Amorphous Powder Magnetic Core Oxide Layer for Low Loss
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Solution Overview
Problem
Existing methods for producing powder magnetic cores with amorphous magnetic powders fail to provide a heat-resistant core with high initial permeability and low iron loss, as they cause crystallization at high temperatures, and existing insulating binders do not adequately form uniform oxide films to maintain insulation and mechanical integrity.
Innovation Solution
A powder magnetic core composed of Fe-based Cr-containing amorphous alloy with specific composition and a production method involving non-oxidizing and oxidizing heat treatments to form a uniform oxide film on the magnetic particle surface, controlling the thickness of oxygen and carbon regions to ensure insulation and mechanical stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If heat treatment is performed at high temperature (approximately 700°C) to convert silicone resin into SiO2 for heat resistance, then heat resistance is improved, but crystallization occurs in amorphous magnetic powder causing magnetic performance degradation
Solution Approach 1:
The patent changes the chemical composition parameters of the amorphous magnetic powder by adding specific amounts of Al (1-5 atomic percent) and Si (1-5 atomic percent). This compositional modification enables the material to withstand heat treatment temperatures of 500-700°C without crystallization, while maintaining amorphous structure and magnetic performance. The altered composition parameters create a more thermally stable amorphous phase.
Solution Approach 2:
The patent creates a composite system combining amorphous magnetic powder with specific alloying elements (Al, Si, Cr, B) and an organic binder. This composite structure provides both the magnetic properties needed and the thermal stability required. The multi-component amorphous alloy forms a stable glassy phase that resists crystallization during heat treatment, enabling simultaneous achievement of heat resistance and magnetic performance.
2Stability of the object's composition
If heat treatment is limited to low temperature (approximately 500°C) to prevent crystallization, then amorphous structure is maintained, but heat resistance is insufficient
Solution Approach 1:
The patent modifies the compositional parameters of the amorphous alloy by incorporating Al (1-5 atomic percent) and Si (1-5 atomic percent), which significantly raise the glass transition temperature and crystallization temperature. This enables the material to maintain its amorphous structure at heat treatment temperatures up to 700°C, thereby achieving both structural stability and enhanced heat resistance simultaneously.
3Reliability
If conventional insulating binders are used, then insulation between particles is achieved, but uniform oxide film formation is insufficient leading to inadequate insulation and mechanical integrity at high temperatures
Solution Approach 1:
The patent introduces Al and Si as intermediary elements that facilitate uniform oxide film formation on the surface of magnetic particles during heat treatment. These elements have high affinity for oxygen and form stable Al2O3 and SiO2 oxides that create a uniform protective layer. This intermediary mechanism ensures consistent insulation properties and mechanical integrity at high temperatures, overcoming the limitations of conventional binder-based insulation.
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 heat-resistant powder magnetic core with low iron loss and high initial permeability, maintaining insulation and mechanical integrity even under high temperatures.
Implementation Method 1
a production method involving non-oxidizing and oxidizing heat treatments to form a uniform oxide film on the magnetic particle surface
Implementation Method 2
the amorphous soft magnetic material constituting the magnetic particle is used after heat treatment to improve the magnetic characteristics (to relieve strain caused by powder compacting, etc.)
Data Source
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AI summary
A powder magnetic core containing a magnetic particle of an Fe-based Cr-containing amorphous alloy and an organic binding substance is provided as a powder magnetic core with a small loss and high initial permeability. When the depth profile of the composition is determined from the surface of the magnetic particle in the powder magnetic core, the depth profile has the following characteristics. (1) An oxygen-containing region with an O/Fe ratio of 0.1 or more can be defined from the surface of the magnetic particle, and the oxygen-containing region has a depth of 35 nm or less from the surface of the magnetic particle. (2) A carbon-containing region with a C/O ratio of 1 or more can be defined from the surface of the magnetic particle, and the carbon-containing region has a depth of 5 nm or less from the surface of the magnetic particle. (3) The oxygen-containing region has a Cr-concentrated portion with a bulk Cr ratio of more than 1.