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Process for the production of ultrafine powders

A technology of ultra-fine powder and manufacturing method, which is applied in chemical instruments and methods, oxide/hydroxide preparation, alumina/hydroxide preparation, etc., and can solve problems such as limitation and long-time grinding

Inactive Publication Date: 2001-06-20
ADVANCED NANO TECH +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, obtaining smaller particle sizes usually requires a long grinding time and a lot of energy, so it is limited by economic considerations

Method used

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  • Process for the production of ultrafine powders
  • Process for the production of ultrafine powders
  • Process for the production of ultrafine powders

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0048] Example 1 - by Ce(OH) 4 Synthesis of ultrafine CeO 2 particles

[0049] The material used is Ce(OH) 4 (97%, -100 mesh) and NaCl (>99.5%, ≤500 microns). Under the air atmosphere, add 28.4% (weight) Ce(OH) 4 Ce(OH) 4 Raw material mixture with NaCl powder, and sealed, the ratio of the two raw materials is equivalent to Ce(OH) 4 +9NaCl. The mass ratio of spheres to added powder was 40:1. Grind for 1-10 hours on a SPEX 8000 mixer / mill. After grinding, the powder was calcined at 500° C. for 1 hour in air. Wash the powder with distilled water using an ultrasonic bath and centrifuge to remove NaCl. The washed powder was evaporated and dried at 60°C in air. CeO 2 The particle size is measured by X-ray diffraction, transmission electron microscopy (TEM) and BET surface area to be 10-30 nm. figure 1 Representative nanoparticles of samples after milling for 6 h are shown.

[0050] In the second experiment, a 1 liter capacity grinder was used instead of the SPEX grinder...

Embodiment 2

[0052] Example 2 - by SnCl 2 Synthetic SnO 2

[0053] The material used is SnCl 2 (>99%) and NaCl (>99.5%). In an argon atmosphere, add SnCl in a SPEX mixer / mill equipped with 50 g of 6.4 mm diameter steel grinding media 2 The starting mixture with NaCl powder has a total mass of 5 g and a volume ratio of 1:10. The mass ratio of balls to powder was 10:1. Grinding was carried out for 3 hours. After grinding, the powder was heated at 800 °C for 30 min in an air atmosphere to make the SnCl 2 oxidation. The powder was then washed with distilled water to remove the NaCl diluent. The washed powder was dried in an oven at 60°C. Obtaining isolated equiaxed SnO 2 Nanoparticles, whose particle size is 20-200 nanometers, have many small crystal faces on the particle surface. Figure 3 shows the SnO formed after heat treatment 2 Transmission electron micrograph (TEM) of the particles.

Embodiment 3

[0054] Example 3 - by Al(OH) 3 Synthetic Al 2 o 3

[0055] The material used is Al(OH) 3 (-100 mesh) and NaCl (>99.5%, ≤500 microns). In a nitrogen atmosphere, a 7-liter mill containing 25 kg of stainless steel balls with a diameter of 6 mm was added containing 9% (by weight) Al(OH) 3 (corresponding to 10% by volume of Al(OH) 3 ) of Al(OH) 3 Mix the stock with NaCl powder and seal. The mass ratio of spheres to added powder was 22:1. Grind for 2 hours. After grinding, the powder was calcined at 850° C. for 1 hour in air. Using an ultrasonic bath and centrifuge, the powder was washed with deionized water to remove NaCl. The washed powder was evaporated and dried at 60°C in air. X-ray diffraction measurements show that during heat treatment Al(OH) 3 Dehydration forms gamma alumina. Al formed 2 o 3 The particle size was 11 nm as measured by BET surface area.

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Abstract

A process for the production of ultrafine powders consisting of individual particles with sizes in the range of 1 nm to 200 nm, which is based on the mechanical milling of two or more non-reacting powders. The process includes subjecting a suitable precursor metal compound and a non-reactant diluent phased to mechanical milling which through the process of mechanical activation reduces the microstructure of the mixture of the form of nano-sized grains of the metal compound uniformly dispersed in the diluent phase. Heat treating the milled powder converts the nano-sized grains of the precursor metal compound into a desired metal oxide phase. Alternatively, the precursor metal compound may itself be an oxide phase which has the requisite milling properties to form nanograins when milled with a diluent. An ultrafine powder is produced by removing the diluent phase such that nano-sized grains of the desired metal oxide phase are left behind. The process facilitates a significant degree of control over the particle size and size distribution of the particles in the ultrafine powder by controlling the parameters of mechanical activation and heat treatment.

Description

field of invention [0001] The present invention relates to a method for producing an ultrafine powder, in particular (though not limited to) a method for producing an ultrafine powder composed of single particles with a particle size of 1-200 nanometers. background of the invention [0002] Ultrafine powders have great potential and can be used in a wide range of applications, including catalysts, magnetic recording media, optoelectronic materials, magnetic fluids, and composite materials. Ultrafine metal powders can already be prepared by physical methods such as vapor deposition and spraying and are of high quality, i.e. clean in surface and uniform in particle size distribution. However, the industrial use of these powders is limited by low yield and high cost. Additional chemical manufacturing methods such as thermal decomposition and precipitation are currently being investigated to prepare a wide variety of powders. Chemical methods can provide a large number of indu...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B02C19/18B01J19/00B22F9/04B22F9/20C01B13/14C01B13/18C01B13/32C01F7/44C01F11/06C01F17/235C01G1/02C01G9/02C01G19/02C01G23/00C01G23/04C01G23/047C01G23/08C01G25/02C01G99/00C22B5/02C22C1/04C22F1/04
CPCC01G19/02C01G23/006C01B13/145C01G25/02C01G23/047C01G9/02C01F7/44C01G23/08C01P2006/12C01F17/0043C01P2002/72C01P2002/01C01G1/02C01P2004/64C01P2004/04B82Y30/00C01F17/235B22F9/02B82Y40/00
Inventor P·G·麦克考密克都筑拓也
Owner ADVANCED NANO TECH
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