Preparation method of aluminum nitride insulation layer cathode hot wire

A technology of aluminum nitride and insulating layer, which is used in the preparation of hot wire coating and the preparation of coated hot wire for cathode components, can solve the mismatch between the expansion of alumina coating and hot wire, and cannot meet the high performance of cathode components requirements, easy cracking and falling off, etc., to achieve the effect of improving coating cracking and falling off, low density and low equipment requirements

Active Publication Date: 2016-09-07
UNIV OF SCI & TECH BEIJING
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  • Summary
  • Abstract
  • Description
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  • Application Information

AI Technical Summary

Problems solved by technology

At present, electrophoretic deposition, plasma spraying and other methods are used to coat alumina ceramics on the surface of the hot wire. The existing technology solves the problem of alumina coating and hot wire expansion by doping yttrium oxide in the alumina ceramics and improving the coating process. Mismatch causes problems such as easy crackin

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Example Embodiment

[0019] Example 1

[0020] 1. Select high-purity aluminum nitride powder with an average particle size of 1.2 μm and yttrium oxide powder with an average particle size of 0.03 μm as raw materials.

[0021] 2. Add aluminum nitride powder to isopropanol, add yttrium oxide powder according to the mass fraction of aluminum nitride 1%, add dispersant polyacrylic acid, and ultrasonically disperse for 60 minutes to prepare a stable suspension with a solid content of 9%.

[0022] 3. Put the wound tungsten rhenium wire with 3% rhenium content and diameter of 0.15mm into 20% sodium hydroxide solution to boil, ultrasonic cleaning for 10 minutes, fix the cleaned tungsten rhenium wire on the metal platinum electrode. Put it into the electrolytic cell, the electrode spacing is 20mm, the direct current voltage of 50V is applied, the electrode and the hot wire are removed after the deposition thickness is 0.02mm.

[0023] 4. Dry the hot wire in a drying box at 80°C for 2 hours, debinding at 600°C in a...

Example Embodiment

[0024] Example 2

[0025] 1. Select high-purity aluminum nitride powder with an average particle size of 2 μm and yttrium oxide powder with an average particle size of 0.03 μm as raw materials.

[0026] 2. Add aluminum nitride powder to butyl acetate, add yttrium oxide powder according to the mass fraction of aluminum nitride 2%, add dispersant polycarboxylic acid, and ultrasonically disperse for 20 minutes to prepare a stable suspension with a solid content of 5% .

[0027] 3. Put the wound tungsten rhenium wire with 20% rhenium content and diameter 0.5mm into 20% sodium hydroxide solution to boil, ultrasonically clean for 10 minutes, fix the cleaned tungsten rhenium wire on the platinum electrode, put it in In the electrolytic cell, the electrode spacing is 30mm, and 60V DC voltage is applied. After the deposition thickness is 0.1mm, the electrode and hot wire are removed.

[0028] 4. Dry the hot wire in a drying box at 80°C for 2 hours, debinding at 600°C in a hydrogen atmosphere ...

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Abstract

The invention belongs to the field of a microwave device and relates to a preparation method of an aluminum nitride insulation layer cathode hot wire formed, with the aluminium nitride materials being as raw materials and through an electrophoretic deposition method, by preparing a layer of compact aluminium nitride ceramic coating on the surface of the cathode hot wire for a travelling wave tube. Aluminum nitride powders are subjected to ultrasonic dispersion through organic solvents of alcohol and the like to obtain a stable suspension liquid; a layer of aluminium nitride film is deposited on the surface of a cleaned tungsten-rhenium wire through electrophoretic deposition; and the cathode hot wire having the compact aluminium nitride insulation layer is obtained after high-temperature sintering. The method is simple in process and low in device requirement; the coating and the tungsten-rhenium wire have better thermal expansion matching; the coating is not easy to crack or shed, and the coating has the advantages of high thermal conductivity and large resistivity; and the prepared coating hot wire is long in service life and high in reliability.

Description

technical field [0001] The invention belongs to the field of microwave devices, and in particular provides a method for preparing a hot wire coating, which is used for preparing a coated hot wire for a cathode assembly. Background technique [0002] The cathode assembly is an important part of the electron gun and is widely used in various fields of electric vacuum microwave devices. The cathode filament heats the cathode to cause the cathode to emit electrons, so the performance of the filament is critical to the reliability and lifetime of microwave devices. In order to prevent the hot wire from short-circuiting with the cathode when it works at a high temperature of 1400-1500 ° C, a thin insulating layer is often coated on the surface of the hot wire. At present, electrophoretic deposition, plasma spraying and other methods are used to coat alumina ceramics on the surface of the hot wire. The existing technology solves the problem of alumina coating and hot wire expansio...

Claims

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Application Information

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IPC IPC(8): H01J9/04C25D15/00
CPCC25D15/00H01J9/042
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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