NdFeB Magnet Diffusion Coating for Uniform Coercivity
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Solution Overview
Problem
Existing methods for improving the coercivity of neodymium-iron-boron magnets using heavy rare earth elements result in low hardness and strength, easy scratching, irregular shrinkage, poor diffusion uniformity, and excessive consumption of these elements, leading to property differences between the magnet's surface and center.
Innovation Solution
A method involving a heavy rare earth slurry composed of spherical high-temperature resistant ceramic powder and heavy rare earth diffusion source powder, coated on neodymium-iron-boron magnets, followed by high-temperature diffusion and aging, forms a coating with a basic structure that enhances hardness, prevents shrinkage, and ensures uniform diffusion.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heavy rare earth powder is mixed with antioxidant, adhesive and organic solvent to form a coating, then the coercivity of the magnet is improved, but the coating has low hardness and strength, making it easily scratched and worn
Solution Approach 1:
The patent applies composite materials by combining heavy rare earth diffusion source powder with spherical high-temperature resistant ceramic powder, adhesive, and organic solvent to form a composite coating slurry. The ceramic powder acts as a reinforcement filler that significantly enhances the hardness and strength of the coating while maintaining the heavy rare earth diffusion function, thereby resolving the contradiction between improving coercivity and maintaining coating strength.
2Reliability
If heavy rare earth elements are added to the magnet surface, then the coercivity is improved, but the coating shrinks irregularly during diffusion, causing local loss and accumulation of heavy rare earth elements
Solution Approach 1:
The patent utilizes porous materials by incorporating spherical high-temperature resistant ceramic powder into the coating formulation. This creates a porous or network structure that maintains structural integrity during high-temperature diffusion, preventing irregular shrinkage. The ceramic powder framework stabilizes the coating structure, ensuring uniform diffusion of heavy rare earth elements and preventing local loss or accumulation, thereby improving manufacturing precision.
3Reliability
If heavy rare earth elements are oversupplied during diffusion, then the surface coercivity is improved, but excessive amounts of rare earth elements are consumed and the centre and surface have large differences in properties
Solution Approach 1:
The patent applies local quality by creating a coating where heavy rare earth diffusion source powder is distributed within a ceramic powder matrix. This formulation enables controlled and uniform diffusion of heavy rare earth elements from the surface into the magnet bulk, achieving adequate surface coercivity without oversupply. The ceramic powder framework regulates the diffusion process, ensuring efficient utilization of rare earth elements and reducing both excessive consumption and property differences between surface and centre.
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 improves the coercivity of neodymium-iron-boron magnets by enhancing the coating's hardness and wear resistance, ensuring uniform distribution of heavy rare earth elements, reducing waste, and maintaining magnetic properties across the magnet's surface and center.
Implementation Method 1
subjecting the neodymium-iron-boron magnet coated with the heavy rare earth coating to high-temperature diffusion and aging treatment
Implementation Method 2
drying the heavy rare earth slurry to form a heavy rare earth coating
Implementation Method 3
spherical high-temperature resistant ceramic powder
Data Source
Figure 1~2
AI summary
The present disclosure relates to the technical field of neodymium-iron-boron preparation, in particular to a method for improving the coercivity of a neodymium-iron-boron magnet and a magnet prepared by the method. The method specifically includes: (S1) subjecting a heavy rare earth diffusion source powder, an organic adhesive, a spherical high-temperature resistant ceramic powder and an organic solvent to mixing and stirring to prepare a heavy rare earth slurry; (S2) coating a surface of a neodymium-iron-boron magnet with the heavy rare earth slurry and drying the heavy rare earth slurry to form a heavy rare earth coating; and (S3) performing high-temperature diffusion and aging treatment. According to the method above, the heavy rare earth coating has high hardness and strength. In addition, the neodymium-iron-boron magnet has higher and more uniform properties after diffusion, and less heavy rare earth elements are consumed.