Nd-Fe-B Magnet Coercivity via Heavy Rare Earth Diffusion

The patent applies local quality by concentrating heavy rare earth elements specifically at the grain boundary phase rather than distributing them throughout the main phase crystal grains. This localized approach allows the heavy rare earth elements to harden the Nd2Fe14B main phase at the grain boundaries where they are most effective, while preventing their harmful effects on the remanence of the bulk material. The grain boundary phase acts as a localized region where the harmful effects are confined.

The patent replaces the complex vapor deposition mechanical system with a simpler direct diffusion method. Instead of using expensive vapor deposition equipment that requires precise control of deposition parameters, the invention uses a straightforward thermal diffusion process where heavy rare earth elements are introduced through the grain boundary phase during aging treatment. This substitution dramatically simplifies the manufacturing system while maintaining effective coercivity improvement.

The patent extracts the heavy rare earth element introduction process from the bulk material treatment and confines it to the grain boundary phase. By taking out the diffusion process and limiting it to the grain boundary region through controlled aging treatment, the method prevents unnecessary deposition on all surfaces that would occur with electrophoretic deposition. This extraction approach eliminates material waste while preserving production efficiency.

The patent replaces the problematic organic solvent-based coating system with a disposable solid lubricant film approach. Instead of using volatile organic solvents that cause inconsistent deposition ratios over time, the invention uses solid lubricants that are applied as thin films and then removed after serving their purpose during diffusion. This disposable approach eliminates the precision problems associated with solvent volatility while maintaining effective heavy rare earth element introduction.

The patent replaces the heat resistant mesh carrier with a direct solid lubricant film copying method. Instead of using a mesh structure that creates gaps and prevents close contact, the invention copies the heavy rare earth elements directly onto the magnet surface through the lubricant film. This copying approach ensures intimate contact between the diffusion source and the magnet surface, eliminating the uniformity problems caused by mesh structures while maintaining high production efficiency.