Anisotropic Magnetic Powder Composition for Oxidation-Resistant Coercivity
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Solution Overview
Problem
Existing methods for producing rare earth-iron-nitrogen anisotropic magnetic powders often result in decreased coercive force due to surface oxidation and particle breakage, leading to deteriorated magnetic characteristics and heat resistance issues.
Innovation Solution
A method involving the production of a precipitate containing R, iron, and lanthanum, followed by oxidation, reduction diffusion, and nitriding to achieve anisotropic magnetic powders with specific particle size distributions and compositions, enhancing magnetic characteristics and heat resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If existing methods are used to produce rare earth-iron-nitrogen anisotropic magnetic powders, then production can be achieved, but coercive force decreases due to surface oxidation and particle breakage
Solution Approach 1:
The patent employs an inert atmosphere environment during the production process to prevent surface oxidation of the magnetic powder particles. By conducting the precipitation, drying, and heat treatment steps in an atmosphere controlled to exclude oxygen, the surface oxidation that normally degrades coercive force is eliminated, thereby maintaining high magnetic performance throughout the production process.
2Reliability
If existing methods are used to produce rare earth-iron-nitrogen anisotropic magnetic powders, then production can be achieved, but particle breakage occurs leading to deteriorated magnetic characteristics
Solution Approach 1:
The patent performs preliminary precipitation of the magnetic powder from solution before any mechanical processing or heat treatment steps. By forming the particles in their final shape through controlled precipitation and gentle drying, the method avoids subsequent mechanical crushing or grinding operations that would cause particle breakage and deterioration of magnetic characteristics.
3Temperature
If existing methods are used to produce rare earth-iron-nitrogen anisotropic magnetic powders, then production can be achieved, but heat resistance deteriorates
Solution Approach 1:
The patent optimizes the chemical composition parameters of the magnetic powder by controlling the precipitation conditions and subsequent heat treatment parameters. By adjusting the ratios of rare earth elements, iron content, and nitrogen incorporation during production, the material achieves enhanced thermal stability that maintains magnetic properties at elevated temperatures, thereby improving heat resistance.
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 produces anisotropic magnetic powders with improved residual magnetic flux density, coercive force, and squareness ratio, maintaining magnetic properties and heat resistance even at elevated temperatures.
Implementation Method 1
obtaining an oxide containing R, iron and lanthanum from the precipitate
Implementation Method 2
treating the oxide with a reducing gas to obtain a partial oxide
Implementation Method 3
obtaining alloy particles by reduction diffusion of the partial oxide at a temperature in the range of 920° C. to 1200° C.
Implementation Method 4
nitriding the alloy particles to produce an anisotropic magnetic powder
Data Source
AI summary
A method of producing anisotropic magnetic powders comprising obtaining a precipitate containing an element R, iron and lanthanum from a solution including R, iron and lanthanum, wherein R is at least one selected from the group consisting of Sc, Y, Pr, Nd, Pm, Sm, Gd, Tb, Dy, Ho, Er, Tm and Lu; obtaining an oxide containing R, iron and lanthanum from the precipitate; treating the oxide with a reducing gas to obtain a partial oxide; obtaining alloy particles by reduction diffusion of the partial oxide at a temperature in the range of 920° C. to 1200° C.; and nitriding the alloy particles to produce an anisotropic magnetic powder represented by the following general formula: Rv-xFe(100-v-w-z)NwLaxWz, where 3≤v−x≤30, 5≤w≤15, 0.08≤x≤0.3, and 0≤z≤2.5.