Hexagonal Ferrite Magnetic Powder Coating for SNR and Durability
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Solution Overview
Problem
Existing magnetic recording media face challenges in achieving simultaneous improvements in signal-to-noise ratio (SNR) and durability, despite the use of hexagonal ferrite magnetic powders with rare earth elements and aluminum hydroxide coatings, which do not provide sufficient durability enhancement.
Innovation Solution
A hexagonal ferrite magnetic powder with controlled average valence of Fe site atoms by incorporating Co and Nb, and adhering aluminum hydroxide on the particle surface, achieving an Al/Fe molar ratio of 0.030 to 0.200, Co/Fe molar ratio of 0.002 to 0.030, and Nb/Fe molar ratio of 0.005 to 0.050, thereby optimizing SNR and durability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If hexagonal ferrite magnetic powder with rare earth element and Bi incorporated and aluminum hydroxide adhered on particle surface is applied, then SNR is improved, but durability is insufficient
Solution Approach 1:
The patent applies parameter changes by precisely controlling the Fe site valence within the range of 3.015 to 3.040 through incorporation of Co and Nb elements with specific molar ratios. This parameter optimization resolves the contradiction by achieving both improved SNR through enhanced magnetic characteristics and improved durability through stabilized particle properties, overcoming the insufficient durability of previous formulations.
Solution Approach 2:
The patent uses composite materials by incorporating multiple elements (Co, Nb, and aluminum hydroxide) into the hexagonal ferrite magnetic powder structure. This composite approach resolves the contradiction by combining the SNR-improving effects of rare earth elements with the durability-enhancing properties of aluminum hydroxide coating and the stabilizing effects of Co and Nb, achieving both high SNR and durability simultaneously.
2Measurement precision
If magnetic layer surface smoothness is increased to improve electromagnetic conversion characteristics, then recording density is improved, but durability during running deteriorates
Solution Approach 1:
The patent applies local quality by providing aluminum hydroxide coating specifically on the particle surface of the magnetic powder. This localized modification resolves the contradiction by maintaining smooth magnetic layer surface for improved electromagnetic conversion characteristics while the aluminum hydroxide coating on particles provides durability enhancement during running, addressing both requirements through localized material properties.
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 magnetic powder significantly enhances the SNR and durability of the magnetic recording medium by stabilizing the magnetic layer's smoothness and electromagnetic conversion characteristics, even after extensive use.
Implementation Method 1
aluminum hydroxide adhered on the particle surface
Implementation Method 2
incorporating Co and Nb and aluminum hydroxide is adhered on the particle surface
Data Source
AI summary
Provided is a hexagonal ferrite magnetic powder for a magnetic recording medium, containing hexagonal ferrite magnetic particles having aluminum hydroxide adhered on the surface thereof, the hexagonal ferrite magnetic powder having an Al/Fe molar ratio of 0.030 to 0.200, a Co/Fe molar ratio of 0.002 to 0.030, and a Nb/Fe molar ratio of 0.005 to 0.050, and having an Fe site valence AFe of 3.015 to 3.040 as calculated by AFe=(3+2×[Co/Fe]+5×[Nb/Fe])/(1+[Co/Fe]+[Nb/Fe]) wherein [Co/Fe] represents the Co/Fe molar ratio and [Nb/Fe] represents the Nb/Fe molar ratio, and preferably having an activation volume Vact of 1400 to 1800 nm3. This magnetic powder simultaneously achieves an increase in magnetic characteristics including SNR of a magnetic recording medium and a further increase in durability thereof.