Hexagonal Ferrite Particle Sintering Prevention
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Solution Overview
Problem
Existing methods for manufacturing hexagonal ferrite magnetic particles, such as coprecipitation and reverse micelle methods, face challenges in achieving finer particles due to sintering and aggregation during calcination, which hinders the production of high-density magnetic recording media.
Innovation Solution
A method involving the calcination of particles coated with a glass component, where the glass component is adhered to particles containing an iron salt and an alkaline earth metal salt, followed by removal of the glass component to inhibit sintering and ensure hexagonal ferrite formation, allowing for the production of microparticulate hexagonal ferrite magnetic particles.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If coprecipitation method is used to manufacture hexagonal ferrite particles, then manufacturing process is simple, but particles sinter and aggregate during calcination making it difficult to obtain finer particles
Solution Approach 1:
The glass component is coated on the particle surface before calcination to prevent sintering during the heating process. This preliminary protective action allows the particles to maintain their fine size throughout the calcination process that would otherwise cause aggregation.
Solution Approach 2:
The glass component acts as an intermediary substance between the particle surfaces, preventing direct contact and sintering during calcination. The glass coating serves as a barrier that mediates the interaction between particles at high temperatures.
2Manufacturing precision
If reverse micelle method is used to manufacture hexagonal ferrite particles, then particle size can be reduced, but particles still sinter and aggregate during calcination
Solution Approach 1:
The glass component is coated on the particle surface before calcination to prevent sintering during the heating process. This preliminary protective action allows the particles to maintain their fine size throughout the calcination process that would otherwise cause aggregation.
Solution Approach 2:
The glass coating changes the surface properties of the particles, providing thermal stability and preventing sintering at calcination temperatures. This parameter change in surface composition enables the particles to withstand high-temperature processing without aggregation.
3Manufacturing precision
If alkaline earth metal compound is used to coat coprecipitate to prevent sintering, then some sintering prevention is achieved, but the effect is not adequate for higher density recording
Solution Approach 1:
The invention changes the material parameter from alkaline earth metal compound to glass component, which provides superior sintering prevention effectiveness. The glass component's compositional flexibility and melting characteristics offer better protection against particle aggregation during calcination.
Solution Approach 2:
The glass component represents a composite material system that combines multiple oxides (such as SiO2, B2O3, Al2O3) to achieve enhanced sintering prevention properties that single-component alkaline earth metal compounds cannot provide.
4Reliability
If excessive glass component coating is applied to particles before calcination, then sintering is prevented, but hematite formation occurs preferentially over ferrite
Solution Approach 1:
The invention optimizes the glass component content parameter to a specific range (0.01-10 wt%, preferably 0.05-5 wt%) to balance sintering prevention with proper phase formation. This precise parameter control ensures enough glass to prevent sintering but not so much as to inhibit ferrite formation.
Solution Approach 2:
The invention incorporates control based on the calcination atmosphere and glass component quantity to feedback-adjust the formation process, ensuring that hexagonal ferrite is the principal component in the XRD pattern while still maintaining sintering prevention.
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
This approach effectively prevents sintering during calcination, enabling the production of hexagonal ferrite magnetic particles with sizes ranging from 10 to 20 nm, suitable for high-density magnetic recording media, by ensuring hexagonal ferrite is the principal component in the calcined product.
Implementation Method 1
coating them with a glass component, and then subjecting them to calcination, it was possible to prevent sintering during calcination
Implementation Method 2
providing hexagonal ferrite magnetic particles by conducting calcination of particles containing an iron salt and an alkaline earth metal salt to cause ferritization
Implementation Method 3
coating them with a glass component
Data Source
AI summary
The method of manufacturing hexagonal ferrite magnetic particles, which includes providing hexagonal ferrite magnetic particles by conducting calcination of particles comprising an alkaline earth metal salt and an iron salt to cause ferritization; and further includes causing a glass component to adhere to the particles and then conducting the calcination of the particles to form a calcined product in which hexagonal ferrite is detected as a principal component in X-ray diffraction analysis; and removing the glass component from a surface of the calcined product that has been formed.