Hexagonal Ferrite Powder for High-Density Magnetic Recording
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Solution Overview
Problem
Magnetic recording media face challenges in achieving high-density recording while maintaining good electromagnetic characteristics, as reducing particle size in hexagonal ferrite powder leads to deteriorated electromagnetic performance, especially when reproducing high-density signals.
Innovation Solution
Developing hexagonal ferrite powder with an average particle size ranging from 10 nm to 50 nm, characterized by a switching field distribution (SFD) of 0.80 or less at 23°C and a ratio of SFD at -190°C to SFD at 23°C greater than 0.80, which enhances electromagnetic characteristics by maintaining signal output and reducing noise.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If the particle size of hexagonal ferrite powder is reduced to achieve higher density recording, then noise is reduced, but electromagnetic characteristics deteriorate due to a drop in output
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size of hexagonal ferrite powder within the range of 10 nm to 50 nm, and by controlling the switching field distribution parameters (SFD23°C ≤ 0.80 and SFD-190°C/SFD23°C > 0.80). These parameter optimizations resolve the contradiction by achieving the right balance between small particle size (for noise reduction) and adequate magnetic output (for electromagnetic characteristics).
Solution Approach 2:
The patent uses hexagonal ferrite powder as a composite ferromagnetic material in the magnetic layer, combining it with binder and other components to form a composite magnetic recording medium. This composite structure allows the system to achieve both noise reduction through fine particles and maintained electromagnetic characteristics through the overall composition design.
2Quantity of substance
If the particle size of hexagonal ferrite powder is reduced to achieve higher density recording, then recording density increases, but electromagnetic characteristics deteriorate
Solution Approach 1:
The patent resolves this contradiction by changing the particle size parameter to the optimal range of 10 nm to 50 nm, which is small enough to enable high-density recording but large enough to maintain adequate magnetic output. The switching field distribution parameters are also optimized to ensure electromagnetic characteristics are preserved despite the reduced particle size.
3Reliability
If the switching field distribution is reduced to improve electromagnetic characteristics, then signal output is maintained, but particle size control becomes more difficult
Solution Approach 1:
The patent specifies precise parameter ranges for particle size (10 nm to 50 nm) and switching field distribution (SFD23°C ≤ 0.80, SFD-190°C/SFD23°C > 0.80) that simultaneously achieve both electromagnetic characteristics and manufacturing feasibility. These parameter definitions provide clear manufacturing targets that balance performance requirements with production capabilities.
Data Source
AI summary
Hexagonal ferrite powder has an average particle size falling within a range of 10 nm to 50 nm, a switching field distribution SFD23° C. measured at a temperature of 23° C. that is less than or equal to 0.80, and a ratio of a switching field distribution SFD−190° C. that is measured at a temperature of −190° C. to the SFD23° C. (SFD−190° C./SFD23° C.) that is greater than 0.80.