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Nano-rare earth tungsten powder and its preparation method

A nano-rare earth and tungsten powder technology, applied in the field of powder metallurgy, can solve the problems of uneven distribution of rare earth elements, difficult replenishment of rare earth oxides, process repeatability, high temperature resistance, ion bombardment resistance, and unsatisfactory emission uniformity.

Inactive Publication Date: 2003-09-17
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0003] Rare earth tungsten thermionic emission materials have many advantages, but in order to achieve a good balance between emission and lifetime, the content of rare earth oxides on the surface must be controlled; traditional rare earth tungsten thermionic emission materials, the rare earth oxides on the surface are difficult to In addition, the process repeatability, high temperature resistance, ion bombardment resistance, and emission uniformity of these thermionic emission materials are not ideal.
[0004] So far, the methods of adding rare earth elements to electron emitters are mainly mechanical mixing and liquid-solid mixing, and most of them face some common problems: (1) The distribution of rare earth elements after adding is not uniform, resulting in uneven emission and abnormal Schott Emergence of the base effect
(2) The diffusion properties of rare earth elements and their oxides are poor, making it difficult to replenish and affect the improvement of the life of thermionic emission materials

Method used

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  • Nano-rare earth tungsten powder and its preparation method
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  • Nano-rare earth tungsten powder and its preparation method

Examples

Experimental program
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Effect test

example 1

[0024] Example 1: 155.66 grams of ammonium metatungstate white crystal powder is dissolved in 1000 milliliters of water, another 1.2910 grams of cerous nitrate white crystal powder is dissolved in 100 milliliters of water, after the two solutions are clarified, the two are mixed (where CeO 2 accounted for W-CeO 2 The weight percentage of mixed powder is 0.5%), pending clarification. Using a nitrogen spray gun with a gun pressure of 5 atm, disperse the clear mixed solution in liquid nitrogen. Then put the frozen material frozen in liquid nitrogen into the FTDDura-stop MP type freeze dryer of FTS company for vacuum drying. ℃; the working pressure within 2700-3900 minutes is 150 mTorr and the temperature is -12 °C; the working pressure within 3900-4700 minutes is 80 mTorr and the temperature is 0 °C; the working pressure within 4700-4900 minutes The temperature is 0 millitorr and the temperature is 15°C; the freeze-dried mixed powder is subjected to secondary reduction, the dop...

example 2

[0025] Example 2: 153.00 grams of ammonium metatungstate white crystal powder is dissolved in 1000 milliliters of water, another 5.6802 grams of cerous nitrate white crystal powder is dissolved in 100 milliliters of water, after the two solutions are clarified, the two are mixed (where CeO 2 accounted for W-CeO 2 The weight percent of mixed powder is 2.2%), pending clarification. Using a nitrogen spray gun with a gun pressure of 4 atm, disperse the clear mixed solution in liquid nitrogen. Then put the frozen material frozen in liquid nitrogen into the FTDDura-stop MP type freeze dryer of FTS company for vacuum drying. ℃; the working pressure within 2700-3900 minutes is 170 mTorr and the temperature is -12 °C; the working pressure within 3900-4700 minutes is 80 mTorr and the temperature is -3 °C; the working time within 4700-4900 minutes The pressure was 10 millitorr and the temperature was 25°C. The freeze-dried mixed powder is subjected to secondary reduction, the doped ce...

example 3

[0026] Example 3: 140.80 grams of ammonium metatungstate white crystal powder is dissolved in 1000 milliliters of water, another 25.8191 grams of cerous nitrate white crystal powder is dissolved in 100 milliliters of water, after two kinds of solutions are clarified, the two are mixed (wherein CeO 2 accounted for W-CeO 2 The weight ratio of mixed powder is 10.0%), pending clarification. Using a nitrogen spray gun with a gun pressure of 2 atm, disperse the clear mixed solution in liquid nitrogen. Then put the frozen material frozen in liquid nitrogen into the FTDDura-stop MP type freeze dryer of FTS company for vacuum drying. ℃; the working pressure within 2700~3900 minutes is 160 mTorr and the temperature is -10 °C; the working pressure within 3900~4700 minutes is 100 mTorr and the temperature is -1 °C; the working time within 4700~4900 minutes The pressure was 5 millitorr and the temperature was 20°C. The freeze-dried mixed powder is subjected to secondary reduction, the d...

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Abstract

A nano-class RE-W particle contains RE oxide powder (CeO2, La2O3, or Y2O3) (0.5-30 wt%) and W (70-99.5 wt%), and is prepared through dissolving the ammonium metatungstate powder and RE oxide powder in water respectively, mixing, clarifying, dispersing it in liquid nitrogen by nitrogen sprayer for pre-freezing, vacuum freeze drying, and secondary reducing in hydrogen atmosphere. Its advantage is molecule-class mixing uniformly.

Description

technical field [0001] A nanometer rare earth tungsten powder and a preparation method thereof belong to the technical field of powder metallurgy. Background technique [0002] Rare earth tungsten powder can be used to prepare various rare earth tungsten alloys. Rare earth tungsten alloys are not only widely used in electronics, electric light sources and electric power industries, but also in aerospace, weapons, casting, oil drilling, instrumentation, mechanical tools and other departments. The application of tungsten electron emission materials with rare earth addition to various vacuum electron sources, ion sources, hot cathode materials, electrodes, etc. has always been a research direction of great concern in the fields of metallurgy, welding, surface treatment, and vacuum electronics at home and abroad. It has broad application prospects in civilian use, and can replace radioactive thoriated tungsten electron emission materials that have been used for many years, and ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F9/22B22F9/26
Inventor 聂祚仁席晓丽左铁镛
Owner BEIJING UNIV OF TECH
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