Sintered NdFeB Magnet Diffusion to Prevent Adhesion and Raise Hcj
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Solution Overview
Problem
Existing diffusion processes for sintered neodymium-iron-boron magnets face issues such as fusion and adhesion between the diffusion source and substrate, insufficient improvement in Hcj, difficulty in improving diffusion efficiency, inability to reuse the diffusion source, and inapplicability to larger-sized products.
Innovation Solution
A novel R H< x M 1< y B z alloy, comprising Dy or Tb, Ti, Zr, and Al, is used as a diffusion source with a three-staged heating and cooling mode, and a detachable reaction bucket to enhance Hcj and magnetic energy product, while allowing reuse and application to larger magnets.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If magnets are arranged at intervals during diffusion treatment to prevent adhesion, then appearance quality is improved, but operational efficiency and production efficiency deteriorate
Solution Approach 1:
A boron-containing diffusion source is introduced as an intermediary material between magnets during diffusion treatment. This diffusion source acts as a protective barrier that prevents direct contact and adhesion between magnet surfaces, eliminating the need for spacing arrangements while maintaining appearance quality. The boron-containing material serves multiple functions: preventing adhesion, enabling diffusion treatment, and improving magnetic properties simultaneously.
Solution Approach 2:
The patent combines multiple functions into a single process step: the diffusion source serves both as a protective barrier against adhesion and as the actual diffusion medium for improving magnetic properties. This merging of functions eliminates the need for separate spacing arrangements and enables continuous processing, thereby improving both appearance quality and production efficiency.
2Reliability
If heavy rare-earth elements are used to improve coercivity, then Hcj increases, but Br decreases and costs increase
Solution Approach 1:
The patent applies local quality by concentrating heavy rare-earth elements specifically at the grain boundaries through diffusion treatment, rather than uniformly distributing them throughout the magnet. This localized approach ensures that coercivity is improved at the critical grain boundary regions where magnetic domains interact, while the bulk magnet composition remains optimized for high remanence, thus improving Hcj without significantly reducing Br.
Solution Approach 2:
The patent changes the distribution parameter of heavy rare-earth elements from uniform distribution to localized concentration at grain boundaries. This parameter change is achieved through controlled diffusion processes that transport heavy rare-earth elements to specific regions, thereby improving coercivity through grain boundary strengthening while preserving the overall magnetic properties and reducing the total amount of heavy rare-earth elements required.
3Reliability
If heavy rare-earth elements are used to improve coercivity, then Hcj increases, but production costs increase
Solution Approach 1:
The patent employs a reusable diffusion source that can be recovered and reused multiple times. The boron-containing diffusion source is applied to multiple magnets in sequence, and after use, it can be recovered and reused for subsequent diffusion treatments. This recovering and reuse approach significantly reduces the consumption of expensive heavy rare-earth elements per unit product, thereby lowering production costs while maintaining high coercivity improvements.
Solution Approach 2:
The patent optimizes the concentration and distribution parameters of heavy rare-earth elements through controlled diffusion, achieving effective coercivity improvement with minimal element usage. By precisely controlling the diffusion process parameters (temperature, time, concentration gradients), the patent maximizes the effectiveness of heavy rare-earth elements at grain boundaries while minimizing overall consumption, thus reducing production costs.
4Reliability
If diffusion source is used to improve Hcj, then coercivity increases, but diffusion efficiency is insufficient
Solution Approach 1:
The patent utilizes phase transitions in the boron-containing diffusion source during the diffusion process. The diffusion source undergoes phase changes at specific temperatures that facilitate enhanced element release and diffusion into the magnet substrate. These phase transitions accelerate the diffusion kinetics, improving both the effectiveness of Hcj improvement and the overall diffusion efficiency, thereby reducing processing time and increasing productivity.
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 solution effectively improves Hcj and magnetic energy product, reduces production costs, and enables efficient production of high-performance sintered neodymium-iron-boron magnets with reduced adhesion and increased production efficiency, applicable to larger sizes.
Implementation Method 1
a new process of diffusing rare-earth elements and rare-earth alloys into the sintered neodymium-iron-boron grain boundary to improve the Hcj performance
Implementation Method 2
three-staged heating and cooling mode
Implementation Method 3
three-staged heating and cooling mode
Implementation Method 4
prepared by the procedures of rapid hardening and strip casting, hydrogen decrepitation, jet milling, pressing, sintering
Data Source
AI summary
Disclosed in the present disclosure are a high-performance sintered neodymium-iron-boron magnet and a preparation method therefor. The magnet is prepared by means of diffusion heat treatment, using R1mFenBpM2w as a substrate and the alloy RHxM1yBz as a diffusion source. The present disclosure uses the alloy RHxM1yBz as a diffusion source and adopts a detachable material reaction bucket for diffusion, efficiently producing a cost-effective rare earth permanent magnet. This solves the problems of fusion and adhesion between a diffusion source and a substrate in a diffusion process, increases the Hcj of the sintered neodymium-iron-boron magnet, and solves the problem of improving efficiency in a diffusion process. Furthermore, the diffusion source of the present disclosure can be reused to reduce the production cost of the sintered neodymium-iron-boron magnet and can be applied to a magnet of a large size, and can in particular ensure mass production of a cost-effective sintered neodymium-iron-boron product with a thickness of 8-30 mm in an orientation direction.