CN102528024B - A kind of preparation method of insulating iron powder for soft magnetic composite material - Google Patents

Abstract

The invention discloses a method for preparing insulating iron powder for soft magnetic composite materials, which belongs to the technical field of magnetic functional materials and powder metallurgy. The process is as follows: the coating process is to add industrially produced high-purity iron powder with a concentration of 0.1-5g/ml into 0.002-0.05g/ml of fluotitanic acid or fluozirconic acid coating solution, and stir at a temperature of 20-70°C React for 5-60 minutes, filter and wash, and dry at 50-120°C to obtain insulating iron powder. The advantages are that the preparation process is simple, the efficiency is high, and the coating is complete. The insulating coating layer on the surface of the iron powder can effectively reduce the magnetic loss of the soft magnetic composite material powder core, and the comprehensive magnetic properties of the powder core can be adjusted by controlling the thickness of the insulating layer.

Description

A kind of preparation method of insulating iron powder for soft magnetic composite material

technical field

The invention belongs to the technical field of magnetic functional materials and powder metallurgy, and in particular relates to a preparation method of insulating iron powder for soft magnetic composite materials.

Background technique

Soft magnetic composites (Soft Magnetic Composites, hereinafter referred to as SMC) are manufactured by powder metallurgy technology and are composed of surface-insulated metal powder particles (such as pure iron powder), which can be pressed into parts with complex shapes in one step and have good three-dimensional properties. Isotropic magnetic properties and thermal characteristics, as well as low eddy current loss at medium and high frequencies, can be used as iron core materials in some motors with complex shapes and magnetic circuits and motors operating at higher frequencies, and can be widely used while being able to perform Revolutionizing power motor design. With the development of miniaturization and high frequency of electronic devices, micro-motors, low-power motors and anti-electromagnetic interference components are widely used in automobiles, robots, office and home automation equipment, and the application of SMC with unique properties in these fields There will be huge economic benefits.

AB公司的专利(申请号：97192452.X，公开号：CN1211943A)(申请号：200480025248.8，公开号：CN1845805A)技术中均采用磷化工艺获得绝缘铁粉；日本JFE公司的专利(申请号：200480025248.8，公开号：CN1518011A)技术中采用磷酸铝盐包覆软磁粉末制得绝缘软磁粉。日本TDK株式会社(申请号：97102244.5，公开号：CN1167990A)通过在铁粉中添加二氧化硅、硅氧烷树脂和有机钛化合物成功制得了由铁粉和硅钛氧膜层组成的软磁包覆粉。此外，国内也有类似的专利技术出现，如江苏天一超细金属粉末有限公司的专利技术(申请号：200610040493.7，公开号：CN1895820A)提供了一种用偶联剂、氨水改性羰基铁粉或二氧化硅表面后采用物理方法制备纳米二氧化硅包覆羰基铁粉的方法，湖州科达磁电有限公司的技术(申请号：200710186855.8，公开号：CN101226807A)采用溶胶凝胶法制备了二氧化硅和有机聚合物复合绝缘包覆铁粉的SMC。Insulating iron powder is an important raw material for preparing SMC cores, which directly affects the performance and structural strength of the cores. In recent years, famous foreign companies have successively developed insulating iron powder, such as Swedish AB Company's Somaloy ^TM series, Canada QMP Company's ATOMET EM-1 and Japan's JFE Company's KIPMG270H, etc., and applied for related patents in China. Germany's Robert Bosch Co., Ltd. (Robert Bosch GmbH) patent (application number: 03811970.6, publication number: CN1656575A) and Sweden

AB company's patent (application number: 97192452.X, publication number: CN1211943A) (application number: 200480025248.8, publication number: CN1845805A) technology uses phosphating process to obtain insulating iron powder; Japanese JFE company's patent (application number: 200480025248.8 , Publication No.: CN1518011A) Insulation soft magnetic powder is obtained by coating soft magnetic powder with aluminum phosphate salt. Japan TDK Corporation (application number: 97102244.5, publication number: CN1167990A) has successfully prepared a soft magnetic package composed of iron powder and silicon titanium oxide film layer by adding silicon dioxide, siloxane resin and organic titanium compound to iron powder. Dust. In addition, there are similar patented technologies in China. For example, the patented technology of Jiangsu Tianyi Superfine Metal Powder Co., Ltd. (application number: 200610040493.7, publication number: CN1895820A) provides a carbonyl iron powder modified with coupling agent and ammonia or The method of preparing nano-silica-coated carbonyl iron powder by physical methods after the surface of silica, the technology of Huzhou Keda Magnetoelectric Co., Ltd. (application number: 200710186855.8, publication number: CN101226807A) prepared carbonyl iron powder by sol-gel method Silicon and organic polymer composite insulating coated iron powder SMC.

There are more or less problems in the preparation of insulating iron powder by the above methods, such as easy brittleness of the insulating film layer, uneven coating, complicated preparation process, low efficiency, etc. It is very necessary to further explore SMC insulating soft magnetic powder with excellent performance . So far, there is no domestic report on the use of hexafluorotitanic acid and hexafluorozirconic acid for iron powder insulation treatment.

Contents of the invention

The object of the present invention is to provide a method for preparing insulating iron powder for soft magnetic composite (SMC). The prepared fluorotitanium/iron zirconate inorganic insulating film can improve the resistivity of iron powder, play an insulating role, and can greatly reduce the magnetic loss of SMC; on the other hand, the insulating film has good high temperature resistance and can withstand Heat treatment at a temperature above 550°C without damage, and heat treatment at this temperature can further reduce the coercive force and magnetic loss of the SMC core. The method has the advantages of simple process, uniform coating and high efficiency.

The main technological process of the present invention is: high-purity iron powder→insulation treatment (mechanical stirring)→filtering→washing→drying→insulating iron powder. The technical solution adopted to solve the above technical problems is: add a certain concentration of iron powder into the fluorotitanic acid or fluorozirconic acid treatment solution and stir for a certain period of time, control certain reaction conditions, so that the surface of the iron powder is uniformly coated with a certain thickness High quality fluorotitanium/zirconate coating. Concrete process steps are as follows:

(1) Prepare a coating treatment solution, specifically: hexafluorotitanic acid or hexafluorozirconic acid as the solute, absolute ethanol or acetone as the solvent, and control the concentration of the solute to 0.002-0.05 g/ml;

(2) Add high-purity iron powder into the coating treatment solution, while controlling the concentration of iron powder to 0.1-5g/ml, controlling the temperature of the treatment solution to 20-70°C, and mechanically stirring for 5-60 minutes;

(3) filtering and washing, and drying at 50-120° C. to obtain insulating iron powder.

The high-purity iron powder is one or more than two kinds of atomized iron powder, reduced iron powder, electrolytic iron powder or carbonyl iron powder with a purity of more than 99%.

Preferably, the solvent in the above step (1) can be absolute ethanol or acetone, and preferably absolute ethanol; the solute concentration is preferably 0.005-0.01 g/ml.

As a preference, the high-purity iron powder in the above step (2) can be atomized iron powder, reduced iron powder, electrolytic iron powder and carbonyl iron powder, and is preferably water atomized iron powder, which has high purity and good compaction performance. It is preferably 0.1-2g/ml; the temperature of the treatment solution is preferably 30-60°C; the reaction time is preferably 20-30min.

Raw iron powder provides basic magnetic properties for SMC magnetic cores. The concentration of the treatment solution, reaction temperature and time will directly affect the quality and thickness of the insulating film, and further affect the final performance of the magnetic core. As the thickness of the insulating film increases within a certain range, the magnetic loss of the magnetic core will be greatly reduced, but the magnetic permeability will also be lost; if the thickness exceeds a certain range, its magnetic properties will deteriorate rapidly, the magnetic permeability will be greatly reduced, and the magnetic loss will increase. Controlling the appropriate treatment process and conditions can produce the actually required insulating iron powder with excellent magnetic properties.

The advantages of the present invention are:

1. The insulating layer on the surface of the iron powder has good high temperature resistance, which improves the problem that the insulating iron powder has been limited by the insulating layer and the heat treatment temperature is too low;

2. The SMC magnetic core prepared by the present invention has good comprehensive magnetic properties, and can be adjusted according to actual needs;

3. The process is simple, the efficiency is high, and it is suitable for industrial application.

Detailed ways

The present invention will be further described below in conjunction with specific examples, but the examples do not limit the present invention, and the parts not mentioned in the invention are applicable to the prior art.

Example 1

Take a certain amount of hexafluorotitanic acid solution and add it to absolute ethanol to form a reaction solution, control the concentration of hexafluorotitanic acid to 0.005g/ml, heat the temperature of the reaction solution in a water bath to 30°C, and atomize the high-purity 99.5% Add iron powder (control its concentration to 0.2g/ml) into the reaction liquid and stir it mechanically for 30 minutes, wash with absolute ethanol three times after centrifugal filtration, and place it at 50°C to fully dry to obtain insulating iron powder. After the insulation treatment, the surface of the iron powder becomes smoother, the gloss is better, and the coating layer is uniform and complete. Comparing the magnetic properties of the core made of iron powder before and after the coating treatment, it is found that the maximum relative permeability of the insulated iron powder core changes from 328 to 291, and the magnetic loss at the magnetic induction 1T frequency 50Hz decreases from 9.1W/kg to 6.8W/kg, and the magnetic loss at the magnetic induction 1T frequency of 400Hz dropped from 212W/kg to 85.2W/kg, and the magnetic loss was reduced by 60%.

Example 2

The raw iron powder is mixed iron powder with a mass ratio of atomized iron powder and reduced iron powder of 1:1, and the purity is 99.3%. Take a certain amount of hexafluorozirconic acid solution and add it to anhydrous acetone to form a reaction solution, control the concentration of hexafluorozirconic acid to 0.05g/ml, heat the temperature of the reaction solution in a water bath to 60°C, and add the prepared mixed iron powder to the reaction solution In the process, the concentration of iron powder was controlled at 5g/ml, mechanically stirred for 60min, washed with anhydrous acetone for 3 times after centrifugal filtration, and fully dried at 120°C to obtain insulating iron powder. Comparing the magnetic properties of the core made of iron powder before and after coating treatment, it is found that the maximum relative permeability of the insulated iron powder core changes from 318 to 263, and the magnetic loss at the magnetic induction 1T frequency 400Hz drops from 201W/kg to 63.5W/kg.

Example 3

The raw material iron powder is mixed iron powder with a mass ratio of atomized iron powder and carbonyl iron powder of 1:1, and the purity is 99.4%. Take a certain amount of hexafluorotitanic acid solution and add it to absolute ethanol to make a reaction solution, control the concentration of hexafluorotitanic acid to 0.02g/ml, heat the temperature of the reaction solution to 50°C in a water bath, and add the prepared mixed iron powder to the reaction solution In the process, the concentration of iron powder was controlled at 2 g/ml, mechanically stirred for 5 minutes, washed with absolute ethanol for 3 times after centrifugal filtration, and fully dried at 80°C to obtain insulating iron powder. Comparing the maximum relative magnetic permeability of the magnetic core made of iron powder before and after coating treatment from 302 to 225, the magnetic loss at the magnetic induction 1T frequency of 400Hz dropped from 196W/kg to 92W/kg.

Example 4

The raw iron powder is reduced iron powder with a purity of 99.4%. Take a certain amount of hexafluorozirconic acid solution and add it to absolute ethanol to form a reaction solution, control the concentration of hexafluorozirconic acid to 0.002g/ml, heat the temperature of the reaction solution in a water bath to 70°C, add iron powder into the reaction solution, and control The concentration is 0.5g/ml, mechanically stirred and reacted for 20min, washed with absolute ethanol three times after centrifugal filtration, and fully dried at 80°C to obtain insulating iron powder. The maximum relative magnetic permeability of the prepared magnetic core is 268, and the magnetic loss is 106 W/kg when the magnetic induction 1T frequency is 400 Hz.

Example 5

The raw material iron powder is electrolytic iron powder with a purity of 99.2%. Take a certain amount of hexafluorozirconic acid solution and add it to absolute ethanol to form a reaction solution, control the concentration of hexafluorozirconic acid to 0.01g/ml, heat the temperature of the reaction solution in a water bath to 40°C, add iron powder into the reaction solution, and control The concentration is 1g/ml, mechanically stirred for 30 minutes, washed with absolute ethanol for 3 times after centrifugal filtration, and fully dried at 80°C to obtain insulating iron powder. The maximum relative magnetic permeability of the prepared magnetic core is 239, and the magnetic loss is 96 W/kg when the magnetic induction 1T frequency is 400 Hz.

Example 6

The raw material iron powder is carbonyl iron powder with a purity of 99.0%. Take a certain amount of hexafluorotitanic acid solution and add it to anhydrous acetone to form a reaction solution, control the concentration of hexafluorotitanic acid to 0.01g/ml, heat the temperature of the reaction solution in a water bath to 50°C, add iron powder into the reaction solution, and control The concentration is 2g/ml, mechanically stirred for 20 minutes, washed with anhydrous acetone for 3 times after centrifugal filtration, and fully dried at 70°C to obtain insulating iron powder. The maximum relative magnetic permeability of the prepared magnetic core is 187, and the magnetic loss is 90.6 W/kg when the magnetic induction 1T frequency is 400 Hz.

Claims (3)

1. A preparation method of insulating iron powder for soft magnetic composite materials, characterized in that: the process steps are as follows: (1) Preparation of coating treatment solution: hexafluorotitanic acid or hexafluorozirconic acid as solute, absolute ethanol or acetone as solvent, control solute concentration to 0.002-0.05g/ml; (2) Add high-purity iron powder into the coating treatment solution, control the concentration of high-purity iron powder at 0.1-5g/ml at the same time, control the temperature of the treatment solution at 20-70°C, and mechanically stir for 5-60 minutes; (3) Filter and wash, and dry at 50-120°C to obtain insulating iron powder; The high-purity iron powder is one or more than two kinds of atomized iron powder, reduced iron powder, electrolytic iron powder or carbonyl iron powder with a purity of more than 99%. 2. The preparation method of insulating iron powder for soft magnetic composite materials according to claim 1, characterized in that: the solvent in step (1) is absolute ethanol; the concentration of hexafluorotitanic acid or hexafluorozirconic acid is 0.005 ~0.01g/ml. 3. The preparation method of insulating iron powder for soft magnetic composite materials according to claim 1, characterized in that: the concentration of high-purity iron powder in step (2) is 0.1-2g/ml, the reaction temperature is 30-60°C, and the reaction The time is 20-30 minutes.