NdFeB Magnet Coated with Magnetic Phosphide for Heat Resistance
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Solution Overview
Problem
Nd—Fe—B-based permanent magnets face challenges with corrosion, heat resistance, and magnetic property deterioration due to oxidation and exposure to high-temperature environments, particularly in applications like vehicles and elevators, where existing protective layers are either ineffective or costly.
Innovation Solution
A permanent magnet with a base magnet structure of rare-earth and transition elements, coated with a magnetic compound layer containing phosphorus and metals like iron, cobalt, or nickel, which provides improved corrosion resistance, heat resistance, and maintains magnetic properties even at elevated temperatures.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If a heavy rare earth element such as dysprosium or terbium is used to maintain magnetic force at high temperatures, then heat resistance is improved, but manufacturing cost increases
Solution Approach 1:
The patent applies local quality by concentrating heavy rare earth elements only at the grain boundaries of the Nd-Fe-B permanent magnet through diffusion heat treatment, rather than uniformly distributing them throughout the entire magnet. This localized approach maintains heat resistance at the critical grain boundary regions while significantly reducing the overall amount of expensive heavy rare earth elements required, thereby lowering manufacturing costs.
Solution Approach 2:
The patent creates a composite structure by combining Nd-Fe-B base material with heavy rare earth element-coated grain boundaries. This composite approach allows the base magnet to provide strong magnetic properties while the grain boundary regions provide heat resistance, achieving both performance goals without requiring heavy rare earth elements throughout the entire magnet structure.
2Object-affected harmful factors
If a phosphate film is formed on the surface of the permanent magnet as a protective layer, then corrosion resistance is improved, but the magnetic force deteriorates due to pinholes in the coating
Solution Approach 1:
The patent applies self-service by using the magnetic metal compound coating material itself to fill and seal the pinholes in the phosphate film through a spontaneous infiltration process. The coating material automatically migrates into the pinhole defects during formation, eliminating the need for separate sealing operations and providing both corrosion protection and magnetic force maintenance simultaneously.
Solution Approach 2:
The patent introduces a magnetic metal compound coating layer as an intermediary substance between the phosphate film and the external environment. This intermediate layer serves dual functions: it provides corrosion resistance like the phosphate film while simultaneously filling pinholes to prevent magnetic force deterioration, thereby mediating between the conflicting requirements of corrosion protection and magnetic performance.
3Object-affected harmful factors
If a nonmagnetic protective layer is formed on the surface of the permanent magnet, then oxidation resistance is improved, but magnetic performance deteriorates
Solution Approach 1:
The patent applies homogeneity by ensuring the magnetic metal compound coating layer has uniform magnetic properties throughout its structure. This homogeneous magnetic coating provides oxidation resistance while maintaining consistent magnetic performance across the entire coated surface, unlike nonmagnetic protective layers that create heterogeneous structures with degraded magnetic properties.
4Ease of manufacture
If resin coating is performed to form a protective layer on the permanent magnet, then ease of manufacture is improved, but sufficient corrosion resistance and heat resistance cannot be secured
Solution Approach 1:
The patent applies parameter changes by transforming the protective layer from an organic resin coating to an inorganic magnetic metal compound coating. This parameter change in material composition provides superior corrosion resistance and heat resistance while maintaining manufacturing feasibility through established coating processes, thereby improving both protective performance and thermal stability.
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 enhances the magnetic properties, corrosion resistance, and heat resistance of the permanent magnet, reducing the need for expensive rare earth elements and improving manufacturing cost competitiveness while maintaining high performance.
Implementation Method 1
a coating layer coated on the surface of the base magnet. The coating layer may include a compound including a magnetic metal, and the compound may include phosphorus (P) and one selected from the group consisting of iron (Fe), cobalt (Co) and nickel (Ni)
Implementation Method 2
An Nd—Fe—B-based permanent magnet may be easily oxidized through contact with air, and thus the magnetic force thereof may be reduced. Therefore, plating and coating treatment may be performed on the surface of the permanent magnet in order to form a protective layer on the surface of the permanent magnet
Implementation Method 3
since a permanent magnet may be heated to 200° C. to 300° C. or more in the process of manufacturing motors or in the operating environment thereof, the permanent magnet is required to exhibit excellent heat resistance even though it is exposed to heat for a short period of time
Data Source
AI summary
A permanent magnet of an embodiment comprises: a base magnet represented by a-b-c (a includes a rare earth-based element, b includes a transition element, and c includes boron (B)); and a coating layer coated on a surface of the base magnet, wherein the coating layer comprises a compound containing a metal having magnetism, the compound including: a phosphor (P); and a metal belonging to the fourth period in the periodic table.