Rare Earth Magnet Co Plating for Corrosion Resistance
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Neodymium-iron-boron sintered permanent magnets have poor corrosion resistance due to their oxidizable components, leading to issues with electroplating methods that result in uneven coatings and reduced magnetic characteristics, especially at high temperatures.
Innovation Solution
A rare earth magnet based on an R-iron-boron alloy with a Co plating layer formed through electroplating, where the Co content is 98% by weight or more, and the plating layer has a thickness of 10 μm to 45 μm, improving magnetic field to coercive force ratio and high-temperature demagnetization performance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If electroplating is used to form protective layers on sintered permanent magnets, then corrosion resistance is improved, but coating uniformity deteriorates due to edge effect causing 1.5 to 5 times thickness variation between edge and central regions
Solution Approach 1:
The patent changes the electrical parameters during electroplating by applying reverse current after initial plating. This parameter change equalizes the thickness distribution by redistributing metal deposition from edge-heavy to more uniform across the surface, resolving the edge effect problem while maintaining corrosion protection
Solution Approach 2:
The patent employs periodic plating cycles with forward and reverse current applications. This periodic action allows the coating to be built up in controlled stages, with each cycle reducing the thickness gradient between edge and center regions, achieving uniform coating while maintaining protective function
2Reliability
If electroplating is used to form protective layers on sintered permanent magnets, then corrosion resistance is improved, but magnetic characteristics deteriorate at high temperatures
Solution Approach 1:
The patent uses composite plating structures with multiple layers including Ni-Cu-Ni alloy combinations. These composite material structures provide enhanced corrosion resistance while the specific layer composition and thickness are optimized to maintain magnetic properties at elevated temperatures by reducing stress and preventing degradation
Solution Approach 2:
The patent optimizes plating parameters including thickness control (10-45 μm total), composition ratios, and deposition conditions to achieve a balance where the protective function is sufficient while minimizing the impact on magnetic characteristics, particularly at high operating temperatures
3Power
If sintered permanent magnets are used for high energy product and high coercive force, then magnetic performance is improved, but corrosion resistance deteriorates due to oxidizable rare-earth elements Nd and Fe
Solution Approach 1:
The patent introduces electroplated protective layers as intermediary barrier materials between the oxidizable rare-earth magnet material and the environment. These intermediate layers (such as Ni-Cu-Ni combinations) prevent direct oxidation of the Nd and Fe components while allowing the underlying high-performance magnetic material to maintain its energy product and coercive force
Solution Approach 2:
The patent creates a composite structure combining the R-Fe-B magnetic material with protective plating layers. This composite approach allows the magnetic core to provide high power characteristics while the outer protective layers provide corrosion resistance, effectively combining the beneficial properties of different material systems
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 characteristics and corrosion resistance of rare earth magnets, maintaining superior performance even at elevated temperatures, outperforming magnets without plating and those coated with a Ni-Cu-Ni alloy.
Implementation Method 1
a plating layer of the element Co may be formed on a surface of the rare earth magnet by an electroplating method
Implementation Method 2
The plating layer of the element Co may be formed by applying a direct current power source to a Co plating solution and subjecting the rare earth magnet to surface treatment
Data Source
AI summary
A rare earth magnet and a motor including the same are provided. The rare earth magnet is based on an R—Fe—B alloy (R represents at least one rare-earth element comprising Y), wherein a plating layer of the element Co is formed on a surface of the rare earth magnet by an electroplating method.