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Nano tungsten powder preparing method through adding of surface active agent via freezing drying

A surfactant, nano-tungsten powder technology, applied in nanotechnology, metal processing equipment, transportation and packaging, etc., can solve the problems of agglomerated grain size, grain growth, non-uniformity, etc., to achieve small particle size distribution, powder The effect of reduced agglomeration and low cost

Active Publication Date: 2018-10-26
TIANJIN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

This is because during the freeze-drying process, even if the concentration of tungstate is small, the solution will segregate when it solidifies, resulting in the overall growth of the crystal grains in the subsequent calcination and reduction process, agglomeration and uneven grain size

Method used

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  • Nano tungsten powder preparing method through adding of surface active agent via freezing drying
  • Nano tungsten powder preparing method through adding of surface active agent via freezing drying
  • Nano tungsten powder preparing method through adding of surface active agent via freezing drying

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0035] (1) First dissolve 0.1g polyvinylpyrrolidone PVP K-12 in 100mL deionized water, then dissolve 2g AMT in it, and finally add the solution to 200ml with deionized water (the concentration of AMT is 0.01g / mL) , using ultrasonic treatment (ultrasonic treatment power 60W, ultrasonic time 1h) to fully dissolve and disperse.

[0036] (2) Pour the solution into a watch glass and place it in the refrigerator. The pre-freezing temperature is -30°C, and the cooling rate is 5°C / min, and the pre-freezing is 2 hours.

[0037] (3) After the temperature of the lyophilizer reaches the freezing temperature of -58~-50℃ and stabilizes, put the pre-frozen watch glass into the lyophilizer, turn on the vacuum pump and maintain a vacuum degree of 1~10Pa, and freeze-dry for 36 hours.

[0038] (4) Calcining the freeze-dried powder in the air at 500°C for 0.5h to remove the surfactant and obtain WO 3 powder.

[0039] (5) The WO 3 The powder is subjected to two-step reduction in hydrogen gas fl...

Embodiment 2

[0041] (1) First dissolve 0.2g polyvinylpyrrolidone PVP K-12 in 25mL deionized water, then dissolve 2gAMT in it, and finally add the solution to 50ml with deionized water (the concentration of AMT is 0.04g / mL), use Ultrasonic treatment (ultrasonic treatment power 200W, ultrasonic time 0.33h) to fully dissolve and disperse.

[0042] (2) Pour the solution into a watch glass and place it in the refrigerator. The pre-freezing temperature is -20°C, and the cooling rate is 1°C / min, and the pre-freezing is for 6 hours.

[0043] (3) After the temperature of the lyophilizer reaches the freezing temperature of -58~-50℃ and stabilizes, put the pre-frozen watch glass into the lyophilizer, turn on the vacuum pump and maintain a vacuum degree of 1~10Pa, and freeze-dry for 12 hours.

[0044] (4) Calcining the lyophilized powder in the air at 450°C for 2h to remove the surfactant and obtain WO 3 powder.

[0045] (5) The WO 3The powder is subjected to two-step reduction in hydrogen gas flow...

Embodiment 3

[0047] (1) First dissolve 0.04g polyvinylpyrrolidone PVP K-12 in 10mL deionized water, then dissolve 4gAMT in it, and finally add the solution to 20ml with deionized water (the concentration of AMT is 0.2g / mL), use Ultrasonic treatment (ultrasonic treatment power 50W, ultrasonic time 1h) to fully dissolve and disperse.

[0048] (2) Pour the solution into a watch glass and place it in the refrigerator. The pre-freezing temperature is -25°C, and the cooling rate is 10°C / min, and the pre-freezing is 0.5h.

[0049] (3) After the temperature of the lyophilizer reaches the freezing temperature of -58~-50℃ and stabilizes, put the pre-frozen watch glass into the lyophilizer, turn on the vacuum pump and maintain a vacuum degree of 1~10Pa, and freeze-dry for 8 hours.

[0050] (4) Calcining the freeze-dried powder in the air at 480°C for 0.5h to remove the surfactant and obtain WO 3 powder.

[0051] (5) The WO 3 The powder is subjected to two-step reduction in hydrogen gas flow (550°C...

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Abstract

The invention provides a nano tungsten powder preparing method through adding of a surface active agent via freezing drying. According to the method, on the basis of freezing drying, one of surface active agents including polyethylene glycol PEG, fatty alcohol-polyoxyethylene ether AE and polyvinylpyrrolidone PVP is added for in-situ preparing of ultra-fine nano tungsten powder. The surface activeagent and ammonium metatungstate are dissolved in water, and ultrasonic treatment is conducted for sufficient dispersing and dissolving; then pre-freezing is conducted in a refrigerator and other low-temperature environments; after pre-freezing, the mixture is placed in a freezing drying machine to be frozen dry; after freezing dry, grinding is conducted, the surface active agent is removed through roasting in air, and the ultrafine WO3 powder is obtained; and finally, hydrogen is subjected to two-step reduction, and the ultrafine nano tungsten powder is obtained. The powder prepared throughthe freezing drying method after the surface active agent which is PEG, or AE or PVP is small in particle aggregation, the average grain size reaches 10-30 nm, and grain granularity distribution is extremely narrow. The ultrafine nano tungsten powder prepared through the method has obvious advantages.

Description

technical field [0001] The invention proposes a technology for preparing nano-tungsten powder which is freeze-dried by adding a surfactant, and belongs to the technical field of powder preparation engineering. Background technique [0002] Tungsten powder is the main raw material of cemented carbide, and its application involves machining, mining, geological drilling, construction tools, light bulb lighting, military engineering and other fields. It is difficult to sinter and densify micron-sized tungsten powder by traditional powder metallurgy method, which usually requires high sintering temperature and long sintering time. The activation sintering developed in recent years is an effective way to increase the density, including the addition of activated metal elements (such as Fe, Ni, Cu, etc.) and the use of ultrafine tungsten powder. Adding activated metal elements will lead to a serious decrease in alloy density. The method to obtain high-density tungsten alloy at lowe...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F9/22B22F1/00B82Y40/00
CPCB82Y40/00B22F9/22B22F1/054
Inventor 马宗青扈伟强董智柳楠刘永长王祖敏余黎明李冲刘晨曦
Owner TIANJIN UNIV
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