Powder Magnetic Core Insulation via Oxide Phase Bonding
Solution Overview
Problem
Powder magnetic cores with Fe-based soft magnetic material powders face issues with insufficient insulation properties and rust due to breakage of insulating layers during high-pressure molding, leading to increased eddy-current loss and the need for additional rust prevention treatments.
Innovation Solution
A method involving the use of Fe-M (M: Al or Cr)-based alloy particles bonded via an oxide phase, where the element M is concentrated, involving steps of mixing with a binder, pressing, demolding, processing to remove expansion deformations, and high-temperature oxidation to form an oxide phase for enhanced insulation and rust prevention.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If high-pressure molding is applied to consolidate Fe-based soft magnetic material powder, then the density and mechanical strength of the powder magnetic core are improved, but the insulating layer on alloy particles breaks causing insufficient insulation properties and increased eddy-current loss
Solution Approach 1:
The insulating layer is formed on the alloy particles before the high-pressure molding process. This preliminary formation of the insulating layer protects the particles during subsequent molding, preventing direct metal-to-metal contact and reducing eddy-current loss while still achieving adequate mechanical strength through the binder system.
2Reliability
If the green compact is subjected to machining processing to remove conductive portions, then the surface insulation properties are improved, but plastic deformation occurs causing additional insulating layer breakage and direct particle contact
Solution Approach 1:
The harmful conductive portions are selectively removed from the green compact surface through machining processing. By extracting these problematic areas where direct particle contact occurs, the surface insulation properties are improved without compromising the overall structural integrity, as the removal is targeted and controlled.
3Loss of energy
If an insulating layer is formed on alloy particles to prevent direct contact, then eddy-current loss is reduced, but the insulating layer breaks during molding and additional rust prevention treatments are required
Solution Approach 1:
The insulating layer serves multiple functions simultaneously: it prevents direct metal-to-metal contact between alloy particles during high-pressure molding, reduces eddy-current loss by maintaining electrical insulation, and provides rust prevention by protecting the alloy surface from oxidation. This multi-functionality eliminates the need for separate rust prevention treatments and simplifies the overall manufacturing process.
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 method achieves a powder magnetic core with excellent rust prevention and high insulation properties, reducing eddy-current loss and eliminating the need for separate rust prevention treatments.
Implementation Method 1
a fourth step of subjecting the green compact after the third step to a heat treatment to oxidize surfaces of the Fe-M (M: Al or Cr)-based alloy particles at a high temperature, so that the oxide phase is formed
Data Source
AI summary
A powder magnetic core manufacturing method includes: a first step of mixing a binder with a soft magnetic material powder containing Fe-M (M: Al or Cr)-based alloy particles on which an insulating layer is formed; a second step of filling a pressing die with a mixture obtained through the first step, subjecting the mixture to pressing to obtain a green compact, and slidingly demolding the green compact from the pressing die; a third step of processing the green compact after the second step and removing expansion deformed matter of the alloy particles present in a region of pressing flaws formed on a surface of the green compact during the slidingly demolding; and a fourth step of subjecting the green compact after the third step to heat treatment to oxidize surfaces of the Fe-M (M: Al or Cr)-based alloy particles at high temperature, so that the oxide phase is formed.