CN110947956A

CN110947956A - Forming process of high-strength and high-permeability soft magnetic composite material

Info

Publication number: CN110947956A
Application number: CN201911149427.7A
Authority: CN
Inventors: 张修齐; 郭文英; 梁丽萍; 刘向东; 吴清祥
Original assignee: Shandong Jingchuang Technology Research Institute Of Magnetoelectrics Industry Co ltd
Current assignee: Shandong Jingchuang Technology Research Institute Of Magnetoelectrics Industry Co ltd
Priority date: 2019-11-21
Filing date: 2019-11-21
Publication date: 2020-04-03
Anticipated expiration: 2039-11-21
Also published as: CN110947956B

Abstract

The invention relates to a forming process of a soft magnetic composite material with high strength and high magnetic conductivity, belonging to the technical field of soft magnetic composite material forming. The method comprises the following steps: step 1: mixing materials, namely uniformly mixing a certain amount of lubricant with soft magnetic powder, and heating the mixture to 90-110 ℃; step 2: performing first compression molding; and step 3: annealing for the first time; and 4, step 4: dissolving and permeating, namely soaking the sample annealed in the step 3 in a silane coupling agent for a period of time, and taking out; and 5: pressing for the second time; step 6: and (5) carrying out secondary annealing treatment. The invention adopts a secondary pressing and secondary annealing mode and is matched with a dissolved and infiltrated silane coupling agent, so that the density of the molding material can be effectively improved, and the performance of the soft magnetic composite material can be further optimized.

Description

Forming process of high-strength and high-permeability soft magnetic composite material

Technical Field

The invention relates to the technical field of soft magnetic composite material forming, and particularly provides a forming process of a high-strength and high-permeability soft magnetic composite material.

Background

The soft magnetic composite material (SMC) is prepared from iron powder particles through insulation treatment, bonding, pressing and heat treatment, and is widely applied to the fields of energy, traffic, national defense and the like. The soft magnetic composite material combines the advantages of metal and ferrite, so that the resistivity of the soft magnetic composite material is greatly improved, the eddy current loss can be effectively reduced, the saturation magnetization intensity is higher, and the requirements of miniaturization and integration of power electronic devices can be met.

The electromagnetic and mechanical properties of the soft magnetic composite material depend not only on the powder but also on the additives in the powder, as well as on the pressing and annealing processes thereof. In order to ensure that the cladding layer of the soft magnetic composite material is not damaged, the soft magnetic composite material does not need to be sintered at high temperature, generally, the annealing is carried out at 400-650 ℃, and thus the green strength and the annealing strength of the soft magnetic composite material are lower; meanwhile, due to low-temperature annealing, the internal pores of the soft magnetic composite material are difficult to reduce through sintering diffusion, so that the density is low, however, the density is the largest factor influencing the magnetic conductivity of the soft magnetic composite material, and therefore, the magnetic conductivity of the soft magnetic composite material is improved through improving the density, which is a very feasible scheme.

Disclosure of Invention

In order to solve the problems in the prior art, the invention provides a forming process of a soft magnetic composite material with high strength and high magnetic permeability. The invention adopts a secondary pressing and secondary annealing mode and is matched with a dissolved and infiltrated silane coupling agent, so that the density of the molding material can be effectively improved, and the performance of the soft magnetic composite material can be further optimized.

In order to solve the technical problems, the invention provides the following technical scheme:

the invention provides a forming process of a soft magnetic composite material with high strength and high magnetic permeability, which comprises the following steps:

step 1: mixing material

Uniformly mixing a certain amount of lubricant and soft magnetic powder, wherein a material mixing instrument is a conical mixer, the material mixing time is 1h, the powder and the lubricant can be fully and uniformly mixed, and the mixture is heated to 90-110 ℃ for pressing;

step 2: first pressing

Filling the powder into a die with a lubricated die wall, and performing compression molding by adopting a bidirectional compression mode (ensuring that the density of a sample after compression is uniform everywhere);

and step 3: first annealing

Annealing the sample pressed in the step 2 at 480 +/-20 ℃ in a nitrogen atmosphere for 20-40min, and cooling to room temperature;

and 4, step 4: dissolving and permeating

Soaking the sample annealed in the step 3 in a silane coupling agent for a period of time to ensure that the coupling agent can be fully dissolved and infiltrated into the pores of the sample, and taking out;

and 5: second pressing

The method for pressing adopts a mode of lubricating the die wall, namely uniformly smearing the mixed solution of zinc stearate and alcohol on the surface of a die, blowing dry by electric air, and then putting the sample treated in the step 4 into a second set of die (the size of the die is slightly larger than that of the die pressed for the first time, and the size is usually about 0.1% larger than that of a part) for pressing again;

step 6: second annealing

And (4) keeping the temperature of the sample pressed in the step (5) for 2-8min at the temperature of 630 +/-20 ℃ in a nitrogen atmosphere.

Further, in the step 1, the lubricant is micro powder wax, and the using amount of the micro powder wax is 0.2-0.3% of the mass of the soft magnetic powder; the soft magnetic powder is of the Somaloy 5P series.

Further, in the step 2, the die wall lubrication specifically comprises: and uniformly coating the mixed solution of zinc stearate and alcohol on the inner surface of the mould, and drying by blowing.

Further, the mass volume ratio of the zinc stearate to the alcohol is 1g/10 ml.

Furthermore, the pressure of the compression molding is 1100MPa, the dwell time is 3-5s, and the sample can be compressed and compacted as much as possible.

Further, in the step 3, the temperature is increased to 400 ℃ at a temperature increase rate of more than 15 ℃/min, the temperature is increased from 400 ℃ to 450 ℃ at a temperature increase rate of 2-3 ℃/min, and the temperature is increased to 450-480 +/-20 ℃ at a rate of more than 5 ℃/min.

Further, in the step 4, the silane coupling agent is KBM-403, KBM-503 or KBM-603 silane coupling agent; the soaking time is 1-3 h.

Further, in the step 5, the pressing pressure is 1100MPa, and the dwell time is 2-4 s.

Further, in the step 6, the temperature is increased to 400 ℃ at a temperature increase rate of more than 15 ℃/min, the temperature is increased from 400 ℃ to 450 ℃ at a temperature increase rate of 2-3 ℃/min, and the temperature is increased to 450-630 +/-20 ℃ at a rate of more than 5 ℃/min.

Compared with the prior art, the invention has the following beneficial effects:

according to the invention, after the molding material is pressed and annealed once in the prior art, the formed material is subjected to infiltration treatment, so that the silane coupling agent is filled in the pores generated in the annealed material, and then the formed material is subjected to pressing and annealing again, so that the density of the molded material can be effectively improved. Meanwhile, specific pressing and annealing treatment process parameters are selected, so that the strength, the magnetic conductivity, the saturation magnetic induction intensity and the like of the prepared material are greatly improved, the power consumption of the material is almost unchanged, and the high-strength and high-magnetic conductivity soft magnetic composite material is successfully prepared.

Drawings

FIG. 1 is a gold phase diagram of soft magnetic composite materials prepared in example 1, comparative example 10 and comparative example 7 of the present invention;

fig. 2 is SEM images of soft magnetic composite materials prepared in example 1 of the present invention and comparative example 10.

Detailed Description

In order to make the technical problems, technical solutions and advantages of the present invention more apparent, the following detailed description is given with reference to the accompanying drawings and specific embodiments.

In the present invention, the materials and reagents used are not specifically described, and are commercially available.

The invention provides a forming process of a soft magnetic composite material with high strength and high magnetic permeability, and the specific embodiment is as follows.

Example 1

A forming process of a high-strength and high-permeability soft magnetic composite material comprises the following steps:

step 1: mixing material

Mixing W-special micro wax powder (the mass fraction is 0.2%) into Somaloy 5P, wherein a mixing instrument is a conical mixer, the mixing time is 1h, the powder and the lubricant can be fully and uniformly mixed, and the mixed powder is heated to 90-110 ℃ for later use;

the soft magnetic powder is a Herganas Somaloy 5P material, and the properties of the material are shown in Table 1.

TABLE 1

Lubricant: the added lubricant is W-special micro powder wax, which is high melting point polyamide wax produced by German Hessit company, and the specific physical and chemical parameters are shown in Table 2.

TABLE 2

Step 2: first pressing

This suppression adopts the mode of internal lubrication + mould wall, and the powder that will mix is filled inside the mould to scribble the mixed solution of zinc stearate and alcohol on the die cavity inner wall, weathered with the electric hair drier. The sample can be pressed and compacted as far as possible by adopting a bidirectional pressing mode (ensuring that the density of the pressed sample is uniform everywhere), the pressure maintaining time is 3s, and the pressing force of the press is adjusted to 1100MPa for pressing;

and step 3: first annealing

Heating the sample pressed in the step 2 to 400 ℃ at a speed of 18 ℃/min, heating the sample to 500 ℃ at a heating rate of 2 ℃/min from 400 ℃ to 450 ℃, annealing the sample in a nitrogen atmosphere for 30min at a heating rate of 6 ℃/min, and cooling the sample to room temperature;

and 4, step 4: dissolving and permeating

Soaking the sample annealed in the step 3 in a silane coupling agent with the mark of KBM-403 for 2 hours to ensure that the coupling agent can be fully dissolved and infiltrated into the pores of the sample, and taking out;

the silane coupling agent is a KBM-403 silane coupling agent manufactured by shin-Etsu chemical Co., Ltd, and the specific properties are shown in Table 3.

TABLE 3

And 5: second pressing

The method for pressing adopts a mode of die wall lubrication, namely uniformly smearing the mixed solution of zinc stearate and alcohol on the surface of a die, blowing to dry by using an electric blower, then putting the sample treated in the step 4 into a second set of die (the size of the die is slightly larger than that of the die pressed for the first time, and the size height is about 0.1% larger than that of a part under the common condition) for pressing again, wherein the pressing pressure is 1100MPa, and the pressure maintaining time is 2 s;

step 6: second annealing

And (3) heating the sample pressed in the step (5) to 400 ℃ at a heating rate of 20 ℃/min, heating to 650 ℃ at a heating rate of 2 ℃/min from 400 ℃ to 450 ℃, heating to 650 ℃ at a heating rate of 10 ℃/min, and keeping the temperature for 5min in a nitrogen atmosphere.

Example 2

A forming process of a soft magnetic composite material with high strength and high magnetic permeability is disclosed, wherein in the step 1, the addition amount of a lubricant is 0.3% of the mass of soft magnetic powder; the pressure maintaining time in the first pressing process is 5 s; the silane coupling agent adopted by the solution and permeation is KBM-503, and the soaking time is 1 h; the pressure maintaining time in the second pressing process is 4 s; the remaining conditions were the same as in example 1.

Example 3

A forming process of a soft magnetic composite material with high strength and high magnetic permeability is disclosed, wherein in the step 1, the addition amount of a lubricant is 0.2% of the mass of soft magnetic powder; the pressure maintaining time in the first pressing process is 4 s; the silane coupling agent adopted by the solution and permeation is KBM-603, and the soaking time is 3 h; the pressure maintaining time in the second pressing process is 3 s; the remaining conditions were the same as in example 1.

Example 4

A forming process of a soft magnetic composite material with high strength and high magnetic permeability is disclosed, wherein in the step 1, the addition amount of a lubricant is 0.2% of the mass of soft magnetic powder; the pressure maintaining time in the first pressing process is 5 s; the first annealing treatment conditions are as follows: heating to 400 ℃ at the speed of 20 ℃/min, heating to 460 ℃ at the speed of 3 ℃/min from 400 ℃ to 450 ℃, annealing in a nitrogen atmosphere for 30min, and cooling to room temperature; the silane coupling agent adopted by the solution and permeation is KBM-503, and the soaking time is 1 h; the pressure maintaining time in the second pressing process is 4 s; the conditions of the second annealing treatment are as follows: heating to 400 ℃ at a speed of 20 ℃/min, heating to 610 ℃ at a speed of 3 ℃/min from 400 ℃ to 450 ℃, and annealing for 8min in a nitrogen atmosphere at a speed of 10 ℃/min. The remaining conditions were the same as in example 1.

Example 5

A forming process of a soft magnetic composite material with high strength and high magnetic permeability is disclosed, wherein in the step 1, the addition amount of a lubricant is 0.3% of the mass of soft magnetic powder; the pressure maintaining time in the first pressing process is 4 s; the first annealing treatment conditions are as follows: heating to 400 ℃ at the speed of 18 ℃/min, heating to 480 ℃ at the speed of 2 ℃/min from 400 ℃ to 450 ℃, annealing in a nitrogen atmosphere for 30min, and cooling to room temperature; the silane coupling agent adopted by the solution and permeation is KBM-603, and the soaking time is 3 h; the pressure maintaining time in the second pressing process is 3 s; the pressure maintaining time in the second pressing process is 4 s; the conditions of the second annealing treatment are as follows: heating to 400 ℃ at the speed of 18 ℃/min, heating to 630 ℃ at the speed of 8 ℃/min at the speed of 2 ℃/min from 400 ℃ to 450 ℃, and annealing for 3min in a nitrogen atmosphere. The remaining conditions were the same as in example 1.

To further illustrate the beneficial effects of the present invention, a comparative example was constructed as follows, using example 1 as an example only, for reasons of space.

1. Influence of lubricant addition amount and lubrication mode

Comparative example 1

In the step 1, the adding amount of the lubricant is 0.1 percent of the mass of the soft magnetic powder; the remaining conditions were the same as in example 1.

Comparative example 2

The lubricant added in step 1 was omitted and the remaining conditions were the same as in example 1.

Comparative example 3

In the step 1, the adding amount of the lubricant is 0.4 percent of the mass of the soft magnetic powder; the die wall lubrication step was omitted in step 2, and the mixed powder was directly subjected to the two-way pressing, with the remaining conditions being the same as in example 1.

The properties of the soft magnetic composite materials prepared in examples 1 to 3 and comparative examples 1 to 3 were measured, and the results are shown in Table 4.

TABLE 4

The increased amount of the lubricant causes the volatilization of the lubricant after annealing of the soft magnetic composite material, leaving pores in the original positions of the lubricant, and the amount of the lubricant added is decreased in order to increase the density. As is apparent from Table 4, the soft magnetic composite material prepared by adding the lubricant of the present invention in an amount of 0.2 to 0.3% and using the method of die wall lubrication has better strength and maximum permeability than the comparative example, and this manner shows lower loss.

2. Influence of pressing pressure

Comparative example 4

The first pressing pressure was 800MPa, and the other conditions were the same as in example 1.

Comparative example 5

The first pressing pressure was 1000MPa, the second pressing pressure was 800MPa, and the other conditions were the same as in example 1.

Comparative example 6

The first pressing pressure was 800MPa, and the second pressing pressure was 800MPa, except that the conditions were the same as in example 1.

Comparative example 7

And (3) conventional pressing mode: the pressing forming is carried out only once, the pressing pressure is 1100MPa, the annealing is carried out only once, the annealing temperature is 650 ℃, the temperature is kept for 5min, the solution infiltration is not carried out, and the other conditions are the same as the conditions of the embodiment 1.

The properties of the soft magnetic composite materials prepared in example 1 and comparative examples 4 to 7 were measured, and the results are shown in Table 5.

TABLE 5

From the above table, the density and magnetic performance are greatly improved and the power consumption is slightly reduced by the selection of the pressing process and the pressing pressure.

Strength, Bs and μ compared to conventional pressing (comparative example 7)_maxAnd the density is greatly improved, the power consumption is greatly reduced, and the specific improvement percentage is shown in table 6.

TABLE 6

3. Influence of annealing temperature

Comparative example 8

Heating the sample pressed in the step 2 to 400 ℃ at a speed of 18 ℃/min, annealing in a nitrogen atmosphere for 30min, and cooling to room temperature; the remaining conditions were the same as in example 1.

Comparative example 9

And (3) heating the sample pressed in the step (5) to 400 ℃ at a heating rate of 20 ℃/min, heating to 600 ℃ at a heating rate of 2 ℃/min from 400 ℃ to 450 ℃, heating to 600 ℃ at a heating rate of 10 ℃/min, and preserving heat for 5min in a nitrogen atmosphere. The remaining conditions were the same as in example 1.

The performance test was performed on the materials after the first annealing and the soft magnetic composite materials obtained by the second annealing in the above example 1 and comparative examples 8 to 9, respectively, and the results are shown in table 7.

TABLE 7

As can be seen from table 7, the annealing process performed twice at 500 ℃→ 650 ℃ results in a higher saturation magnetic flux (1.62), and the maximum permeability reaches 545, and the power consumption is correspondingly reduced.

4. Influence of the infiltration step

Comparative example 10

The leaching step was omitted and the remaining conditions were the same as in example 1.

The soft magnetic composite materials prepared in example 1 and comparative example 10 were subjected to the performance test, respectively, and the results are shown in table 8.

TABLE 8

It can be known through comparison that after the link of dissolving and permeating is added between primary annealing and secondary pressing, the strength is further improved, compared with the process without dissolving and permeating, the strength is improved by 45.5%, compared with the conventional pressing, the strength is improved by 62.5%, the density is almost unchanged compared with the density without dissolving and permeating, compared with the conventional pressing, the density is improved by 2.1%, and the Bs is almost unchanged compared with the density without dissolving and permeating, compared with the conventional pressing, the density is improved by 8%, and the maximum magnetic permeability mu is maximum_maxCompared with the method without dissolving and permeating, the method improves the speed by 24.8 percent, improves the speed by 63 percent compared with the conventional pressing, and correspondingly reduces the power consumption slightly.

As can be seen by comparing the three process modes, namely the metallographic diagram 1 and the SEM diagram 2, the metallographic phase contains a large number of pores in the conventional pressing mode (comparative example 7), and the magnetic permeability of the SMC material is in direct proportion to the density of the SMC material, so that the magnetic permeability is adversely affected by the existence of the large number of pores.

In the secondary pressing process (comparative example 10), since the particles were slipped due to dislocation when the pressing was performed for the second time, the strength was not significantly improved after the secondary annealing. After the solution infiltration process (example 1), the strength between the particles is improved due to the existence of the silane coupling agent.

In conclusion, the invention has the advantages that the strength, the magnetic conductivity, the saturation magnetic induction intensity and the like of the prepared material are greatly improved through secondary pressing, secondary annealing and silane coupling agent filling, the power consumption of the prepared material is almost not changed, and the soft magnetic composite material with high strength and high magnetic conductivity is successfully prepared.

While the foregoing is directed to the preferred embodiment of the present invention, it will be understood by those skilled in the art that various changes and modifications may be made without departing from the spirit and scope of the invention as defined in the appended claims.

Claims

1. A forming process of a soft magnetic composite material with high strength and high magnetic permeability is characterized by comprising the following steps:

step 1: mixing material

Uniformly mixing a certain amount of lubricant with the soft magnetic powder, and heating the mixture to 90-110 ℃;

step 2: first pressing

Filling the powder into a die with a lubricated die wall, and performing compression molding by adopting a bidirectional compression mode;

and step 3: first annealing

Heating the sample pressed in the step 2 to 480 +/-20 ℃, annealing for 20-40min in a nitrogen atmosphere, and cooling to room temperature;

and 4, step 4: dissolving and permeating

Soaking the sample annealed in the step 3 in a silane coupling agent for a period of time, and taking out;

and 5: second pressing

Pressing the sample treated in the step 4 again by adopting a mode of die wall lubrication;

step 6: second annealing

And (4) heating the sample pressed in the step (5) to 630 +/-20 ℃, and preserving heat for 2-8min in a nitrogen atmosphere.

2. The forming process of the soft magnetic composite material with high strength and high permeability according to claim 1, wherein in the step 1, the lubricant is micro wax powder, and the amount of the micro wax powder is 0.2 to 0.3 percent of the mass of the soft magnetic powder; the soft magnetic powder is of the Somaloy 5P series.

3. A process for forming a high strength, high permeability soft magnetic composite according to claim 1, wherein in step 2, the die wall lubrication is specifically: and uniformly coating the mixed solution of zinc stearate and alcohol on the inner surface of the mould, and drying by blowing.

4. A process for forming a high strength, high permeability soft magnetic composite according to claim 3, wherein the mass to volume ratio of zinc stearate to alcohol is 1g/10 ml.

5. A forming process of a high strength and high permeability soft magnetic composite material according to claim 4, characterized in that the pressure of the press forming is 1100MPa, and the dwell time is 3-5 s.

6. A process for forming a high strength and high permeability soft magnetic composite material according to claim 1, wherein in step 3, the temperature is raised at a rate of > 15 ℃/min to 400 ℃, at a rate of 2-3 ℃/min to 450 ℃, and at a rate of > 5 ℃/min to 450-480 ± 20 ℃.

7. A process for forming a high strength, high permeability soft magnetic composite according to claim 1, wherein in step 4, the silane coupling agent is KBM-403, KBM-503 or KBM-603 silane coupling agent; the soaking time is 1-3 h.

8. A process for forming a high strength and high permeability soft magnetic composite material according to claim 1, wherein in step 5, the pressing pressure is 1100MPa and the dwell time is 2-4 s.

9. A forming process of a high-strength and high-permeability soft magnetic composite material according to claim 1, wherein in the step 6, the temperature is raised at a rate of more than 15 ℃/min to 400 ℃, the temperature is raised at a rate of 2-3 ℃/min from 400 ℃ to 450 ℃, and the temperature is raised at a rate of more than 5 ℃/min to 450-630 +/-20 ℃.