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Production for powdery diffused cathode base material containing scandium

A technology for diffusing cathodes and powder raw materials, applied in the field of rare earth refractory metal cathode materials, can solve the problems of extremely difficult to fully cover the matrix frame, slow diffusion of scandium oxide, difficult emission recovery, etc.

Inactive Publication Date: 2005-07-27
BEIJING UNIV OF TECH
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  • Claims
  • Application Information

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Problems solved by technology

[0004] One of the main disadvantages of scandium-containing diffused cathodes is that due to the slow diffusion rate of scandium oxide, it is extremely difficult to fully cover the large-scale matrix frame, resulting in poor emission uniformity; correspondingly, it is difficult to recover the emission after high temperature and ion bombardment

Method used

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  • Production for powdery diffused cathode base material containing scandium
  • Production for powdery diffused cathode base material containing scandium
  • Production for powdery diffused cathode base material containing scandium

Examples

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example 1

[0016] Example 1. Dissolve 1.6748 grams of scandium nitrate, 12.7305 grams of ammonium metatungstate, and 10 grams of citric acid in water respectively, then mix the scandium nitrate solution and ammonium metatungstate solution, stir while slowly adding the citric acid solution, and then add 4ml Ethylene glycol solution. The mixed solution was placed in a water bath at 60°C until the solution became a sol. The colloid is dried and aged at 80°C to form a yellow powder. The powder is heated and kept at 550°C for 2 hours in the atmosphere, and then reduced in a hydrogen furnace. The first reduction temperature is 600°C and the time is 1 hour; the second step The reduction temperature is 850° C. and the reduction time is 2 hours. Cool down to room temperature to obtain Sc 2 o 3 Doped tungsten powder, where Sc 2 o 3 Accounting for 1% of the total mass, the particle size distribution curve of the powder is shown in Table 1. The powder was made into a porous body by the convent...

example 2

[0017] Example 2. Dissolve 1.6748 grams of scandium nitrate, 12.7305 grams of ammonium metatungstate, and 10 grams of citric acid in water respectively, then mix the scandium nitrate solution and ammonium metatungstate solution, stir while slowly adding the citric acid solution, and then add 4ml Ethylene glycol solution. The mixed solution was placed in a water bath at 60°C until the solution became a sol. The colloid is dried and aged at 90°C to form a yellow powder, and the powder is heated and kept at 550°C for 2 hours in an atmospheric atmosphere, and then reduced in a hydrogen furnace. The first reduction temperature is 500°C and the time is 1 hour; the second step The reduction temperature is 1000° C. and the reduction time is 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, see powder XRD figure 1 , the particle morphology see figure 2 . The powder is made into a porous body ac...

example 3

[0018] Example 3. Dissolve 1.6748 grams of scandium nitrate, 12.7305 grams of ammonium metatungstate, and 10 grams of citric acid in water respectively, then mix the scandium nitrate solution and ammonium metatungstate solution, stir while slowly adding the citric acid solution, and then add 6ml Ethylene glycol solution. The mixed solution was placed in a water bath at 80°C until the solution became a sol. The colloid is dried and aged at 120°C to form a yellow powder. The powder is heated and kept at 550°C for 2 hours in the atmosphere, and then reduced in a hydrogen furnace. The first reduction temperature is 500°C and the time is 1 hour; the second step The reduction temperature is 1000° C. and the reduction time is 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. The powder was made into a porous body by the conventional powder metallurgy method, impregnated with barium calcium aluminate to obtain a...

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Abstract

A process for preparing the dispersed Sc-contained powder used as the raw material of cathode includes such steps as respectively dissolving scandium nitrate and ammonium metatungstate in water, mixing, adding the solution of citric acid and glycol, water-bath heating to 60-90 deg.C while stirring to obtain sol, baking at 80-150 deg.C to obtain gel, and thermal decomposing at 500-600 deg.C for 0.5-1 hr and then at 850-1000 deg.C for 1-2 hr.

Description

1. Technical field [0001] The invention discloses a method for preparing high current density scandium-containing diffused cathode substrate powder raw materials, which belongs to the technical field of rare earth refractory metal cathode materials. 2. Background technology [0002] At present, diffused cathodes are mainly used in microwave vacuum devices. For most devices, the cathode current density is usually 2-10A / cm2. It is required that the cathode can provide 100A / cm2, so the main task at present is to develop a practical low-temperature high-current-density cathode. In recent years, the research on scandium-containing diffusion cathodes is an important direction to realize low-temperature and high-current-density cathodes. [0003] Various variants of scandium-containing diffusion cathodes have been developed so far. Compared with the traditional barium tungsten cathode, the scandium-containing diffusion cathode reduces the work function to 1.5-1.6eV, and the worki...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): B22F9/26
Inventor 王金淑周美玲王亦曼刘伟
Owner BEIJING UNIV OF TECH
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