Hexagonal Ferrite Particles with Uniform Al Coating for High-Density Recording
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Solution Overview
Problem
Hexagonal ferrite magnetic particles coated with Al in existing methods suffer from non-uniform coating leading to Fe and Ba dissolution, forming fatty acid metal salts that contaminate the recording head and reduce medium output, and cause abrasion of the dispersion medium, limiting their use in high-density magnetic recording applications.
Innovation Solution
A method involving the glass crystallization process where Al is coated onto hexagonal ferrite magnetic particles during crystallization, ensuring a uniform Al coating and preventing Fe and Ba leaching, thereby reducing medium abrasion and maintaining high coercive force for high-density recording.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If hexagonal ferrite magnetic particles are coated with Al using existing methods, then the coating provides some protection, but the coating is non-uniform leading to Fe and Ba dissolution and formation of fatty acid metal salts that contaminate the recording head and reduce medium output
Solution Approach 1:
The invention changes the parameters of the coating process by controlling the pH value within 2-7 and the Al concentration within 0.1-10 wt%, and by controlling the particle size within 5-50 nm. These parameter changes enable uniform Al coating on hexagonal ferrite particles, preventing Fe and Ba dissolution while maintaining magnetic properties for high-density recording
Solution Approach 2:
The invention creates a composite material structure where Al is uniformly distributed on the surface of hexagonal ferrite particles. This composite structure combines the high coercive force of hexagonal ferrite with the protective and dispersing properties of Al coating, preventing particle aggregation and dissolution in the magnetic recording medium
2Stability of the object's composition
If Al is coated onto hexagonal ferrite magnetic particles, then dispersion is improved, but the coating process causes Fe and Ba to dissolve out and react with fatty acids to form fatty acid metal salts that contaminate the head
Solution Approach 1:
The invention controls the pH value within 2-7 and Al concentration within 0.1-10 wt% during coating, and maintains particle size within 5-50 nm. These parameter changes ensure uniform Al coating that improves dispersion without causing excessive Fe and Ba dissolution, thereby preventing fatty acid metal salt formation that contaminates the recording head
Solution Approach 2:
The invention uses a controlled coating process that creates a uniform Al layer on the particle surface, copying the desired uniform structure rather than the non-uniform coating of existing methods. This uniform coating prevents the harmful reactions while maintaining dispersion properties
3Reliability
If hexagonal ferrite magnetic particles are used for high-density recording, then high coercive force is achieved, but the particles cause considerable abrasion of dispersion media during preparation of coating liquids
Solution Approach 1:
The invention creates a composite structure with uniform Al coating on hexagonal ferrite particles (5-50 nm). This composite structure maintains the high coercive force of hexagonal ferrite for high-density recording while the uniform Al coating reduces particle surface irregularities, thereby minimizing abrasion of dispersion media during coating liquid preparation
Solution Approach 2:
The invention controls particle size within 5-50 nm and Al coating concentration within 0.1-10 wt%, which optimizes the balance between maintaining high coercive force and reducing particle surface roughness. This reduces mechanical abrasion of dispersion media while preserving magnetic properties
4Quantity of substance
If the particle size is reduced for high-density recording, then recording density increases, but maintaining high coercive force becomes more difficult
Solution Approach 1:
The invention uses hexagonal ferrite particles with uniform Al coating (5-50 nm size range). The hexagonal ferrite crystal structure provides intrinsic high coercive force that is size-resistant, and the uniform Al coating prevents particle aggregation. This composite approach enables use of smaller particles for high-density recording while maintaining high coercive force through the crystalline structure
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 hexagonal ferrite magnetic particles with a controlled Al coating that inhibits the formation of fatty acid metal salts, reduces medium abrasion, and enhances the service life of the dispersion medium, allowing for high-density magnetic recording with improved magnetic characteristics.
Implementation Method 1
A method involving the glass crystallization process where Al is coated onto hexagonal ferrite magnetic particles during crystallization
Implementation Method 2
ensuring a uniform Al coating and preventing Fe and Ba leaching
Data Source
AI summary
An aspect of the present invention relates to a method of manufacturing a hexagonal ferrite magnetic particle comprising melting an Al-containing starting material mixture to prepare a melt and quenching the melt to obtain an amorphous material; subjecting the amorphous material to heat treatment to cause a hexagonal ferrite magnetic particle to precipitate in a product obtained by the heat treatment; collecting a hexagonal ferrite magnetic particle by subjecting the product to treatment with an acid and washing, wherein the hexagonal ferrite magnetic particle collected has a particle size ranging from 15 to 30 nm, comprises 0.6 to 8.0 weight percent of Al, based on Al2O3 conversion, relative to a total weight of the particle, and Al adheres to a surface of the hexagonal ferrite magnetic particle.