Soft Magnetic Alloy Powder Crystallization for Low Coercive Force
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Solution Overview
Problem
Existing methods for producing soft magnetic powders, as described in JP-A-2022-175110, do not sufficiently reduce coercive force without impairing production efficiency, leading to variations in magnetic properties.
Innovation Solution
A method involving the production of an amorphous alloy powder with specific composition and particle size, followed by a heat treatment at controlled temperatures and pressures to crystallize the alloy, resulting in a soft magnetic alloy powder with uniform crystal grains and low coercive force.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heat treatment is performed at temperatures below crystallization temperature to reduce defects and anisotropy, then coercive force is reduced, but production efficiency deteriorates and some particles still do not achieve sufficient coercive force reduction
Solution Approach 1:
The patent applies parameter changes by precisely controlling heat treatment temperature (500-600°C) and time (5-60 minutes) to transform the amorphous structure into fine crystal grains (1-30 nm), achieving reliable coercive force reduction while maintaining production efficiency through optimized process parameters
Solution Approach 2:
The patent utilizes phase transitions by heating the amorphous alloy powder through its crystallization temperature range, transforming it from an amorphous phase to a crystalline phase with fine grain structure, thereby achieving the desired magnetic properties while controlling the process for efficient production
2Reliability
If heat treatment temperature is increased to ensure complete crystallization, then coercive force is reliably reduced, but production efficiency deteriorates due to longer processing time and energy consumption
Solution Approach 1:
The patent optimizes the heat treatment temperature parameter to a specific range (500-600°C) that enables complete crystallization and coercive force reduction while minimizing energy consumption and processing time, balancing reliability and energy efficiency
3Stability of the object's composition
If heat treatment time is extended to ensure uniform crystal grain formation, then magnetic property uniformity is improved, but production efficiency deteriorates
Solution Approach 1:
The patent optimizes heat treatment time parameters (5-60 minutes) to achieve uniform crystal grain formation and consistent magnetic properties across all particles, while maintaining production efficiency through carefully controlled processing duration
Solution Approach 2:
The patent performs preliminary preparation by controlling the amorphous alloy powder composition and particle size distribution before heat treatment, ensuring uniform crystal grain formation during heat treatment and reducing the required processing time, thereby improving both uniformity and production efficiency
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 produces a soft magnetic alloy powder with stable magnetic properties, low coercive force, and reduced hysteresis loss, suitable for applications in dust cores and electronic devices.
Implementation Method 1
a heat treatment step of subjecting the amorphous alloy powder to a heat treatment at a temperature of 500° C. or higher and 600° C. or lower to crystallize the amorphous alloy powder
Implementation Method 2
By performing the heat treatment, it is possible to reduce various defects and anisotropy (stress-induced anisotropy) that are introduced during the production of the soft magnetic powder
Data Source
AI summary
A method for producing a soft magnetic alloy powder includes: a step of producing an amorphous alloy powder that has an average particle diameter of 10.0 μm or more and 45.0 μm or less and that is formed of a composition represented by a composition formula FexCuaNbb (Si1-yBy)100-x-a-b, where 0.3≤a≤2.0, 2.0≤b≤4.0, and 72.5≤x<75.5 are satisfied, and y is a number that satisfies f(x)≤y≤0.99, and f(x)=(4×10−34)x17.56; and a step of heating at a temperature of 500° C. or higher and 600° C. or lower to produce a soft magnetic alloy powder containing 30 vol % or more of crystal grains having a crystal grain size of 1.0 nm or more and 30.0 nm or less, and volume resistivity of a green compact is 10.0×10−3 [Ω·cm] or less.