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Discharge plasma method for preparing nano composite rare-earth tungsten electron emitting material

An electron emission material, discharge plasma technology, applied in the manufacture of discharge tubes/lamps, main electrodes of discharge tubes, and electrode systems, etc. difficulties, etc.

Inactive Publication Date: 2005-12-28
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

It can be seen that there are obvious deficiencies in the traditional process: 1. The distribution of the added rare earth elements is uneven, resulting in uneven emission and the appearance of abnormal Schottky 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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  • Discharge plasma method for preparing nano composite rare-earth tungsten electron emitting material
  • Discharge plasma method for preparing nano composite rare-earth tungsten electron emitting material
  • Discharge plasma method for preparing nano composite rare-earth tungsten electron emitting material

Examples

Experimental program
Comparison scheme
Effect test

example 1

[0017] Example 1: The weight ratio is 0.5% La 2 o 3 , 99.5% W nano-La-W powder is loaded into the graphite mold, and then the graphite mold is put into the discharge plasma system for discharge plasma sintering. Make sure that the center of the powder is aligned with the temperature measurement point. After the discharge plasma system is sealed, vacuumize it. When the vacuum degree reaches 1Pa, start to heat up at a rate of 150°C / min. When the temperature reaches 1300°C, heat preservation is started. The heat preservation and sintering time is 8 minutes. The sintering pressure during the sintering process is 50Mpa. After reaching the holding time, cool down to below 600°C with the sintering furnace, then take out the graphite mold and continue cooling at room temperature, and obtain a sintered body after demoulding. Then use conventional wire cutting to remove the 0.5mm surface layer of the sintered body, that is, the obtained La-W emission material is nano-La 2 o 3 The pa...

example 2

[0018] Example 2: The weight ratio is 10.0% La 2 o 3 , 90.0% W nano-La-W powder is loaded into the graphite mold, and then the graphite mold is put into the discharge plasma system for discharge plasma sintering, and the center position of the powder must be aligned with the temperature measurement point. After the discharge plasma system is sealed, vacuumize it. When the vacuum degree reaches 5Pa, start to heat up at a rate of 50°C / min. When the temperature reaches 1400°C, start to keep warm. The sintering time of heat preservation is 5min. 10Mpa. After reaching the holding time, cool down to below 600°C with the sintering furnace, then take out the graphite mold and continue cooling at room temperature, and obtain a sintered body after demoulding. Then use conventional wire cutting to remove the 0.5mm surface layer of the sintered body, that is, the obtained La-W emission material is nano-La 2 o 3 The particles are evenly distributed in the W matrix.

example 3

[0019] Example 3: The weight ratio is 20.0% La 2 o 3 , 80.0% W nano-La-W powder is loaded into the graphite mold, and then the graphite mold is put into the discharge plasma system for discharge plasma sintering. Make sure that the center of the powder is aligned with the temperature measurement point. After the discharge plasma system is sealed, vacuumize it. When the vacuum reaches 10Pa, start to heat up at a rate of 300°C / min. When the temperature reaches 1800°C, start to keep warm. The sintering time is 3min. The sintering pressure during sintering is 70Mpa. After reaching the holding time, cool down to below 600°C with the sintering furnace, then take out the graphite mold and continue cooling at room temperature, and obtain a sintered body after demoulding. Then use conventional wire cutting to remove the 0.5mm surface layer of the sintered body, that is, the obtained La-W emission material is nano-La 2 o 3 The particles are evenly distributed in the W matrix.

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Abstract

The invention discloses a discharge plasma preparation method of a nanocomposite rare earth tungsten electron emission material, which belongs to the technical field of rare earth refractory metal electron emission materials. In view of the existing technical problems, a preparation method with uniform distribution of rare earth elements and good diffusion performance is provided: the raw materials are put into a graphite mold and then put into a discharge plasma system for sintering, wherein the raw materials are known particles with a particle size of 20nm to 30nm 99.5% to 70.0% by weight of tungsten powder and 0.5% to 30.0% by weight of rare earth oxide CeO with particles below 10nm 2 or La 2 o 3 or Y 2 o 3 ; When the vacuum is pumped to 1Pa~10Pa, the temperature rise rate is 50~300℃ / min to 1200℃~1800℃ for 3min~10min, the sintering pressure in the sintering process is: 10Mpa~70Mpa, after cooling to below 600℃ Take out the graphite mold and continue cooling at room temperature, and obtain a sintered body after demoulding; cut off the surface layer of the sintered body of 0.5-1 mm to obtain the material of the present invention. It can be seen from the figure that the material has high zero-field emission current density, low work function, and excellent thermionic emission performance.

Description

technical field [0001] The invention discloses a discharge plasma preparation method of a nanocomposite rare earth tungsten electron emission material, which belongs to the technical field of rare earth refractory metal electron emission materials. Background technique [0002] Electron emission materials are used in various vacuum electron sources, ion sources, hot cathode electrodes, etc., and have always been a research direction of great concern at home and abroad in the fields of metallurgy, welding, surface treatment, and vacuum electronics. Rare earth tungsten thermionic emission materials are the current hot The frontier of electron emitter research has broad application prospects in military and civilian use, and can replace radioactive thoriated tungsten electron emission materials that have been used for many years. It has very valuable environmental coordinated development value and realizes green production and green consumption in this field. [0003] Since the...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B22F3/105H01J1/14H01J9/02
Inventor 聂祚仁席晓丽左铁镛
Owner BEIJING UNIV OF TECH