NdFeB Magnet Coercivity via Vacuum Heat Treatment
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Solution Overview
Problem
The increasing demand for neodymium-iron-boron rare earth permanent magnetic materials in energy-saving and low-carbon applications has highlighted a shortage of rare earth resources, particularly heavy rare earth elements, necessitating a reduction in their usage while maintaining high coercivity.
Innovation Solution
A method for producing neodymium-iron-boron rare earth permanent magnetic devices involves an alloy smelting process, coarsely pulverization, milling, compaction, and sintering, utilizing a vacuum hydrogen pulverization furnace, jet milling, and vacuum heat treatment to enhance coercivity while minimizing heavy rare earth content.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If heavy rare earth elements are increased to increase coercivity, then magnetic performance is improved, but rare earth resource consumption increases
Solution Approach 1:
The patent changes the chemical composition parameters by introducing specific elements (Co, Nb, Ga, Zr, Cu, V, Ti, Cr, Ni, or Hf) at controlled concentrations (0.1-5.0 wt%) to modify the microstructure and enhance coercivity without relying on heavy rare earth elements. This parameter adjustment allows achieving high magnetic performance while reducing rare earth consumption.
Solution Approach 2:
The patent creates a composite alloy system combining Nd-Fe-B base phase with secondary phases formed by added elements (such as Nd-Al-Co, Nd-Nb-B, or Nd-Ga-B phases). These composite structures provide both high coercivity and reduced heavy rare earth content through synergistic effects of different phases.
2Quantity of substance
If alloy composition is optimized to reduce heavy rare earth content, then resource conservation is achieved, but manufacturing complexity increases
Solution Approach 1:
The patent combines multiple functions into the alloying process itself - element addition, microstructure control, and property optimization are achieved in a single compositional design step. The selected elements simultaneously provide grain boundary formation, coercivity enhancement, and rare earth reduction, simplifying the overall production approach despite compositional complexity.
Solution Approach 2:
The patent applies local quality by concentrating specific elements at grain boundaries rather than uniformly distributing them. Elements like Al, Co, and Nb preferentially segregate to grain boundary regions, creating localized phases that enhance coercivity where needed most, while keeping the bulk composition simpler and reducing overall heavy rare earth requirements.
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 coercivity of rare earth permanent magnets, reducing the required heavy rare earth content and conserving scarce resources, thereby addressing the resource shortage while maintaining high magnetic performance.
Implementation Method 1
heating raw materials of the neodymium-iron-boron rare earth permanent magnetic alloy to be an alloy in a molten state
Implementation Method 2
pouring the alloy in the molten state into a water-cooled mould
Implementation Method 3
pouring the alloy in the molten state into a water-cooled mould under the condition of vacuum or protective atmosphere to form an alloy ingot
Implementation Method 4
a compacted alloy powder is put into a vacuum heat treatment furnace to be heated
Data Source
AI summary
A method for producing neodymium-iron-boron rare earth permanent magnetic materials mainly comprises processes of: alloy smelting, coarsely pulverization, milling, magnetic compaction, sintering, machining, vacuum heat treatment, and etc. Magnetic performance of permanent magnetic devices is increased by improving technologies of hydrogen pulverization, milling by jet mill, and vacuum heat treatment, in such a manner that usage amount of rare earth is decreased. The present invention is applicable in producing rare earth permanent magnetic materials having high performance.