Rare-Earth Magnet Coating via Slurry Net Belt System
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Solution Overview
Problem
Existing methods for producing rare-earth magnets face challenges in uniformly and efficiently applying a rare-earth compound powder, leading to inconsistent coating thickness, low adhesion, and excessive consumption of precious rare-earth elements, which affects the magnetic properties of the magnets.
Innovation Solution
A method involving a net belt conveyor system with a coating tank that continuously feeds a slurry of rare-earth compound powder onto sintered magnet bodies, allowing for controlled application and drying, ensuring uniform coating and efficient absorption of the rare-earth elements, thereby forming a dense and well-adhered powder coating film.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If the immersion method or spraying method is used to apply rare-earth compound powder, then the coating process is simple to implement, but the coating amount cannot be controlled uniformly and the coating film density is low
Solution Approach 1:
The patent introduces a slurry as an intermediary medium to carry the rare-earth compound powder. The slurry consists of powder dispersed in water or organic solvent with appropriate viscosity, which serves as a mediator between the coating applicator and the magnet surface, enabling controlled and uniform application that neither direct immersion nor spraying can achieve
Solution Approach 2:
The patent controls the viscosity of the slurry within a specific range (10-1000 cP) to optimize coating performance. By adjusting slurry parameters such as powder concentration, solvent type, and viscosity, the coating process achieves both ease of application and precise control over coating amount and film density
2Reliability
If a sufficient coating amount is applied to ensure saturation of coercivity increase, then the magnetic properties are improved, but the consumption of precious rare-earth elements increases unnecessarily
Solution Approach 1:
The patent applies slurry containing rare-earth compound powder in controlled amounts that are sufficient to achieve the desired coercivity increase but not excessive. The slurry formulation and application process are optimized to provide just the right amount of powder for saturation of the coercivity effect, avoiding unnecessary consumption of precious rare-earth elements
Solution Approach 2:
The patent replaces mechanical mixing and application methods with a chemically stabilized slurry system. The slurry maintains stable dispersion of powder particles through proper formulation, allowing for precise delivery and absorption control that reduces waste compared to traditional mechanical application methods
3Loss of substance
If the coating film is made thinner to reduce material consumption, then the rare-earth element usage is optimized, but the adhesion force of the coating film becomes insufficient
Solution Approach 1:
The patent optimizes multiple parameters including slurry viscosity (10-1000 cP), powder particle size distribution, and solvent composition to achieve thin yet strongly adhering coating films. These parameter optimizations ensure that even thin coatings maintain sufficient adhesion force for withstanding subsequent heat treatment and handling
Solution Approach 2:
The patent creates a composite coating structure where rare-earth compound powder particles are embedded in a binder matrix formed by the slurry components. This composite structure provides both the desired thin profile for material efficiency and the mechanical strength for adequate adhesion, as the binder holds the powder particles firmly to the magnet surface
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
This approach enables the production of rare-earth magnets with improved magnetic properties, including increased coercivity, by ensuring uniform and controlled application of the rare-earth compound, reducing waste, and enhancing the workability of the coating process.
Implementation Method 1
a slurry dispersing the powder in a solvent
Implementation Method 2
drying the sintered magnet bodies to remove the solvent of the slurry
Implementation Method 3
heat treated to permit a rare-earth element to be absorbed in the sintered magnet bodies
Implementation Method 4
absorbed and diffused in the sintered magnet bodies
Data Source
AI summary
A coating tank 1 provided with a net belt passage opening is prepared, a slurry obtained by dispersing a rare-earth-compound powder in a solvent is continuously supplied to the coating tank 1 to cause the coating tank 1 to overflow, and a plurality of sintered magnet bodies 10 are arranged on a net belt conveyor 5, continuously conveyed horizontally thereon, and passed through the slurry in the coating tank 1 via the net belt passage opening, to apply the slurry to the sintered magnet bodies. The slurry is subsequently dried to continuously apply the powder to the plurality of sintered magnet bodies. As a result, the rare-earth-compound powder can be uniformly applied to the surfaces of the sintered magnet bodies, and the application operation can be performed extremely efficiently.