Ferrite Sintered Magnet Composition for High Br and HcJ
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Solution Overview
Problem
Existing ferrite sintered magnets face challenges in achieving high residual magnetic flux density (Br) and coercive force (HcJ) with a small amount of Co, while maintaining production stability and cost-effectiveness.
Innovation Solution
A ferrite sintered magnet with a hexagonal M-type structure comprising A, R, Fe, and Co in the atomic ratio A1-xRx(Fe12-yCoy)zO19, where A includes Sr, Ba, or Pb, and R is La or rare earth elements, with specific content ranges for Co, CaO, SiO2, BaO, Al2O3, and Cr2O3 to optimize magnetic properties and production stability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a small amount of Co is used in the ferrite sintered magnet, then cost-effectiveness is improved, but achieving high Br and HcJ becomes difficult
Solution Approach 1:
The patent applies parameter changes by precisely controlling the composition ratios of multiple elements (A, R, Fe, Co) and their oxidation states. By adjusting the atomic ratios within specific ranges and controlling the oxidation environment during sintering, the patent achieves high magnetic performance with reduced Co content. This resolves the contradiction by optimizing the magnetic properties through compositional parameters rather than relying on high Co concentration.
Solution Approach 2:
The patent employs composite materials by combining multiple rare earth elements (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu) with alkaline earth metals (Sr, Ba, Pb) in a ferrite matrix. This multi-element composite structure creates synergistic effects that enhance magnetic properties (Br and HcJ) while reducing the required Co content, thereby resolving the contradiction between low Co usage and high magnetic performance.
2Reliability
If the composition is optimized for high Br and HcJ, then magnetic performance is improved, but production stability may deteriorate
Solution Approach 1:
The patent defines specific ranges for compositional parameters (atomic ratios of A, R, Fe, Co) that balance magnetic performance and production stability. By specifying narrow but achievable ranges for these parameters, the patent ensures that high Br and HcJ can be consistently obtained during mass production, resolving the contradiction between optimized performance and production stability.
Solution Approach 2:
The patent incorporates feedback mechanisms by establishing clear compositional specifications and ranges that can be monitored and controlled during production. The defined parameter ranges serve as feedback criteria to maintain consistency in magnetic properties across production batches, ensuring both high performance and production stability.
3Ease of manufacture
If the Co content is reduced, then cost-effectiveness is improved, but achieving high coercive force (HcJ) becomes difficult
Solution Approach 1:
The patent changes the approach to achieving high HcJ by optimizing the overall compositional parameters rather than relying on high Co content. By adjusting the atomic ratios of A, R, Fe, and Co within specific ranges and controlling the sintering oxidation conditions, the patent achieves high coercive force with reduced Co content, thereby improving cost-effectiveness while maintaining magnetic performance.
Solution Approach 2:
The patent uses a composite material system combining multiple rare earth elements with alkaline earth metals in a ferrite structure. This composite approach creates synergistic magnetic effects that enhance HcJ without requiring high Co content, resolving the contradiction between cost-effectiveness and coercive force achievement.
Data Source
AI summary
To provide a ferrite sintered magnet having a high residual magnetic flux density (Br) and a high coercive force (HcJ), and also able to produce at a low cost. The ferrite sintered magnet includes a hexagonal M-type ferrite including A, R, Fe, and Co in an atomic ratio of A1-xRx(Fe12-yCoy)zO19. A is at least one selected from Sr, Ba, and Pb. R is La only or La and at least one selected from rare earth elements. 0.13≤x≤0.23, 10.80≤(12−y)z≤12.10, and 0.13≤yz≤0.20 are satisfied.