Inert Cleaning of Nd2Fe14B Magnet Powder to Prevent Hydrogenation
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Solution Overview
Problem
Conventional methods for manufacturing Nd2Fe14B permanent magnet powder face challenges in controlling grain size and microstructure, leading to adverse effects on magnetic properties due to difficulties in chemical composition and the introduction of impurities during the cleaning process, particularly with the use of aqueous solvents which can cause hydrogenation and side reactions.
Innovation Solution
A cleaning device and method utilizing a vacuum manifold to maintain an inert state and a cleaning solution of NH4NO3 and methanol with zeolite to prevent hydrogenation and minimize side reactions, ensuring the magnet powder remains in an inert environment throughout the cleaning process, thereby preventing damage and improving purity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional cleaning solutions (ultrapure water, dilute acid, alcohol mixture) are used to remove calcium impurities, then cleaning effectiveness is improved, but calcium impurities remain or secondary impurities are introduced or side reactions damage the magnet powder
Solution Approach 1:
The patent uses non-aqueous organic solvents (ether, esters, ketones, hydrocarbons) to create an inert cleaning environment that prevents side reactions with the magnet powder while effectively removing calcium impurities. The inert atmosphere eliminates water-related hydrogenation and oxidation reactions that occur with conventional aqueous cleaning solutions.
Solution Approach 2:
The patent introduces non-aqueous organic solvents as intermediary substances that facilitate the removal of calcium impurities without directly reacting with the magnet powder. These solvents act as mediators between the calcium impurities and the cleaning process, enabling effective cleaning while preserving the integrity of the magnetic material.
2Object-generated harmful factors
If non-aqueous organic solvents are used to prevent side reactions, then hydrogenation is reduced, but the solvents still contain water which can hydrate the magnetic material
Solution Approach 1:
The patent changes the water content parameter of the cleaning solvent to extremely low levels (0.01% or less, preferably 0.001% or less). This parameter change transforms the solvent from conventional organic solvents that contain significant water to ultra-dry solvents that effectively prevent both hydrogenation and hydration of the magnet powder.
Solution Approach 2:
The patent replaces conventional drying methods with molecular sieve-based drying technology. The molecular sieves selectively adsorb water molecules from the organic solvents at the molecular level, achieving ultra-low water content that prevents hydration while maintaining the benefits of non-aqueous solvent cleaning.
3Manufacturing precision
If bottom-up approaches based on chemical reaction are used to manufacture magnet powder, then control over chemical composition is improved, but calcium impurities are introduced requiring extensive cleaning
Solution Approach 1:
The patent applies inert atmosphere cleaning using ultra-dry non-aqueous organic solvents to remove calcium impurities generated during bottom-up manufacturing. This cleaning method effectively eliminates calcium while preventing the formation of hydrated calcium compounds that would be difficult to remove, thereby maintaining the chemical composition control benefits of bottom-up approaches.
Solution Approach 2:
The patent uses molecular sieves as intermediary substances to selectively adsorb and remove trace water and calcium-related impurities from the magnet powder. This intermediary cleaning step preserves the carefully controlled chemical composition achieved through bottom-up manufacturing while eliminating the calcium impurities that necessarily form during the process.
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 solution effectively removes impurities and reduces hydrogenation, resulting in high-purity Nd2Fe14B powder with improved magnetic properties and reduced manufacturing costs by maintaining an inert environment and using zeolite to adsorb moisture and hydrogen, thus minimizing side reactions and enhancing the magnetic material's performance.
Implementation Method 1
a vacuum manifold provided to maintain the magnet powder and the cleaning material contained in the flask in an inert state during cleaning
Implementation Method 2
a cold trap provided to condense the gas sucked into the vacuum pump
Implementation Method 3
using zeolite to adsorb moisture and hydrogen, thus minimizing side reactions
Data Source
AI summary
Provided is a cleaning device for cleaning a magnet powder including: a flask provided to contain the magnet powder and a cleaning material used to clean the magnet powder; and a vacuum manifold provided to maintain the magnet powder and the cleaning material contained in the flask in an inert state during cleaning.Provided is a method for cleaning a magnet powder including a loading operation for loading a magnet powder, a cleaning solution, and zeolite into a flask; a gas injecting operation for injecting an inert gas into the flask; and a vacuum drying operation for drying the magnet powder and the zeolite in a vacuum.Provided is a method for manufacturing a magnet powder including: preparing a primary mixture by mixing neodymium (III) nitrate, boric acid, and iron (III) nitrate nonahydrate; preparing an oxide by heat-treating the primary mixture; removing a residual organic material of the oxide by heat-treating the oxide; preparing a hydrogen-reduced oxide by reacting the oxide, from which the residual organic material is removed, with hydrogen by heat treatment; preparing a secondary mixture by mixing the hydrogen-reduced oxide with calcium; obtaining a product by subjecting the secondary mixture to reduction-diffusion reaction by heat treatment; and obtaining Nd2Fe14B powder by pulverizing the product.