A cobalt plating solution, cobalt-coated carbonyl iron powder material and preparation method thereof

Abstract

The present application is applicable to the field of material technology, and provides a cobalt plating solution, a cobalt-coated carbonyl iron powder material and a preparation method thereof. Each 1L of the cobalt plating solution includes the following raw materials: 20-80g of cobalt salt, 20-80g of reducing agent, 40-120g of complexing agent, 0.005-0.01g of stabilizer, 30-70g of buffer and 2-3g of dispersant. The present application can obtain alloy coatings with different cobalt contents by adjusting the proportion of cobalt salt in the cobalt plating solution, control the coating thickness, and accelerate the mutual dissolution of iron and cobalt by ball milling, forming a three-phase alloy layer of iron, iron-cobalt and cobalt on the surface of the carbonyl iron powder, producing excellent magnetic properties and corrosion resistance.

Description

Technical Field

[0001] The present application belongs to the field of material technology, and in particular relates to a cobalt plating solution, a cobalt-coated carbonyl iron powder material and a preparation method thereof. Background Art

[0002] Carbonyl iron powder is a metal iron powder prepared by carbonyl powder metallurgy. Because of its small particle size (less than 10um), high activity, irregular shape (onion-shaped layered structure), and high magnetic flux at high and ultra-high frequencies, it is widely used in the manufacture of magnetic materials and plays an irreplaceable role in the production of high-frequency iron powder cores. However, it has a high density and is difficult to disperse. If it is placed in the air for a long time, it is easy to absorb oxygen and water in the air and cause the iron to slowly oxidize. Therefore, it is necessary to modify the surface of the carbonyl iron powder appropriately.

[0003] However, existing carbonyl iron powder modified materials still have the problems of poor corrosion resistance and poor magnetic properties. Summary of the invention

[0004] The purpose of the embodiments of the present application is to provide a cobalt plating solution, aiming to solve the problem that the existing carbonyl iron powder modified material still has poor corrosion resistance and poor magnetic properties.

[0005] The embodiment of the present application is implemented as follows: a cobalt plating solution, each 1L of the cobalt plating solution includes the following raw materials of mass:

[0006] Cobalt salt 20-80g, reducing agent 20-80g, complexing agent 40-120g, stabilizer 0.005-0.01g, buffer 30-70g and dispersant 2-3g.

[0007] Another object of the embodiment of the present application is a method for preparing a cobalt-coated carbonyl iron powder material, comprising:

[0008] Weigh various raw materials according to the formula of the cobalt plating solution, and mix them to prepare a cobalt plating solution;

[0009] The cobalt plating solution is placed under a temperature condition of 70-85° C. for hydrothermal treatment, carbonyl iron powder is added for reaction, and the pH value is controlled to 4-5 by a pH regulator;

[0010] The carbonyl iron powder after the reaction is washed and dried, and then placed in a ball mill for dry ball milling to obtain a cobalt-coated carbonyl iron powder material, wherein the ball milling speed is 300-500 r / min, the ball milling time is 20-140 h, and the ball-to-material ratio is 10-20:1.

[0011] Another object of an embodiment of the present application is a cobalt-coated carbonyl iron powder material, wherein the cobalt-coated carbonyl iron powder material is prepared by the method for preparing the cobalt-coated carbonyl iron powder material.

[0012] The cobalt plating solution provided in the embodiment of the present application can obtain alloy coatings with different cobalt contents by adjusting the proportion of cobalt salt in the cobalt plating solution, and the thickness of the coating can be controlled. The mutual dissolution of iron and cobalt can be accelerated by ball milling to form a three-phase alloy layer of iron, iron-cobalt and cobalt on the surface of carbonyl iron powder, thereby producing excellent magnetic properties and corrosion resistance. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 This is a morphology characterization diagram of a cobalt-coated carbonyl iron powder material provided in an embodiment of the present application;

[0014] Figure 2 This is a morphology characterization diagram of another cobalt-coated carbonyl iron powder material provided in an embodiment of the present application;

[0015] Figure 3 It is the MH diagram of the original carbonyl iron powder and the cobalt-coated carbonyl iron powder materials provided in the examples of the present application;

[0016] Figure 4 This is the XRD diagram of the cobalt-coated carbonyl iron powder material provided in the examples of the present application. DETAILED DESCRIPTION

[0017] In order to make the purpose, technical solution and advantages of the present application more clearly understood, the present application is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present application and are not used to limit the present application.

[0018] In order to solve the problem that the existing carbonyl iron powder modified materials still have poor corrosion resistance and poor magnetic properties, the embodiment of the present application provides a cobalt plating solution, which can obtain alloy coatings with different cobalt contents by adjusting the proportion of cobalt salt in the cobalt plating solution, and can control the coating thickness. The mutual dissolution of iron and cobalt is accelerated by ball milling to form a three-phase alloy layer of iron, iron-cobalt and cobalt on the surface of the carbonyl iron powder, thereby producing excellent magnetic properties and corrosion resistance.

[0019] Among magnetic metals, Co has an extremely high Curie temperature and good magnetic properties. While improving the corrosion resistance of carbonyl iron powder, it also produces some unique magnetic properties. Therefore, the present application selects the method of chemical cobalt plating to modify the carbonyl surface.

[0020] Specifically, the embodiment of the present application provides a cobalt plating solution, and each 1L of the cobalt plating solution includes the following raw materials of mass:

[0021] Cobalt salt 20-80g, reducing agent 20-80g, complexing agent 40-120g, stabilizer 0.005-0.01g, buffer 30-70g and dispersant 2-3g.

[0022] In the embodiment of the present application, the cobalt salt is optionally one of cobalt chloride and cobalt sulfate; as a source of cobalt element, it provides cobalt ions for the entire reaction. The type of cobalt salt is mainly selected based on cost, but if the content of cobalt salt is too much, it will cause the coating layer to collapse or the thickness is too large, resulting in a significant decrease in saturation magnetization. If the content is too little, the coating effect is not obvious.

[0023] In the embodiment of the present application, the reducing agent is optionally one of sodium hypophosphite, sodium borohydride, and alkylamine borane; its function is to reduce nickel ions and provide electrons required for reduction. If the reducing agent is different, such as sodium hypophosphite or sodium borohydride, less phosphorus or boron impurities will be introduced into the coating. At the same time, if the reducing agent is used in excessive amounts, it will cause excessive impurity content, affecting product performance.

[0024] In the embodiment of the present application, optionally, the complexing agent is one of lactic acid and anhydrous citric acid; its function is to prevent precipitation and improve the stability of the plating solution.

[0025] In the embodiment of the present application, optionally, the stabilizer is one of lead nitrate and thiourea; its function is to inhibit the spontaneous decomposition of the plating solution so that the plating process can proceed in an orderly manner under control.

[0026] In the embodiment of the present application, optionally, the buffer is acetic acid or sodium acetate; its function is to control the pH of the plating solution within a certain range.

[0027] In the embodiment of the present application, optionally, the dispersant is polyethylene glycol; its function is to prevent powder agglomeration.

[0028] The present application also provides a method for preparing a cobalt-coated carbonyl iron powder material, comprising:

[0029] Weigh various raw materials according to the formula of the cobalt plating solution, and mix them to prepare a cobalt plating solution;

[0030] The cobalt plating solution is placed under a temperature condition of 70-85° C. for hydrothermal treatment, carbonyl iron powder is added for reaction, and the pH value is controlled to 4-5 by a pH regulator;

[0031] The carbonyl iron powder after the reaction is washed and dried, and then placed in a ball mill for dry ball milling to obtain a cobalt-coated carbonyl iron powder material, wherein the ball milling speed is 300-500 r / min, the ball milling time is 20-140 h, and the ball-to-material ratio is 10-20:1.

[0032] The dry ball milling speed is set at 300-500 r / min, the ball milling time is 20-140 h, the ball-to-material ratio is 10-20:1, and the purpose of dry ball milling is to accelerate the mutual dissolution of iron and cobalt.

[0033] In the embodiment of the present application, optionally, the method for preparing the cobalt-coated carbonyl iron powder material further comprises:

[0034] The cobalt-coated carbonyl iron powder material is placed in a ball mill for wet ball milling, wherein the ball milling speed is 300-330 r / min, the material-liquid ratio is 1:0.2-0.5, the ball milling time is 10-20 h, and the ball-to-material ratio is 10-15:1.

[0035] The wet ball milling speed is set at 300-330 r / min, the material-liquid ratio is 1:0.2-0.5, the ball milling time is 10-20 h, the ball-to-material ratio is 10-15:1, and the purpose of wet ball milling is to refine the powder.

[0036] The embodiment of the present application also provides a cobalt-coated carbonyl iron powder material, and the cobalt-coated carbonyl iron powder material is prepared by the preparation method of the cobalt-coated carbonyl iron powder material.

[0037] Examples of certain embodiments of the present application are given below, which are not intended to limit the scope of the present application.

[0038] In addition, it should be noted that the numerical values ​​given in the following examples are as accurate as possible, but those skilled in the art understand that due to unavoidable measurement errors and experimental operation problems, each number should be understood as an approximate number rather than an absolutely accurate value.

[0039] Example 1

[0040] This embodiment is used for chemical cobalt plating on the surface of carbonyl iron powder. The cobalt plating solution solvent is deionized water. The mass concentration of each component in each 1L of the cobalt plating solution is: 50g / L cobalt chloride, 40g / L sodium hypophosphite, 50g / L lactic acid, 40g / L acetic acid, 2g / L polyethylene glycol and 10mg / L lead nitrate and thiourea. The pH value of the cobalt plating solution is 5, and the carbonyl iron powder loading amount is 2g / L.

[0041] Step 1: Degreasing: Place the carbonyl iron powder to be surface treated in a dry beaker, add enough acetone to cover the iron powder, and place in an ultrasonic cleaner for 10 minutes.

[0042] Step 2: washing with deionized water to wash the dried carbonyl iron powder.

[0043] Step three: wash twice and repeat the operation in step two.

[0044] Step 4: Prepare a cobalt plating solution. Prepare 1L of cobalt plating solution according to the above ratio. Add 50g of cobalt chloride, 50g of lactic acid, 40g of sodium hypophosphite, 40g of acetic acid, 10mg of lead nitrate and thiourea, and 2g of polyethylene glycol in the following order.

[0045] Step 5: Heat the cobalt plating solution. Place the prepared cobalt plating solution in a water bath, heat to 80°C, add carbonyl iron powder, stir continuously with a stirrer, and monitor the pH in real time with a pH agent. The pH value will gradually decrease as the reaction proceeds. Use 10% sodium hydroxide solution to adjust and keep the pH stable. The reaction time is 3 hours.

[0046] Step six, washing with water, allowing the carbonyl iron powder suspension after the reaction to stand, pouring off the upper solution, washing the carbonyl iron powder with a large amount of deionized water to remove impurity ions on the surface, and placing it in a vacuum drying oven for drying.

[0047] Step seven, wash twice with water and repeat the operation in step six.

[0048] Step 8: Place the dried powder into a planetary ball mill, set the speed to 300 r / min, the ball milling time to 40 h, and the ball-to-material ratio to 10:1.

[0049] Step nine, after the dry ball milling is completed, anhydrous ethanol is added to the ball mill, the material-liquid ratio is 1:0.5, the ball mill speed is set to 300r / min, the ball milling time is 10h, and the ball-to-material ratio is 10:1 to obtain the cobalt-coated carbonyl iron powder material.

[0050] Example 2

[0051] This embodiment is used for chemical cobalt plating on the surface of carbonyl iron powder. The cobalt plating solution solvent is deionized water. The mass concentration of each component in each 1L of the cobalt plating solution is: 80g / L cobalt sulfate, 70g / L sodium hypophosphite, 80g / L lactic acid, 70g / L acetic acid, 2g / L polyethylene glycol and 10mg / L lead nitrate and thiourea. The pH value of the cobalt plating solution is 4, and the carbonyl iron powder loading amount is 2g / L.

[0052] Step 1: Degreasing: Place the carbonyl iron powder to be surface treated in a dry beaker, add enough acetone to cover the iron powder, and place in an ultrasonic cleaner for 10 minutes.

[0053] Step 2: washing with deionized water to wash the dried carbonyl iron powder.

[0054] Step three: wash twice and repeat the operation in step two.

[0055] Step 4: Prepare the plating solution. Prepare 1L of plating solution according to the above ratio. Add 80g of cobalt sulfate, 80g of lactic acid, 70g of sodium hypophosphite, 70g of acetic acid, 10mg of lead nitrate and thiourea, and 2g of polyethylene glycol in the following order.

[0056] Step 5, heating nickel plating. Put the prepared nickel plating into a water bath, heat to 75°C, add carbonyl iron powder, stir continuously with a stirrer, and monitor the pH in real time with a pH agent. The pH value will gradually decrease as the reaction proceeds. Use 10% sodium hydroxide solution to adjust and keep the pH stable. The reaction time is 5 hours.

[0057] Step six, washing with water, allowing the carbonyl iron powder suspension after the reaction to stand, pouring off the upper solution, washing the carbonyl iron powder with a large amount of deionized water to remove impurity ions on the surface, and placing it in a vacuum drying oven for drying.

[0058] Step seven, wash twice with water and repeat the operation in step six.

[0059] Step 8: Place the dried powder into a planetary ball mill, set the speed to 300 r / min, the ball milling time to 120 h, and the ball-to-material ratio to 15:1.

[0060] Step nine, after the dry ball milling is completed, anhydrous ethanol is added to the ball mill, the material-liquid ratio is 1:0.2, the ball mill speed is set to 300 r / min, the ball milling time is 20 h, and the ball-to-material ratio is 15:1 to obtain the cobalt-coated carbonyl iron powder material.

[0061] Example 3

[0062] This embodiment is used for chemical cobalt plating on the surface of carbonyl iron powder. The cobalt plating solution solvent is deionized water. The mass concentration of each component in each 1L of the cobalt plating solution is: 30g / L cobalt chloride, 30g / L sodium borohydride, 40g / L anhydrous citric acid, 30g / L acetic acid, 2g / L polyethylene glycol and 10mg / L lead nitrate and thiourea. The pH value of the cobalt plating solution is 5, and the carbonyl iron powder loading amount is 2g / L.

[0063] Step 1: Degreasing: Place the carbonyl iron powder to be surface treated in a dry beaker, add enough acetone to cover the iron powder, and place in an ultrasonic cleaner for 10 minutes.

[0064] Step 2: washing with deionized water to wash the dried carbonyl iron powder.

[0065] Step three: wash twice and repeat the operation in step two.

[0066] Step 4: Prepare a cobalt plating solution. Prepare 1L of cobalt plating solution according to the above ratio. Add 30g of cobalt chloride, 40g of anhydrous citric acid, 30g of sodium borohydride, 30g of sodium acetate, 5mg of lead nitrate and thiourea, and 2g of polyethylene glycol in the following order.

[0067] Step 5: Heat the cobalt plating solution. Place the prepared cobalt plating solution in a water bath, heat to 85°C, add carbonyl iron powder, stir continuously with a stirrer, and monitor the pH in real time with a pH agent. The pH value will gradually decrease as the reaction proceeds. Use 10% sodium hydroxide solution to adjust the pH to keep it stable. The reaction time is 2 hours.

[0068] Step six, washing with water, allowing the carbonyl iron powder suspension after the reaction to stand, pouring off the upper solution, washing the carbonyl iron powder with a large amount of deionized water to remove impurity ions on the surface, and placing it in a vacuum drying oven for drying.

[0069] Step seven, wash twice with water and repeat the operation in step six.

[0070] Step 8: Place the dried powder into a planetary ball mill, set the speed to 300 r / min, the ball milling time to 25 h, and the ball-to-material ratio to 10:1.

[0071] Step nine, after the dry ball milling is completed, anhydrous ethanol is added to the ball mill, the material-liquid ratio is 1:0.5, the ball mill speed is set to 300r / min, the ball milling time is 10h, and the ball-to-material ratio is 10:1 to obtain the cobalt-coated carbonyl iron powder material.

[0072] The cobalt-coated carbonyl iron powder material prepared in Example 1 was tested by scanning electron microscopy. The test results are as follows: Figure 1-2 As shown, both are morphological characterization images with different magnifications.

[0073] The cobalt-coated carbonyl iron powder material prepared in Example 1 was subjected to XRD test, and the test results are as follows: Figure 4 shown.

[0074] The magnetic properties of the cobalt-coated carbonyl iron powder materials prepared in Examples 1-3 were tested and analyzed, and the results are shown in Table 1. The saturation magnetic induction intensity of the cobalt-coated iron powder in Example 2 dropped sharply because the coating layer was too thick, and it recovered after ball milling. In addition, the magnetic property change trend of the cobalt-coated carbonyl iron powder material (cobalt-coated iron powder) prepared in Example 1 before and after ball milling and the original carbonyl iron powder is shown in Table 1. Figure 3 As shown in the figure, according to the specific parameters of Example 1, the saturation magnetic induction intensity of the material increases and the coercive force decreases slightly after ball milling.

[0075] Table 1

[0076]

[0077] In summary, the cobalt plating solution provided in the embodiment of the present application can obtain alloy coatings with different cobalt contents by adjusting the proportion of cobalt salt in the cobalt plating solution, the thickness of the coating can be controlled, and the mutual dissolution of iron and cobalt can be accelerated by ball milling to form a three-phase alloy layer of iron, iron-cobalt and cobalt on the surface of carbonyl iron powder, thereby producing excellent magnetic properties and corrosion resistance.

[0078] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the present application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application shall be subject to the attached claims.

[0079] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should be included in the protection scope of the present application.

Claims

1. A method for preparing a cobalt-coated carbonyl iron powder material, characterized in that , weighing various raw materials according to the formula of the cobalt plating solution, mixing and configuring the cobalt plating solution; subjecting the cobalt plating solution to hydrothermal treatment at a temperature of 70-85° C., adding carbonyl iron powder to react, and controlling the pH to 4-5 by a pH regulator; The carbonyl iron powder after the reaction is washed and dried, and then placed in a ball mill for dry ball milling to obtain a cobalt-coated carbonyl iron powder material, wherein the ball milling speed is 300-500 r / min, the ball milling time is 20-140 h, and the ball-to-material ratio is 10-20:1; Each 1L of the cobalt plating solution includes the following raw materials in mass: 20-80g of cobalt salt, 20-80g of reducing agent, 40-120g of complexing agent, 0.005-0.01g of stabilizer, 30-70g of buffer and 2-3g of dispersant.

2. The method for preparing a cobalt-coated carbonyl iron powder material according to claim 1, characterized in that , the cobalt salt is one of cobalt chloride and cobalt sulfate.

3. The method for preparing a cobalt-coated carbonyl iron powder material according to claim 1, characterized in that , the reducing agent is one of sodium hypophosphite, sodium borohydride, and alkylamine borane.

4. The method for preparing a cobalt-coated carbonyl iron powder material according to claim 1, characterized in that , the complexing agent is one of lactic acid and anhydrous citric acid.

5. The method for preparing a cobalt-coated carbonyl iron powder material according to claim 1, characterized in that , the stabilizer is one of lead nitrate and thiourea.

6. The method for preparing a cobalt-coated carbonyl iron powder material according to claim 1, characterized in that , the buffer is acetic acid.

7. The method for preparing a cobalt-coated carbonyl iron powder material according to claim 1, characterized in that , the dispersant is polyethylene glycol.

8. The method for preparing a cobalt-coated carbonyl iron powder material according to claim 1, characterized in that , further comprising: placing the cobalt-coated carbonyl iron powder material in a ball milling mechanism for wet ball milling treatment, wherein the ball milling speed is 300-330 r / min, the material-liquid ratio is 1:0.2-0.5, the ball milling time is 10-20 h, and the ball-to-material ratio is 10-15:

1.

9. A cobalt-coated carbonyl iron powder material, characterized in that The cobalt-coated carbonyl iron powder material is prepared by the preparation method of the cobalt-coated carbonyl iron powder material according to claim 1 or 8.

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