Nanocrystal Powder Core Curing Below Crystallization Temperature

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Solution Overview

Problem

Existing methods for manufacturing powder cores require high-temperature heat-treatment, leading to uneven nanocrystal formation, excessive compound formation, and deterioration of magnetic properties, as well as limitations in binder selection and coil wire rod degradation.

Innovation Solution

A method involving heat-treating amorphous soft magnetic alloy powder to form nanocrystals, mixing with a malleable powder, pressure-molding, and curing the binder at a temperature below the crystallization initiation temperature to avoid further crystallization, allowing for a uniform nanocrystal structure and improved magnetic properties.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Manufacturing precision

If heat-treatment at relatively high temperature is applied to cause nanocrystallization after pressure-molding, then nanocrystal formation is achieved, but magnetic properties deteriorate and binder selection is restricted

Engineering Contradiction:

Improvenanocrystal formation uniformityVSAvoidmagnetic properties

Core Design Contradiction:

Manufacturing precisionVSReliability

Solution Approach 1:

The patent applies preliminary nanocrystallization heat-treatment to the amorphous soft magnetic alloy powder before pressure-molding to form the green compact. This preliminary action creates a uniform nanocrystal structure in advance, eliminating the need for subsequent high-temperature heat-treatment that would deteriorate magnetic properties and restrict binder selection.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent changes the timing parameter of the nanocrystallization process from post-molding to pre-molding. By controlling the heat-treatment temperature to be below the crystallization initiation temperature of the amorphous soft magnetic alloy powder during binder curing, uniform nanocrystal formation is achieved without the harmful effects of high-temperature post-molding treatment.

Inventive Principle:

Principle #35Parameter changes

2Stability of the object's composition

If heat-treatment at relatively high temperature is applied after pressure-molding, then nanocrystallization occurs, but crystal grains grow roughly and compounds form in large quantities

Engineering Contradiction:

Improvenanocrystal structureVSAvoidcrystal grain uniformity

Core Design Contradiction:

Stability of the object's compositionVSManufacturing precision

Solution Approach 1:

The patent performs nanocrystallization heat-treatment on the amorphous powder before pressure-molding, creating a uniform nanocrystal structure in advance. This preliminary action prevents subsequent high-temperature heat-treatment that would cause rough crystal grain growth and excessive compound formation.

Inventive Principle:

Principle #10Preliminary action

Solution Approach 2:

The patent controls the heat-treatment temperature parameter to remain below the crystallization initiation temperature of the amorphous soft magnetic alloy powder during the binder curing process. This parameter control maintains uniform nanocrystal structure while curing the binder, preventing rough crystal grain growth and excessive compound formation.

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

This approach prevents the deterioration of magnetic properties and coil wire rods, enhances the choice of binders, and achieves a powder core with high magnetic flux saturation density and reduced core loss, while maintaining a uniform nanocrystal structure.

Implementation Method 1

heat-treating an amorphous soft magnetic alloy powder to obtain a nanocrystal powder

Methodology Applied

Scientific EffectCrystallization: Crystallisation

Implementation Method 2

curing the binder by heat-treating the green compact at a temperature which is equal to or higher than the curing initiation temperature of the binder and lower than the crystallization initiation temperature of the amorphous soft magnetic alloy powder

Methodology Applied

Scientific EffectCuring:

Data Source

PatentUS11996224B2Method for manufacturing a powder core, the powder core and an inductor

Publication Date: 2024.05.28 TOKIN CORP

AI summary

This method for manufacturing a powder core is provided with: a step for heat-treating amorphous soft magnetic alloy powder to obtain nanocrystal powder; a step for obtaining granulated powder from nanocrystal powder, malleable powder, and a binder; a step for pressure-molding the granulated powder to obtain a green compact; a step for curing the binder by heat-treating the green compact at a temperature which is equal to or higher than the curing initiation temperature of the binder and lower than the crystallization initiation temperature of the amorphous soft magnetic alloy powder.