SU387453A1 - CATHODE - Google Patents

Description

one

The invention relates to electronic engineering, in particular, to the manufacture of efficient ter- rors for MO and secondary electron cathodes.

Known cathodes of two-component alloys of platinum ground metals Ru, Rh, Pd, Os, Ir, Pt with rare earth metals (SEM) -La, Ce, Pr, Nd, Sra, which have relatively high emission properties. For these metals, alloying is characterized by the formation of intermetallic compounds, the increased thermochemical strength of which leads to a low rate of entry of the active metal to the alloy surface, which leads to a decrease in the emission stability at temperatures below 1000 ° C, as well as to an increase in the cathodes under poor vacuum conditions. Therefore, under insufficient vacuum conditions, low temperatures, ion bombardment, and other factors driving them, their destruction of the cathode surface, the slow rate of entry of active metal (REM) to the alloy surface leads to a drop in emission. Cathodes based on these alloys are not form-stable at high temperatures. Therefore, it is difficult to use these alloys in devices with poor vacuum conditions, low operating temperatures (below 1300 ° C). These conditions take place in such devices and systems as accelerators, M-type amplifiers, electron beam melting, welding, electron beam recording systems on thermoplastic.

It is proposed to produce effective emission alloys based on platinum group metals (Ru, Rh, Pd, Os, I g, Pt), rare earth metals (La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tu, YB, Lu) and metals of the IV, V, VI groups of the periodic system (Ti, Zr,

Hf, V, Nb, ta, Cr, Mo, W). The electron work function of these alloys is in the range of 2.4-2.9 eV, and the maximum coefficient of secondary electron emission of these alloys is 2–3. The indicated emission parameters of the cathodes

remain at a decrease in temperature to 600 ° C. The introduction of a refractory metal increases the efficiency of the cathodes, improves thermal dimensional stability and reduces the consumption of the platinum group metal.

In the proposed ternary alloys, the concentration of the components can vary in the following ranges of values (in wt.%) Without a substantial change in the emission characteristics of the alloys: platinum group metal -

1-99; metal IV, V, VI groups of the periodic system of 0.25 - 99; REM -0.1-33.

The proposed cathode alloys can be made by ordinary melting in an arc furnace with a non-consumable electrode in a copper water-cooled crystallizer in an atmosphere of inert gas followed by 1, by its rolling in

ribbon wire. The alloy can be made by vacuum melting. In that case, if the receiving tape is difficult or impractical, the cathode can be made directly from the ingot by electrospark erosion.

Subject invention

Claims (2)

1. Cathode for electronic devices based on an alloy of one of the platinum metals group and one of the rare earth metals, characterized in that, in order to expand the range of operating temperatures of the cathode, it contains one of the refractory metals that do not form intermetallic compounds, such as titanium, with the rare earth metal. 2. The cathode according to claim 1, characterized in that it contains 0.5-99 wt. % of the specified refractory metal.