Nd-Fe-B Magnet Aluminum Coating via Multi-Arc Sputtering
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Solution Overview
Problem
Nd-Fe-B permanent magnets are prone to rusting in damp environments due to their composition of rare earth metals, and existing surface treatment methods like electroplating have limitations, particularly when using multi-arc ion coating at high temperatures which can result in a rough aluminum coating.
Innovation Solution
A method involving pre-treatment, multi-arc sputtering with controlled vacuum and gas conditions, arc deposition, and post-coating passivation to apply a uniform aluminum coating on Nd-Fe-B permanent magnets, using a jig and N50 permanent magnet to control arc rotation and distance for efficient coating, followed by dipping in a passivating agent.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If multi-arc ion plating is performed at high temperature, then coating efficiency is improved, but the aluminum coating becomes rough due to low melting point of aluminum
Solution Approach 1:
The patent changes the temperature parameter from high to low (room temperature or lower) during multi-arc ion plating to prevent aluminum melting and maintain coating smoothness. This parameter change resolves the contradiction by sacrificing some coating efficiency to achieve the desired surface quality.
Solution Approach 2:
The patent introduces an intermediary cooling mechanism (cooling plate or cooling gas) between the heat source and the substrate to maintain low temperature during coating. This intermediary allows the coating process to proceed while preventing thermal damage to the aluminum coating.
2Reliability
If aluminum coating thickness is increased to improve corrosion resistance, then rust prevention is enhanced, but coating uniformity and surface quality may deteriorate
Solution Approach 1:
The patent employs continuous rotation of the substrate holder during multi-arc ion plating to ensure uniform coating distribution. This continuous motion prevents localized overheating and ensures even coating thickness, allowing thicker coatings to be applied while maintaining uniformity.
Solution Approach 2:
The patent introduces dynamic motion (rotation and/or oscillation) of the substrate during coating deposition. This dynamic approach ensures uniform heat distribution and coating thickness, enabling thicker coatings to be applied without sacrificing surface quality or uniformity.
3Strength
If pre-treatment steps are added to improve coating adhesion, then coating durability is enhanced, but process complexity increases
Solution Approach 1:
The patent performs preliminary surface treatment (cleaning, degreasing, or plasma treatment) before coating to enhance adhesion. This preliminary action ensures proper surface preparation without requiring complex in-situ treatment systems, resolving the contradiction by using simple pre-processing steps.
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 method provides a smooth, durable aluminum coating that effectively prevents rusting, as demonstrated by improved performance in salt spray and shear force tests, with varying aluminum film thicknesses achieving enhanced corrosion resistance.
Implementation Method 1
Evacuating the multi-arc sputtering equipment with a vacuum system until the pressure reaches 1×10 -2Pa
Implementation Method 2
disposing an aluminum coating on a surface of the Nd-Fe-B permanent magnet by a multi-arc sputtering method
Implementation Method 3
multi-arc sputtering equipment
Implementation Method 4
a N50 grade permanent magnet is placed at the back of the target to control arc rotation within the multi-arc sputtering equipment and adjust a distance between the N50 permanent magnet and the aluminum target
Implementation Method 5
dipping the Nd-Fe-B permanent magnet in a passivating agent after the aluminum coating is disposed on the Nd-Fe-B permanent magnet
Data Source
AI summary
According to the present invention there is provided a method for disposing an aluminum coating on Nd-Fe-B permanent magnets. The method includes the steps of: a) Performing a pre-treatment of the Nd-Fe-B permanent magnets; b) Fixing the Nd-Fe-B permanent magnets on a jig and placing the same in a multi-arc sputtering equipment; c) Evacuating the multi-arc sputtering equipment with a vacuum system until the pressure reaches 1×10-2Pa to 3×10-2Pa, then introducing argon gas until the pressure reaches 1×10-1Pa to 5×10-1Pa, starting bias voltage treatment of the Nd-Fe-B permanent magnets for 1 to 10 minutes at 800V to 1000V; d) Stopping bias voltage treatment and then evacuating the multi-arc sputtering equipment until the pressure reaches 1×10-3Pa to 8×10-3Pa, then refilling argon gas until the pressure reaches 3×10-1Pa to 5×10-1Pa, then starting arc deposition from a target source and maintain a DC current between 50A to 70A, turn on bias voltage and maintain voltage between 100V to 200V, and maintain coating the magnets for 0.5 to 5h; e) Cooling down on 20°C to 100°C and taking out the Nd-Fe-B permanent magnets from the multi-arc sputtering equipment; and f) Dipping the Nd-Fe-B permanent magnets into a passivating agent for 1 to 20 minutes and then rinse with water.