A kind of preparation method of aluminum nitride insulating layer cathode heating wire

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...

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 cracking and falling off, leakage breakdown, etc.

However, with the development of microwave devices in the direction of high power and high reliability, the existing technology can no longer meet the high performance requirements of the cathode assembly, so the development of an insulating coating that better matches the heating wire is particularly necessary