JPH0221531A - Coated particle cathode for electron tube - Google Patents

Abstract

PURPOSE:To make it possible to obtain a coated particle cathode for electron tube with no unevenness of electron emitting property by including a specific amount of at least one sort of zirconium, magnesium, and silicon in the nickel for covering. CONSTITUTION:In the nickel used for covering, 0,0001% to 0.1% of at least one sort of zirconium, magnesium, and silicon is included. And the addition of an activator to the covering nickel layer 2 is carried out when barium strontium carbonate particles 1 are stirred in a solvent prior to letting flow the nickel gas produced from nickel carbonate in the manufacture process of the coated particles(CP). In this case, the zirconium, magnesium, and silicon are added actually in the form of zirconium hydride, magnesium carbonate, and silicon made into minute powder. Consequently, a cathode with a good cathode surface condition can be obtained in a short time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a coated particle cathode for an electron tube.

[Conventional technology]

Conventionally, coated particle cathodes (hereinafter referred to as CPC), in which coated particles (hereinafter referred to as CP) in which barium strontium carbonate particles are coated with nickel to a thickness of several microns to more than ten microns, are coated on a nickel substrate.
It is possible to obtain a larger amount of electron emission than an oxide cathode in which barium strontium carbonate is coated on a nickel substrate.

CP is obtained by passing nickel gas obtained by reducing nickel carbonate into a solution of barium strontium carbonate and amyl acetate with stirring.

CP is coated on a nickel substrate and cathodically decomposed in vacuum, ie heated to 900-1000°C.

By heating, barium strontium carbonate is decomposed into carbon dioxide gas and barium strontium oxide. The generated carbon dioxide gas breaks through the covering nickel layer and is released. Therefore, in the CPC after cathodic decomposition, barium strontium oxide is partially coated with nickel and arranged on the nickel substrate.

[Problem to be solved by the invention]

The conventional CPC described above releases electrons through a chemical reaction between barium strontium oxide on the cathode surface and an activator such as zirconium or magnesium contained in the nickel substrate and diffused to the cathode surface.

As mentioned above, CP is coated with nickel,
Although it has the property of emitting a large amount of electrons, nickel also has the disadvantage of retarding the diffusion of the activator, and therefore CPC requires a long aging period until sufficient activator diffuses to the cathode surface. It has the disadvantage that it requires

Here, the method of aging the cathode at a high temperature in order to promote the diffusion of a large amount of the activator has the disadvantage that there is a limit to the aging time per cathode temperature because it promotes sintering of the CP.

Furthermore, there is a drawback that the electron emission characteristics of the cathode vary due to variations in the coating thickness of the nickel film.

An object of the present invention is to provide a coated particle cathode for an electron tube that can be aged for a short time and has uniform electron emission characteristics.

[Means to solve the problem]

The present invention provides a coated particle cathode for an electron tube in which barium strontium carbonate particles whose surfaces are coated with nickel are coated on a nickel substrate, and in which at least one of zirconium, magnesium, and silicon is added to the coated nickel by o, oooi%. Contains ~0.1%.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a longitudinal sectional view of an embodiment of the present invention.

As shown in FIG. 1, barium strontium carbonate particles 1 are coated with 1!2 nickel containing zirconium hydride in a weight ratio of 0.05% to nickel. . The nickel substrate 3 contains 0.08% zirconium in nickel.

The addition of the activator to the coated nickel layer 2 is carried out during the CP manufacturing process, when the barium strontium carbonate particles 1 are being stirred in a solvent before passing through the nickel gas produced from nickel carbonate. At this time, zirconia to be added 1. Magnesium and silicon are actually zirconium hydride, magnesium carbonate, and silicon, respectively, which are added in the form of fine powders of 10 μm or less.

Also, if the amount added is less than 0.001%, there is no effect, and if it is added more than 0.1%, the compound formed between barium, nickel, and the additive will inhibit the diffusion of the activator. , the electron emission characteristics as a cathode are extremely deteriorated.

〔Effect of the invention〕

As explained above, in the present invention, by adding an activator to the nickel layer of the CP, cathode decomposition and cathode activation can be performed at a temperature below the sintering temperature of the CP. It has the effect that can be obtained in a shorter time than CPC.

In addition, compared to our comparison, the aging time was reduced to 1/2, and the variation in electron emission characteristics was also reduced by about half.

[Brief explanation of the drawing]

FIG. 1 is a longitudinal sectional view of one embodiment of the present invention. 1... Barium strontium carbonate particles, 2... Nickel layer, 3... Nickel substrate. -, :, Figure 1: Nickel substrate

Claims (1)

[Claims] In a coated particle cathode for an electron tube in which barium strontium carbonate particles whose surfaces are coated with nickel are coated on a nickel substrate, at least one of zirconium, magnesium, and silicon is contained in the coated nickel by 0.0001% to 0.1%. A coated particle cathode for electron tubes characterized by containing %.