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CN-122025332-A - High-insulation double-inorganic-coated magnetic powder core based on buffer regulation and control and preparation method thereof

CN122025332ACN 122025332 ACN122025332 ACN 122025332ACN-122025332-A

Abstract

The invention discloses a high-insulation double-inorganic-coating magnetic powder core based on buffer regulation and control and a preparation method thereof, comprising the following steps of (1) fully mixing a surface regulator for phosphating, a surfactant, nitrate, metal-based phosphate and phosphating buffer with water to prepare metal-based phosphating solution, adding metal soft magnetic powder into the metal-based phosphating solution, stirring, generating a double-inorganic coating layer of an oxide layer and a phosphating layer on the surface of the magnetic powder, cleaning the magnetic powder, and drying to obtain insulating-coating magnetic powder; and (2) adding the insulating coated magnetic powder into resin dissolved by an organic reagent and a coupling agent for granulating to obtain magnetic powder particles, and pressing, forming and curing the magnetic powder particles to obtain the high-insulation double-inorganic coated magnetic powder core. The invention utilizes the phosphating buffer to regulate and control the concentration of H + in the phosphating solution, obviously reduces the porosity of the coating layer, effectively blocks the insulation breakdown path, improves the insulation resistance and breakdown voltage of the magnetic powder core, and simultaneously maintains the characteristics of high magnetic conductivity and low magnetic loss.

Inventors

  • YU HONGYA
  • SHI JIE
  • ZHOU YANG
  • Xu Shuainan
  • YUAN TONGXIN
  • LIU ZHONGWU

Assignees

  • 华南理工大学

Dates

Publication Date
20260512
Application Date
20260305

Claims (10)

  1. 1. The preparation method of the high-insulation double-inorganic-coated magnetic powder core based on buffer regulation is characterized by comprising the following steps of: (1) Metal base phosphating treatment, namely fully mixing a surface regulator for phosphating, a surfactant, nitrate, metal base phosphate and a phosphating buffer agent with water to prepare metal base phosphating solution, adding metal soft magnetic powder into the metal base phosphating solution for stirring, wherein the phosphating buffer agent has the effect of regulating the concentration of H + and can regulate the supersaturation degree of a reaction interface, generating a double inorganic coating layer of an oxide layer and a phosphating layer on the surface of the magnetic powder, cleaning the magnetic powder, and drying to obtain insulating coated magnetic powder; (2) And granulating and shaping, namely adding the insulating coated magnetic powder into resin dissolved by an organic reagent and a coupling agent for granulating to obtain magnetic powder particles, and pressing, shaping and solidifying the magnetic powder particles to obtain the high-insulation double-inorganic coated magnetic powder core.
  2. 2. The method according to claim 1, wherein the surface conditioner for phosphating comprises one or more of a zinc-based surface conditioner for phosphating, a manganese-based surface conditioner for phosphating, a calcium-based surface conditioner for phosphating, and a molybdenum-based surface conditioner for phosphating, and the surfactant comprises one or more of an OP-series emulsifier, a tx-series emulsifier, and an np-series emulsifier.
  3. 3. The method according to claim 2, wherein the surface conditioner for zinc phosphating is a zinc salt-titanium salt mixed system, the surface conditioner for manganese phosphating is a manganese salt-titanium salt mixed system, the surface conditioner for calcium phosphating is a calcium salt-titanium salt mixed system, and the surface conditioner for molybdenum phosphating is an ammonium molybdate-titanium salt mixed system.
  4. 4. The method according to claim 3, wherein the nitrate comprises one or more of zinc nitrate, manganese nitrate, calcium nitrate and sodium nitrate, the metal-based phosphate comprises one or more of zinc dihydrogen phosphate, manganese dihydrogen phosphate, calcium dihydrogen phosphate and sodium dihydrogen phosphate, the titanium salt is one or more of phthalate, titanium sulfate, titanium chloride, titanium phosphate and colloidal titanium, the zinc salt is one or more of zinc oxide, zinc phosphate, zinc chloride and zinc nitrate, the manganese salt is one or more of manganese phosphate, manganese nitrate, manganese oxide and manganese chloride, and the calcium salt is one or more of calcium chloride, calcium phosphate, calcium nitrate and calcium oxide.
  5. 5. The preparation method of any one of claims 1-4, wherein the phosphating buffer is one or more of manganese carbonate, calcium carbonate, zinc carbonate, a dihydric phosphate-dihydric phosphate system and an acetic acid-acetate dihydric system, and the pH value of the solution in the phosphating process is 2.0-6.0.
  6. 6. The method according to any one of claims 1 to 4, wherein the metal soft magnetic powder is one or more of carbonyl iron powder, reduced iron powder, feSi-based alloy powder, feNi-based alloy powder, amorphous/nanocrystalline powder.
  7. 7. The method according to any one of claims 1 to 4, wherein the surfactant and the surface conditioner for phosphating in the step (1) are added in an amount of 0.1 to 2.0 wt% by weight of the metal soft magnetic powder, and the concentrations of the nitrate, the metal-based phosphate and the phosphating buffer are 0.1 to 5.0 wt% by weight of the metal soft magnetic powder.
  8. 8. The preparation method of the insulating coated magnetic powder is characterized in that the organic reagent in the step (2) is alcohol or acetone, the resin is organic silicon resin, the coupling agent is silane coupling agent, the mass ratio of the insulating coated magnetic powder to the resin to the coupling agent is 100 (1-10) (0.1-2), the compression molding condition is 400 MPa-2000 Mpa, the pressure maintaining condition is 5.5+/-4.5 s, the curing condition is that the temperature is increased to 180+/-20 ℃ for curing, and the heating speed is 1-10 ℃ per minute.
  9. 9. The high-insulation double-inorganic-coated magnetic powder core prepared by the method of any one of claims 1-8.
  10. 10. An inductor characterized by being prepared by using the high-insulation double-inorganic-coated magnetic powder core according to claim 9.

Description

High-insulation double-inorganic-coated magnetic powder core based on buffer regulation and control and preparation method thereof Technical Field The invention relates to the technical field of soft magnetic materials, in particular to a high-insulation double-inorganic-coated magnetic powder core based on buffer regulation and control and a preparation method thereof. Background The magnetic powder core is a novel soft magnetic material which takes metal magnetic powder as a raw material, is coated with an insulating medium on the surface of the powder, and is pressed into a required shape by adopting a powder metallurgy process, and is widely applied to the fields of energy, information, traffic, national defense and the like, such as a power transformer, an inductor, an inverter, a filter and the like. In the extreme service environment of high power and high current, the long-term service reliability of electronic components has become a core requirement for restricting the industrial technology upgrade. As modern electronic equipment continuously iterates to the directions of high power density and high integration level, the exponential increase of the power density and the integration level leads to the gradual complexity of a circuit topology structure, so that the problems of voltage amplitude rising, waveform distortion aggravation and the like are caused, and the current leakage risk and the dielectric breakdown probability of electronic components are obviously increased. Under the background of the industry, the high-power-consumption integrated system brings out more severe technical requirements on the insulation and voltage resistance of core components such as inductors and transformers, so that the application and market of the inductor can be greatly expanded by pertinently improving the insulation performance of the magnetic powder core. The conventional phosphating preparation process is simple and has been widely applied to industrial production, but the film forming mechanism mainly depends on that the concentration of H + at the interface is gradually reduced due to the acid etching of the metal matrix, and the concentration difference between the interface and H + in the reaction solution can cause the cathode reaction to be converted into oxygen absorption corrosion. The oxygen absorption corrosion can cause oxygen concentration difference, the metal matrix below phosphide becomes a primary cell anode, obvious pitting corrosion process occurs, and the change of the H + concentration can cause more pores to be generated between the insulating coating layer and the metal matrix. When the inductor is in a working state, electrons can cause inter-particle insulation failure through pores of the coating layer and form a communicated conductive network, so that the insulation resistance of the magnetic powder core is greatly reduced, the probability of electric breakdown of an insulation medium in the inductor is further remarkably improved, the long-term service reliability of electronic components is seriously affected, and the use requirement in a high-power scene cannot be met. At present, research on improvement of the insulating property of a magnetic powder core in academia and industry mainly focuses on reducing the porosity of a coating layer and improving the uniform compactness of the coating layer by optimizing a coating method so as to further block a conductive path. Patent CN 109794600B optimizes the insulation effect of soft magnetic powder by adding a sodium hydroxide neutralizer into the phosphating solution, but the method cannot dynamically regulate and control the concentration stability of H + of the phosphating solution. Patent CN112289536a proposes to prepare a silicon dioxide coating layer with low porosity on the surface of magnetic powder by sol-gel method, which can also effectively improve insulation property, but has higher production cost, and is not beneficial to industrialized large-scale application. Disclosure of Invention Aiming at the defects in the prior art, the invention adopts the phosphating solution of the combination of the surfactant, the surface regulator for phosphating, the nitrate, the metal-based phosphate and the phosphating buffer to form a double-layer inorganic coating layer of oxide and phosphating layer on the surface of the magnetic powder, reduces the porosity of the coating layer, reduces the breakdown path of the magnetic powder, improves the insulating property of the magnetic powder core, has simple process and is suitable for industrial production. The technical scheme of the invention is as follows: A preparation method of a high-insulation double-inorganic-coated magnetic powder core based on buffer regulation comprises the following steps: (1) The metal-based phosphating treatment, namely fully mixing a surface regulator for phosphating, a surfactant, nitrate, metal-based phosphate and a phosphating buffer with water to p