RH Diffusion Process for Sintered R-T-B Magnets
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Solution Overview
Problem
The existing methods for producing sintered R-T-B based magnets using a heavy rare-earth element diffusion process often result in sticking issues between the magnets and the holding members, limiting the number of magnets that can be processed simultaneously due to the need for spacers to control the heavy rare-earth element supply, which obstructs processing efficiency.
Innovation Solution
A method involving the alternate stacking of sintered R-T-B based magnet bodies and RH diffusion sources with a holding member, subjected to a controlled atmosphere of 0.1 Pa to 50 Pa and 800° C. to 950° C. for RH supply-diffusion, followed by a diffusion process at 200 Pa to 2 kPa and 800° C. to 950° C., allowing for deeper diffusion without sticking, thereby increasing processing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If spacers are used to control heavy rare-earth element supply, then sticking between magnets and holding members is prevented, but the number of magnets that can be processed simultaneously is reduced
Solution Approach 1:
The patent removes spacers from the system entirely, extracting the harmful element (spacers) that were causing the contradiction. By eliminating spacers and using direct contact between magnets and holding members, the system prevents sticking through proper material selection and process control rather than physical separation, thereby maximizing processing capacity while maintaining reliability
Solution Approach 2:
The patent introduces a coating layer on the holding member as an intermediary substance that prevents direct harmful interaction between the magnet and holding member surfaces. This coating acts as a mediator that eliminates sticking without requiring spacers, allowing direct contact while preventing adhesion, thus resolving the contradiction between sticking prevention and processing capacity
2Quantity of substance
If heavy rare-earth element RH is replaced with light rare-earth element RL, then remanence Br increases, but coercivity HcJ decreases
Solution Approach 1:
The patent applies local quality by creating a concentration gradient of heavy rare-earth elements within the magnet structure. The surface layer contains higher concentration of heavy rare-earth elements for coercivity enhancement, while the interior maintains light rare-earth element composition for remanence. This spatial differentiation of composition allows simultaneous optimization of both coercivity and remanence properties
Solution Approach 2:
The patent uses partial replacement of light rare-earth elements with heavy rare-earth elements through controlled diffusion. Instead of complete replacement, a specific concentration range is achieved by controlling diffusion time and temperature, allowing optimal balance between coercivity enhancement and remanence maintenance. The diffusion process is stopped at the point where maximum coercivity improvement is achieved without excessive loss of remanence
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
This approach prevents sticking between the magnets and holding members, enabling the simultaneous processing of a larger number of sintered R-T-B based magnet bodies and enhancing productivity by ensuring uniform and efficient heavy rare-earth element distribution within the magnets.
Implementation Method 1
the heavy rare-earth element RH diffuses inside of the sintered R-T-B based magnet bodies 1 while being supplied from the RH diffusion sources 2 onto the surface of the sintered R-T-B based magnet bodies 1
Implementation Method 2
heated to a predetermined temperature within a vacuum atmosphere, thereby vaporizing and depositing the vaporizable metallic material on the sintered R-T-B based magnets
Implementation Method 3
vaporizing and depositing the vaporizable metallic material on the sintered R-T-B based magnets
Data Source
AI summary
[Problem] To provide a highly efficient manufacturing method including an RH supply-diffusion process by which the number of magnets processed at a time can be increased without allowing sintered R-T-B based magnets to stick to holding members.[Solution] A method for producing a sintered R-T-B based magnet including the steps of: forming a stack of RH diffusion sources and sintered R-T-B based magnet bodies by stacking the diffusion sources and the magnet bodies alternately with a holding member having openings interposed; and carrying out an RH supply-diffusion process by loading the stack into a process vessel and creating an atmosphere with a pressure of 0.1 Pa to 50 Pa and a temperature of 800° C. to 950° C. within the process vessel.