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High-thermal-conductivity insulating medium fast-heating cathode hot wire assembly and preparation method thereof

A technology of insulating medium and heating wire assembly, which is applied in the field of indirect heating fast heating cathode, can solve the problems of reducing reliability and service life, limiting the heating rate of cathode, insufficient high temperature strength, etc., and achieves short preheating time and high shock resistance. , the effect of high heating efficiency

Inactive Publication Date: 2016-09-07
UNIV OF SCI & TECH BEIJING
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  • Description
  • Claims
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Problems solved by technology

However, the thermal conductivity of alumina is limited to 20-30W / (m K), the large specific heat capacity, and high density limit the heating rate of the cathode, and the addition of additives leads to insufficient high-temperature strength and high-temperature reaction between oxygen and tungsten wire. its reliability and service life

Method used

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  • High-thermal-conductivity insulating medium fast-heating cathode hot wire assembly and preparation method thereof
  • High-thermal-conductivity insulating medium fast-heating cathode hot wire assembly and preparation method thereof

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Embodiment 1

[0021] 1. The high-purity AlN powder is pre-fired at a high temperature of 800°C for 5 hours, crushed by a jet mill, and sieved with an air vibrating sieve to obtain a powder of 5-10 μm;

[0022] 2. Mix collodion solution dissolved in ethanol and ether mixture with AlN powder, and add 2% Y 2 o 3 Powder and 2% CaF 2 Powder, ball milling to obtain a slurry with good fluidity;

[0023] 3. After vacuum degassing, the slurry is poured into the cathode cylinder, and then the tungsten-rhenium alloy hot wire with a rhenium element mass fraction of 20-25% is slowly put into the cathode cylinder containing the slurry, and the speed is 5000r / min along the axis of the cathode cylinder Centrifuge for 5 minutes, put it into a drying oven and dry for 2 hours at a drying temperature of 60°C.

[0024] 4. Put the hot wire and cathode cylinder assembly prepared in the previous step into a tungsten wire furnace at a sintering temperature of 1800°C, sintering in a hydrogen, nitrogen or argon at...

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Abstract

The invention provides a high-thermal-conductivity insulating medium fast-heating cathode hot wire assembly and a preparation method thereof. The high-thermal-conductivity insulating medium fast-heating cathode hot wire assembly comprises a tungsten cathode (1), a cathode tube (2), hot wires (3) and an insulating medium (4). The cathode tube (2) and the hot wires (3) are closely packaged into an integrated structure through the insulating medium (4). High-solid-content ceramic slurry is prepared by mixing organic solvents of alcohol and the like and aluminum nitride powders; the slurry is poured into the cathode tube and the hot wires are added to the cathode tube; and the high-thermal-conductivity insulating medium fast-heating cathode hot wire assembly is obtained through high-temperature sintering after centrifugal treatment and forming densifying. The high-thermal-conductivity insulating medium fast-heating cathode hot wire assembly is far higher in thermal conductivity than a conventional aluminum oxide ceramic assembly, and has higher heat transfer efficiency; the cathode hot wire assembly is shorter in preheating time, and can reach an operating temperature of 1050 DEG C within 5 s; the cathode hot wire assembly is higher in high-temperature strength and good in antiknock performance, meets the quick starting requirement under high shock vibration, is excellent in performance, high in reliability and long in service life, and can be widely applied to a quick start traveling-wave tube.

Description

technical field [0001] The invention belongs to the field of indirect heating fast-heating cathodes, and specifically prepares a fast-heating cathode heating wire assembly. In particular, it provides a high thermal conductivity aluminum nitride ceramic insulating dielectric cathode heating wire assembly technology, which helps to shorten the warm-up time and plays a very important role in improving the key performance of the fast-start traveling wave tube. Background technique [0002] The cathode heating wire assembly is widely used in microwave electronic devices such as traveling wave tubes and klystrons. The heating wire heats up rapidly after passing the current, and the tungsten cathode heats up rapidly through the insulating medium and the cathode cylinder. The insulating medium and the cathode cylinder are in close contact. The existing The heat transfer medium is alumina. The existing patent shortens the preheating time by adopting the design and optimization of th...

Claims

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Application Information

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Patent Type & Authority Applications(China)
IPC IPC(8): H01J23/04C04B35/581
CPCC04B35/581C04B2235/3225C04B2235/445H01J23/04
Inventor 郝俊杰张晓冬郭志猛罗骥陈存广赵翔
Owner UNIV OF SCI & TECH BEIJING
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