Composite Magnetic Powder Material for Low-Pressure Molding

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Solution Overview

Problem

Existing magnetic materials face challenges in achieving low core loss while maintaining high saturated magnetic flux density, especially when using amorphous powders which require high molding pressures and result in large core losses.

Innovation Solution

A magnetic powder material composition comprising 45-80 wt% amorphous powders and 20-55 wt% crystalline powders, with specific elemental ratios and particle sizes, combined with a thermosetting resin for pressure molding, to achieve low core loss and improved magnetic permeability.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Loss of energy

If amorphous powders are used to reduce coercivity and hysteresis loss, then core loss is improved, but molding pressure becomes excessively high

Engineering Contradiction:
Improvecore lossVSAvoidmolding pressure
Core Design Contradiction:
Loss of energyVSStress or pressure

Solution Approach 1:

The invention uses a composite magnetic powder material consisting of amorphous magnetic powder (40-70 wt%) and crystalline magnetic powder (30-60 wt%). The amorphous powder provides low coercivity and reduced hysteresis loss, while the crystalline powder facilitates easier molding at lower pressures. This composite structure resolves the contradiction by combining the advantages of both material types.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

The invention optimizes the particle size distribution of the magnetic powders, with amorphous powder having a volume average diameter of 5-20 μm and crystalline powder having a volume average diameter of 3-15 μm. By controlling these particle size parameters, the invention achieves both low core loss and reduced molding pressure requirements.

Inventive Principle:
Principle #35Parameter changes

2Quantity of substance

If metallic magnetic material powders are used to achieve high saturated magnetic flux density, then magnetic element performance is improved, but core loss increases

Engineering Contradiction:
Improvesaturated magnetic flux densityVSAvoidcore loss
Core Design Contradiction:
Quantity of substanceVSLoss of energy

Solution Approach 1:

The composite magnetic powder material combines amorphous magnetic powder (providing low core loss through small coercivity) with crystalline magnetic powder (providing high saturated magnetic flux density). This composite approach allows the magnetic element to achieve both high magnetic flux density and low core loss simultaneously.

Inventive Principle:
Principle #40Composite materials

3Manufacturing precision

If high molding pressure is applied to amorphous powders to achieve predetermined density, then molding completeness is improved, but core loss increases

Engineering Contradiction:
Improvemolding densityVSAvoidcore loss
Core Design Contradiction:
Manufacturing precisionVSLoss of energy

Solution Approach 1:

The invention uses a composite of amorphous and crystalline magnetic powders where the crystalline component (30-60 wt%) has better plastic deformability and can be molded at lower pressures. This reduces the molding pressure needed to achieve predetermined density, thereby preventing the generation of large core loss while still achieving complete molding.

Inventive Principle:
Principle #40Composite materials

Solution Approach 2:

By optimizing the particle size parameters (amorphous powder: 5-20 μm volume average diameter, crystalline powder: 3-15 μm volume average diameter) and their ratio, the invention achieves good packing density and molding completeness at lower molding pressures, avoiding the core loss associated with high-pressure molding of pure amorphous powders.

Inventive Principle:
Principle #35Parameter changes

Applied Scientific Principles

This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.

Function Achieved in This Case

The solution enables the production of magnetic elements with reduced core loss and improved productivity, allowing for low-pressure molding and enhanced electrical properties, suitable for compact and efficient high-frequency applications.

Implementation Method 1

A magnetic powder material containing from 45 to 80 wt % of amorphous powders and from 55 to 20 wt % of crystalline powders

Methodology Applied
Scientific EffectMagnetic properties: Magnetism

Implementation Method 2

core loss generated by the raw material of the dust core, substantially 80 to 90% is caused by hysteresis loss

Methodology Applied
Scientific EffectHysteresis loss: Magnetic Hysteresis

Implementation Method 3

containing a thermosetting resin for pressure molding

Methodology Applied
Scientific EffectCuring: Phase Change

Data Source

PatentUS9117582B2Magnetic powder material, low-loss composite magnetic material containing same, and magnetic element using same
Publication Date: 2015.08.25 SUMIDA CORP

AI summary

The present invention provides a material which can be used for low pressure molding, and which has a low core loss while maintaining the characteristic of an amorphous powder that is the high coercive force. It provides a magnetic powder material containing, relative to the weight thereof, amorphous powders of 45 to 80 wt %, crystalline powders of 55 to 20 wt %, and a bonding agent. The magnetic powder material contains, relative to the mass thereof, Si of 4.605 to 6.60 mass %, Cr of 2.64 to 3.80 mass %, C of 0.225 to 0.806 mass %, Mn of 0.018 to 0.432 mass %, B of 0.99 to 2.24 mass %, P of equal to or less than 0.0248 mass %, S of equal to or less than 0.0165 mass %, Co of equal to or less than 0.0165 mass %, and a balance of Fe and inevitable impurities.