Metal Magnet Coating Martens Hardness Impact Resistance
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Solution Overview
Problem
Metal magnets, such as rare earth magnets, face challenges with corrosion and abrasion, particularly when subjected to repeated impact, which conventional coating layers with adjusted Vickers hardness fail to adequately address, leading to insufficient scratch resistance and reduced motor performance over time.
Innovation Solution
A metal magnet with a coating layer having a Martens hardness of 2000 N/mm2 or more and an elastic resilience of 25% or less, which reduces deformation and resilience upon impact, providing excellent scratch resistance and preventing damage from disturbing particles, while maintaining corrosion protection and manufacturing efficiency.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If the Vickers hardness of the coating layer is increased to improve scratch resistance, then the coating layer becomes more resistant to abrasion, but the coating layer becomes more brittle and susceptible to damage from repeated impact
Solution Approach 1:
The invention changes the measurement parameter for hardness from Vickers hardness to Martens hardness, which provides a more accurate assessment of the coating layer's resistance to repeated impact. It also introduces elastic resilience as a new parameter to evaluate the coating's ability to withstand impact without becoming brittle
Solution Approach 2:
The invention uses a composite coating layer structure with a Ni-P alloy base layer and a Ni-B alloy top layer, where each layer has different properties that complement each other, providing both high hardness and good impact resistance
2Reliability
If a coating layer is applied to protect the magnet body from corrosion, then corrosion resistance is improved, but the coating layer may be damaged by repeated impact, exposing the magnet body to corrosion
Solution Approach 1:
The invention applies a corrosion-protective coating layer with specific mechanical properties (high Martens hardness and low elastic resilience) before the magnet is subjected to repeated impact, ensuring that the coating maintains its integrity and continues to protect against corrosion throughout the magnet's service life
Data Source
AI summary
A metal magnet 10 including a magnet body 12 and a coating layer 14 over the magnet body 12, in which the coating layer 14 has a Martens hardness of 2000 N/mm2 or more and an elastic resilience of 25% or less, and a motor including the metal magnet 10.