Ceramic-Coated Soft Magnetic Powder for Low Coercive Force
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Solution Overview
Problem
Existing soft magnetic particle powders face issues with increased coercive force due to strain from mechanical energy application, leading to deteriorated magnetic properties and uneven insulating layer thickness, which affects the annealing effect and insulation properties.
Innovation Solution
An insulating material-coated soft magnetic powder with a core particle containing a soft magnetic material like Fe-Si-Cr-Al, an oxide film, and an insulating film with ceramic, where the oxide and ceramic diffuse at the interface, providing improved adhesion and maintaining insulation properties even at high temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If mechanical energy including compression and shearing force is applied to form insulating layer on metal particles, then insulating layer is formed on particle surface, but strain increases inside metal particles causing coercive force to increase and magnetic properties to deteriorate
Solution Approach 1:
The patent introduces an intermediary substance (organic insulating material) that facilitates insulating layer formation without requiring intense mechanical energy. The organic insulating material coats the metal particle surfaces through a gentler process, avoiding the strain-induced coercive force increase while still achieving the necessary insulation between particles.
Solution Approach 2:
The patent changes the formation parameters of the insulating layer by using organic insulating material with specific physical and chemical properties. This allows the insulating layer to form at lower mechanical energy levels, preventing strain accumulation in the metal particles while maintaining adequate insulation for high-temperature processing.
2Object-generated harmful factors
If annealing is performed to reduce strain in metal particles, then strain is reduced, but coercive force increased by mechanical energy application cannot be sufficiently reduced
Solution Approach 1:
The patent applies preliminary action by forming the insulating layer from organic insulating material before annealing. This pre-formed insulating layer protects the metal particles during subsequent thermal processing, allowing strain reduction through annealing while preventing excessive coercive force increase that would otherwise occur during the heating and cooling cycles.
3Reliability
If high annealing temperature is used to achieve sufficient annealing effect, then strain reduction is improved, but insulating layer with uneven film thickness cannot withstand the temperature causing insufficient annealing effect
Solution Approach 1:
The patent changes the material parameters of the insulating layer by using organic insulating material with superior thermal stability and more uniform coating characteristics. This material composition and uniform film thickness enable the insulating layer to withstand higher annealing temperatures without degradation, allowing sufficient strain reduction to be achieved.
4Reliability
If uneven film thickness of insulating layer is present, then insulating property becomes insufficient, but increasing annealing temperature is limited by the insulating layer's inability to withstand high temperature
Solution Approach 1:
The patent changes multiple parameters simultaneously: the material composition (organic insulating material), the film thickness (5-300 nm), and the uniformity of the coating. These parameter optimizations work together to create an insulating layer that provides both sufficient insulation properties and the thermal stability required for high-temperature annealing processes.
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 a soft magnetic powder with low coercive force and high insulation resistance, reducing eddy current loss and enhancing magnetic properties like permeability and flux density, suitable for high-frequency applications.
Implementation Method 1
the oxide contained in the oxide film and the ceramic contained in the insulating film are diffused to each other at an interface between the oxide film and the insulating film
Implementation Method 2
strain is removed by annealing the soft magnetic particle powder at a high temperature
Data Source
AI summary
An insulating material-coated soft magnetic powder includes: a core particle that includes a base portion containing a soft magnetic material containing Fe as a main component and at least one of Si, Cr, and Al, and that includes an oxide film provided on a surface of the base portion and containing an oxide of at least one of Si, Cr, and Al; and an insulating film that is provided on a surface of the core particle and that contains a ceramic, in which a thickness of the insulating film is 5 nm or more and 300 nm or less, and the oxide contained in the oxide film and the ceramic contained in the insulating film are mutually diffused at an interface between the oxide film and the insulating film.