Co-Al Alloyed NdFeB Nanoparticles via Microwave Combustion
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Solution Overview
Problem
Conventional hard magnetic materials, such as Nd—Fe—B, require excessive rare earth elements and fail to achieve predicted magnetic properties due to issues like boron evaporation and temperature gradients in synthesis processes.
Innovation Solution
A microwave-assisted combustion process followed by a reduction diffusion process using boric acid, glycine, and calcium hydride, which reduces amorphous boron requirements, minimizes temperature gradients, and avoids boron hydride evaporation, producing Co, Al alloyed NdFeB nanoparticles with improved magnetic properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional synthesis techniques (melt spinning, ball milling, HDDR) are used to produce Nd-Fe-B magnetic materials, then the materials can be manufactured, but excessive rare earth materials are required and boron evaporation occurs leading to boron deficient phases
Solution Approach 1:
The patent introduces boric acid as an intermediary substance that serves multiple functions: it provides boron source, acts as flux to lower processing temperature, and prevents boron evaporation. The boric acid decomposes to form boron oxide which then reacts with calcium hydride to produce amorphous boron in situ, eliminating the need for excess boron and preventing boron deficient phases.
Solution Approach 2:
The patent changes the chemical form of boron from elemental boron or boron hydride to boric acid. This parameter change allows the boron to be delivered in a non-volatile form that decomposes at lower temperatures, preventing evaporation losses and enabling more precise control of boron content in the final magnetic material.
2Temperature
If conventional heating methods are used in synthesis processes, then materials can be heated, but temperature gradients occur leading to non-uniform heating and reduced magnetic properties
Solution Approach 1:
The patent replaces conventional thermal conduction heating with microwave heating. Microwaves provide volumetric heating throughout the material simultaneously, eliminating temperature gradients and hot spots that occur with conventional surface-to-core heating methods. This results in more uniform phase distribution and improved magnetic properties.
3Quantity of substance
If elemental powder forms of starting materials are used in synthesis, then the magnetic material can be produced, but the process is costly and requires excessive rare earth materials
Solution Approach 1:
The patent changes the starting materials from elemental powders to nitrate salt forms. These salts dissolve in water to form aqueous solutions that can be uniformly mixed and processed. The salt form allows for more precise control of stoichiometry and reduces the need for excess rare earth materials, while also lowering costs through the use of readily available chemical reagents.
Solution Approach 2:
The patent utilizes aqueous solution chemistry to deliver the rare earth elements. By dissolving nitrate salts in water, the rare earth ions are transported in solution form, allowing for uniform distribution and precise control of composition. This hydraulic approach replaces mechanical mixing of powders and enables more efficient use of rare earth materials.
4Use of energy by moving object
If conventional synthesis processes are used, then magnetic materials can be produced, but energy consumption is high due to prolonged heating and multiple processing steps
Solution Approach 1:
The patent utilizes the phase transition of boric acid decomposition and the exothermic reaction between boron oxide and calcium hydride. These phase transitions and chemical reactions provide self-heating that reduces or eliminates the need for external energy input during critical stages of the process, significantly reducing overall energy consumption while maintaining high synthesis efficiency.
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 process results in enhanced magnetic properties, reduced energy consumption, and cost-effectiveness by using salt forms of starting materials, eliminating boron deficient phases, and improving coercivity through efficient heating and removal of non-magnetic by-products.
Implementation Method 1
subjecting the third solution to microwave radiation, thereby forming an first powder of NdFeCoAlB oxides
Implementation Method 2
microwave assisted combustion process
Implementation Method 3
reduction diffusion process
Implementation Method 4
reduction diffusion process
Implementation Method 5
washing the annealed second powder with a solution of ethylenediaminetetraacetic acid
Data Source
AI summary
A process for producing Co, Al alloyed NdFeB nanoparticles, by a microwave assisted combustion process, followed by a reduction diffusion process, includes the steps of: preparing a first solution of boric acid dissolved in 4 N HNO3, dissolving iron nitrate nonahydrate, neodymium nitrate hexahydrate, cobalt nitrate hexahydrate, aluminium nitrate, the first solution in deionized water to form a second solution, adding glycine to the second solution in a molar ratio of 1:1 to form a third solution, subjecting the third solution to microwave radiation, thereby forming an first powder of NdFeCoAlB oxides, mixing the first powder with calcium hydride in a mass ratio of 1:1.1 (NdFeCoAlB oxides:CaH2) to form a second powder, compacted into a powder block, annealing the second powder in a vacuum furnace, washing the annealed second powder with a solution of ethylenediaminetetraacetic acid; and vacuum drying the second powder.