Preparation method of novel iron-silicon functional gradient magnetic powder core material

Abstract

The invention provides a preparation method of a novel iron-silicon functional gradient magnetic powder core material, and relates to the technical field of powder metallurgy and functional gradient materials.The preparation method comprises the steps that a series of iron-silicon alloy powder with the silicon content ranging from 0% to 10% is prepared, phosphoric acid coating is conducted on the iron-silicon alloy powder, and multiple kinds of composite powder with different silicon contents are obtained; filling a mold with a plurality of composite powder with different silicon contents layer by layer according to gradient change, and performing primary isostatic pressing shaping to obtain a pressed magnetic powder core; and annealing and glue discharging are conducted on the pressed magnetic powder core, and the prepared finished magnetic powder core material is obtained. The novel iron-silicon alloy functionally gradient magnetic powder core material is prepared by combining two processes of magnetic powder core preparation and functionally gradient material preparation, so that the defect that an existing magnetic powder core is too single in component and performance is overcome. In addition, a traditional cold pressing annealing process is adopted, the process is mature and reliable, the steps are simple and convenient, and the time and economic cost is low.

Description

Technical Field

[0001] The invention relates to the technical field of powder metallurgy and functional gradient materials, and in particular to a method for preparing a novel iron-silicon functional gradient magnetic powder core material. Background Art

[0002] With the rapid development of science and technology, electronic power equipment is gradually developing towards high frequency, miniaturization, and high power density, which puts higher requirements on the performance of magnetic materials. Iron-silicon composite material is an alloy material with iron and silicon as the main components, usually prepared by powder metallurgy. By optimizing the composition and process, this material can greatly reduce eddy current losses while maintaining high saturation magnetic induction intensity, temperature stability and good DC bias performance, and its magnetostrictive effect is extremely small. Magnetic powder cores made of iron-silicon alloy powder are ideal materials to replace silicon steel sheets in traditional transformers and reactors.

[0003] However, traditional transformer and reactor core materials usually have uniform composition and performance, which makes it difficult to meet the requirements for different performance under complex working conditions. The new functional gradient material magnetic powder core can achieve an optimized combination of multiple performances in the same magnetic powder core by designing the gradient distribution of the internal composition and structure of the magnetic powder core. For example, in electronic devices, the new functional gradient material magnetic powder core can reduce losses and improve the magnetic permeability and physical strength of the parts with greater force through gradient design. In addition, since the magnetostrictive effect of the magnetic powder core material is not significant, the use of magnetic powder cores to replace traditional core materials in transformers and reactors can easily solve the vibration and noise problems that were difficult to deal with in the past. Therefore, designing a new type of soft magnetic composite functional gradient magnetic powder core material is of great significance for the manufacture of a new generation of high-efficiency, low-loss, and low-noise transformers and reactors.

[0004] However, the formula of high-quality magnetic powder core materials widely used at present is relatively fixed, and its homogenous material composition makes it have only a single property as a whole, which is difficult to meet the diverse performance requirements of various parts of the core. At the same time, the main methods for preparing functional gradient materials are mostly complex and time-consuming and economically expensive. Summary of the invention

[0005] In order to overcome the deficiencies of the prior art, the purpose of the present invention is to provide a method for preparing a novel iron-silicon functional gradient magnetic powder core material, which can effectively promote the development of a new generation of high-efficiency, low-loss, low-noise transformers and reactors.

[0006] To achieve the above object, the present invention provides the following solutions:

[0007] A method for preparing a novel iron-silicon functional gradient magnetic powder core material, comprising:

[0008] S1: preparing a series of iron-silicon alloy powders with silicon contents ranging from 0% to 10%, and coating the iron-silicon alloy powders with phosphoric acid to obtain composite powders with various silicon contents;

[0009] S2: Filling a plurality of composite powders with different silicon contents into the mold layer by layer according to a gradient change, and performing isostatic pressing to form a compacted magnetic powder core;

[0010] S3: annealing and debinding the pressed magnetic powder core to obtain a finished magnetic powder core material.

[0011] Preferably, a series of iron-silicon alloy powders with silicon contents ranging from 0% to 10% are prepared, and the iron-silicon alloy powders are coated with phosphoric acid to obtain composite powders with various silicon contents, including:

[0012] Composite powders with different silicon contents were placed in beakers respectively, and 0.5wt% phosphoric acid accounting for the total weight of the magnetic powder was added. The mixture after the reaction was placed in an oven to completely dry the mixture to obtain composite powders with different silicon contents.

[0013] Preferably, the method for preparing the iron-silicon alloy powder comprises:

[0014] Powder with a target particle size accounting for 80% of the total weight of the powder and iron-silicon alloy powder with a particle size half finer than the target particle size accounting for 20% of the total weight of the powder are mixed thoroughly.

[0015] Preferably, the insulation temperature of the oven is 80°C.

[0016] Preferably, during the drying process of the mixture, the beaker is taken out every five minutes and the mixture therein is stirred to prevent the powder from agglomerating.

[0017] Preferably, if the composite powder after drying is agglomerated, the composite powder is put into a mortar and crushed.

[0018] Preferably, a plurality of composite powders with different silicon contents are loaded into a mold layer by layer according to a gradient change, and subjected to isostatic pressing and shaping to obtain a pressed magnetic powder core, comprising:

[0019] The coated composite powder is mixed with a binder and a release agent, and the composite powders with different silicon contents are loaded into a pressing mold layer by layer according to a gradient change, and then the mold is subjected to an isostatic pressing and shaping.

[0020] Preferably, the adhesive is a silicone resin, and the weight ratio of the adhesive to the total weight of the magnetic powder is adjusted according to the magnetic powder, the coating process and the pressing pressure; the release agent is zinc stearate.

[0021] Preferably, during the isostatic pressing and shaping process, the isostatic pressing pressure of the press is adjusted according to the required electromagnetic properties and density of the magnetic powder core.

[0022] Preferably, the pressed magnetic powder core is annealed and debinded, comprising:

[0023] The pressed magnetic powder core was sintered in a tubular furnace under a nitrogen atmosphere; the nitrogen flow rate was 0.3 cm 3 / h; the sintering temperature is 800°C; the heating rate of the tubular furnace is 10°C / min, and the insulation time is 1h.

[0024] According to the specific embodiments provided by the present invention, the present invention discloses the following technical effects:

[0025] The present invention provides a method for preparing a novel iron-silicon functional gradient magnetic powder core material. By combining the two processes of magnetic powder core preparation and functional gradient material preparation, a novel iron-silicon alloy functional gradient magnetic powder core material is prepared, thereby overcoming the shortcomings of the current magnetic powder core that the composition and performance are too single. In addition, the present invention adopts a traditional cold pressing annealing process, which is mature and reliable, with simple steps, and low time and economic costs. The preparation method of the present invention only needs to load composite materials with different silicon contents into the corresponding positions of the mold according to the requirements of different parts of the device for material properties, and can flexibly adjust the powder particle size, overall density and various physical and electromagnetic properties of each layer of the functional gradient magnetic powder core material to meet the differentiated specific performance requirements of each point of the device. At the same time, a functional gradient magnetic powder core material can be conveniently made with only one pressing. The present invention effectively promotes the update and development of a new generation of high-efficiency, low-loss, low-noise transformers and reactors. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0027] Figure 1 A flow chart of a method provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0029] In order to make the above-mentioned objects, features and advantages of the present invention more obvious and easy to understand, the present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0030] Figure 1 A flow chart of a method provided by an embodiment of the present invention, such as Figure 1 As shown, the present invention provides a method for preparing a novel iron-silicon functional gradient magnetic powder core material, comprising:

[0031] Step 100: preparing a series of iron-silicon alloy powders with silicon contents ranging from 0% to 10%, and coating the iron-silicon alloy powders with phosphoric acid to obtain composite powders with various silicon contents;

[0032] Step 200: Filling a plurality of composite powders with different silicon contents into a mold layer by layer according to a gradient change, and performing an isostatic pressing to form a compacted magnetic powder core;

[0033] Step 300: annealing and debinding the pressed magnetic powder core to obtain a finished magnetic powder core material.

[0034] As an optional implementation, the present invention provides a method for preparing a novel iron-silicon functional gradient magnetic powder core material based on a conventional cold pressing annealing process, the method comprising:

[0035] S1: preparing a series of iron-silicon alloy powders with silicon contents ranging from 0% to 10% and coating them with phosphoric acid;

[0036] S2: Filling a plurality of composite powders with different silicon contents into a mold layer by layer according to a gradient change, and performing an isostatic pressing to shape them;

[0037] S3: annealing and debinding the pressed magnetic powder core;

[0038] It can be seen from the above technical scheme that the embodiment of the present invention provides a method for preparing a new type of iron-silicon functional gradient magnetic powder core material based on the traditional cold pressing annealing process. By combining the two processes of magnetic powder core preparation and functional gradient material preparation, a new type of iron-silicon alloy functional gradient magnetic powder core material is prepared, thereby overcoming the shortcomings of the current magnetic powder core that the composition and performance are too single. In addition, the present invention adopts the traditional cold pressing annealing process, which is mature and reliable, with simple steps, and low time and economic costs. The formula can be flexibly adjusted according to demand to obtain functional gradient magnetic powder cores with different performances. The present invention effectively promotes the update and development of a new generation of high-efficiency, low-loss, and low-noise transformers and reactors.

[0039] In this embodiment, in step S1, a series of iron-silicon alloy powders with silicon contents ranging from 0% to 10% are prepared and coated with phosphoric acid. The focus of this embodiment is to control the silicon content in the composite powder according to the different properties of the prepared magnetic powder core. Therefore, after determining the silicon content of the composite powder according to the required properties, the target composite powder is obtained by reasonably mixing iron-silicon alloy powders with different contents.

[0040] Specifically, when preparing iron-silicon alloy powder and coating it with phosphoric acid, iron-silicon alloy powders with different silicon contents are placed in beakers respectively, and phosphoric acid accounting for 0.5wt% of the total weight of magnetic powder is added. The mixture after the reaction is placed in an oven to make it completely dry. Subsequently, according to the performance requirements of the device, composite powder components with different performances can be selected and filled into the appropriate position of the mold. For example, for places such as core columns that require high mechanical strength, powders with higher silicon content should be selected to fill this part.

[0041] The iron-silicon alloy powder before coating can be mixed with powder of target particle size accounting for 80% of the total mass of the powder and iron-silicon alloy powder of half finer particle size than the target particle size accounting for 20% of the total mass of the powder to increase the proportion of magnetic soft magnetic powder in the finished magnetic powder core.

[0042] For the iron-silicon alloy powder with the target silicon content, an existing iron-silicon alloy powder with a higher silicon content than the target and a powder with a lower silicon content can be directly selected and uniformly mixed in different proportions.

[0043] Phosphoric acid needs to be mixed with anhydrous ethanol in advance, and the amount of anhydrous ethanol added is such that the mixed solution can just cover the magnetic powder after being added to the iron-silicon alloy powder.

[0044] During the drying process of the mixture, the beaker should be taken out every five minutes and the mixture in it should be stirred to prevent the powder from agglomerating. If the iron-silicon composite powder agglomerates after drying, it should be crushed in a mortar.

[0045] In this embodiment, in step S2, the coated iron-silicon composite powder is mixed with an appropriate amount of adhesive and a release agent, and the iron-silicon composite powders with different silicon contents are loaded into the pressing mold layer by layer according to the gradient change, and then the mold is subjected to an isostatic pressing and shaping. The focus of this embodiment is that the preparation method only needs to load composite materials of different proportions into different positions of the mold according to the properties required there, so as to flexibly adjust the powder particle size, overall density and various physical and electromagnetic properties of each layer of the functional gradient magnetic powder core material according to specific needs. At the same time, a functional gradient magnetic powder core material can be conveniently made with only one pressing. The preparation method has low equipment requirements and a mature and simple process.

[0046] Specifically, the coated iron-silicon composite powder is mixed with a proper amount of adhesive and a release agent, and the iron-silicon composite powders with different silicon contents are loaded into a pressing mold layer by layer according to a gradient change, and then the mold is subjected to an isostatic pressing to shape.

[0047] The adhesive is a silicone resin, and the weight ratio of the adhesive to the total magnetic powder can be adjusted according to the magnetic powder, the coating process and the pressing pressure. If the pressing pressure is small, the amount of the adhesive added should be increased. In this method, the amount of the adhesive added to the total magnetic powder weight is 0.5wt%. The release agent is zinc stearate, and the amount of the release agent added to the total magnetic powder weight is 0.3wt%.

[0048] In the process of layered filling of iron-silicon composite powders with different silicon contents, one kind of iron-silicon composite powder needs to be filled into the mold first, and then leveled with a powder scraper. The mold is then placed in a press for pre-pressing to ensure that the layered interface of the functional gradient magnetic powder core material is relatively flat.

[0049] During the layer-by-layer powder filling process, if the iron-silicon composite powder with the required specific silicon content is not prepared in advance, several existing composite powders with different silicon contents coated with phosphoric acid can be mixed in different proportions to obtain the composite powder with that content and fill it into the prepared position of the mold.

[0050] For different composite powders loaded in the mold, the number of layers of laid powder and the thickness of each layer can be flexibly adjusted according to the requirements for the performance of the magnetic powder core. By controlling the silicon content of each layer of powder, the proportion of organic resin and the particle size, the electromagnetic and mechanical properties of each layer of the iron-silicon functional gradient magnetic powder core material can be flexibly controlled.

[0051] During the isostatic pressing process, the isostatic pressing pressure of the press can be adjusted according to the electromagnetic properties and density of the required magnetic powder core. If the magnetic powder core needs to have a high density and a high saturation magnetic flux, the processing pressure should be increased. This method uses a pressure of 1300MPa and a holding time of 30s. Only one pressing is required to produce a customized multi-layer iron-silicon functional gradient magnetic powder core material compact.

[0052] In this embodiment, in step S3, the pressed magnetic powder core is annealed and debinded.

[0053] Specifically, the pressed iron-silicon composite functional gradient magnetic powder core was sintered in a tubular furnace under a nitrogen atmosphere. The nitrogen flow rate was 0.3 cm 3 The sintering temperature is 800°C, the heating rate of the tube furnace is 10°C / min, and the holding time is 1h.

[0054] The beneficial effects of the present invention are as follows:

[0055] The present invention only needs to load composite materials with different silicon contents into the corresponding positions of the mold according to the requirements of different parts of the device for material properties, so as to flexibly adjust the powder particle size, overall density and various physical and electromagnetic properties of each layer of the functional gradient magnetic powder core material to meet the differentiated specific performance requirements of each point of the device. At the same time, a functional gradient magnetic powder core material can be conveniently made with only one pressing. Due to its low equipment requirements and mature and simple preparation process, the difficulty of preparing this new type of iron-silicon functional gradient magnetic powder core material is greatly reduced, and the practicality of the material is improved.

[0056] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0057] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the present invention. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scope. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. A method for preparing a novel iron-silicon functional gradient magnetic powder core material, characterized in that: include: S1: preparing a series of iron-silicon alloy powders with silicon contents ranging from 0% to 10%, and coating the iron-silicon alloy powders with phosphoric acid to obtain composite powders with various silicon contents; S2: Filling a plurality of composite powders with different silicon contents into the mold layer by layer according to a gradient change, and performing isostatic pressing to form a compacted magnetic powder core; S3: annealing and debinding the pressed magnetic powder core to obtain a finished magnetic powder core material.

2. The method for preparing the novel iron-silicon functional gradient magnetic powder core material according to claim 1, characterized in that: A series of iron-silicon alloy powders with silicon contents ranging from 0% to 10% were prepared, and the iron-silicon alloy powders were coated with phosphoric acid to obtain a variety of composite powders with different silicon contents, including: Composite powders with different silicon contents were placed in beakers respectively, and 0.5wt% phosphoric acid accounting for the total weight of the magnetic powder was added. The mixture after the reaction was placed in an oven to completely dry the mixture to obtain composite powders with different silicon contents.

3. The method for preparing the novel iron-silicon functional gradient magnetic powder core material according to claim 1, characterized in that: The method for configuring the iron-silicon alloy powder comprises: Powder with a target particle size accounting for 80% of the total weight of the powder and iron-silicon alloy powder with a particle size half finer than the target particle size accounting for 20% of the total weight of the powder are mixed thoroughly.

4. The method for preparing the novel iron-silicon functional gradient magnetic powder core material according to claim 2, characterized in that: The insulation temperature of the oven is 80°C.

5. The method for preparing the novel iron-silicon functional gradient magnetic powder core material according to claim 2, characterized in that: During the drying process of the mixture, the beaker was taken out every five minutes and the mixture therein was stirred to prevent the powder from agglomerating.

6. The method for preparing the novel iron-silicon functional gradient magnetic powder core material according to claim 2, characterized in that: If the composite powder after drying is agglomerated, the composite powder is crushed in a mortar.

7. The method for preparing the novel iron-silicon functional gradient magnetic powder core material according to claim 1, characterized in that: The composite powders with different silicon contents are loaded into the mold layer by layer according to the gradient change, and subjected to isostatic pressing and shaping to obtain the pressed magnetic powder core, including: The coated composite powder is mixed with a binder and a release agent, and the composite powders with different silicon contents are loaded into a pressing mold layer by layer according to a gradient change, and then the mold is subjected to an isostatic pressing and shaping.

8. The method for preparing the novel iron-silicon functional gradient magnetic powder core material according to claim 7, characterized in that: The adhesive is silicone resin, and the weight ratio of the adhesive to the total weight of the magnetic powder is adjusted according to the magnetic powder, the coating process and the pressing pressure; the release agent is zinc stearate.

9. The method for preparing the novel iron-silicon functional gradient magnetic powder core material according to claim 7, characterized in that: During the isostatic pressing process, the isostatic pressing pressure of the press is adjusted according to the electromagnetic properties and density of the required magnetic powder core.

10. The method for preparing the novel iron-silicon functional gradient magnetic powder core material according to claim 1, characterized in that: Annealing and debinding of the pressed magnetic powder core, including: The pressed magnetic powder core was sintered in a tubular furnace under a nitrogen atmosphere; the nitrogen flow rate was 0.3 cm 3 / h; the sintering temperature is 800°C; the heating rate of the tubular furnace is 10°C / min, and the insulation time is 1h.

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