Magnetic Powder Production via Ferrous Oxide Phase Transition
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Solution Overview
Problem
The existing methods for producing ε-iron oxide result in large variations in particle size, which negatively impact the magnetic properties of the magnetic powder used in recording media.
Innovation Solution
A method involving heat treatment of ferrous oxide particles to produce ε-iron oxide particles with a coefficient of variation not exceeding 30% and a specific ratio of sub-peak to main peak height in the Switching Field Distribution curve, ensuring uniform particle size and improved magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If existing methods (heat treatment of iron oxyhydroxide or reverse micelle method) are used to produce ε-iron oxide, then the magnetic powder can be obtained, but the particle size variation is large which deteriorates magnetic properties
Solution Approach 1:
The patent changes the chemical composition parameters of the starting material from iron oxyhydroxide to ferrous oxide (FeO), and adjusts the heat treatment parameters (temperature range, atmosphere) to produce ε-iron oxide with controlled particle size and uniform distribution, thereby improving both manufacturing precision and magnetic property reliability
Solution Approach 2:
The patent utilizes the phase transition of ferrous oxide to ε-iron oxide through controlled heat treatment, transforming the crystal structure while maintaining particle size uniformity. This phase transition approach enables precise control over the final product's magnetic properties and particle characteristics
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 achieves a magnetic powder with excellent magnetic properties, suitable for high-density recording media, by controlling particle size distribution and maintaining a low sub-peak to main peak ratio, thereby enhancing recording performance.
Implementation Method 1
performing heat treatment on first particles that contain ferrous oxide to prepare second particles that contain ε-iron oxide
Implementation Method 2
performing heat treatment on first particles that contain ferrous oxide to prepare second particles that contain ε-iron oxide
Implementation Method 3
particles containing ε-iron oxide, in which a coefficient of variation represented by the following formula (1) is not more than 30%, and a ratio Y/X of a sub-peak height Y near a zero magnetic field to a main peak height X in an SFD (Switching Field Distribution) curve is not more than 0.5
Data Source
AI summary
A method of producing a magnetic powder includes performing heat treatment on first particles that contain ferrous oxide to prepare 5 second particles that contain ε-iron oxide.