Ferrite Sintered Magnet Composition for Thin-Magnet Coercive Force
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Solution Overview
Problem
Ferrite sintered magnets face demagnetization issues when thickness is reduced for miniaturization, leading to concerns about coercive force and magnetic properties, especially at lower temperatures.
Innovation Solution
A ferrite sintered magnet with a magnetoplumbite-type crystal structure, composed of specific rare earth elements and calcium or barium, with controlled boron content and ratios, achieving high coercive force and stability across temperature variations.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If the thickness of ferrite sintered magnets is decreased to diminish installation space, then the installation space is reduced, but the magnet may be demagnetized by the demagnetizing field
Solution Approach 1:
The patent changes the chemical composition parameters of the ferrite magnet by incorporating specific rare earth elements (R) and elements (A such as Ca, Sr, Ba) in controlled ratios defined by equations (1)-(3). This compositional parameter change increases the coercive force HcJ to 4000 Oe or more, allowing thin magnets to resist demagnetizing fields while maintaining reduced thickness for compact installation space
Solution Approach 2:
The patent creates a composite ferrite material system combining multiple elements (rare earth elements R, elements A from Ca/Sr/Ba, and Fe) with specific compositional ratios. This multi-element composite structure enhances the magnetic properties and coercive force, enabling the magnet to maintain high performance even at reduced thickness where demagnetizing effects would normally be problematic
2Reliability
If various elements are added to improve Br and HcJ, then the magnetic properties are improved, but the composition becomes more complex
Solution Approach 1:
The patent systematically controls the compositional parameters within specific ranges defined by equations (1)-(3), where x, y, and m are constrained to optimize magnetic properties. This parameter optimization approach improves Br and HcJ while preventing excessive complexity by establishing clear compositional boundaries and relationships between elements
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 ferrite sintered magnets with enhanced coercive force and temperature stability, enabling miniaturization of motors and generators while maintaining magnetic performance.
Implementation Method 1
a ferrite phase having a magnetoplumbite-type crystal structure
Data Source
AI summary
Provided is a ferrite sintered magnet including a ferrite phase having a magnetoplumbite-type crystal structure. x, y, and m satisfy the following Equations (1), (2), and (3) when composition of the ferrite sintered magnet is represented by R1-xAxFem-yCoy, where R denotes at least one kind of element selected from rare earth elements including Y and A denotes Ca or Ca and elements including at least one kind selected from Sr or Ba. The content of B in the ferrite sintered magnet is from 0.1% to 0.6% by mass in terms of B2O3.0.2≤x≤0.8 (1)0.1≤y≤0.65 (2)3≤m<14 (3)