Optimization method of carbonyl iron powder and carbonyl iron powder

Abstract

The embodiment of the invention relates to the technical field of corrosion prevention of metal powder, in particular to an optimization method of carbonyl iron powder and the carbonyl iron powder. According to the method, carbonyl iron powder is added into a nickel plating solution to be subjected to a nickel plating reaction, obtained reactants are dried, and nickel-plated iron powder is obtained; and the nickel-plated iron powder is added into tetraethoxysilane coating liquid to be subjected to a coating reaction, obtained reactants are dried, and the nickel-plated iron powder sequentially coated with the nickel layer and the silicon dioxide layer is obtained. A nickel layer is deposited on the surface of the carbonyl iron powder through a chemical nickel plating method, silicon dioxide deposition on the surface of the nickel-plated iron powder is achieved through a silicon source provided by tetraethoxysilane, finally the carbonyl iron powder coated with double-layer antioxidant substances is prepared, and the corrosion resistance in the salt mist environment is improved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the technical field of metal powder anti-corrosion, and in particular to an optimization method for carbonyl iron powder and carbonyl iron powder. Background Art

[0002] Carbonyl iron powder is an ultrafine powder obtained by thermal decomposition of pentacarbonyl iron Fe(CO)5. Due to its small particle size (below 10μm), large specific surface area, high activity, onion-shaped irregular structure and many unique properties, it is widely used in military, electronics, chemical, medicine, food, agriculture and other fields: such as traditional powder metallurgy and injection molding, high-frequency magnetic cores and various soft magnetic material components, superhard materials and diamond tools, diamond catalysts, medicine and nutrition, microwave absorbing materials, stealth materials, magnetic selection and improvement, etc.

[0003] As a traditional microwave powder adsorption material, carbonyl iron powder has high magnetic flux and good magnetic conductivity stability under high-frequency and ultra-high-frequency conditions. Therefore, it is widely used in electronic equipment for one-piece molded inductors, magnetic dielectric cores, high-frequency magnetic cores, and a variety of soft magnetic material components. However, many studies on carbonyl iron powder materials have shown that carbonyl iron powder is very easy to oxidize when used in a hot and humid environment, and has poor corrosion resistance. Obvious rust spots will appear on the surface of the device, reducing the service life, affecting the performance, and causing material failure. Summary of the invention

[0004] The embodiment of the present application provides a method for optimizing carbonyl iron powder, which can improve the salt spray corrosion resistance of carbonyl iron powder.

[0005] In order to solve the above technical problems, in the first aspect, an optimization method of carbonyl iron powder is provided in an embodiment of the present application, comprising:

[0006] Adding carbonyl iron powder into a nickel plating solution to generate a nickel plating reaction, and drying the obtained reactant to obtain nickel-plated iron powder;

[0007] The nickel-plated iron powder is added into a ethyl orthosilicate coating liquid to generate a coating reaction, and the obtained reactant is dried to obtain a nickel-plated iron powder coated with a nickel layer and a silicon dioxide layer in sequence.

[0008] In some embodiments, the concentration of the tetraethyl orthosilicate coating solution is 5-10%.

[0009] In some embodiments, before adding the carbonyl iron powder into the nickel plating solution to generate the nickel plating reaction, the method further includes: performing a roughening treatment and / or an activation treatment on the surface of the carbonyl iron powder.

[0010] In some embodiments, the step of adding carbonyl iron powder to a nickel plating solution to generate a nickel plating reaction, and drying the obtained reactant to obtain nickel-plated iron powder comprises:

[0011] Adding the carbonyl iron powder into the nickel plating solution to generate a nickel plating reaction;

[0012] After the nickel plating reaction is completed, natural sedimentation and filtration are performed to obtain the first reactant;

[0013] The first reactant is washed with anhydrous ethanol for 3-5 times, and the first reactant is dried in a constant temperature drying oven until it is cooled to room temperature at constant weight to obtain the nickel-plated iron powder.

[0014] In some embodiments, the method further includes: annealing the nickel-plated iron powder.

[0015] In some embodiments, the nickel-plated iron powder is added to a ethyl orthosilicate coating solution to undergo a coating reaction, and the obtained reactant is dried to obtain a nickel-plated iron powder sequentially coated with a nickel layer and a silicon dioxide layer, comprising:

[0016] Putting the nickel-plated iron powder into the ethyl orthosilicate coating solution to generate a silicon dioxide coating reaction;

[0017] After the coating reaction is completed, natural sedimentation and filtration are performed to obtain the second reactant;

[0018] The second reactant is washed with anhydrous ethanol for 3-5 times, and the product is dried in a constant temperature drying oven until it is cooled to room temperature at a constant weight to obtain the nickel-plated iron powder sequentially coated with a nickel layer and a silicon dioxide layer.

[0019] In a second aspect, an embodiment of the present application provides a carbonyl iron powder, wherein the carbonyl iron powder is sequentially coated with a metal nickel layer and a silicon dioxide layer.

[0020] In some embodiments, the nickel content in the carbonyl iron powder is 4%-12%.

[0021] In some embodiments, the silicon dioxide layer has a thickness of 10-20 nm.

[0022] In a third aspect, an embodiment of the present application provides a carbonyl iron powder prepared based on the optimization method described in the first aspect above.

[0023] Beneficial effects of the embodiments of the present invention: Different from the prior art, the embodiments of the present invention provide a method for optimizing carbonyl iron powder, wherein the carbonyl iron powder is added to a nickel plating solution to generate a nickel plating reaction, and the obtained reactant is dried to obtain a nickel-plated iron powder; the nickel-plated iron powder is added to an ethyl orthosilicate coating solution to generate a coating reaction, and the obtained reactant is dried to obtain a nickel-plated iron powder coated with a nickel layer and a silicon dioxide layer in sequence. The nickel-plated iron powder prepared in the present application is coated with a double layer of antioxidant material, which improves the corrosion resistance in a salt spray environment. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] One or more embodiments are exemplarily described by pictures in the corresponding drawings, and these exemplified descriptions do not constitute limitations on the embodiments. Elements with the same reference numerals in the drawings represent similar elements, and unless otherwise stated, the figures in the drawings do not constitute proportional limitations.

[0025] Figure 1 It is a schematic flow chart of a method for optimizing carbonyl iron powder provided in some embodiments of the present application. DETAILED DESCRIPTION

[0026] The present invention is described in detail below in conjunction with specific embodiments. The following embodiments will help those skilled in the art to further understand the present invention, but are not intended to limit the present invention in any form. It should be noted that, for those of ordinary skill in the art, several variations and improvements may be made without departing from the concept of the present invention. These all belong to the protection scope of the present invention.

[0027] 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.

[0028] It should be noted that, if there is no conflict, the various features in the embodiments of the present invention can be combined with each other, all within the scope of protection of the present application. In addition, although the functional modules are divided in the device schematic diagram and the logical order is shown in the flow chart, in some cases, the steps shown or described can be performed in a different order than the module division in the device or the flow chart. In addition, the words "first", "second", "third", etc. used herein do not limit the data and execution order, but only distinguish the same items or similar items with basically the same functions and effects.

[0029] Unless otherwise defined, all technical and scientific terms used in this specification have the same meaning as those commonly understood by those skilled in the art of the present invention. The terms used in this specification and in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. The term "and / or" used in this specification includes any and all combinations of one or more of the related listed items.

[0030] In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] For example, Figure 1 The process of the optimization method of carbonyl iron powder provided by some embodiments of the present application is shown, and the method comprises:

[0032] Step a: adding carbonyl iron powder into a nickel plating solution to generate a nickel plating reaction, and drying the obtained reactant to obtain nickel-plated iron powder.

[0033] Among them, carbonyl iron powder is an ultrafine powder prepared by thermal decomposition of pentacarbonyl iron Fe(CO)5; nickel plating solution is a chemical solution that can reduce nickel ions in the solution through a reducing agent and deposit them on a catalytically active surface, thereby depositing a nickel coating. The nickel plating solution is usually composed of a nickel-containing main salt, a reducing agent, a chelating agent, a stabilizer, a buffer, an accelerator and other additives.

[0034] In this embodiment, a nickel plating reaction is generated by adding carbonyl iron powder to a nickel plating solution, and after the nickel plating is completed, the obtained reactant is dried to obtain a carbonyl iron powder coated with a nickel layer, i.e., a nickel-plated iron powder. The nickel layer is plated on the surface of the micron-sized carbonyl iron powder by chemical plating.

[0035] In some embodiments, the amount of nickel plating solution is calculated based on the concentration of 4%-12% of nickel contained in the nickel-plated iron powder after the nickel plating reaction occurs. In some embodiments, the amount of nickel plating solution is calculated based on the concentration of 6% of nickel contained in the nickel-plated iron powder after the nickel plating reaction occurs. In some embodiments, the amount of nickel plating solution is calculated based on the concentration of 8% of nickel contained in the nickel-plated iron powder after the nickel plating reaction occurs. In some embodiments, the amount of nickel plating solution is calculated based on the concentration of 10% of nickel contained in the nickel-plated iron powder after the nickel plating reaction occurs.

[0036] The main characteristics of carbonyl iron powder used in inductor products are high magnetic permeability and poor salt spray resistance. Introducing a nickel layer into the carbonyl iron powder through a nickel plating coating reaction can improve the salt spray resistance, but it will reduce the magnetic permeability. Therefore, it is necessary to comprehensively consider the balance of the above properties to determine the impact of nickel layers at different contents on the performance of iron powder.

[0037] Adding a suitable amount of carbonyl iron powder to a nickel plating solution and plating a nickel layer on the surface of the carbonyl iron powder can achieve a balance between magnetic permeability and salt spray resistance during use.

[0038] In some embodiments, the nickel-containing main salt used in the nickel plating solution is nickel sulfate hexahydrate or nickel chloride, the reducing agent used in the nickel plating solution is sodium hypophosphite, and the nickel plating solution also contains a complexing agent and a stabilizer substance.

[0039] Among them, the complexing agent can be, for example, aliphatic carboxylic acids (lactic acid, succinic acid, citric acid), aliphatic carboxylate (sodium citrate, sodium pyrophosphate), the stabilizer can be, for example, lead nitrate, thiourea, boric acid, and the pH buffer can be, for example, acetic acid / sodium acetate, ammonium chloride / triethanolamine.

[0040] In some embodiments, before performing step a, adding the carbonyl iron powder into the nickel plating solution to initiate the nickel plating reaction, the surface of the carbonyl iron powder needs to be roughened and / or activated.

[0041] Since the carbonyl iron powder has a large surface area, it is necessary to modify its surface before coating to improve the surface reaction activity and facilitate the subsequent coating reaction.

[0042] In this embodiment, the surface of the carbonyl iron powder is roughened and / or activated in order to increase the adsorption of metal ions. The roughening treatment causes micro-etching of the surface of the carbonyl iron powder through an ion replacement reaction, which can increase the roughness of the carbon fiber surface and enhance the adhesion and effect of subsequent treatments. The activation reaction introduces nucleation sites for the nickel plating reaction through an ion replacement reaction, which can cause a layer of easily oxidizable substances to be adsorbed on the surface of the carbon fiber, thereby increasing the activity of the carbon fiber surface and making the nickel metal during the nickel plating reaction more easily adhere to the iron powder surface, thereby improving the adhesion and uniformity of the coating.

[0043] In some embodiments, roughening the surface of the carbonyl iron powder specifically includes:

[0044] The carbonyl iron powder and the stannous chloride roughening solution are subjected to a roughening reaction at room temperature for 10-30 minutes, and then the precipitate is filtered and washed with sufficient deionized water for 3-5 times to obtain a roughened iron powder, wherein the concentration of the stannous chloride roughening solution is 10 g / L, and the mass ratio of the carbonyl iron powder to the stannous chloride roughening solution is 1:10-4:10.

[0045] In some embodiments, the activation treatment of the surface of the carbonyl iron powder specifically includes:

[0046] The carbonyl iron powder / coarsened iron powder is activated with lead chloride activation solution at room temperature for 5-10 minutes, and then filtered to obtain a precipitate, which is then washed with sufficient deionized water for 3-5 times to obtain activated iron powder, wherein the concentration of the lead chloride activation solution is 1 g / L, and the mass ratio of the carbonyl iron powder to the lead chloride activation solution is 1:10-4:10.

[0047] In some embodiments, step a specifically includes: adding carbonyl iron powder to a nickel plating solution to cause a nickel plating reaction; after the nickel plating reaction is completed, natural sedimentation and filtration are carried out to obtain a first reactant; the first reactant is washed with anhydrous ethanol for 3-5 times, and the first reactant is dried in a constant temperature drying oven until it is cooled to constant weight and cooled to room temperature to obtain nickel-plated iron powder.

[0048] In some embodiments, step a further comprises annealing the nickel-plated iron powder.

[0049] Since the surface of the carbonyl iron powder is easily introduced with oxygen and some water vapor after the nickel plating reaction occurs, the nickel-plated iron powder is annealed. The annealing treatment can remove the oxygen on the surface of the nickel-plated iron powder and at the same time achieve the densification of the nickel plating layer.

[0050] In some embodiments, annealing the nickel-plated iron powder specifically includes:

[0051] The nickel-plated iron powder is annealed in a hydrogen atmosphere at an annealing temperature of 300-800°C, with a temperature curve of 5-20°C / min. The temperature is raised to the annealing temperature, maintained at the temperature for 30-80 minutes, and then cooled to room temperature at a cooling rate of 5-20°C / min to obtain the annealed nickel-plated iron powder.

[0052] For example, the annealing temperature may be 400°C, or 500°C, or 600°C, or 700°C. For example, the temperature curve may be 10°C / min, or 15°C / min. For example, the holding time may be 40min, or 60min. For example, the cooling rate may be 10°C / min, or 15°C / min.

[0053] In this embodiment, the surface oxygen element is removed by hydrogenation and temperature treatment, thereby reducing the rust reaction during storage and use. At the same time, high temperature annealing treatment can achieve the densification of the trace nickel layer, which is beneficial to the application of iron powder under high frequency conditions.

[0054] Step b: adding nickel-plated iron powder to a ethyl orthosilicate coating solution to cause a coating reaction, and drying the obtained reactant to obtain a nickel-plated iron powder coated with a nickel layer and a silicon dioxide layer in sequence.

[0055] The ethyl orthosilicate coating liquid provides a silicon source, and the product of ethyl orthosilicate after hydrolysis reaction and polycondensation reaction is amorphous silicon dioxide, which can achieve quantitative coating on the surface of nickel-plated iron powder.

[0056] In this embodiment, nickel-plated iron powder is added to a ethyl orthosilicate coating solution to generate a coating reaction, and the obtained reactant is dried to obtain a nickel-plated iron powder coated with a silicon dioxide layer. Silicon dioxide is deposited on the surface of the nickel-plated iron powder to improve the corrosion resistance in a salt spray environment.

[0057] In some embodiments, the concentration of the ethyl orthosilicate coating solution is 5-10%. In some embodiments, the concentration of the ethyl orthosilicate coating solution is 6%. In some embodiments, the concentration of the ethyl orthosilicate coating solution is 8%.

[0058] In this embodiment, a suitable reaction concentration is formulated to achieve a specific coating layer thickness, thereby increasing the use frequency of carbonyl iron powder and reducing eddy current losses.

[0059] In some embodiments, the thickness of the silicon dioxide layer in the nickel-plated iron powder sequentially coated with a nickel layer and a silicon dioxide layer obtained after the coating reaction is 10-20 nm.

[0060] This thickness can achieve a balance between the magnetic permeability and salt spray resistance of the coated nickel-plated iron powder during use.

[0061] In some embodiments, the concentration of the ethyl orthosilicate coating solution is 20-50 g / L, and the ethyl orthosilicate coating solution is composed of ethyl orthosilicate, ethanol and water, wherein the ratio of anhydrous ethanol to water is 10:90-30:70, and the reaction temperature is 30-60°C.

[0062] In some embodiments, the concentration of the ethyl orthosilicate coating solution is 30 g / L; in some embodiments, the concentration of the ethyl orthosilicate coating solution is 40 g / L; in some embodiments, the reaction temperature is 40° C.; in some embodiments, the reaction temperature is 50° C.;

[0063] In some embodiments, step b specifically includes: putting nickel-plated iron powder into a ethyl orthosilicate coating solution to cause a silica coating reaction. After the coating reaction is completed, natural sedimentation and filtration are carried out to obtain a second reactant, and the second reactant is washed with anhydrous ethanol for 3-5 times, and the product is dried in a constant temperature drying oven until it is cooled to constant weight and cooled to room temperature to obtain nickel-plated iron powder coated with a nickel layer and a silica layer in sequence.

[0064] In some embodiments, the reaction rate is adjusted by ammonia water during the coating reaction, wherein the ratio of ammonia water to tetraethyl orthosilicate is 1:3-3:1.

[0065] The optimization method of carbonyl iron powder provided in the present application comprises adding carbonyl iron powder to a nickel plating solution to generate a nickel plating reaction, and drying the obtained reactant to obtain nickel-plated iron powder; adding the nickel-plated iron powder to an ethyl orthosilicate coating solution to generate a coating reaction, and drying the obtained reactant to obtain a nickel-plated iron powder coated with a nickel layer and a silicon dioxide layer in sequence. The nickel-plated iron powder prepared in the present application is coated with a double layer of antioxidant material, which improves the corrosion resistance in a salt spray environment.

[0066] The present application also provides a carbonyl iron powder, wherein the carbonyl iron powder is sequentially coated with a metal nickel layer and a silicon dioxide layer.

[0067] In this embodiment, the carbonyl iron powder sequentially coated with a metal nickel layer and a silicon dioxide layer has a stronger corrosion resistance in a salt spray environment.

[0068] In some embodiments, the nickel content of the carbonyl iron powder is 4%-12%. In some embodiments, the nickel content of the carbonyl iron powder is 6%. In some embodiments, the nickel content of the carbonyl iron powder is 8%. In some embodiments, the nickel content of the carbonyl iron powder is 10%.

[0069] In some embodiments, the thickness of the silicon dioxide layer is 10-20 nm. In some embodiments, the thickness of the silicon dioxide layer is 12 nm. In some embodiments, the thickness of the silicon dioxide layer is 15 nm. In some embodiments, the thickness of the silicon dioxide layer is 18 nm.

[0070] This thickness selection can achieve a balance between the magnetic permeability and salt spray resistance of the coated nickel-plated iron powder during use.

[0071] The present application also provides a carbonyl iron powder prepared based on the aforementioned optimization method.

[0072] The carbonyl iron powder is coated with a double layer of antioxidant material, thereby improving the corrosion resistance in a salt spray environment.

[0073] Several embodiments of the present application are provided below.

[0074] Example 1

[0075] (1) Carbonyl iron powder and 10 g / L stannous chloride roughening solution were subjected to roughening reaction at room temperature at a mass ratio of 1:10 for 10 min, the precipitate was filtered, and washed with sufficient deionized water for 3-5 times to obtain roughened iron powder.

[0076] (2) The coarsened iron powder and 1 g / L lead chloride activation solution are activated at a mass ratio of 1:10 at room temperature for 10 min, the precipitate is filtered, and washed with sufficient deionized water for 3-5 times to obtain activated iron powder.

[0077] (3) Calculate the amount of nickel plating solution according to the nickel content of 6%, add activated iron powder to the plating solution for plating reaction, and after the nickel plating reaction is completed, carry out natural sedimentation, filter to obtain a precipitate, use anhydrous ethanol to wash 3-5 times, use a constant temperature drying oven to dry the product until constant weight is cooled to room temperature, and obtain nickel-containing iron powder. Annealing treatment is performed on the nickel-containing iron powder, using a hydrogen atmosphere, the annealing temperature is 300-800°C, the temperature curve during annealing is 5-20°C / min, the temperature is raised to the annealing temperature, the temperature is maintained for 30-80min, and the nickel-plated iron powder is cooled to room temperature at a rate of 5-20°C / min.

[0078] (4) A 50 g / l ethyl orthosilicate solution was prepared, wherein the ratio of water to ethanol in the ethyl orthosilicate solution was 10:90, and nickel-plated iron powder was added to the ethyl orthosilicate coating solution. The reaction was carried out at a temperature of 30-60° C. for 2 h, and ammonia water was used to adjust the reaction rate of the coating solution. After the reaction was completed, the precipitate was filtered to obtain a precipitate, and the precipitate was washed with sufficient anhydrous ethanol for 3-5 times. The product was dried in a constant temperature drying oven at 80° C. until constant weight was reached and cooled to room temperature to obtain a silica-coated nickel-plated iron powder.

[0079] Example 2

[0080] (1) Carbonyl iron powder and 10 g / L stannous chloride roughening solution were subjected to roughening reaction at room temperature at a mass ratio of 1:10 for 10 min, the precipitate was filtered, and washed with sufficient deionized water for 3-5 times to obtain roughened iron powder.

[0081] (2) The coarsened iron powder and 1 g / L lead chloride activation solution are activated at a mass ratio of 1:10 at room temperature for 10 min, the precipitate is filtered, and washed with sufficient deionized water for 3-5 times to obtain activated iron powder.

[0082] (3) Calculate the amount of nickel plating solution according to the nickel content of 8%, add activated iron powder to the plating solution for plating reaction, and after the nickel plating reaction is completed, naturally settle and filter to obtain a precipitate, wash it with anhydrous ethanol for 3-5 times, and use a constant temperature drying oven to dry the product until it is cooled to room temperature at constant weight to obtain nickel-containing iron powder. Anneal the nickel-containing iron powder, use a hydrogen atmosphere, the annealing temperature is 300-800°C, the temperature curve during annealing is 5-20°C / min, heat to the annealing temperature, hold the temperature for 30-80min, and cool to room temperature at a rate of 5-20°C / min to obtain nickel-plated iron powder.

[0083] (4) A 50 g / l ethyl orthosilicate solution was prepared, wherein the ratio of water to ethanol in the ethyl orthosilicate solution was 10:90, and nickel-plated iron powder was added to the ethyl orthosilicate coating solution. The reaction was carried out at a temperature of 30-60° C. for 2 h, and ammonia water was used to adjust the reaction rate of the coating solution. After the reaction was completed, the precipitate was filtered to obtain a precipitate, and the precipitate was washed with sufficient anhydrous ethanol for 3-5 times. The product was dried in a constant temperature drying oven at 80° C. until constant weight was reached and cooled to room temperature to obtain a silica-coated nickel-plated iron powder.

[0084] Example 3

[0085] (1) Carbonyl iron powder and 10 g / L stannous chloride roughening solution were subjected to roughening reaction at room temperature at a mass ratio of 1:10 for 10 min, the precipitate was filtered, and washed with sufficient deionized water for 3-5 times to obtain roughened iron powder.

[0086] (2) The coarsened iron powder and 1 g / L lead chloride activation solution are activated at a mass ratio of 1:10 at room temperature for 10 min, the precipitate is filtered, and washed with sufficient deionized water for 3-5 times to obtain activated iron powder.

[0087] (3) The amount of nickel plating solution is calculated according to the nickel content of 12%, and the activated iron powder is added to the plating solution for plating reaction. After the nickel plating reaction is completed, the solution is naturally precipitated and filtered to obtain a precipitate, which is washed with anhydrous ethanol for 3-5 times, and the product is dried in a constant temperature drying oven until it is cooled to room temperature at constant weight to obtain a nickel-containing iron powder. The nickel-containing iron powder is annealed in a hydrogen atmosphere at an annealing temperature of 300-800° C. The temperature curve during annealing is 5-20° C. / min, the temperature is raised to the annealing temperature, the temperature is maintained for 30-80 min, and the nickel-plated iron powder is cooled to room temperature at a rate of 5-20° C. / min to obtain a nickel-plated iron powder.

[0088] (4) A 50 g / l ethyl orthosilicate solution was prepared, wherein the ratio of water to ethanol in the ethyl orthosilicate solution was 10:90, and nickel-plated iron powder was added to the ethyl orthosilicate coating solution. The reaction was carried out at a temperature of 30-60° C. for 2 h, and ammonia water was used to adjust the reaction rate of the coating solution. After the reaction was completed, the precipitate was filtered to obtain a precipitate, and the precipitate was washed with sufficient anhydrous ethanol for 3-5 times. The product was dried in a constant temperature drying oven at 80° C. until constant weight was reached and cooled to room temperature to obtain a silica-coated nickel-plated iron powder.

[0089] Comparative Example 1

[0090] Use bare carbonyl iron powder without nickel coating.

[0091] The silicon dioxide coated nickel-plated iron powders in Examples 1 to 3 and the bare carbonyl iron powder without nickel coating in Comparative Example 1 were tested for their anti-rust ability in a salt spray environment.

[0092] The specific steps are as follows:

[0093] The silica-coated nickel-plated iron powder in Examples 1 to 3 and the bare carbonyl iron powder without nickel coating in Comparative Example 1 were mixed with epoxy resin at a mass fraction of 95:5, and stirred evenly at a speed of 800-1000r / min using a double planetary mixer. After drying the solvent, the powder was pressed into a ring shape at 400-600Mpa. The mixed magnetic powder was pressed into a magnetic ring with OD=16.6mm, ID=10.2mm and a density of 6.0-6.8g / cm3. The magnetic ring was placed in a neutral salt spray environment for 8 hours and 24 hours.

[0094] The test results are shown in Table 1 below:

[0095] Table 1: Comparison of salt spray performance of silicon dioxide coated nickel-plated iron powder and carbonyl iron bare powder

[0096]

[0097] It can be seen from Table 1 that the rust resistance of bare carbonyl iron powder in a salt spray environment is relatively poor, while the rust resistance of the silica-coated nickel-plated iron powder in a salt spray environment is significantly improved after two coatings. In Example 1, no rust spots appear in an 8-hour salt spray test, and in a 24-hour salt spray test, the rust resistance is greater than 90%.

[0098] Therefore, the nickel-plated iron powder coated with a nickel layer and a silicon dioxide layer provided in the embodiment of the present application has good salt spray resistance. The embodiment of the present application obtains nickel-plated iron powder by adding carbonyl iron powder to a nickel plating solution to generate a nickel plating reaction, and drying the obtained reactant; the nickel-plated iron powder is added to an ethyl orthosilicate coating solution to generate a coating reaction, and the obtained reactant is dried to obtain a nickel-plated iron powder coated with a nickel layer and a silicon dioxide layer in sequence, and the nickel-plated iron powder is coated with a double layer of antioxidant substances, which improves the corrosion resistance in a salt spray environment.

[0099] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit them. Under the concept of the present invention, the technical features in the above embodiments or different embodiments may also be combined, the steps may be implemented in any order, and there are many other changes in different aspects of the present invention as described above, which are not provided in detail for the sake of simplicity. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they may still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for optimizing carbonyl iron powder, characterized in that: The method comprises: Adding carbonyl iron powder into a nickel plating solution to generate a nickel plating reaction, and drying the obtained reactant to obtain nickel-plated iron powder; The nickel-plated iron powder is added into a ethyl orthosilicate coating liquid to generate a coating reaction, and the obtained reactant is dried to obtain a nickel-plated iron powder coated with a nickel layer and a silicon dioxide layer in sequence.

2. The optimization method according to claim 1, characterized in that: The concentration of the ethyl orthosilicate coating liquid is 5-10%.

3. The optimization method according to any one of claims 1 to 2, characterized in that: Before adding the carbonyl iron powder into the nickel plating solution to cause the nickel plating reaction, the method further comprises: The surface of the carbonyl iron powder is roughened and / or activated.

4. The optimization method according to claim 3, characterized in that: The step of adding carbonyl iron powder into a nickel plating solution to generate a nickel plating reaction and drying the obtained reactant to obtain nickel-plated iron powder comprises: Adding the carbonyl iron powder into the nickel plating solution to generate a nickel plating reaction; After the nickel plating reaction is completed, natural sedimentation and filtration are performed to obtain the first reactant; The first reactant is washed with anhydrous ethanol for 3-5 times, and the first reactant is dried in a constant temperature drying oven until it is cooled to room temperature at constant weight to obtain the nickel-plated iron powder.

5. The optimization method according to claim 4, characterized in that: The method further comprises: The nickel-plated iron powder is subjected to annealing treatment.

6. The optimization method according to claim 5, characterized in that: The nickel-plated iron powder is added to a ethyl orthosilicate coating liquid to undergo a coating reaction, and the obtained reactant is dried to obtain a nickel-plated iron powder sequentially coated with a nickel layer and a silicon dioxide layer, comprising: Putting the nickel-plated iron powder into the ethyl orthosilicate coating solution to generate a silicon dioxide coating reaction; After the coating reaction is completed, natural sedimentation and filtration are performed to obtain the second reactant; The second reactant is washed with anhydrous ethanol for 3-5 times, and the product is dried in a constant temperature drying oven until it is cooled to room temperature at a constant weight to obtain the nickel-plated iron powder sequentially coated with a nickel layer and a silicon dioxide layer.

7. A carbonyl iron powder, characterized in that: The carbonyl iron powder is coated with a metal nickel layer and a silicon dioxide layer in sequence.

8. The carbonyl iron powder according to claim 7, characterized in that: The nickel content in the carbonyl iron powder is 4%-12%.

9. The carbonyl iron powder according to claim 7, characterized in that: The thickness of the silicon dioxide layer is 10-20 nm.

10. A carbonyl iron powder prepared by the optimization method according to any one of claims 1 to 6.

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