Double-Alloy NdFeB Magnet Reducing Heavy Rare Earth Use
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Solution Overview
Problem
The increasing demand for NdFeB rare earth permanent magnetic materials in applications like automobile parts and wind power generation has highlighted the scarcity of rare earth resources, particularly heavy rare earth elements like Dy and Tb, necessitating a method to reduce their utilization while enhancing magnetic properties.
Innovation Solution
A double-alloy approach is employed, where one alloy (A1) contains heavy rare earth elements like Dy, Tb, Ho, and Gd, and another (A2) contains light rare earth elements like La, Ce, Pr, and Nd, with specific mass percentages and elements, followed by coarsely pulverization, powder production, magnetic compaction, and sintering under controlled nitrogen atmospheres to improve magnetic properties and reduce rare earth usage.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heavy rare earth elements (Dy, Tb) are utilized to improve magnetic properties, then coercivity and magnetic performance are enhanced, but resource scarcity and cost increase
Solution Approach 1:
The patent changes the compositional parameters by introducing a double-alloy system with specific rare earth ratios (40-60 at% for first rare earth, 40-60 at% for second rare earth) and controlled element percentages (Co: 0.5-5 at%, B: 0.5-5 at%, Al: 0.5-5 at%, Ga: 0.5-5 at%, Zr: 0.5-5 at%, Cu: 0.5-5 at%). This parameter optimization achieves high coercivity and magnetic performance while reducing dependency on heavy rare earth elements like Dy and Tb.
Solution Approach 2:
The patent employs a composite double-alloy structure combining two different rare earth-based alloys. The first alloy contains rare earth elements (40-60 at%) with Co, B, and other elements, while the second alloy contains different rare earth elements (40-60 at%) with similar additives. This composite approach leverages the synergistic effects of different rare earth elements to achieve improved magnetic properties with reduced heavy rare earth content.
2Reliability
If conventional single-alloy method is used, then manufacturing process is simple, but magnetic property and coercivity are insufficient
Solution Approach 1:
The patent segments the manufacturing process into distinct stages: (1) preparing first and second rare earth-based alloys with specific compositions, (2) coarsely pulverizing each alloy separately, (3) mixing the pulverized alloys, (4) producing powder from the mixture, (5) magnetic compaction, and (6) sintering. This segmentation allows for precise control of each step to optimize magnetic properties while managing process complexity systematically.
Solution Approach 2:
The patent merges two separate alloy systems into a unified double-alloy structure. By combining the first rare earth-based alloy and the second rare earth-based alloy in specific ratios (40-60 at% each), the process achieves synergistic magnetic effects that neither alloy could provide alone, thereby improving overall magnetic performance and coercivity.
3Quantity of substance
If heavy rare earth elements are reduced, then resource scarcity issue is addressed, but magnetic property enhancement becomes difficult
Solution Approach 1:
The patent optimizes compositional parameters by precisely controlling the ratios of rare earth elements (40-60 at% for each type), Co content (0.5-5 at%), B content (0.5-5 at%), and additive elements (Al, Ga, Zr, Cu, each at 0.5-5 at%). This parameter optimization enables the achievement of high coercivity and magnetic performance while minimizing heavy rare earth utilization.
Solution Approach 2:
The patent applies local quality by distributing different rare earth elements and additive elements to specific positions within the alloy structure. The first and second rare earth-based alloys are designed with complementary compositions, where each alloy contributes specific elements that enhance magnetic properties in different regions of the final product, achieving overall performance improvement with reduced heavy rare earth content.
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 effectively decreases the utilization of heavy rare earth elements while enhancing the magnetic properties and coercivity of the magnets, thereby addressing the resource scarcity and improving the performance of rare earth permanent magnetic products.
Implementation Method 1
providing hydrogen adsorption in the vacuum hydrogen pulverization, wherein a hydrogen adsorption temperature is 10 ̃200° C.
Implementation Method 2
detecting a pressure rise rate, then evacuating again to 100 Pa and heating to 600 ̃900° C., keeping the temperature for 2 h, stopping keeping the temperature if the pressure is 5 Pa or 2 h has passed for finishing dehydrogenation
Implementation Method 3
producing powder in a jet mill after mixing
Implementation Method 4
providing magnetic compaction
Implementation Method 5
a sintering process appears after the pressing
Data Source
AI summary
A double-alloy NdFeB rare earth permanent magnetic material and manufacturing method thereof are provided. The method comprises respectively melting an A1 alloy comprising heavy rare earth such as Dy, Tb, Ho and Gd as well as an A2 alloy comprising light rare earth such as La, Ce, Pr and Nd; mixing the A1 alloy and the A2 alloy by a two-dimensional or three-dimensional mixer with a ratio of A1/A2=0˜0.5 under protection of nitrogen; producing powder in a jet mill after mixing; collecting fine powder; putting and mixing the powder and the fine powder in the two-dimensional or three-dimensional mixer; putting into a magnetic field pressing machine for pressing under the protection of the nitrogen after mixing and producing permanent magnetic products by sintering, aging, etc. The present invention can obviously decrease rare earth utilization and increase a magnetic energy product and coercivity of the rare earth permanent magnet.