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Preparation method of field emission micro-nano tungsten emitter

An emitter and field emission technology, applied in the field of powder metallurgy, can solve the problems of large particle size of powder raw materials, unsuitable emitters, large product pores, etc., to eliminate internal stress, achieve precise control, and improve the effect of opening porosity

Active Publication Date: 2022-03-29
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The focus of this patent is to add alloying elements to solve the problem of sintering densification and use micro-injection molding technology to solve the forming problem of micro-parts, which has nothing to do with the preparation of the emitter
Chinese patent (CN102259189A) discloses a method for preparing a porous cathode substrate. However, due to the severe agglomeration of untreated powder raw materials and the large particle size of the powder, the resulting product has large pores and uneven distribution, and there are many closed pores. Suitable for emitter applications

Method used

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  • Preparation method of field emission micro-nano tungsten emitter
  • Preparation method of field emission micro-nano tungsten emitter

Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0023] 1) The raw material powder is tungsten powder with a Fischer particle size of 0.3 μm and a purity greater than 99.9%;

[0024] 2) First clean the jet mill equipment, turn on the main control to preheat for 10-30 minutes, fill in high-purity nitrogen with a purity greater than 99.9%, start the grinding valve, adjust the grinding pressure to 0.5Mpa, add raw tungsten powder into the grinding chamber to deagglomerate, and Adjust the frequency of the sorting wheel to 40Hz. After collecting all the powder, repeat the above operation to obtain the jet milled powder twice;

[0025] 3) The jet-milled powder is heated up to 300°C at 5°C / min in an atmosphere of high-purity hydrogen with a purity greater than 99.9%, kept for 180min, and then calcined once to eliminate the internal stress generated during the jet-milling process;

[0026] 4) The calcined powder is mixed with an organic binder (microcrystalline wax is 55%, polyethylene wax is 3%, linear low density polyethylene is 10...

Embodiment 2

[0030] 1) The raw material powder is tungsten powder, the Fischer particle size is 0.5 μm, and the purity is greater than 99.9%;

[0031]2) First clean the jet mill equipment, turn on the main control to preheat for 10-30 minutes, fill in high-purity nitrogen with a purity greater than 99.9%, start the grinding valve, adjust the grinding pressure to 0.6Mpa, add raw tungsten powder into the grinding chamber to deagglomerate, and Adjust the frequency of the sorting wheel to 50Hz. After collecting all the powder, repeat the above operation to obtain a jet mill treatment powder.

[0032] 3) The jet milled powder is heated up to 400°C at a rate of 5°C / min in a high-purity hydrogen atmosphere with a purity greater than 99.9%, and kept for 60 minutes, and then calcined twice to eliminate the internal stress generated during the jet milling process ;

[0033] 4) The calcined powder is mixed with an organic binder (microcrystalline wax is 55%, polyethylene wax is 6%, linear low densit...

Embodiment 3

[0037] 1) The raw material powder is tungsten powder, the Fischer particle size is 0.8μm, and the purity is greater than 99.9%;

[0038] 2) First clean the jet mill equipment, turn on the main control to preheat for 10 to 30 minutes, fill in high-purity nitrogen with a purity greater than 99.9%, start the grinding valve, adjust the grinding pressure to 0.7Mpa, add raw tungsten powder into the grinding chamber to deagglomerate, and Adjust the frequency of the sorting wheel to 60Hz. After collecting all the powder, repeat the above operation to obtain three jet milling powders;

[0039] 3) The jet-milled powder is heated up to 500°C at 5°C / min in a high-purity hydrogen atmosphere with a purity greater than 99.9%, kept at a temperature of 100min, and calcined three times to eliminate the internal stress generated during the jet-milling process;

[0040] 4) The calcined powder is mixed with an organic binder (microcrystalline wax is 60%, polyethylene wax is 3%, linear low density ...

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Abstract

The invention discloses a forming method of a field emission micro-nano tungsten emitter, and belongs to the technical field of powder metallurgy. Firstly, the powder state of tungsten powder is improved through one-time or multi-time jet milling treatment, near-spherical tungsten powder particles with fine granularity, high dispersion and narrow distribution are obtained, and a more uniform open pore structure can be formed in the forming stage. Secondly, the treated powder is subjected to one-time or multiple-time calcination treatment, so that internal stress generated in the jet milling process is eliminated; and uniformly mixing the powder with a binder to prepare a feed, forming a tungsten blank with the required shape and size on micro-injection forming equipment, and finally degreasing and sintering to prepare the field emission micro-nano tungsten emitter with uniform pores. According to the field emission micro-nano tungsten emitter, the raw material powder and micro powder injection forming process is remarkably optimized, the prepared field emission micro-nano tungsten emitter is low in impurity content and uniform in pore, the grain size is smaller than or equal to 1 micron, the pore diameter is 200-800 nm, the porosity is 15-35%, and the opening porosity accounts for 95% or above of the total porosity.

Description

technical field [0001] The invention belongs to the technical field of powder metallurgy, and in particular relates to a forming method of a field emission micro-nano tungsten emitter. Background technique [0002] With the continuous development of modern small satellites, not only attitude and orbit control are required, but even orbital maneuvering capabilities are required. For this reason, it is necessary to develop and research its corresponding micro propulsion system. The field emission electric thruster is a new type of microbull-level electric propulsion system, which has the characteristics of small thrust and wide range of precise adjustment, high specific impulse, high efficiency, low power consumption and cost, compact structure, and light weight. The micro-nano tungsten emitter is an essential part of the field emission electric thruster, which can play a key role in storing and transporting the propellant, and affects the launch performance of the thruster. ...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F5/00B22F9/04B22F3/22B22F3/10B22F1/142B22F1/103B22F1/065
CPCB22F5/00B22F9/04B22F3/225B22F3/1025B22F2009/044B22F2998/10
Inventor 秦明礼吴昊阳许贺彬王杰贾宝瑞曲选辉杨军军
Owner UNIV OF SCI & TECH BEIJING
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