NdFeB Magnet Composite Phase Structure for Coercivity and Cost Reduction
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Solution Overview
Problem
The existing methods for manufacturing NdFeB rare earth permanent magnets face challenges such as high cost and scarcity of heavy rare earth elements, complexity in processing, oxidation issues, and reduced magnetic properties due to the use of nanometer oxides, which hinder mass production and application in energy-efficient technologies.
Innovation Solution
A high-performance NdFeB rare earth permanent magnet with a composite main phase structure, where a PR2(Fe1-x-yCoxAly)14B main phase is surrounded by a ZR2(Fe1-w-nCowAln)14B phase without a grain boundary phase, utilizing La and Nd oxide particles in the grain boundary to enhance coercivity and corrosion resistance, and a manufacturing method involving hydrogen decrepitation and jet milling to refine alloy flakes and distribute metal oxides for improved magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If nanometer oxides are added to improve coercivity, then magnetic performance is enhanced, but manufacturing complexity increases and safety risks arise
Solution Approach 1:
The patent replaces expensive and difficult-to-manufacture nanometer oxides with conventional metal oxides that are readily available, safe to handle, and easy to process. This substitution maintains the grain boundary modification function while eliminating the safety hazards and manufacturing complexity associated with nanometer-scale materials.
Solution Approach 2:
The patent changes the particle size parameter of the oxide additives from nanometer scale to conventional micrometer scale. This parameter change makes the oxides safer to handle, easier to manufacture, and simpler to process while still achieving effective grain boundary modification and coercivity enhancement.
2Reliability
If heavy rare earth elements are used to improve magnetic properties, then coercivity increases, but cost increases and resource scarcity becomes a problem
Solution Approach 1:
The patent applies local quality by concentrating heavy rare earth elements specifically at the grain boundaries rather than distributing them uniformly throughout the bulk material. This localized approach maximizes the coercivity enhancement effect while minimizing the total quantity of heavy rare earth elements required.
Solution Approach 2:
The patent creates a composite structure consisting of a light rare earth-based main phase (Nd-Fe-B) with heavy rare earth oxide modifications at the grain boundaries. This composite approach allows the bulk material to maintain good magnetic properties while the grain boundary phase provides coercivity enhancement, reducing overall heavy rare earth content.
3Ease of manufacture
If main phase alloy is molten with low rare earth content, then manufacturing is simplified, but α-Fe production increases and remanence is reduced
Solution Approach 1:
The patent applies preliminary action by adding aluminum to the alloy composition before melting. This preliminary compositional adjustment prevents excessive α-Fe formation during the melting and solidification process, ensuring that the main phase forms with appropriate rare earth content to maintain high remanence while still allowing for simplified melting operations.
4Reliability
If grain boundary phase is modified with nanometer oxides, then coercivity is improved, but oxidation resistance deteriorates and processing becomes difficult
Solution Approach 1:
The patent replaces vulnerable nanometer oxides with more robust conventional metal oxides for grain boundary modification. These conventional oxides provide similar coercivity enhancement benefits while being more resistant to oxidation and easier to process, eliminating the susceptibility issues associated with nanometer-scale oxide particles.
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
Significantly improves magnetic energy product, coercivity, and corrosion resistance while reducing the usage of heavy rare earth elements, making the magnets more suitable for energy conservation, automotive, and wind power applications, and simplifying the manufacturing process for mass production.
Implementation Method 1
utilizing hydrogen decrepitation and jet milling to refine alloy flakes
Implementation Method 2
utilizing hydrogen decrepitation and jet milling to refine alloy flakes and distribute metal oxides
Implementation Method 3
utilizing La and Nd oxide particles in the grain boundary to enhance coercivity
Data Source
AI summary
A NdFeB rare earth permanent magnet with composite main phase and a manufacturing method thereof are provided. In the composite main phase, a PR2(Fe1-x-yCoxAly)14B main phase is the core, ZR2(Fe1-w-nCowAln)14B main phase surrounds a periphery of the PR2(Fe1-x-yCoxAly)14B main phase, and no grain boundary phase exists between ZR2(Fe1-w-nCowAln)14B main phase and the PR2(Fe1-x-yCoxAly)14B main phase, wherein ZR represents a group of rare earth elements in which a content of heavy rare earth is higher than an average content of heavy rare earth in the composite main phase, PR represents a group of rare earth elements in which a content of heavy rare earth is lower than an average content of heavy rare earth in the composite main phase. The manufacturing method includes steps of LR—Fe—B-Ma alloy melting, HR—Fe—B-Mb alloy melting, alloy hydrogen decrepitating, metal oxide micro-powder surface absorbing and powdering, magnetic field pressing, sintering and ageing.