Flaky Magnetic Powder for Rotating Electric Machines
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Solution Overview
Problem
Current soft magnetic materials fail to simultaneously achieve high saturation magnetization, high magnetic permeability, low losses, high thermal stability, and excellent mechanical characteristics, especially at high frequencies, which are essential for efficient rotating electric machines, power semiconductor devices, and high-frequency communication equipment.
Innovation Solution
A pressed powder material composed of flaky magnetic metal particles with specific dimensions and orientations, along with an intercalated phase containing oxygen, carbon, nitrogen, or fluorine, is developed. The flaky particles have a thickness of 10 nm to 100 μm and a length-to-thickness ratio of 5 to 10,000, with a difference in coercivity based on direction, enhancing magnetic permeability and reducing losses.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If conventional soft magnetic materials are used, then saturation magnetization can be achieved, but losses increase at high frequencies
Solution Approach 1:
The magnetic material is divided into fine flaky particles with thickness of 10 nm to 100 μm and length-to-thickness ratio of 5 to 10,000. This segmentation reduces eddy current paths and minimizes electromagnetic losses at high frequencies while maintaining saturation magnetization through the distributed particle structure.
Solution Approach 2:
The invention uses composite flaky particles consisting of magnetic metal phases (Fe, Co, Ni or their alloys) combined with non-magnetic phases (oxides, resins, or organic compounds). This composite structure reduces magnetic losses and improves thermal stability while maintaining high saturation magnetization through the magnetic phase composition.
2Use of energy by moving object
If magnetic permeability is increased, then efficiency improves, but losses increase
Solution Approach 1:
The invention optimizes the aspect ratio (length-to-thickness ratio) of flaky particles to be 5 to 10,000 and controls the volume ratio of magnetic to non-magnetic phases. These parameter changes enable high magnetic permeability while reducing losses by controlling domain wall motion and minimizing eddy current effects through the specific particle geometry.
3Power
If saturation magnetization is increased, then power handling capability improves, but ferromagnetic resonance loss increases
Solution Approach 1:
The invention creates local magnetic anisotropy through the flaky particle morphology and phase distribution. The non-magnetic phases are strategically distributed within and between magnetic particles, creating localized regions that suppress ferromagnetic resonance losses while maintaining high saturation magnetization in the magnetic phases for power handling capability.
4Reliability
If material density is increased, then magnetic properties improve, but mechanical brittleness increases
Solution Approach 1:
The flaky particles are embedded in a resin or organic compound matrix that provides mechanical toughness while the magnetic phases maintain high saturation magnetization. This composite structure reduces brittleness by distributing stress across the flexible polymer matrix while maintaining dense magnetic packing for reliable magnetic properties.
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 material exhibits improved magnetic permeability, reduced losses, and enhanced thermal and mechanical stability, making it suitable for high-frequency applications and complex shapes, while maintaining high saturation magnetization and strength.
Implementation Method 1
the flaky magnetic metal particles having a difference in coercivity on the basis of direction within the flat surface
Data Source
AI summary
A pressed powder material of embodiments is a pressed powder material including a plurality of flaky magnetic metal particles and an intercalated phase, each of the flaky magnetic metal particles having a flat surface and a magnetic metal phase containing at least one first element selected from the group consisting of Fe, Co, and Ni, the flaky magnetic metal particles having an average thickness of from 10 nm to 100 μm and an average value of the ratio of the average length in the flat surface with respect to the thickness of from 5 to 10,000, the intercalated phase existing between the flaky magnetic metal particles and containing at least one second element selected from the group consisting of oxygen (O), carbon (C), nitrogen (N), and fluorine (F), wherein in the pressed powder material, the flat surface is oriented in parallel to a plane of the pressed powder material and has the difference in coercivity on the basis of direction within the plane, the intercalated phase includes an oxide and a resin, the softening temperature of the oxide is higher than the softening temperature of the resin, and the oxide is fixed to at least a portion of the flaky magnetic metal particles.