Injection molding method of a metal soft magnetic powder core

Abstract

The application discloses a kind of injection molding methods of metal soft magnetic powder core, belong to material science technology field.The specific operation steps of the present application are as follows: (1) the-80 mesh gas atomized iron silicon alloy powder is screened into three different particle sizes of gas atomized iron silicon alloy powder, three different particle size powders are mixed, to get graded powder;(2) in graded powder, add ethanol, tetraethyl orthosilicate, deionized water and ammonia, stirring uniformly under water bath condition, to get insulating powder;(3) in insulating powder, add surfactant and water, stirring uniformly, to get powder slurry;(4) mix powder slurry with resin solution uniformly, to get molding material;(5) the molding material is poured into cylindrical silica gel mold, ultrasonic vibration treatment, drying, demolding, to get metal soft magnetic powder core.The surfactant of the present application reduces the water consumption by 50%;The synergistic effect of polyester and polyether significantly improves the comprehensive performance of metal soft magnetic powder core.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of material science, and particularly relates to a method for improving the injection molding performance of a metal soft magnetic powder core by using a surfactant. BACKGROUND

[0002] Metal soft magnetic powder cores are widely used in electronic components. At present, the mainstream molding method of metal soft magnetic powder cores is mold pressing molding, and the operation steps thereof include: firstly, insulating coating is performed on metal soft magnetic powder; then, a binder is added; then, the pretreated powder is loaded into a mold, and a press is used to apply pressure to the powder to press the powder into a relatively simple shaped blank; then, the shaped blank after pressing needs to be heat treated; and finally, the product can be obtained. However, the mold pressing molding method has obvious defects. For example, the tonnage of the press is large, the energy consumption of the equipment is large, and the mold is severely worn; when the pressure of the press is too large, the insulating coating layer will be damaged, and after the insulating coating layer between the magnetic powder particles falls off, the magnetic powder particles will directly contact each other, which will reduce the resistivity of the soft magnetic composite material and increase the eddy current loss; the mold pressing molding can only meet the molding of products with relatively simple and single shapes. SUMMARY

[0003] In order to effectively reduce the defects such as cracks and deformation of the finished metal soft magnetic powder core and realize the production and demolding of metal soft magnetic powder cores with different shapes, the present application provides an injection molding method for a metal soft magnetic powder core.

[0004] An injection molding method for a metal soft magnetic powder core, and the operation steps are as follows:

[0005] (1) Screen -80 mesh gas atomized iron-silicon alloy powder into three different particle sizes of gas atomized iron-silicon alloy powder, namely first-stage powder, second-stage powder and dust removal powder; mix the first-stage powder, the second-stage powder and the dust removal powder uniformly according to a mass ratio of 6:1:3 to obtain graded powder;

[0006] (2) Add 100 ml of ethanol, 16 ml of tetraethyl orthosilicate, 16 ml of deionized water and 4 ml of ammonia water to 10 g of the graded powder, and stir uniformly under water bath conditions to obtain insulating powder coated with silicon dioxide (SiO2);

[0007] (3) In the insulating powder, add a surfactant in an amount of 0.6-0.8% of the mass of the insulating powder, and add water in an amount of 9-10% of the mass of the insulating powder, and stir uniformly to obtain powder slurry;

[0008] (4) Mix the powder slurry and a resin solution according to a mass ratio of 20:1-1.5, and stir uniformly to obtain molding material with adhesion;

[0009] (5) Pour the molding material into a cylindrical glue mold, vibrate in an ultrasonic cleaning machine for a certain time to reduce air holes, then place in air to dry, demold, and obtain a metal soft magnetic powder core;

[0010] The density of the metal soft magnetic powder core is 6.76-6.79 g / cm 3 , and the resistivity is 0.381-0.493 kΩ·m.

[0011] Further technical solutions are as follows:

[0012] In step (1), the first-stage powder is -800-+200 mesh powder, the second-stage powder is -400-+600 mesh powder, and the dedusting powder is -1000-+5000 mesh powder.

[0013] In step (2), the water bath temperature is 50℃, and the stirring time is 4 h.

[0014] In step (3), the surfactant is prepared by uniformly mixing polyester substances and polyether substances at a mass ratio of 1:1.

[0015] The polyester substances are polyethylene terephthalate (PET), and the polyether substances are polyethylene glycol (PEG).

[0016] In step (4), the resin solution is prepared by uniformly mixing bisphenol A type liquid epoxy resin (e44 epoxy resin), polyamide resin curing agent (593 curing agent) and ethanol solution with a concentration of 99.7% at a mass ratio of 3:1:4.

[0017] In step (5), the ultrasonic cleaning temperature is room temperature, the ultrasonic frequency is 75 KHz, and the ultrasonic time is 10 min.

[0018] The beneficial technical effects of the present application are embodied in the following aspects:

[0019] 1. The powder slurry for injection molding in the present application, which is added with a surfactant, not only reduces the water usage by 50%, but also significantly improves the flowability, molding density, molding pressure and other key performances of the powder slurry in the molding process. As a polyester material, polyethylene terephthalate (PET) mainly improves the molding performance of the metal soft magnetic powder core by enhancing the mechanical strength of the reinforcing material, improving the adhesion, improving the heat resistance and insulation, ensuring the stability of the material structure and reducing the eddy current loss. As a polyether material, polyethylene glycol (PEG) has good flowability and lubricity, which can effectively reduce the friction between powder particles, enhance the dispersibility and filling property of the slurry, reduce molding defects and cracks, and at the same time reduce the molding pressure, improve the molding efficiency and product quality. The synergistic effect of the two substances significantly improves the comprehensive performance of the powder core molding process. Therefore, the powder slurry for injection molding in the present application has the following advantages: (1) higher flowability: the flowability of the molding material is improved, so that the powder can better fill the mold. (2) improved molding density: improved molding density is beneficial to improve the magnetic performance of the powder core. (3) reduced defects: cracks and deformation defects are significantly reduced, improving the product qualification rate. (4) reduced molding pressure: the molding pressure is reduced, saving energy. The density and resistivity of the injection molding sample and the ordinary mold pressing molding process sample are compared, and the data shows that the density of the metal soft magnetic powder core prepared by the method of the present application is 6.76-6.79 g / cm3, and the resistivity is 0.381-0.493 kΩ·m. Compared with the sample prepared by mold pressing, the density reaches 98.9%-99.4% of that of the sample prepared by mold pressing, and the resistivity is equivalent to 50%-64.7% of that of the sample prepared by mold pressing. This shows that the method of the present application realizes the processing of high-density and high-resistivity metal soft magnetic powder core products under the condition of meeting the demand, improves the efficiency, and the equipment is simple and the cost is low.

[0020] The injection molding method of the present application uses a silica gel mold for rapid molding, protects the insulation layer, has a high production speed, can meet complex geometric shapes, facilitates demolding, and can also select different thermoplastic and thermosetting plastics for injection molding according to the specific requirements of the product. BRIEF DESCRIPTION OF DRAWINGS

[0021] Figure 1 Fig. 3 is a graph of the magnetic permeability of three different metal soft magnetic powder cores varying with frequency.

[0022] Figure 2 Fig. 4 is a graph of the loss of three different metal soft magnetic powder cores. DETAILED DESCRIPTION

[0023] The present application will be further described below by examples in conjunction with the drawings. EXAMPLE

[0024] The operation steps of the metal soft magnetic powder core injection molding are as follows:

[0025] (1) Screen -80 mesh gas atomized iron silicon alloy powder into three different particle sizes of gas atomized iron silicon alloy powder, -800~+200 mesh first grade powder, -400~+600 mesh second grade powder and -1000~+5000 mesh dust removal powder; mix the first grade powder, the second grade powder and the dust removal powder uniformly according to the mass ratio of 6:1:3 to obtain a graded powder.

[0026] (2) Add 1000ml of ethanol, 160ml of tetraethyl orthosilicate, 160ml of deionized water and 40ml of ammonia water into 100g of the graded powder, stir in a 50℃ water bath for 4 hours to obtain silica (SiO2) coated insulation powder.

[0027] (3) Add a surfactant in an amount of 0.6% of the mass of the insulation powder and water in an amount of 10% of the mass of the insulation powder into the insulation powder, stir uniformly to obtain a powder slurry.

[0028] The surfactant is made of polyethylene terephthalate (PET) and polyethylene glycol (PEG) mixed uniformly according to the mass ratio of 1:1.

[0029] (4) Mix the powder slurry with a resin solution according to the mass ratio of 20:1, stir uniformly to obtain a molding material with adhesion.

[0030] Mix bisphenol A type liquid epoxy resin (e44 epoxy resin), polyamide resin curing agent (593 curing agent) and ethanol uniformly according to the mass ratio of 3:1:4 to prepare a resin solution.

[0031] (5) Pour the above powder molding material into a cylindrical silica gel mold, reduce the pores in an ultrasonic frequency of 75KHz for 10min in an ultrasonic cleaning machine at room temperature, dry in air, demold to obtain a metal soft magnetic powder core product. Test the density and resistivity of the product to obtain the density of 6.76 g / cm 3 and the resistivity of 0.381 kΩ*m. Example

[0032] The operation steps of the metal soft magnetic powder core injection molding are as follows:

[0033] (1) Screen -80 mesh gas atomized iron silicon alloy powder into three different particle sizes of gas atomized iron silicon alloy powder, -800~+200 mesh first grade powder, -400~+600 mesh second grade powder and -1000~+5000 mesh dust removal powder; mix the first grade powder, the second grade powder and the dust removal powder uniformly according to the mass ratio of 6:1:3 to obtain a graded powder.

[0034] (2) In 100 g of the graded powder, 1000 ml of ethanol, 160 ml of tetraethyl orthosilicate, 160 ml of deionized water and 40 ml of ammonia water were added, and stirring was carried out in a water bath at 50°C for 4 hours to obtain a silica (SiO2) coated insulating powder.

[0035] (3) In the insulating powder, a surfactant was added in an amount of 0.8% of the mass of the insulating powder, and water was added in an amount of 9% of the mass of the insulating powder, and stirring was carried out to obtain a powder slurry;

[0036] (4) The powder slurry was mixed with a resin solution in a mass ratio of 20:1.5, and stirring was carried out to obtain a molding material with adhesion.

[0037] A bisphenol A type liquid epoxy resin (e44 epoxy resin), a polyamide resin curing agent (593 curing agent) and ethanol were mixed in a mass ratio of 3:1:4 to prepare a resin solution.

[0038] (5) The powder molding material was poured into a cylindrical silica gel mold, and vibration was carried out in an ultrasonic cleaning machine at an ultrasonic frequency of 75 KHz for 10 min at room temperature to reduce pores, and then the product was dried in air, demolded to obtain a metal soft magnetic powder core product. The product was tested for density and resistivity, and the density of the product was 6.79 g / cm 3 , and the resistivity was 0.493 kΩ*m.

[0039] Referring to Figure 1 , wherein A is a conventional die-molding metal soft magnetic powder core sample, B is a metal soft magnetic powder core sample prepared in Example 1, and C is a metal soft magnetic powder core sample prepared in Example 2.

[0040] From Figure 1 It can be seen that the permeability of the three metal soft magnetic powder cores has good stability in the frequency range of 100-1000 KHz, and changes little with the increase of frequency. The permeability of the metal soft magnetic powder core A sample prepared by the conventional process die-molding is the highest, and is between 60.06-60.60; the permeability of the metal soft magnetic powder core B sample prepared in Example 1 is the lowest, and is between 56-56.19. Compared with the metal soft magnetic powder core C sample prepared in Example 2, the amount of the surface additive of the metal soft magnetic powder core B sample is small, the amount of water added is large, and the injection molding pressure is small, which leads to the lowest density of the metal soft magnetic powder core B sample. Figure 1 The permeability of the metal soft magnetic powder core C sample prepared in Example 2 is between 56.72-57.11, and the change trend of the permeability of the three metal soft magnetic powder core samples is consistent with the density.

[0041] Referring to Figure 2wherein A is a conventional molded metal soft magnetic powder core sample, B is a metal soft magnetic powder core sample prepared in Example 1, and C is a metal soft magnetic powder core sample prepared in Example 2.

[0042] It can be seen that the loss of the three metal soft magnetic powder cores increases with the increase of the frequency in the frequency range of 1-3 MHz, because the hysteresis loss and the eddy current loss, which are the main components of the loss of the metal soft magnetic powder core, both increase with the increase of the frequency. The loss of the conventional molded metal soft magnetic powder core sample A increases at the slowest rate, the loss of the metal soft magnetic powder core sample B prepared in the present application increases at the fastest rate, and the loss of the metal soft magnetic powder core sample C prepared in Example 2 increases at a rate between the two. Figure 2

[0043] Those skilled in the art will easily understand that the above is only a preferred embodiment of the present application, and is not intended to limit the present application, and any modification, equivalent replacement and improvement made within the spirit and principle of the present application shall be included in the protection scope of the present application.​

Claims

1. A method for injection molding of a metal soft magnetic powder core, characterized by, The operation steps are as follows: (1) Screen -80 gas atomized iron silicon alloy powder into three different particle sizes of gas atomized iron silicon alloy powder, namely first grade powder, second grade powder and dust removal powder; mix the first grade powder, the second grade powder and the dust removal powder uniformly according to the mass ratio of 6:1:3 to obtain a graded powder; (2) Add 100ml of ethanol, 16ml of tetraethyl orthosilicate, 16ml of deionized water and 4ml of ammonia water to 10g of the graded powder, and stir uniformly under water bath condition to obtain a silica coated insulating powder; (3) In the insulating powder, add a surfactant in an amount of 0.6-0.8% of the mass of the insulating powder, and add water in an amount of 9-10% of the mass of the insulating powder, and stir uniformly to obtain a powder slurry; (4) Mix the powder slurry with a resin solution according to the mass ratio of 20:1-1.5, and stir uniformly to obtain a molding material with adhesion; (5) Pour the molding material into a cylindrical glue mold, vibrate in an ultrasonic cleaner for a certain time to reduce pores, and then dry in air, demold to obtain a metal soft magnetic powder core; The metal soft magnetic powder core has a density of 6.76-6.79 g / cm 3 , and a resistivity of 0.381-0.493 kΩ·m.

2. The method for injection molding of a metal soft magnetic powder core according to claim 1, characterized in that: In step (1), the first grade powder is -800-+200 mesh powder, the second grade powder is -400-+600 mesh powder, and the dust removal powder is -1000-+5000 mesh powder.

3. The method for injection molding of a metal soft magnetic powder core according to claim 1, wherein: In step (2), the water bath temperature is 50℃, and the stirring time is 4h.

4. The method for injection molding of a metal soft magnetic powder core according to claim 1, wherein: In step (3), the surfactant is mixed uniformly according to the mass ratio of 1:1 from polyester and polyether.

5. The method for injection molding of a metal soft magnetic powder core according to claim 4, wherein: The polyester is polyethylene terephthalate, and the polyether is polyethylene glycol.

6. The method for injection molding of a metal soft magnetic powder core according to claim 1, wherein: In step (4), the resin solution is mixed uniformly according to the mass ratio of 3:1:4 from bisphenol A type liquid epoxy resin, polyamide resin curing agent and 99.7% ethanol solution.

7. The method for injection molding of a metal soft magnetic powder core according to claim 1, wherein: In step (5), the ultrasonic cleaning temperature is room temperature, the ultrasonic frequency is 75KHz, and the ultrasonic time is 10min.

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