COMPOUND MAGNETIC POWDER AND MAGNETIC POWDER CORES, AND METHODS FOR MAKING THEM THEREOF

Abstract

The present invention provides a compound powder for making magnetic powder cores, a kind of magnetic powder core, and a process for making them. Said compound powder is a mixture composing of powder A and powder B, the content of powder A is 50-96 wt % and the content of powder B is 4-50 wt %, wherein powder A is at least one selected from iron powder, Fe—Si powder, Fe—Si—Al powder, Fe-based nanocrystalline powder, Fe-based amorphous powder, Fe—Ni powder and Fe—Ni—Mo powder; powder B bears different requirement characteristics from powder A and is at least one selected from iron powder, Fe—Si powder, Fe—Si—Al powder, Fe-based nanocrystalline powder, Fe-based amorphous powder, Fe—Ni powder and Fe—Ni—Mo powder. Said powder B adopts Fe-based amorphous soft magnetic powder with good insulation property as insulating agent and thus core loss of magnetic powder core decreases. The decrease of magnetic permeability of magnetic powder core resulting from a traditional insulating agent is remedied and the initial magnetic permeability of magnetic powder core is improved by taking advantage of soft magnetic properties of Fe-based amorphous powder.

Description

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a curve graph illustrating the change of unit magnetic permeability of compound magnetic powder core prepared by mixing amorphous powder and MPP with different DC bias force.

FIG. 2 is a curve graph illustrating the change of magnetic permeability and quality factor of compound magnetic powder core prepared by mixing nanocrystalline powder and amorphous powder in different frequencies.

FIG. 3 is a curve graph illustrating the change of magnetic permeability and quality factor of compound magnetic powder core prepared by mixing amorphous powder and Fe—Si—Al powder in different frequencies.

FIG. 4 is a curve graph illustrating the change of quality factor of compound magnetic powder core prepared by mixing Fe—Si—Al powder and Hi-Flux powder in different frequencies.

FIG. 5 is a curve graph illustrating the change of specific magnetic conductivities of compound magnetic powder core prepared by mixing Fe—Si—Al powder and Hi-Flux powder with different DC bias force.

FIG. 6 is a curve graph illustrating the change of quality factor of compound magnetic powder core prepared by mixing amorphous, Fe—Si—Al and Hi-Flux powder and quality factor of Hi-Flux core in different frequencies.

FIG. 7 is a curve graph illustrating the change of specific magnetic permeability of compound magnetic powder core prepared by mixing amorphous, Fe—Si—Al and Hi-Flux powder and that of Hi-Flux core with different DC bias force.

FIG. 8 is the X-ray diffraction pattern of amorphous magnetic powder functioning as insulation agent.

FIG. 9 is a photo of morphology of the powder mentioned in FIG. 8.

FIG. 10 is a cross-section view of magnetic powder core used to the process of making low core loss magnetic powder cores.

FIG. 11 is graph illustrating the dependence of on the result of modified MPP magnetic core according to embodiment 6.

FIG. 12 is the result of modified MPP magnetic core according to embodiment 7.

FIG. 13 is the result of modified amorphous magnetic powder core according to embodiment 8.

FIG. 14 is the result of modified amorphous magnetic powder core according to embodiment 9.

FIG. 15 is the result of modified nanocrystalline magnetic powder core according to embodiment 10.

Claims

1. A kind of compound powder for making magnetic powder core, characterized in that, it is a mixture of powder A and powder B, the content of powder A is 50-96 wt % and the content powder B is 4-50 wt %, wherein: powder A is at least one selected from iron powder, Fe—Si powder, Fe—Si—Al powder, Fe-based nanocrystalline powder, Fe-based amorphous powder, Fe—Ni powder and Fe—Ni—Mo powder, the selection of power A has the priority to satisfy the requirement characteristic;Powder B bears different requirements characteristic from powder A, power B is at least one powder selected from iron powder, Fe—Si powder, Fe—Si—Al powder, Fe-based nanocrystalline powder, Fe-based amorphous powder, Fe—Ni powder and Fe—Ni—Mo powder.

2. The compound powder for making magnetic powder core according to claim 1, characterized in that, said requirement characteristics are at least one of magnetic permeability, core loss, magnetic properties at high frequency, inductance stability under DC bias field, temperature stability and cost.

3. The compound powder according to claim 1, characterized in that, said powder A selected from Fe—Ni powder and Fe—Ni—Mo powder having higher cost, said powder B is at least one selected from iron powder, Fe—Si powder, Fe—Si—Al powder, Fe-based nanocrystalline powder and Fe-based amorphous powder having lower cost.

4. The compound powder according to claim 1, characterized in that, said powder A adopts Fe-based amorphous powder with high quality factor at high frequency, and said powder B is at least one powder selected from iron powder, Fe—Si powder, Fe—Si—Al powder, Fe-based nanocrystalline powder with low quality factor at high frequency.

5. The compound powder according to claim 1, is characterized in that, the content of said powder B is preferably 10-50 wt %.

6. A kind of compound powder for making low core loss magnetic powder core, characterized in that, it is a mixture of powder A and powder B where contents of powder A is 80-96 wt % and powder B is 4-20 wt %, wherein: powder A is one selected from iron powder, Fe—Si powder, Fe—Si—Al powder, Fe-based nanocrystalline powder, Fe-based amorphous powder, Fe—Ni powder and Fe—Ni—Mo powder and has top-priority requirement characteristic; powder B is Fe-based amorphous soft magnetic powder with good insulating property.

7. The compound powder for making low core loss magnetic powder core according to claim 6, characterized in that, the content of powder B in said compound powder preferably is 4-20 wt % and the rest is powder A.

8. The compound powder for making low core loss magnetic powder core according to claim 6, characterized in that, the content of powder B of said compound powder is preferably 8-15 wt % and the rest is powder A.

9. The compound powder for making low core loss magnetic powder core according to claim 6, characterized in that, said powder B is Fe-based amorphous soft magnetic powder oxidated on its surface and meets one of the following requirements: Oxygen content is 4000-20000 ppm;Loose packed density ρ≧2.4 g/cm3.

10. The compound powder for making the low core loss magnetic powder core according to claim 9, characterized in that, said powder B is Fe-based amorphous soft magnetic powder oxidated on its surface, wherein the oxygen content is preferably 8000-11000 ppm.

11. The compound powder for making low core loss magnetic powder cores according to claim 6, characterized in that, the mean particle size ratio of powder B to powder A is ½˜ 1/20.

12. The compound powder for making low core loss magnetic powder cores according to claim 9, characterized in that, the mean particle size ratio of powder B to powder A is preferably ⅓˜⅛.

13. A method for preparing a compound powder for making magnetic powder cores, the method includes the following steps: a. Preparing powder A and powder B according to different requirements characteristic, respectively;b. Screening the prepared powder A and powder B, respectively;c. Annealing powder A and powder B according to the pre-determined parameters, respectively.d. Uniformly mixing powder A with powder B, where the content of weight percentage of each is: powder A is 50-96 wt % and the content of powder B is 4-50 wt %, wherein powder A is one selected from iron powder, Fe—Si powder, Fe—Si—Al powder, Fe-based nanocrystalline powder, Fe-based amorphous powder, Fe—Ni powder and Fe—Ni—Mo powder and the selection of powder A has priority to satisfy the in requirement characteristic; powder B bears different requirement characteristic from powder A and is at least one powder selected from iron powder, Fe—Si powder, Fe—Si—Al powder, Fe-based nanocrystalline powder, Fe-based amorphous powder, Fe—Ni powder and Fe—Ni—Mo powder.

14. The method for preparing a compound powder for making magnetic powder core according to claim 13, characterized in that, the mixing time is: 1 minute to 60 minutes.

15. A method for preparing a compound powder for making low core loss magnetic powder core, characterized in that, the process includes the following steps: a. Preparing powder A and powder B according to different requirement characteristic, respectively wherein powder B is made to have good insulating property;b. Screening prepared powder A and powder B, respectively;c. Annealing powder A and powder B according to the pre-determined parameters, respectively.d. Uniformly mixing powder A with powder B, where the content of powder A is 80-96 wt % and the content of powder B is 4-20 wt %, wherein powder A is one selected from iron powder, Fe—Si powder, Fe—Si—Al powder, Fe-based nanocrystalline powder, Fe-based amorphous powder, Fe—Ni powder and Fe—Ni—Mo powder and the selection of powder A has top-priority to satisfy the requirement characteristic; powder B is Fe-based amorphous soft magnetic powder with good insulating property.

16. The method for preparing a compound powder for making low core loss magnetic powder core according to claim 15, characterized in that, the method of preparing powder B is water atomization technology:

17. A kind of magnetic powder core, is characterized in that, the magnetic powder core comprise the following weight percentages: 0.2 wt %-7 wt % of insulating agent, 0.1 wt -5 wt % of adhesive, 0.01 wt-2 wt % of lubricant, the rest of said compound powder according claim 1.

18. The magnetic powder core according to claim 17, characterized in that, said insulating agent is at least one selected from the following groups of substances: Oxide powder selected from SiO2, CaO, Al2O3, TiO2;Salts selected from silicates and phosphates;Mineral powder selected from mica powder and kaolinite.

19. The magnetic powder core according to claim 17, characterized in that, said adhesive is organic adhesive and/or inorganic adhesive, wherein the organic adhesive is at least one selected from epoxy resin , the inorganic adhesive is at least one selected from phosphates.

20. The magnetic powder core according to claim 17, characterized in that, said lubricant is at least one selected from stearates, talc powder and MoS2.

21. The magnetic powder core according to claim 17, characterized in that, the content of said insulating agent is preferably 0.5-5 wt %.

22. The low core loss magnetic powder core, characterized in that, the content of insulating agent is 4-20 wt % , wherein said insulating agent is Fe-based amorphous soft magnetic powder with good insulating property; the content of adhesive is 0.1-5 wt %, the rest is one powder selected from iron powder, Fe—Si powder, Fe—Si—Al powder, Fe-based nanocrystalline powder, Fe-based amorphous powder, Fe—Ni powder and Fe—Ni—Mo powder.

23. The low core loss magnetic powder core according to claim 21, characterized in that, said insulating agent should meet one of the following requirements: Oxygen content is 4000-20000 ppm;Loose packed density ρ≧2.4 g/cm3.

24. The low core loss magnetic powder core according to claim 22, characterized in that, the surface of said insulating agent is seriously oxidated into non-conductive metal oxides of Fe2O3, ZnO, MgO, CuO, ZrO and Al2O3.

25. The low core loss magnetic powder core according to claim 22, characterized in that, said adhesive is at least one selected from epoxy resin, silicone resin, nitrile rubber and polyurethane.

26. The low core loss magnetic powder core according to claim 22, characterized in that, said magnetic powder core further comprises 0-0.5 wt % lubricant, wherein said lubricant is selected from zinc stearate or MoS2.

27. A method for preparing magnetic powder core, characterized in that, said process includes the following steps: e. Mixing said compound powder according to claim 1 with required content of insulating agent, adhesive and lubricant and then fully drying them to form dried powder;f. Compacting said dried powder under a pressure of 500 MPa-3000 MPa to make magnetic powder core;g. Annealing the magnetic powder core;h. Spray-painting the magnetic powder core.

28. A method for preparing magnetic powder core according to claim 27, characterized in that, the annealing temperature of said magnetic powder core is from Tc+20° C. to Tx−20° C.

29. A method for preparing magnetic powder core according to claim 27, characterized in that, the annealing time of said magnetic powder core ranges from 5 minutes to 300 minutes.

30. A method for preparing magnetic powder core according to claim 28, characterized in that, the annealing treatment for said magnetic powder core implemented in hydrogen, nitrogen or argon protective atmosphere, or in a vacuum.

31. A method for preparing low core loss magnetic powder core, characterized in that, said method comprises the following steps: e. Uniformly mixing compound powder for making low core loss magnetic powder core according to claim 6;f. Uniformly mixing the compound powder of step e with adhesive and drying the resultant mixture powder;g. Adding lubricant into the dried powder;h. Putting the dried powder into a mold of magnetic powder core and compacting the mixture of powder under a pressure of 500 MPa-3000 MPa;i. Annealing the molded magnetic powder core;j. Spray-painting the magnetic powder core.

32. A method for preparing low core loss magnetic powder core according to claim 31, characterized in that, the annealing temperature of said magnetic powder core is from >Tc+20° C. to <Tx−20° C. and the annealing time ranger from 5 minutes to 300 minutes.

33. A method for preparing magnetic powder core according to claim 31, characterized in that, the annealing treatment for said magnetic powder core is implemented in hydrogen, nitrogen or argon protective atmosphere or in a vacuum.