Permanent Magnet Grain Refinement for High-Coercivity Sintering
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Solution Overview
Problem
Existing methods for producing permanent magnets, such as neodymium-iron-boron magnets, face challenges in maintaining high coercivity and remanence, especially at elevated temperatures, due to the expense of adding heavy rare earth elements and the difficulty in processing fine-grained powders which are prone to oxidation.
Innovation Solution
A method involving grain refinement of a magnetic base material, particularly before sintering, to create a fine-grained microstructure, which enhances coercivity without risking material oxidation, using powdered alloys like Nd2Fe14B and incorporating rare-earth-rich phases, along with hydrogen treatment to improve properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If heavy rare earth elements (dysprosium, terbium) are added to increase coercivity, then coercivity is improved, but production cost increases and remanence decreases
Solution Approach 1:
The patent changes the microstructural parameters of the permanent magnet by creating a fine-grained structure with specific grain size distributions and phase distributions. This microstructural parameter change achieves coercivity enhancement without relying on heavy rare earth element addition, thereby avoiding the associated cost increase and remanence reduction.
2Strength
If finer-grained powder is used to create a finer microstructure and increase coercivity, then coercivity is improved, but the base material becomes prone to oxidation and may become unusable
Solution Approach 1:
The patent performs preliminary protective actions by creating a fine-grained microstructure through controlled solidification and heat treatment processes before the material is exposed to oxidizing environments. The microstructural design includes protective phase distributions that prevent oxidation of the fine-grained powder, maintaining material stability while achieving high coercivity.
3Strength
If heat treatment is applied to increase coercivity in sintered permanent magnets, then coercivity is improved to a limited extent, but the improvement is insufficient for high-temperature applications
Solution Approach 1:
The patent implements comprehensive parameter changes during the manufacturing process, including controlled cooling rates, heat treatment temperatures and durations, and alloy composition parameters. These parameter optimizations create a fine-grained microstructure with enhanced coercivity that exceeds the limited improvement achievable by conventional heat treatment alone, making the magnets suitable for high-temperature applications.
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 method allows for the production of permanent magnets with high coercivity and stability, maintaining magnetic flux density and alignment even in opposing magnetic fields, suitable for industrial applications like electric motors, without the drawbacks of using expensive rare earth elements or oxidizing fine-grained powders.
Implementation Method 1
A grain refinement is performed on the raw form. In particular, the raw form is subjected to grain refinement
Implementation Method 2
Subsequently, the raw form is sintered, wherein the permanent magnet is produced
Implementation Method 3
The method is suitable for a powdered magnetic base material formed on the basis of a newly melted alloy... Alternatively or additionally, the method is suitable for recycled magnetic material and/or contaminated recycled magnetic material. In addition, material obtained by means of recycling is preferably alloyed with at least one rare earth element, preferably in powdered form, to improve its properties
Data Source
AI summary
The invention relates to a method for producing a permanent magnet from a magnetic base material, whereinthe magnetic base material is shaped, wherein a raw form is created, whereinthe raw form is subjected to grain refinement, whereinthe raw form is sintered, wherein the permanent magnet is produced.