Rare Earth Magnet Amorphous Surface Layer Corrosion Resistance
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Solution Overview
Problem
Conventional rare earth magnets with protecting layers suffer from insufficient anticorrosive properties due to deterioration of magnetic characteristics and poor adhesion between the magnet body and the protecting layer, leading to corrosion and reliability issues.
Innovation Solution
A rare earth magnet with an amorphous layer formed on the magnet body, which is chemically stable and has a structure that prevents corrosion, combined with a passivation layer for further enhanced protection, ensuring close physical properties and adhesion with the magnet body.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If a protecting layer is formed on the surface of the rare earth magnet to improve anticorrosion property, then corrosion resistance is improved, but the magnetic performance deteriorates due to exposure to high temperature during manufacturing
Solution Approach 1:
The patent changes the physical and chemical parameters of the surface layer by controlling the composition ratio of rare earth elements (specifically increasing Nd content to 8-30 atom%) and heat treatment conditions (temperature range 500-900°C for 1-10 hours). This transforms the surface into a protective oxide layer that resists corrosion while maintaining magnetic properties through precise parameter control
Solution Approach 2:
The patent creates a composite structure consisting of the rare earth magnet body (R-Fe-B based) with a modified surface layer containing oxide phases. The surface layer has a different composition and structure than the bulk material, forming a composite system where the surface layer provides corrosion resistance while the bulk maintains magnetic performance
2Reliability
If a resin protecting layer is formed on the magnet body to improve protection, then corrosion resistance is improved, but the physical properties such as coefficient of thermal expansion differ greatly causing cracks and easy removal
Solution Approach 1:
The patent achieves homogeneity in physical properties by forming a protective layer that is chemically and physically compatible with the magnet body. The surface layer is created from the same rare earth elements as the bulk material through controlled oxidation, ensuring matching thermal expansion coefficients and preventing cracks or delamination
Solution Approach 2:
The patent controls the heat treatment parameters (temperature 500-900°C, time 1-10 hours) and composition (rare earth content 8-30 atom% Nd) to transform the surface into a protective oxide layer with physical properties matched to the bulk magnet material, eliminating the mismatch problem of resin coatings
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 amorphous layer effectively prevents corrosion from oxygen, sulfides, and water, providing excellent anticorrosion properties and maintaining magnetic characteristics, while the passivation layer further improves reliability and resistance in harsh environments.
Implementation Method 1
amorphizing the surface layer of a polycrystal magnet body
Implementation Method 2
bombarding the surface layer of the magnet body with solid particles or particle beams
Implementation Method 3
The amorphous layer is a chemically stable layer against such corrosion factor materials as oxygen, sulfide, water, and chloride
Implementation Method 4
forming a passivation layer on the amorphous layer
Implementation Method 5
chemical conversion treatment of the amorphous layer
Data Source
AI summary
The present invention aims to provide a rare earth magnet having sufficiently excellent anticorrosion property. The rare earth magnet 1 according to the present invention to solve the above problems includes a magnet body 10 containing rare earth elements, a substantial amorphous layer 20 formed on a surface of the magnet body 10, and a protecting layer 30 on a surface of the amorphous layer 20, and the amorphous layer 20 contains material identical to main component elements of magnet material contained in the magnet body 10.