SmFeN Anisotropic Magnetic Powder Dispersion With Low Oxidation
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Solution Overview
Problem
Existing methods for producing SmFeN-based anisotropic magnetic powder using ceramic media result in higher oxygen content and lower magnetic properties due to chipping and fine particle formation.
Innovation Solution
The production method involves dispersing SmFeN-based anisotropic magnetic powder using resin-coated metal or ceramic media to achieve smaller particle sizes and reduce oxidation, employing a vibration mill and inert gas atmospheres to enhance magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If hard ceramic media is used for grinding SmFeN-based anisotropic magnetic powder, then the powder can be ground, but chipping occurs forming fine particles resulting in higher oxygen content and lower magnetic properties
Solution Approach 1:
The patent introduces a liquid medium as an intermediary between the grinding media and the SmFeN-based magnetic powder. This liquid medium acts as a cushion that absorbs impact energy during grinding, preventing direct hard contact that causes chipping and fine particle formation. The liquid medium also creates a protective environment that reduces oxidation of the powder particles during the grinding process.
2Ease of operation
If ceramic media is used for dispersing the magnetic powder, then the powder can be dispersed, but the oxygen content increases and magnetic properties deteriorate
Solution Approach 1:
The patent employs an inert atmosphere (such as nitrogen or argon gas) during the dispersing process to replace oxygen-containing environments. This inert atmosphere prevents oxidation of the SmFeN-based magnetic powder particles while they are being dispersed, thereby maintaining their magnetic properties. The inert environment is maintained throughout the dispersing operation to ensure no oxygen contact occurs.
3Length of moving object
If grinding is performed to reduce particle size, then smaller particles are obtained, but chipping forms fine particles increasing oxygen content to above 0.75% by mass
Solution Approach 1:
The patent changes the physical state parameters of the grinding environment by introducing a liquid medium and controlling atmospheric conditions. These parameter changes (liquid medium viscosity, atmospheric composition, temperature control) modify the grinding mechanism from direct solid-to-solid contact to a more controlled process that achieves particle size reduction without the harmful chipping effect, thereby keeping oxygen content below 0.75% by mass.
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 produces SmFeN-based anisotropic magnetic powder with excellent magnetic properties and low oxygen content, achieving average particle sizes less than 2.5 μm and oxygen content below 0.75% by mass, suitable for use in bonded and sintered magnets.
Implementation Method 1
dispersing the SmFeN-based anisotropic magnetic powder before dispersing using a resin-coated metal media or a resin-coated ceramic media
Implementation Method 2
employing a vibration mill and inert gas atmospheres to enhance magnetic properties
Implementation Method 3
employing a vibration mill and inert gas atmospheres to enhance magnetic properties
Data Source
AI summary
A method of producing a SmFeN-based anisotropic magnetic powder is provided, the method including preparing a SmFeN-based anisotropic magnetic powder before dispersing comprising Sm, Fe, W, and N, and dispersing the SmFeN-based anisotropic magnetic powder before dispersing using a resin-coated metal media or a resin-coated ceramic media to obtain a SmFeN-based anisotropic magnetic powder. Also provided is a SmFeN-based anisotropic magnetic powder comprising Sm, Fe, W, and N and having an average particle size of less than 2.5 μm, a residual magnetization or of not less than 130 emu/g, and an oxygen content of not higher than 0.75% by mass.