R-T-B Sintered Magnet Heat Treatment for Coercivity Consistency
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Solution Overview
Problem
R-T-B based sintered magnets experience fluctuations in coercivity (HcJ) due to inconsistent heat treatment times during mass production, especially when using large-sized heat treatment furnaces, leading to variations in magnetic properties depending on the mounting position.
Innovation Solution
A method for manufacturing R-T-B based sintered magnets involving a heat treatment at 450° C. to 470° C. for 4 to 12 hours, with specific compositional ranges of elements like Ga, Cu, and B, to ensure consistent high HcJ and reduced heavy rare-earth element usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If heat treatment is performed in large-sized furnaces during mass production, then productivity is improved, but manufacturing precision deteriorates due to inconsistent heat treatment times and temperature distribution
Solution Approach 1:
The patent applies parameter changes by optimizing the heat treatment temperature range (450-470°C) and time duration (4-12 hours) to achieve stable coercivity. By carefully controlling these parameters within specific ranges, the invention resolves the contradiction between mass production capability and coercivity consistency, allowing large-scale production while maintaining uniform magnetic properties across different positions in the furnace.
2Reliability
If heavy rare-earth elements are added in large amounts to improve coercivity, then magnetic performance is improved, but cost and resource availability deteriorate
Solution Approach 1:
The patent changes the compositional parameters by reducing heavy rare-earth element content to 5% or less while compensating with optimized heat treatment parameters (450-470°C for 4-12 hours). This approach maintains high coercivity through controlled thermal processing rather than relying on large amounts of expensive heavy rare-earth elements, thereby resolving the contradiction between magnetic performance and resource consumption.
Solution Approach 2:
The heat treatment process acts as an intermediary mechanism that enables the patent to achieve high coercivity without excessive heavy rare-earth element addition. By introducing controlled thermal processing as a mediating step, the invention transforms the relationship between composition and magnetic properties, allowing reduced heavy rare-earth content while maintaining performance through microstructural optimization.
3Reliability
If heat treatment time is extended to ensure high coercivity for all positions, then magnetic performance is improved, but production time and energy consumption increase
Solution Approach 1:
The patent optimizes the heat treatment time parameter within the range of 4-12 hours at 450-470°C to achieve the necessary coercivity level. By carefully selecting this time range, the invention ensures adequate treatment for all furnace positions while avoiding excessive duration, thus resolving the contradiction between magnetic performance and production time efficiency.
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 achieves stable high coercivity and suppresses fluctuations in HcJ, ensuring consistent magnetic properties across different positions in large-scale production while minimizing heavy rare-earth element usage.
Implementation Method 1
performing a heat treatment by heating the R-T-B based sintered magnet material at a temperature of 450° C. or higher and 470° C. or lower for 4 hours or more and 12 hours or less
Data Source
AI summary
Disclosed is a method for manufacturing an R-T-B based sintered magnet, which includes the steps of: preparing an R-T-B based sintered magnet material; and performing a heat treatment by heating the R-T-B based sintered magnet material at a temperature of 450° C. or higher and 470° C. or lower for 4 hours or more and 12 hours or less, wherein the R-T-B based sintered magnet material is represented by the formula of: uRwBxGayCuzAlqM (100−u−w−x−y−z−q) T, the content of RH is 5% or less by mass in the R-T-B based sintered magnet, 29.5≤u≤32.0, 0.86≤w≤0.93, 0.2≤x≤1.0, 0.3≤y≤1.0, 0.05≤z≤0.5, 0≤q≤0.1, and a relationship of p<0 is satisfied when p=[B]/10.811×14−[Fe]/55.847−[Co]/58.933.