NdFeB Sintered Magnet Coating for Stable Grain Boundary Diffusion
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Solution Overview
Problem
Existing methods for manufacturing NdFeB sintered magnets face issues with low binding force between the coating and the magnet, high production costs, and poor process control, which affect coercivity and temperature resistance, making them unsuitable for mass production.
Innovation Solution
A UV-curable powder slurry containing heavy rare earth elements, UV monomer, polymerization inhibitor, and dispersant is applied to the NdFeB matrix, followed by curing and vacuum heat treatment, to enhance the binding force and improve coercivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heavy rare earth powder is mixed with silicone grease and applied to magnet surface, then coating can be applied, but binding force between coating and magnet is low causing coating to be easy to scrape off
Solution Approach 1:
The patent changes the binder material from silicone grease to UV-curable resin, fundamentally altering the chemical and physical parameters of the coating system. This enables the coating to achieve high binding force through UV-induced polymerization, resolving the issue of low adhesion and coating instability.
Solution Approach 2:
The patent replaces the mechanical mixing and adhesion mechanism of silicone grease with a photochemical curing mechanism. By using UV irradiation to initiate polymerization, the coating transitions from a mechanically bound state to a chemically crosslinked state, dramatically improving binding force and reliability.
2Ease of operation
If organic solvent is used in slurry for grain boundary diffusion, then slurry can be applied, but organic solvent volatilizes at room temperature causing poor process control and product consistency
Solution Approach 1:
The patent replaces volatile organic solvents with UV-curable resin, changing the physical state and volatility parameters of the slurry. The new formulation maintains good applicability while eliminating the volatility issue, enabling precise process control without sacrificing ease of operation.
Solution Approach 2:
The patent converts the potential harm of solvent volatility into a benefit by using a non-volatile UV-curable resin system. The resin remains stable at room temperature during application, then cures upon UV exposure, turning the previously problematic volatility into a controlled curing mechanism that improves both ease of operation and manufacturing precision.
3Strength
If magnetron sputtering is used to deposit heavy rare earth coating, then coating has high adhesion, but equipment investment and energy consumption are high leading to high production costs
Solution Approach 1:
The patent replaces expensive, complex magnetron sputtering equipment with a simple UV curing process. The UV-curable resin coating achieves comparable or superior adhesion at a fraction of the equipment investment and operational cost, making the process economically viable for mass production.
Solution Approach 2:
The patent substitutes the complex physical vapor deposition mechanism of magnetron sputtering with a simpler photochemical curing process. This replacement dramatically reduces equipment investment and energy consumption while maintaining high coating adhesion, directly addressing the cost issue.
4Manufacturing precision
If coating is applied for grain boundary diffusion, then coercivity can be improved, but carbon residue from coating material remains after sintering affecting magnet quality
Solution Approach 1:
The patent changes the chemical composition of the coating material from carbon-containing organic solvents to UV-curable resin with controlled carbon content. The resin formulation is specifically designed to minimize carbon residue after diffusion, allowing coercivity improvement while reducing harmful carbon contamination in the final magnet product.
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 ensures stable and uniform coating, reduces production costs, and significantly enhances coercivity while maintaining remanence, making it suitable for mass production.
Implementation Method 1
UV monomer, photoinitiator... cured using UV irradiation
Implementation Method 2
heating the magnet to make the heavy rare earth elements on the magnet surface diffuse into the magnet interior
Data Source
AI summary
A magnet preparation method includes coating powder slurry on at least one of a first surface or a second surface of an NdFeB matrix and carrying out a curing reaction, to obtain a coated magnet, and subjecting the coated magnet to a vacuum heat treatment, a grain boundary diffusion treatment, and an aging treatment. The first surface and the second surface are opposite to each other. The powder slurry includes powder containing heavy rare earth element and UV monomer. The UV monomer includes radical-cured UV monomer. A temperature of the vacuum heat treatment is in a range from 250° C. to 600° C.