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Chemical preparation of Nano Fe powder

wallpapers News 2021-07-26
1. Chemical reduction method:
It uses a certain reducing agent to reduce the metal iron salt or its oxide to produce Nano Fe powder. This method can be divided into solid phase reduction method, liquid phase reduction method and gas phase reduction method.
①Solid-phase chemical reduction method: Usually, the hard gel precursor is synthesized by the sol-gel method from the metal iron ion and the network structure matrix composition, and then the Nano Fe powder and the network structure are prepared by heat treatment and H reduction. Of composite particles.
②Liquid-phase chemical reduction method: It uses strong reducing agent such as KBH, NaBH, NH or organometallic reducing agent to reduce metal ions in the liquid system containing Fe and Fe to obtain Nano Fe powders.
③ Gas phase chemical reduction method: It is mainly to reduce the solid metal iron salt by H or CO. During the preparation process, the residence time of the gas and rapid cooling can be controlled to obtain the non-agglomerated Nano Fe powder.
2. Microemulsion method:
Microemulsion is a thermodynamically stable system composed of surfactants, co-surfactants, organic solvents and water. Microemulsion has the ability to maintain a stable size under certain conditions, and can be reorganized even if it is broken, similar to the self-organization and self-replication functions of biological cells, and can provide an ideal microenvironment for preparing uniform-sized nanoparticles. When using this method to prepare nanomaterials, water-insoluble non-polar substances are used as the oil phase of the dispersed phase, the aqueous solution of the reactant is the water phase, and the surfactant is the emulsifier to form a water-in-oil (W/O) microemulsion and a water core as a micro-reactor to control the nucleation and growth of colloidal particles. The metal salt and a certain reducing agent are respectively formulated into microemulsions. When the two microemulsions are mixed, chemical reactions occur in the microemulsion water core due to the collision between the micelle particles, and Nano Fe powder are obtained. The particle size of the particles is affected by the water core. Size control.
3. Electrodeposition method: Electrodeposition method is a promising method for preparing completely dense nanocrystalline materials. The nanocrystalline material produced by it has high density, low porosity, and less restriction by size and shape. In particular, pulse electrodeposition can reduce porosity and internal stress, reduce impurities and hydrogen content, increase brightness, and is very good to control the composition of the deposited coating. Therefore, it is a low-cost method suitable for large-scale production of Nano Fe powder.
4. Pyrolysis method: Use pyrolysis, laser and ultrasound to decompose and nucleate iron carbonyl to produce Nano Fe powder. This is a gas phase thermal decomposition method.
5. High-temperature hydrolysis method: This method uses an autoclave as a special reactor, an aqueous solution as the reaction medium, and performs a series of chemical and physical reactions under a certain temperature and high pressure environment to achieve the preparation of iron-based Nano powders.
6. Active hydrogen-molten metal reaction method: an arc is generated between the plasma containing hydrogen and the metal iron to melt the iron, and the ionized and activated hydrogen is saturated and dissolved in the molten iron and released after reaction. After the molten iron is forced to evaporate and condense, ultrafine particles of iron are formed in the gas.