Sm-Fe-N Magnetic Powder Preparation Without Fine Grinding Damage
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Solution Overview
Problem
Current methods for preparing anisotropic Sm2Fe17N3 magnetic alloy powder are inefficient, energy-intensive, and difficult to scale due to the need for fine grinding, which damages the crystalline structure and reduces coercivity and squareness, and are complex in process flow and control of Sm content.
Innovation Solution
A method involving mixing iron powder, samarium oxide, and calcium granules, followed by reductive diffusion and nitriding in a rotating heat treatment furnace with high-temperature-resistant balls to maintain granularity and morphology, simplifying the process and avoiding the need for fine grinding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If traditional reductive diffusion method is used with fine grinding step, then Sm2Fe17N3 magnetic powder can be obtained, but coercivity and square degree are reduced due to damaged crystalline grain surface integrity
Solution Approach 1:
The invention extracts and removes the fine grinding step from the traditional preparation process. By directly obtaining spherical powder particles through controlled precipitation and heat treatment, the method eliminates the need for subsequent fine grinding that would damage the crystalline structure and reduce magnetic properties.
Solution Approach 2:
The invention performs preliminary action by controlling the precipitation and heat treatment processes to directly form spherical particles with appropriate size and structure. This preliminary shaping prevents the need for later mechanical processing that would compromise the crystalline integrity and magnetic performance.
2Manufacturing precision
If mechanical alloying method is used, then Sm2Fe17N3 material can be prepared, but the process requires long-time high-energy ball milling which is low in efficiency and high in energy consumption
Solution Approach 1:
The invention replaces the mechanical alloying system (high-energy ball milling) with a chemical precipitation and heat treatment system. This substitution eliminates the need for long-duration mechanical processing while achieving the same alloy composition control through controlled chemical reactions and phase transformations.
Solution Approach 2:
The invention changes the process parameters from mechanical energy input (ball milling) to chemical and thermal energy input (precipitation and heat treatment). This parameter change enables faster processing with lower energy consumption while maintaining precise composition control through stoichiometric reagent addition.
3Manufacturing precision
If chemical coprecipitation method is used, then anisotropic Sm2Fe17N3 magnetic powder can be obtained without fine grinding, but the process is complex in process flow and difficult in control of Sm content
Solution Approach 1:
The invention merges the precipitation and heat treatment steps into an integrated process flow. By combining these operations and optimizing the sequence, the method simplifies the overall process while maintaining the ability to produce anisotropic magnetic powder without fine grinding.
Solution Approach 2:
The invention changes the control parameters from complex multi-step chemical coprecipitation to controlled precipitation followed by specific heat treatment parameters. This parameter optimization simplifies the process flow while enabling precise control of Sm content through stoichiometric reagent addition and controlled phase transformations.
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 Sm2Fe17N3 magnetic alloy powder with improved coercivity and squareness by optimizing granularity and morphology, enhancing comprehensive magnetic properties while simplifying the process and reducing energy consumption.
Implementation Method 1
performing reductive diffusion heat treatment: placing the mixture into a rotating heat treatment furnace, adding high-temperature-resistant balls to avoid powder sintering, performing vacuumizing to 1×10−2Pa, introducing a reductive diffusion protective gas, heating a furnace body to 850° C.-950° C., and performing heat preservation for 1-3 hours
Implementation Method 2
performing nitriding heat treatment: cooling the furnace body to 400° C.-500° C., performing vacuumizing to 1×10−2Pa, introducing a nitriding protective gas, performing heat preservation for 1-15 hours
Data Source
AI summary
Disclosed are anisotropic samarium-iron-nitrogen magnetic alloy powder and a preparation method therefor. The anisotropic samarium-iron-nitrogen magnetic alloy powder has a chemical formula of Sm2Fe17N3, and has a Th2Zn17 crystal structure. In the alloy powder, the granularity is: D90≤5 μm and D10≥0.5 μm, the average sphericity ≥0.7, the coercivity Hcj≥10 kOe, and the square degree Q≥0.5. The preparation method includes: S1: mixing iron powder, samarium oxide powder and calcium granules uniformly; S2: placing the mixture into a rotating heat treatment furnace, adding high-temperature-resistant balls, performing vacuumizing, introducing a reductive diffusion protective gas, and heating a furnace body; S3: cooling the furnace body, performing vacuumizing, and introducing a nitriding gas; and S4: taking out and separating the cooled powder and balls, washing the powder, and drying the powder in a vacuum environment to obtain the anisotropic samarium-iron-nitrogen magnetic alloy powder.