Hexagonal Ferrite Powder Size Control for Thin Radio Wave Absorbers
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Solution Overview
Problem
Thin-film radio wave absorbers containing magnetoplumbite-type hexagonal ferrite powders face challenges with radio wave absorption performance and sheet hardness due to particle size issues, where large particles can cause fractures and small particles deteriorate magnetic properties.
Innovation Solution
A powder of magnetoplumbite-type hexagonal ferrite with a particle size distribution where the mode diameter is between 5 µm and 10 µm, and the difference between D90 and D10 is less than 3.0, ensuring optimal radio wave absorption and sheet hardness, produced through a method involving a liquid phase process with specific metal elements like Sr, Ba, and Ca.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If the particle size of magnetoplumbite-type hexagonal ferrite is increased to improve radio wave absorption performance, then radio wave absorption performance improves, but the risk of fracture increases when the thin film is bent or pulled
Solution Approach 1:
The patent applies parameter changes by precisely controlling the particle size distribution parameters (mode diameter between 5-10 μm and (D90-D10)/mode diameter ≤ 3.0) to resolve the contradiction between radio wave absorption performance and sheet hardness. This optimization of size parameters enables the thin film to maintain both excellent radio wave absorption and resistance to fracture.
2Strength
If the particle size of magnetoplumbite-type hexagonal ferrite is decreased to improve sheet hardness, then sheet hardness improves, but magnetic properties deteriorate and radio wave absorption performance decreases
Solution Approach 1:
The patent optimizes the particle size distribution parameters to a specific range (mode diameter 5-10 μm with (D90-D10)/mode diameter ≤ 3.0) that simultaneously ensures excellent magnetic properties for radio wave absorption and sufficient sheet hardness, resolving the contradiction between these two requirements.
3Length of moving object
If a thin film structure is used to reduce the thickness of the radio wave absorber, then the size and weight of the absorber are reduced, but the sheet hardness and resistance to fracture are compromised
Solution Approach 1:
The patent achieves this by optimizing the particle size distribution parameters (mode diameter 5-10 μm and (D90-D10)/mode diameter ≤ 3.0), which enables the magnetic powder to maintain excellent magnetic properties and sheet hardness even when formed into thin films with thickness of 500 μm or less.
4Length of moving object
If a thin film structure is used to reduce the thickness of the radio wave absorber, then the size and weight of the absorber are reduced, but the risk of fracture when bent or pulled increases
Solution Approach 1:
The patent optimizes the particle size distribution parameters (mode diameter 5-10 μm and (D90-D10)/mode diameter ≤ 3.0) to ensure that even in thin film form, the radio wave absorber maintains high resistance to fracture and does not easily break when bent or pulled.
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 solution provides a radio wave absorber with excellent radio wave absorption performance and sheet hardness, even in thin-film form, by balancing particle size to minimize both magnetic property degradation and fracture risk.
Implementation Method 1
A radio wave incident to the radio wave absorber including a magnetic material generates a magnetic field in the magnetic material. In a case where the generated magnetic field is reduced to radio wave energy, part of the energy is lost and absorbed.
Implementation Method 2
in a particle size distribution based on number measured by a laser diffraction scattering method
Data Source
AI summary
The powder of the magnetoplumbite-type hexagonal ferrite is an aggregate of particles of a compound represented by Formula (1), and, in a particle size distribution based on number measured by a laser diffraction scattering method, in a case where a mode value is defined as a mode diameter, a diameter at a cumulative percentage of 10% is defined as D10 and a diameter at a cumulative percentage of 90% is defined as D90, the mode diameter is equal to or greater than 5 µm and less than 10 µm and an expression of (D90 - D10)/mode diameter ≤ 3.0 is satisfied. In Formula (1), A represents at least one metal element selected from the group consisting of Sr, Ba, Ca, and Pb, and x satisfies 1.5 ≤ x ≤ 8.0. A Fe(12-x)AlxO19 ··· Formula (1)