equal to 1.63 T, P1T / 400 Hz is smaller than or equal to 10.21 W / kg and the thickness is 0.02-0.16 mm, chemical nickel plating is conducted on the surface of the cooling copper roller to form a nickel plating layer, the roller attaching performance can be improved by 10% compared with that of the cooling copper roller, the production cost is relatively reduced by 25% compared with the current production cost, the surface of the cooling copper roller is not prone to oxidation, and the qualification rate of the prepared non-oriented silicon steel ultra-thin strip is increased to be not lower than 85% from current 76%.

Description

Technical Field

[0001] The present invention belongs to the field of metal material preparation, and particularly relates to a cooling roller and a preparation method for plane flow casting to produce non-oriented silicon steel ultra-thin strips. Chemical nickel plating on the cooling copper roller can improve the wettability and spreading properties of the silicon steel melt, thereby improving the yield rate, surface quality and magnetic properties of the non-oriented silicon steel ultra-thin strips prepared by plane flow casting. Background Art

[0002] As the power electronics industry develops towards high frequency, miniaturization and high power density, higher and higher requirements are placed on the miniaturization and loss of magnetic devices. The demand for ultra-thin non-oriented silicon steel strips with a thickness of less than 0.10 mm will increase significantly.

[0003] At present, the preparation of ultra-thin silicon steel strips mainly relies on the multi-pass rolling method, but the traditional rolling technology has problems such as long processes, high energy consumption and cost. In recent years, some literature reports have used planar flow casting technology to prepare ultra-thin non-oriented silicon steel strips. This technology directly prepares ultra-thin silicon steel strips by throwing the strips on a cooling copper roller. Compared with the traditional method, this technology has a simpler process flow and higher production efficiency. However, due to the high melting point, poor fluidity and high surface tension of silicon steel melt, the roller adhesion and wettability with the cooling copper roller are poor, so that the qualified rate of ultra-thin non-oriented silicon steel strips produced does not exceed 70%, and the surface quality of the ultra-thin non-oriented silicon steel strips is poor, and the magnetic properties are also poor.

[0004] In order to solve the above problems, improving the wettability between silicon steel melt and cooling copper roller has become a research object of great concern. There are methods to reduce the surface tension and viscosity of the melt by adding surfactant elements during silicon steel smelting, thereby improving the wetting and spreading performance of silicon steel melt and cooling copper roller during plane casting, and improving the formability and surface quality of thin strips, such as the following:

[0005] The document with Chinese patent publication number CN104561838A discloses "A kind of silicon steel ultra-thin strip modified with trace tellurium and its preparation method", which is a method for preparing non-oriented silicon steel thin strip with silicon content of 2.8-3.3wt%, tin content of 0.03-0.06wt%, and tellurium content of 0.003-0.004wt%. The high-temperature melt is rapidly solidified by the strip-spinning method to form a semi-process non-oriented silicon steel ultra-thin strip, which is then obtained by high-temperature annealing to obtain the silicon steel ultra-thin strip modified with trace tellurium.

[0006] The document with Chinese patent publication number CN117026081A discloses "A non-oriented silicon steel ultra-thin strip containing element bismuth and a preparation method thereof", which contains 2-4wt% silicon and 0.005-0.05wt% bismuth. The non-oriented silicon steel ultra-thin strip is prepared by plane flow casting, and then the ultra-thin strip is obtained by flattening and annealing.

[0007] The above two patent documents reduce the surface tension and viscosity of the melt by adding surface active elements such as tellurium or bismuth, thereby improving the wetting and spreading properties of the silicon steel melt and the cooling copper roller. However, tellurium is easily oxidized during the smelting process of silicon steel, while bismuth is easily volatilized during the smelting process, and both are relatively expensive, which makes the smelting of non-oriented silicon steel ultra-thin strips more difficult and the preparation cost high. Although the qualified rate of the non-oriented silicon steel ultra-thin strips produced exceeds 70%, it only does not exceed 76%, and the surface quality, wettability and spreadability of the non-oriented silicon steel ultra-thin strips are still poor. Summary of the invention

[0008] The present invention aims to overcome the problem of poor roll adhesion between silicon steel melt and cooling copper roll in the prior art, and provide a method for ensuring B 50 ≥1.63T, P 1T / 400Hz ≤10.21W / kg, thickness is in the range of 0.04-0.12mm, and by nickel plating on the cooling copper roller, the roller-sticking property of the cooling copper roller can be improved by 10%, and the production cost can be reduced by 25% compared with the current cost, and the qualified rate of the prepared non-oriented silicon steel ultra-thin strip is increased from the current 76% to not less than 85%. Cooling roller and preparation method for plane flow casting of non-oriented silicon steel ultra-thin strip.

[0009] Measures to achieve the above objectives:

[0010] A cooling roller for producing non-oriented silicon steel ultra-thin strip by plane flow casting is composed of a cooling copper roller. The cooling copper roller has a nickel plating layer on its surface and the thickness of the nickel plating layer is controlled to be 30-60 μm.

[0011] The invention is suitable for preparing non-oriented silicon steel with a weight percentage of 2-4.5% silicon and the rest of iron and a small amount of other inevitable impurities. The ultra-thin strip of the prepared non-oriented silicon steel has a thickness of 0.04-0.12 mm.

[0012] A method for preparing a cooling roller for plane flow casting to produce non-oriented silicon steel ultra-thin strips, comprising the following steps:

[0013] 1) Degreasing: Place the cooling copper roller in a degreasing liquid at a temperature of 50-65°C for 15-25 minutes, and continue stirring until the degreasing is completed;

[0014] 2) pickling, placing the degreased cooling copper roller in a pickling solution with a nitric acid concentration of 10 to 15 wt% for pickling for 10 to 15 minutes;

[0015] 3) Alkali washing: the pickled cooling copper roller is placed in an alkaline washing solution containing 4.5-6.0wt% sodium hydroxide and 0.1-0.4wt% sodium dodecylbenzene sulfonate at a temperature of 50-65°C for 15-20 minutes, and then repeatedly rinsed with distilled water until clean;

[0016] 4) performing chemical nickel plating, immersing the cooling copper roller rinsed with distilled water in a chemical nickel plating solution for 30 to 40 minutes, allowing it to fully react and deposit a 30 to 60 μm thick nickel plating layer on the surface of the cooling copper roller, and stirring during this period;

[0017] The temperature of the chemical nickel plating solution is controlled at 70-85° C., and the pH value of the chemical nickel plating solution is controlled at 4.5-5.0; the nickel content of the formed nickel plating layer is not less than 85wt%;

[0018] 5) Rinse with distilled water to clean the residual liquid on the surface of the nickel-plated layer;

[0019] 6) Drying, controlling the drying temperature at 100-110°C and the drying time at 2-3h;

[0020] 7) Reserved.

[0021] The invention is characterized in that the composition and weight percentage of the degreasing liquid are as follows: sodium carbonate: 2.0-3.0%, sodium phosphate: 2.0-3.5%, sodium dodecylbenzene sulfonate: 0.1-0.3%, and the rest is water.

[0022] The invention is characterized in that the composition and weight percentage of the chemical nickel plating solution are as follows: nickel chloride: 9.5-12%, nickel sulfate: 3.0-5.5%, citric acid: 3.5-5.0%, ethylenediamine sulfate: 1.5-3.0%, boric acid: 2.0-3.0%, sodium thiosulfate: 1.5-2.0%, sodium hypophosphite: 2.5-4.0%, and the rest is water; the pH value of the chemical nickel plating solution is 4.5-5.0, and the pH value is adjusted by boric acid.

[0023] Function and mechanism of the main process in the present invention

[0024] The reason why nickel is plated on the surface of the cooling copper roller in the present invention is mainly because compared with adding expensive surfactant elements to the raw materials, the cost of chemical nickel plating on the copper roller is low, the process is simple, and there is no need to consider the problems of oxidation or volatilization of surfactant elements during the smelting process; at the same time, the roller adhesion between the prepared non-oriented ultra-thin strip and the cooling roller is significantly improved, the plastic toughness of the thin strip is good, the yield rate is high, and the quality and magnetic properties are significantly improved. This is because chemical nickel plating on the cooling copper roller can improve the wettability and spreading performance of the silicon steel melt, thereby improving the yield rate, surface quality and magnetic properties of the non-oriented silicon steel ultra-thin strip prepared by plane flow casting. Chemical nickel plating on the copper roller has a low cost, a simple and mature process, and a thin coating thickness that has little effect on the heat transfer of the cooling copper roller. In addition, there is no need to add expensive surfactant elements such as tellurium and bismuth to the non-oriented silicon steel, so smelting is easier and the material preparation cost is lower.

[0025] The present invention carries out the steps of degreasing, pickling, alkali washing, chemical nickel plating, rinsing and drying mainly to ensure that the plating solution formed in the chemical nickel plating process has good stability and suitable reactivity. The synergistic effect of various steps and components helps to form a uniform and dense plating layer and provide the required physical and chemical properties.

[0026] The reason why the concentration of sodium phosphate is controlled at 2.0-3.5% in the present invention is that the addition of phosphorus ions can improve the stability of the solution during the nickel plating process. This helps to prevent the precipitation of metal impurities, maintain the cleanliness of the plating solution, and avoid negative effects on the adhesion of the coating. The phosphorus ions provide active sites for the plating solution to adsorb hydrogen and nickel ions, play a role as a catalyst, accelerate the nickel plating reaction, and deposit more nickel on the surface of the copper roller to form a uniform coating; phosphorus exists in a dense structure, thereby increasing the wear resistance, corrosion resistance and hardness of the coating.

[0027] The present invention controls the nickel chloride concentration to be 9.5-12% and the nickel sulfate concentration to be 3.0-5.5% because the nickel deposition rate is moderate, the hardness and toughness are good in this concentration range, and too high a concentration of nickel chloride or nickel sulfate may increase the deposition rate, more nickel chloride is consumed in a local area of ​​the workpiece, and the nickel layer is unevenly deposited; in addition, the nickel ions are consumed at an accelerated rate, causing the plating solution to become less stable and easy to spontaneously decompose in a short time, causing other impurities to be deposited on the surface of the copper roller, thereby increasing the brittleness of the nickel layer and making the coating surface rougher. Too low a concentration means a slower deposition rate, lower production efficiency, and a thinner coating, which cannot achieve the desired effect.

[0028] The reason why the concentration of sodium hypophosphite is controlled at 2-4.5% in the present invention is that the reaction speed is moderate in this concentration range. Too high a concentration will lead to accelerated reaction, self-decomposition reaction of the plating solution, and increased difficulty in process control. Too low a concentration will not play the role of controlling the pH value of the chemical plating solution and regulating the stability of the plating solution, thereby causing problems such as decreased stability of the plating solution, uneven quality of the coating, and difficulty in controlling the reaction rate. By adjusting the reaction process, the density, glossiness and uniformity of the coating can be improved, ensuring that it has good mechanical properties and appearance characteristics.

[0029] The reason why the present invention controls the concentration of citric acid to be 3.5-5.0% and the concentration of boric acid to be 2.0-3.0% is that the concentration range has a great influence on the quality of the plating solution and the compactness, glossiness and uniformity of the coating. If the concentration of citric acid or boric acid is too high, the plating solution will be too acidic or the buffering capacity will be too strong, causing the quality of the coating to be reduced and the reaction rate to be unstable. If the concentration of citric acid or boric acid is too low, the buffering capacity of the plating solution will be insufficient, making it difficult to maintain stable reaction conditions, thus affecting the quality and uniformity of the coating.

[0030] The reason why the concentration of ethylenediamine sulfate is controlled at 1.5-3.0% in the present invention is that too high a concentration leads to reduced stability of the plating solution, affects the uniformity and quality of the coating, and even produces organic pollutants, increases the brittleness of the coating, reduces the corrosion resistance of the coating, and thus causes defects in the coating; too low a concentration leads to a lack of necessary organic additives in the plating solution, making the coating surface not smooth enough and the brightness reduced. The addition of ethylenediamine sulfate can make the coating surface have better glossiness, and at the same time can adjust the pH value of the plating solution, providing a stable plating solution environment.

[0031] Compared with the prior art, the present invention ensures that B 50 ≥1.63T, P 1T / 400Hz ≤10.21W / kg, thickness in the range of 0.04-0.12mm, by forming a nickel layer on the cooling copper roller through chemical nickel plating, the roller-sticking property of the cooling copper roller can be improved by 10%, and the production cost can be reduced by 25% compared with the current cost, and the qualified rate of the prepared non-oriented silicon steel ultra-thin strip can be increased from the current 76% to not less than 85%. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] Figure 1 It is a structural schematic diagram of the cooling copper roller of the present invention;

[0033] Figure 2 The non-oriented silicon steel ultra-thin strip prepared in the embodiment of the present invention;

[0034] In the figure: 1—Cooling copper roller, 2—Nickel plating layer. DETAILED DESCRIPTION

[0035] The present invention is described in detail below in conjunction with the accompanying drawings:

[0036] Table 1 is a list of main process parameters of various embodiments of the present invention;

[0037] Table 2 is a table of the composition and content values ​​of each solution in the process of each embodiment of the present invention;

[0038] Table 3 is a list of the effect detection results of various embodiments of the present invention.

[0039] A cooling copper roller for preparing non-oriented silicon steel ultra-thin strip by plane flow casting comprises a cooling copper roller 1, the surface of which is treated with chemical nickel plating to form a nickel plating layer 2 with a thickness of 30 to 60 μm.

[0040] Each embodiment is prepared according to the following method, the steps are:

[0041] 1) Degreasing, placing the cooling copper roller 1 in a degreasing liquid at a temperature of 50 to 65° C. for cleaning for 15 to 25 minutes, during which time stirring is continued until the degreasing is completed;

[0042] 2) pickling, placing the degreased cooling copper roller 1 in a pickling solution with a nitric acid concentration of 10 to 15 wt % for pickling for 10 to 15 minutes;

[0043] 3) Alkali washing: the pickled cooling copper roller 1 is placed in an alkaline washing solution containing 4.5-6.0 wt% sodium hydroxide and 0.1-0.4 wt% sodium dodecylbenzene sulfonate at a temperature of 50-65° C. for 15-20 minutes, and then repeatedly rinsed with distilled water until clean;

[0044] 4) performing chemical nickel plating, immersing the cooling copper roller 1 rinsed with distilled water in a chemical nickel plating solution for 30 to 40 minutes, allowing it to fully react and deposit a 30 to 60 μm thick nickel plating layer 2 on the surface of the cooling copper roller 1, and stirring during this period; the temperature of the chemical nickel plating solution is controlled at 70 to 85° C., and the pH value of the chemical nickel plating solution is controlled at 4.5 to 5.0; the nickel content of the formed nickel plating layer is not less than 85 wt %;

[0045] 5) Rinse with distilled water to clean the residual liquid on the surface of the nickel-plated layer 2;

[0046] 6) Drying, controlling the drying temperature at 100-110°C and the drying time at 2-3h;

[0047] 7) Reserved.

[0048] Description of the present invention in the preparation of non-oriented silicon steel ultra-thin strip:

[0049] 1. The following embodiments are all used to prepare non-oriented silicon steel ultra-thin strips containing 2-4.5% silicon by weight, with the remainder being iron and a small amount of other inevitable impurities, and having a thickness in the range of 0.04-0.12 mm.

[0050] 2. The present invention needs to control the relevant parameters of the equipment before the strip is thrown, among which the roller mouth spacing is controlled at 0.1-0.3 mm, the nozzle injection pressure is controlled at 30-70 kPa, and the cooling roller speed is controlled at 10-25 m / s. The reason is that the non-oriented silicon steel ultra-thin strip prepared within the above process parameter range has the best formability, fewer defects and good surface quality.

[0051] 3. The reason why the present invention controls the superheat of the master alloy melt at 30-100°C is that the viscosity of the melt in this temperature range is low, the fluidity is good, and the degree of melt oxidation is low, thereby avoiding problems such as high melt viscosity and poor fluidity due to low superheat and easy oxidation of the melt due to high superheat.

[0052] 4. The present invention requires leveling and annealing of the prepared cast strip, wherein the leveling reduction rate is controlled at 2-5%, the reason being that a small reduction can not only improve the surface quality of the thin strip, but also improve the magnetic properties to a certain extent, but too large a reduction will destroy the favorable texture that has been formed and thus reduce the magnetic properties. The annealing temperature is controlled at 800-1000°C and kept at this temperature for 40-100 minutes, because it can regulate the optimal grain size and texture, so that the magnetic properties are further improved.

[0053] Table 1 List of main process parameters of various embodiments of the present invention

[0054]

[0055] Table 2 Composition and content of each solution in the process of each embodiment of the present invention (wt%)

[0056]

[0057] Table 2

[0058]

[0059]

[0060] Table 3 List of test results of various embodiments of the present invention

[0061]

[0062] As can be seen from Table 3, the quality of the coating is crucial to the successful preparation of non-oriented silicon steel strips. If the chemical nickel plating process parameters are not within the appropriate range, the formed coating is often uneven, resulting in an uneven surface of the strip, poor bonding strength of the coating and easy to fall off, which in turn affects the yield of the strip. In addition, higher porosity will also reduce the surface quality of the strip. Therefore, it is necessary to operate within the above-mentioned chemical nickel plating process parameter range to ensure the uniformity and quality of the coating.

[0063] This specific implementation is only the best example and is not a restrictive implementation of the technical solution of the present invention.

Claims

1. A cooling roller for producing non-oriented silicon steel ultra-thin strip by plane flow casting, which is composed of a cooling copper roller, characterized in that: A nickel plating layer is provided on the surface of the cooling copper roller, and the thickness of the nickel plating layer is controlled to be 30 to 60 μm.

2. A cooling roller for producing non-oriented silicon steel ultra-thin strip by plane flow casting as claimed in claim 1, characterized in that: It is suitable for preparing non-oriented silicon steel with a weight percentage of 2-4.5% silicon, the rest of which is iron and a small amount of other inevitable impurities. The ultra-thin strip of the prepared non-oriented silicon steel has a thickness of 0.04-0.12 mm.

3. A cooling roller and a method for producing a non-oriented silicon steel ultra-thin strip by plane flow casting as claimed in claim 1, comprising the following steps: 1) Degreasing: Place the cooling copper roller in a degreasing liquid at a temperature of 50-65°C for 15-25 minutes and continue stirring until the degreasing is completed; 2) pickling, placing the degreased cooling copper roller in a pickling solution with a nitric acid concentration of 10 to 15 wt% for pickling for 10 to 15 minutes; 3) Alkali washing: the pickled cooling copper roller is placed in an alkaline washing solution containing 4.5-6.0wt% sodium hydroxide and 0.1-0.4wt% sodium dodecylbenzene sulfonate at a temperature of 50-65° C. for 15-20 minutes, and then repeatedly rinsed with distilled water until clean; 4) performing chemical nickel plating, immersing the cooling copper roller rinsed with distilled water in a chemical nickel plating solution for 30 to 40 minutes, allowing it to fully react and deposit a 30 to 60 μm thick nickel plating layer on the surface of the cooling copper roller, and stirring during the reaction; the temperature of the chemical nickel plating solution is controlled at 70 to 85° C., and the pH value of the chemical nickel plating solution is controlled at 4.5 to 5; the nickel content of the formed nickel plating layer is not less than 85 wt %; 5) Rinse with distilled water to clean the residual liquid on the surface of the nickel-plated layer; 6) Drying, controlling the drying temperature at 100-110°C and the drying time at 2-3h; 7) Reserved.

4. A cooling roller and a preparation method for producing non-oriented silicon steel ultra-thin strip by plane flow casting as claimed in claim 3, Features: The composition and weight percentage of the degreasing liquid are as follows: sodium carbonate: 2.0-3.0%, sodium phosphate: 2.0~3.5%, sodium dodecylbenzene sulfonate: 0.1~0.3%, and the rest is water.

5. A cooling roller and preparation method for producing non-oriented silicon steel ultra-thin strip by plane flow casting as claimed in claim 3, characterized in that: The composition and weight percentage content of the chemical nickel plating solution are: nickel chloride: 9.5-12%, nickel sulfate: 3.0-5.5%, citric acid: 3.5-5.0%, ethylenediamine sulfate: 1.5-3.0%, boric acid: 2.0-3.0%, sodium thiosulfate: 1.5-2.0%, sodium hypophosphite: 2.5-4.0%, and the rest is water; the pH value of the chemical nickel plating solution is 4.5-5.0, and the pH value is adjusted by boric acid.

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