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Method for preparing impregnated scandium-tungsten diffusion type cathode material

A cathode material and impregnation-type technology, which is applied in the field of rare earth refractory metal cathode materials, can solve the problems of affecting the quality of the reduced powder, the growth of powder particles, and the lack of uniform doping, etc., to achieve strong process repeatability, simplify the preparation process, The effect of avoiding the introduction of impurity elements

Inactive Publication Date: 2011-06-15
BEIJING UNIV OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

Under such circumstances, the ultrafine rare earth oxides and tungsten oxide particles generated by gel decomposition will agglomerate, which will lead to the growth of powder particles, uneven particle size, and uneven doping to a certain extent, which will eventually affect the quality of the reduced powder.

Method used

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  • Method for preparing impregnated scandium-tungsten diffusion type cathode material
  • Method for preparing impregnated scandium-tungsten diffusion type cathode material
  • Method for preparing impregnated scandium-tungsten diffusion type cathode material

Examples

Experimental program
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Effect test

Embodiment 1

[0020] In this experiment, the precursor powder was prepared on the EYELA Spray Dryer SD-1000 spray dryer. Dissolve 13.2335 grams of ammonium metatungstate and 0.1865 grams of scandium nitrate in water respectively, then add the scandium nitrate solution into the ammonium metatungstate solution and mix, the solution concentration is 20g / L, the feeding speed is 400ml / h, and the inlet temperature is 150 ℃, the outlet temperature is stable at 95 ℃, and the blast speed is 0.4m 3 / min for experiments. The obtained precursor powder was decomposed at 550° C. for 2 hours in the air atmosphere to obtain a composite oxide powder. The powder was kept in a hydrogen reduction furnace at 600°C for 2 hours, and then the temperature was raised to 800°C for 2 hours. Cool down to room temperature to obtain Sc 2 o 3 Doped tungsten powder, where Sc 2 o 3 1% of the total mass. Press the doped tungsten powder made by the above method at a pressure of 1t / cm 2 Press and sinter at 1500°C for 1...

Embodiment 2

[0022] In this experiment, the precursor powder was prepared on the EYELA Spray Dryer SD-1000 spray dryer. Dissolve 12.7305 grams of ammonium metatungstate and 0.9330 grams of scandium nitrate in water respectively, then add the scandium nitrate solution into the ammonium metatungstate solution and mix, the solution concentration is 20g / L, the feeding speed is 400ml / h, and the inlet temperature is 150 °C, the outlet temperature is stable at 95 °C, and the blast speed is 0.6m 3 / min for experiments. The obtained precursor powder was decomposed at 550° C. for 2 hours in the air atmosphere to obtain a composite oxide powder. The powder was kept in a hydrogen reduction furnace at 500°C for 2 hours, and then the temperature was raised to 950°C for 2 hours. Cool down to room temperature to obtain Sc 2 o 3 Doped tungsten powder, where Sc 2 o 3 5% of the total mass. Press the doped tungsten powder made by the above method at a pressure of 1t / cm 2 Press and sinter at 1500°C for...

Embodiment 3

[0024] In this experiment, the precursor powder was prepared on the EYELA Spray Dryer SD-1000 spray dryer. Dissolve 12.7305 grams of ammonium metatungstate and 0.9330 grams of scandium nitrate in water respectively, then add the scandium nitrate solution into the ammonium metatungstate solution and mix, the solution concentration is 20g / L, the feeding speed is 400ml / h, and the inlet temperature is 150 ℃, the outlet temperature is stable at 95 ℃, and the blast speed is 0.4m 3 / min for experiments. The obtained precursor powder was decomposed at 550° C. for 2 hours in the air atmosphere to obtain a composite oxide powder. Precursor powder map see figure 1 . The powder was kept in a hydrogen reduction furnace at 500°C for 2 hours, and then the temperature was raised to 950°C for 2 hours. Cool down to room temperature to obtain Sc 2 o 3 Doped tungsten powder, where Sc 2 o 3 Accounting for 5% of the total mass, the particle morphology is shown in figure 2 , powder XRD see...

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Abstract

The invention discloses a method for preparing an impregnated scandium-tungsten diffusion type cathode material, and belongs to the technical field of refractory metal cathode materials. The method for preparing the impregnated scandium-tungsten diffusion type cathode material comprises the following steps: 1) dissolving ammonium meta-tungstate and scandium nitrate into water to form solution respectively, adding the scandium nitrate solution into the ammonium meta-tungstate solution for mixing, controlling the concentration of the mixed solution to between 20 and 40 g / L, and adopting spray drying to prepare precursor powder of the cathode material, wherein the feeding speed is 400 ml / h; the blowing rate is 0.4 to 0.6 cubic meters per minute; the inlet temperature is 150 DEG C; and the outlet temperature is stabilized at 95 DEG C; 2) decomposing the precursor powder prepared by the spray drying at the temperature of between 500 and 550 DEG C for 2 hours in the atmosphere so as to obtain composite oxide powder; and 3) reducing in the hydrogen atmosphere in two steps: preserving the heat to between 500 and 600 DEG C for 1 to 2 hours, and then raising the temperature to between 800 and 950 DEG C and preserving the heat for 1 to 2 hours to obtain the precursor-doped tungsten powder. The method for preparing the impregnated scandium-tungsten diffusion type cathode material simplifies the preparation technology for the precursor powder, avoids the introduction of impurity elements in the preparation process, and has the advantages of strong repeatability, simple technology, and convenient mass production. The prepared cathode material has excellent emission characteristics at 850 DEG C.

Description

technical field [0001] A method for preparing an impregnated scandium-tungsten diffused cathode material. The invention belongs to the technical field of rare earth refractory metal cathode materials. Background technique [0002] The cathode is the electron source and the core part of the vacuum electronic device. The electron emission cathode material is the core component of the vacuum electronic device. At present, the diffusion type thermionic emission cathode material based on the alkaline earth metal Ba is mainly used in the microwave vacuum device. According to the terahertz The overall design requirements of vacuum electronic devices require electron beam sources to provide high current densities with special shapes (>50A / cm 2 ) Electronic injection, such as cylindrical injection, strip injection, etc., and requires good beam quality of electronic injection, such as uniform current density and neat beam shape. The barium tungsten cathode has been difficult to m...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): H01J9/02
Inventor 王金淑刘伟崔云涛王亦曼赵雷李莉莉张喜珠杨帆周美玲
Owner BEIJING UNIV OF TECH
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