Ferromagnetic Powder Composition for Soft Magnetic Composites
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Solution Overview
Problem
Existing soft magnetic composite materials face challenges in achieving high strength, high permeability, and low core losses while maintaining mechanical strength and magnetic flux density, often requiring toxic solvents and unfavorable drying procedures, and are sensitive to heat treatment temperatures.
Innovation Solution
A ferromagnetic powder composition with a phosphorous-based inorganic insulating layer and a metal-organic layer, combined with a metallic or semi-metallic particulate compound like bismuth oxide and a lubricant, is compacted at high pressure and heat-treated to enhance mechanical and magnetic properties without using toxic solvents.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Loss of energy
If heat treatment temperature and time are increased to reduce hysteresis loss, then magnetic permeability improves, but the insulating coating deteriorates
Solution Approach 1:
The patent uses a composite coating system consisting of an inorganic insulating layer (e.g., phosphate, oxide, or silicate) combined with an organic polymer layer (e.g., silicone resin, phenol resin, or epoxy resin). This composite structure allows the inorganic layer to provide thermal stability and the organic layer to protect against coating deterioration during heat treatment, enabling hysteresis loss reduction while maintaining coating integrity.
Solution Approach 2:
The patent modifies the chemical composition and physical properties of the insulating coating by selecting specific materials with appropriate glass transition temperatures, decomposition temperatures, and thermal expansion coefficients. These parameter changes enable the coating to withstand higher heat treatment temperatures without deterioration, thus allowing greater reduction of hysteresis loss.
2Loss of energy
If iron powder purity is increased to reduce hysteresis loss, then magnetic properties improve, but manufacturing complexity increases
Solution Approach 1:
The patent extracts and addresses the impurity problem by applying surface coating treatments to the iron powder particles. Instead of requiring extremely high purity iron powder, the coating layers (inorganic and organic) are applied to the particle surfaces to eliminate the negative effects of surface impurities and oxidation, thereby reducing hysteresis loss while maintaining simpler manufacturing processes.
Solution Approach 2:
The insulating coating acts as an intermediary layer between the iron powder core and the external environment. This intermediary layer protects the iron powder from oxidation and surface defects, allowing the use of commercially available iron powder with moderate purity levels while still achieving low hysteresis loss in the final product.
3Loss of energy
If electrical resistivity is increased to reduce eddy current loss, then AC loss decreases, but magnetic permeability is reduced
Solution Approach 1:
The patent applies local quality by creating a thin insulating coating layer on the surface of each iron powder particle. This localized insulation increases electrical resistivity at the particle level to reduce eddy currents, while the bulk magnetic properties of the iron powder core remain largely unchanged, thus maintaining magnetic permeability.
Solution Approach 2:
The patent uses thin film coatings (inorganic oxide or silicate layers combined with organic polymer layers) on the iron powder particles. These thin films provide sufficient electrical insulation to reduce eddy current loss while being thin enough to minimize their impact on the overall magnetic permeability of the composite material.
4Loss of energy
If coating thickness is increased to improve electrical insulation, then eddy current loss decreases, but mechanical strength is reduced
Solution Approach 1:
The patent employs thin film coatings consisting of multiple layers (inorganic layer of 1-10 nm thickness combined with organic polymer layer) on the iron powder particles. These thin films provide adequate electrical insulation to reduce eddy current loss while maintaining thin enough dimensions to preserve the mechanical strength and integrity of the compacted magnetic core.
Solution Approach 2:
The patent uses composite coating structures combining inorganic materials (for electrical insulation) with organic polymers (for mechanical flexibility and adhesion). This composite approach achieves the necessary electrical insulation properties while the organic component maintains mechanical strength and prevents coating brittleness.
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 results in soft magnetic composite components with improved mechanical strength, high permeability, and reduced hysteresis and eddy current losses, allowing for optimal heat treatment without coating deterioration, outperforming commercial references in hysteresis loss reduction.
Implementation Method 1
the surface of the core particles is provided with a first phosphorous-based inorganic insulating layer and at least one metal-organic layer... A high electrical resistivity of the component is desirable in order to minimise the eddy currents
Implementation Method 2
The hysteresis loss (DC-loss)... can be minimized by improving the base powder purity and quality, but most importantly by increasing the temperature and/or time of the heat treatment (i.e. stress release) of the component
Implementation Method 3
The hysteresis loss (DC-loss), which constitutes the majority of the total core losses in most motor applications, is brought about by the necessary expenditure of energy to overcome the retained magnetic forces within the iron core component
Implementation Method 4
the SMC material can carry a three dimensional magnetic flux... Soft magnetic materials are used for applications, such as core materials in inductors, stators and rotors for electrical machines
Data Source
AI summary
The present invention concerns a ferromagnetic powder composition comprising soft magnetic iron-based core particles, wherein the surface of the core particles is provided with a first inorganic insulating layer and at least one metal-organic layer, located outside the first layer, of a metal-organic compound having the following general formula: (R1[(R1)x(R2)y(MOn-1)]nR1, wherein M is a central atom selected from Si, Ti, Al, or Zr; O is oxygen; R1 is a hydrolysable group; R2 is an organic moiety and wherein at least one R2 contains at least one amino group; wherein n is the number of repeatable units being an integer between 1 and 20; wherein the x is an integer between 0 and 1; wherein y is an integer between 1 and 2; wherein a metallic or semi- metallic particulate compound having a Mohs hardness of less than 3.5 being adhered to at least one metal-organic layer; and wherein the powder composition further comprises a particulate lubricant. The invention further concerns a process for producing the composition and a method for the manufacturing of soft magnetic composite components prepared from the composition, as well as the obtained component.