DE1253367B - Process for the production of pot-shaped electrodes for electron tubes or for picture display tubes that are operated with high working voltage - Google Patents

Description

FEDERAL REPUBLIC OF GERMANY

GERMAN

PATENT OFFICE

PATENT LETTERING

Int. Cl .:

Number:

File number:

Registration date:

Display day:

Issue date:

HOIj

German class: 21g-13/09

P 12 53 367.4-33 (V 30443)
February 21 , 1966 November 2, 1967 December 11, 1969

The patent specification differs from the patent specification

The invention relates to a method for producing cup-shaped electrodes for electron tubes or for picture display tubes which are operated with high working voltages and which are switched off a non-magnetic, hardenable copper-nickel or Nickel-copper alloy.

Particularly in the case of picture tubes, there are physical conditions which, among other things, result from special properties of the electrode material must be met.

In addition to electrical conductivity, the material must because of the predominantly magnetic deflection of the electron beam in these tubes can be largely non-magnetic. Besides, it must The material must be free of additions that could poison the cathodes.

For manufacturing reasons, mainly deep-drawn cup-shaped electrodes are used Mission. In addition, a high dimensional stability must be guaranteed to avoid changes in geometry switch off the electrodes during assembly.

A whole range of materials has these properties; the developments and efforts about the material properties of the electrode material for electron tubes with high operating voltages but went in a different direction.

Especially with the transition to large screen diagonals, the picture tubes had to achieve the necessary image brightness can be operated with higher anode voltages. So that are to the To make electrode materials increased requirements with regard to their dielectric strength.

As is well known, an attempt is made on the one hand to reduce the electron work function to increase the electrode materials used. On the other hand, because of the mainly occurring peak discharges in the external shape of the electrodes too small Avoided radii and sharp edges. However, this is due to the miniaturization of the whole Electrode system limits. In addition, there are spark discharges at the so-called micro-tips on the rough surface of the electrodes.

A surface structure that is as smooth as possible is therefore required for the electrodes is improved by chemical or mechanical-chemical processes.

The use of bronze and copper-nickel alloys is known as a material for highly stressed Electrodes for electron tubes.

The disadvantage of these materials is that they are necessary for a subsequent mechanical-chemical polishing process for producing pot-shaped
Electrodes for electron tubes or for
Picture tubes that use high
Working voltage are operated

Patented for:

VEB factory for television electronics,
Berlin-Oberschöne Weide, Ostendstr. 1-5

Named as inventor:

Werner Kirschke, Berlin-Wilhelmshagen;

Dipl.-Ing. Dr. Günter Maronna, Berlin-Koepenick

are too soft. This leads to the deformation of the elec-

ao trot.

On the other hand, in the polishing process of the relatively soft material, the microtips become lubricated into the pores on the surface of the material, in which small volumes of gas then

a5 to be closed.

Gas outbreaks then occur during the operation of the electron tube, leading to cathode damage lead and reduce the service life of the electron tubes considerably.

It has therefore become known to use high-purity aluminum for electrodes whose surfaces are through an oxidation process are provided with an insulating layer.

However, for reasons of strength, aluminum can only be used to a limited extent and is suitable for mass production not suitable. The material smears heavily, and the tools for making the deep-drawn cup-shaped Electrodes have to be serviced continuously in order to achieve the required accuracy of the individual parts to be able to adhere to.

It is also known to use austenitic chromium-nickel steels as electrode material. Chrome nickel steel has a high strength and can be carried out using known chemical-mechanical processes polishing. Due to the hardness of the microtips, they break off during the polishing process, so there is no danger the formation of gas inclusions in the surface layer is given. Due to the high strength great forces are required for deformation.

The rapid solidification during the drawing process requires repeated intermediate annealing because of the risk of oxidation caused by the high

909 650/421

Chromium content of the material must take place in a vacuum or in an oxygen-free protective gas atmosphere. The processing effort for this material is very high.

There are also age-hardenable nickel-copper-aluminum alloys known with an aluminum content of 2 to 4%. However, the application of these alloys to high vacuum tubes is increasing rejected because they are very difficult to work with because of their hardness. For this reason Copper alloys with an aluminum content of less than 1% are also preferred is less than 0.5%, known for use in electrical discharge vessels. These alloys however, they cannot be hardened.

It is therefore the purpose of the invention to provide a method for producing cup-shaped electrodes for Electron tubes with sufficient dielectric strength against electric field emission Find.

The task arose, therefore, of a less complex machining process with one material with the necessary electrical and magnetic properties for the stated purpose.

According to the invention, the object is achieved in that the alloy is initially soft, not In the hardened state, machined to give shape according to the usual methods, followed by a thermal Subjected to a hardening process with simultaneous bright annealing and then in one mechanical-chemical process is polished.

The use of a copper-nickel alloy with a has been found to be particularly useful Nickel content of 1 to 30%, silicon for hardening with a content of 0.1 to 3% and / or Aluminum with a proportion of 0.5 to 5% and / or titanium with a proportion of 0.1 to 1.5% is proven.

It has also been shown to be advantageous to add the copper-nickel alloy used to a solution annealing process before mechanical processing subject.

The solution annealing process at a temperature of 900 to HOO ⁰ C and a subsequent quenching to room temperature has a particularly favorable effect. When adding certain elements, e.g. B. aluminum, to a copper-nickel alloy with a Kiipfer portion of 55% occurs an increase in strength: uif, so that an increased deformation work compared to the processing of a conventional copper-nickel alloy has to be done. These difficulties can be avoided by changing the basic composition of the alloy by increasing the copper content to such an extent that lower strength values can be achieved and only by adding further elements the same strength values as with a conventional copper-nickel alloy with a copper content of only 55 %, but can be achieved without additional elements.

If the nickel content is> 60% in a copper-nickel alloy, this material is at room temperature magnetic and useless for use in picture display tubes.

By adding third elements, e.g. B. silicon and / or aluminum, the nickel content can be increased without losing the non-magnetic properties. A nickel-copper alloy with 70% nickel and above 1% silicon is still non-magnetic. Similar conditions occur when aluminum and titanium are struck. Another possibility is that the Copper content is increased. This alloy always remains non-magnetic. With a copper-nickel alloy With a copper content of 60 to 99%, hardening can be achieved by adding 0.1 to • 3% silicon and / or aluminum from 0.5 to 5%

ίο and / or titanium from 0.1 to 1.5% can be achieved.

By precisely coordinating the composition, the strength values can be set in such a way that, in the soft-annealed condition, the same strength is achieved as with a copper-nickel alloy with a copper content of 55%, namely 40 to 50 kp / mm ² . So is z. B. the strength of a nickel-copper-silicon alloy (Cu 99 to 97%, Si 0.5 to 0.8%, Ni remainder) in the soft-annealed state at 30 kp / mm ² . By increasing the

With the nickel content, the strength can be brought into the range from 40 to 50 kp / mm ² , with an improvement in the material against atmospheric influences being achieved at the same time. The hardening effect in copper-nickel-silicon alloys is caused by the fact that silicon and nickel form a chemical compound in the form of nickel silicide, the solubility of which in copper decreases with decreasing temperature.
This means that the essential prerequisites for the hardenability of this group of alloys are given. By quenching at temperatures (900 to 1100 ° C.) which are above the solubility limit, a homogeneous solid solution which is oversaturated with nickel silicide is obtained. In this state, the material is sufficiently soft that it can be deep-drawn in conventional tools without causing great tool wear or high maintenance costs.

Tempering an alloy treated in this way in the temperature range from 350 to 600 ° C increases its yield point, tensile strength and Brinell hardness. If cold deformation is carried out between annealing above the solubility limit and heat hardening, an additional increase in the mechanical values can be achieved during hot hardening. The strength values achieved are above 70 kp / mm ² .

With the electrodes manufactured according to this process is also used in picture display tubes Anode voltages of over 20 kV provide good dielectric strength against so-called cold emissions or against electrical flashovers. The processing effort is less than usual Process or materials.

Claims (4)

Patent claims: 1. Process for the production of cup-shaped electrodes for electron tubes or for picture display tubes, which are operated with high working voltage, and which are made of a non-magnetic, hardenable copper-nickel or. Nickel-copper alloy, characterized in that the alloy is initially in a soft, non-hardened state Machined to shape using conventional methods, followed by a thermal hardening process with simultaneous blank annealing and then polished in a mechanical-chemical process. 2. The method according to claim 1, characterized in that a copper-nickel alloy With a nickel content of 1 to 30%, the hardening silicon with a content of 0.1 up to 3% and / or aluminum with a proportion of 0.5 to 5% and / or titanium with a proportion from 0.1 to 1.5% is added is used. 3. The method according to claim 1 and 2, characterized in that the copper-nickel alloy used is ^{subjected to a solution annealing process at a temperature of 900 to 1100 0} C and then quenched to room temperature before mechanical processing. 4. The method according to claim 1 to 3, characterized in that the copper-nickel alloy used after solution heat treatment and mechanical shaping, is hardened at a temperature of 350 to 600 ° C. Considered publications: German Patent No. 867 165;
German Auslegeschriften No. 1202 090; S27120 VIII c / 21g (published April 5, 1956); T 9446 VIIIc / 21g (published April 12, 1956); Book by E. v. Angerer and H. Ebert: "Technical tricks in physical investigations", 9th edition, 1954, p. 73; "Härterei-Technische-Mitteilungen", Vol. 19, 1964, pp. 79 to 82.