Method for producing Fe-phase-free alpha-Fe16N2 powder through one-step method

The catalytic reaction of nano-scale iron concentrate by pre-oxidation and ammonia-hydrogen mixed gas by a one-step method, solving the problems of low nitriding reaction temperature and incomplete nitriding in the prior art, and achieving efficient preparation of Fe-free phase α″-Fe16N2 Powder improves magnetic properties and production efficiency, and avoids the generation of soft magnetic Fe phase.

CN119284845AActive Publication Date: 2025-01-10CENT SOUTH UNIV
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Patent Information

Application Number
CN202411826810.2
Authority / Receiving Office
CN · China
Patent Type
Applications(China)
Current Assignee / Owner
Filing Date
2024-12-12
Publication Date
2025-01-10
Estimated Expiration
2044-12-12

AI Technical Summary

Technical Problem

The existing reduction-nitriding method prepares α″-Fe16N2 powder with low nitriding reaction temperature, slow nitriding rate, often incomplete nitriding and soft magnetic Fe phase, which affects product performance and reduces temperature after high temperature reduction. Difficult, time-consuming, and it is difficult to preserve intermediate products.

Method used

The Fe-phase-free α″-Fe16N2 powder was prepared by one-step method. By performing surface preoxidation on nano-scale iron concentrate, it can achieve one-step reduction and nitriding at a temperature below 200°C, and catalyzed with ammonia hydrogen mixed gas. The reaction ensures that the nitriding potential energy is always greater than the reduction potential energy and avoids the generation of soft magnetic Fe phases.

Benefits of technology

It realizes efficient preparation of Fe-phase-free α″-Fe16N2 powder under low temperature conditions, improves coercive force and permanent magnet performance, simplifies the production process, improves production efficiency, and avoids the cooling stage. The product structure is Fe4O3 core and α″ -Fe16N2 shell, better magnetic performance.

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Abstract

The invention discloses a method for producing Fe-phase-free alpha ''-Fe16N2 powder through a one-step method, and belongs to the technical field of magnetic materials. The method comprises the steps that iron ore concentrate is subjected to two-stage wet grinding activation to obtain nanoscale iron ore concentrate powder slurry, the nanoscale iron ore concentrate powder slurry is subjected to drying and pre-oxidation treatment to obtain nanoscale iron ore concentrate powder with the surface layer being Fe2O3, then the nanoscale iron ore concentrate powder with the surface layer being Fe2O3 is placed in an ammonia-hydrogen mixed gas environment to be subjected to a reduction-nitridation reaction, and the iron ore concentrate powder with the surface layer being Fe2O3 is obtained. According to the method, the instantaneous high activity of hydrogen reduction iron is better utilized, efficient and sufficient nitridation of iron can be achieved, and compared with an existing conventional technology for preparing alpha ''-Fe16N2 through a reduction-nitridation two-step method, the method has the technical advantages that a product is free of a soft magnetic phase, the permanent magnet performance is good, and the technology is simple and convenient.
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Claims

1. A one-step method for producing Fe-free α″-Fe 16 The method of N2 powder is characterized by: The following steps are involved: 1) The iron ore concentrate is activated by two-stage wet grinding to obtain nano-scale iron ore concentrate powder slurry; 2) placing the nano-scale iron ore concentrate powder slurry in an oxygen-containing atmosphere and performing a drying pre-oxidation treatment at a temperature of 80°C to 120°C to obtain a nano-scale iron ore concentrate powder with a surface layer of Fe2O3; 3) Place the nano-sized iron ore concentrate powder with a surface layer of Fe2O3 in an ammonia-hydrogen mixed gas environment and perform a reduction-nitridation reaction at a temperature of 120-200°C to obtain Fe-free α″-Fe 16 N2 powder; the ammonia-hydrogen mixed gas contains the following components in volume percentage: 85-95% ammonia, 5-10% hydrogen, less than 0.1% water vapor, and the remaining gases are inert gases.

2. A one-step method for producing Fe-free α″-Fe 16 The method of N2 powder is characterized by: The iron concentrate is an iron oxide mineral with an iron grade of more than 70.5% and a mass content of non-oxygen impurities of no more than 1%.

3. A one-step method for producing Fe-free α″-Fe 16 The method of N2 powder is characterized by: The two-stage wet grinding activation adopts nano sand grinding, with water as solvent. The first stage of grinding is equipped with grinding beads with a particle size of 0.2-0.5 mm, and the grinding speed is 1000-2000 r / min. Grind to D 50 The particle size is in the range of 200~500nm. The second stage of grinding is equipped with grinding beads with a particle size of 0.05~0.2mm, and the particles are ground to D 50 The particle size is in the range of 60~100nm.

4. A one-step method for producing Fe-free α″-Fe 16 The method of N2 powder is characterized by: The drying pre-oxidation treatment time of the nano-scale iron ore concentrate powder slurry is 5 to 60 minutes.

5. A one-step method for producing Fe-free α″-Fe 16 The method of N2 powder is characterized by: The pressure of the ammonia-hydrogen mixed gas is 0.1-0.5 MPa.

6. A one-step method for producing Fe-free α″-Fe 16 The method of N2 powder is characterized by: The reduction-nitridation reaction time is 14 to 30 hours.

Citation Information

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