Ionic Liquid Electroplating for NdFeB Magnet Coercivity
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Solution Overview
Problem
Current methods for producing neodymium-iron-boron permanent magnets face challenges in achieving high intrinsic coercive force and magnetic energy product while minimizing the use of heavy rare earth metals, leading to increased production costs and resource depletion.
Innovation Solution
A method involving ionic liquid electroplating to deposit heavy rare earth metals onto the surface of sintered magnets, followed by heat treatment and aging to diffuse these metals into the magnet's intergranular phase, using a specific ionic liquid composition and electroplating conditions to enhance coercive force and magnetic energy product.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heavy rare earth metals are used to increase magnetic energy product and intrinsic coercive force, then magnetic performance is improved, but production cost increases and resource depletion accelerates
Solution Approach 1:
The patent applies local quality by concentrating heavy rare earth metals specifically at the grain boundary phase of the magnet rather than uniformly distributing them throughout the entire magnet structure. This localized approach at the grain boundaries achieves the necessary magnetic performance improvement while minimizing overall heavy rare earth metal consumption.
Solution Approach 2:
The patent uses an ionic liquid as an intermediary medium to enable the electroplating of heavy rare earth metals. The ionic liquid serves as a conductive electrolyte that facilitates the deposition of heavy rare earth metal ions onto the magnet surface, which then diffuse into the grain boundary phase during heat treatment, achieving controlled local enrichment.
2Ease of manufacture
If traditional electrodeposition methods are used with conventional ionic liquids, then heavy rare earth metals can be deposited, but production cost increases due to expensive ionic liquids
Solution Approach 1:
The patent replaces expensive conventional ionic liquids with a cheaper alternative composed of zinc chloride and ethanol. This cost-effective ionic liquid composition maintains the necessary electroplating functionality while significantly reducing production costs, even though it requires careful control of plating conditions.
Solution Approach 2:
The patent changes the fundamental parameters of the ionic liquid system by using zinc chloride-ethanol instead of traditional expensive ionic liquids. This parameter change in composition allows for lower cost operation while still achieving effective heavy rare earth metal deposition through optimized electroplating conditions.
3Reliability
If surface coating methods are used to improve grain boundary, then magnetic performance is enhanced, but additional grinding process is required causing heavy rare earth metal waste
Solution Approach 1:
The patent applies preliminary action by using electroplating to pre-deposit heavy rare earth metals onto the magnet surface before any grinding or finishing operations. The electroplated layer is precisely controlled to form only where needed, and the subsequent heat treatment diffuses these metals into the grain boundary phase, eliminating the need for additional coating and grinding steps that would waste material.
Solution Approach 2:
The patent replaces mechanical coating and grinding processes with electrochemical electroplating followed by thermal diffusion. This substitution of mechanical operations with electrochemical and thermal processes allows for more precise control of heavy rare earth metal distribution and eliminates material waste associated with mechanical grinding.
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 method significantly increases the intrinsic coercive force and magnetic energy product of neodymium-iron-boron magnets while reducing the usage of heavy rare earth metals, improving production efficiency and cost-effectiveness, making it suitable for industrial production.
Implementation Method 1
electroplating a heavy rare earth metal onto a surface of the sintered magnet by using an ionic liquid electroplating process
Implementation Method 2
heat treating the magnet with the coating, so as to diffuse the heavy rare earth metal into the sintered magnet
Data Source
AI summary
The disclosure discloses a method for preparing a permanent magnet material. In this method, an ionic liquid electroplating process is used to electroplate a heavy rare earth metal onto a surface of a sintered magnet to form a magnet with a coating, wherein the sintered magnet has a thickness of 10 mm or less in at least one direction; in the ionic liquid electroplating process, an electroplating solution comprises an ionic liquid, a heavy rare earth salt, a group VIII metal salt, an alkali metal salt and an additive, an anode is a heavy rare earth metal or a heavy rare earth alloy, a cathode is the sintered magnet, an electroplating temperature is 20-50° C., an electroplating time is 15-80 min. The preparation method of the disclosure can improve an intrinsic coercive force of the magnet with low cost and high production efficiency. A utilization rate of heavy rare earth is high.