Sintered Samarium-Cobalt Magnet With Fluoride Nanocoating for High Resistivity
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Solution Overview
Problem
Samarium-cobalt sintered permanent magnets face challenges in achieving high resistivity and maintaining magnetic properties due to their inherent conductivity and high melting point, which leads to electromagnetic eddy currents and temperature rises, compromising their stability and safety.
Innovation Solution
A method involving high-energy ball milling of fluoride powders to achieve a controlled particle size of 10-200 nm, followed by electrochemical deposition and magnetic field orientation molding, ensures uniform fluoride distribution on the magnet surface, enhancing resistivity while preserving magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If fluoride particles are added to improve resistivity, then resistivity increases, but magnetic properties deteriorate due to agglomeration and excessive fluoride content
Solution Approach 1:
The fluoride is divided into ultra-fine particles with controlled size distribution (1-10 μm range with specific d10, d50, d90 parameters) to prevent agglomeration while maintaining uniform distribution in the magnet matrix, thus improving resistivity without sacrificing magnetic properties
Solution Approach 2:
Fluoride particles are strategically distributed in specific regions of the magnet structure, with controlled concentration gradients and preferential positioning at grain boundaries, to maximize resistivity enhancement while minimizing impact on magnetic performance
2Stability of the object's composition
If heat treatment is applied to distribute fluoride uniformly, then fluoride distribution improves, but magnet performance deteriorates due to unreasonable heat treatment processes
Solution Approach 1:
Fluoride particles are pre-dispersed and uniformly distributed in the alloy matrix before the main sintering process, eliminating the need for subsequent heat treatment to achieve uniform distribution, thus preserving magnet performance while ensuring compositional stability
Solution Approach 2:
The sintering process parameters (temperature, time, atmosphere) are optimized to achieve both uniform fluoride distribution and high magnet performance simultaneously, replacing the need for separate heat treatment steps
3Manufacturing precision
If large crystal grain size is used to maintain squareness, then demagnetizing curve squareness improves, but electromagnetic eddy currents increase causing temperature rise
Solution Approach 1:
Fluoride particles are preferentially distributed at grain boundaries and specific regions within grains, creating local electrical insulation that suppresses eddy currents while maintaining the overall large grain size structure needed for good demagnetizing curve squareness
Solution Approach 2:
The magnet is designed as a composite structure with fluoride particles embedded in the magnetic matrix, creating a multi-phase material that combines the advantages of large grain size (good squareness) with fluoride-induced eddy current suppression (lower temperature rise)
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 effectively increases the resistivity of samarium-cobalt magnets while maintaining their magnetic properties, reducing the adverse effects of fluoride agglomeration and heat treatment issues, resulting in improved in-service stability and safety.
Implementation Method 1
electrochemical deposition
Implementation Method 2
high-energy ball milling
Implementation Method 3
magnetic field orientation molding
Data Source
AI summary
The present invention discloses a high-resistivity sintered samarium-cobalt magnet and a preparation method thereof. According to the present invention, considering the specialty of sintered samarium-cobalt magnetic powder, fluoride or oxide is firstly prepared into nano-powder using high-energy ball milling, and the samarium-cobalt magnetic powder is prepared separately by rolling ball milling or high-speed jet milling, and then a certain electric field is applied in a fluoride suspension to drive the fluoride nano-powder to evenly cover a surface of the samarium-cobalt magnetic powder. The present invention breaks through the technical bottleneck that fluoride/oxide can improve the resistivity of a samarium-cobalt magnet but result in deterioration of the magnetic properties.