Siemens Aktiengesellschaft

Heinrich Haessler

Horst Kippenberg

Wilfried Kuhl

Joachim Grosse

Reiner Mueller

Manfred Huehnlein

This invention relates to a new use of a fused material of copper and chrome as a contact material for use in vacuum contactors. In addition, the invention relates also to the contact material itself and to the method of its fabrication, as well as for special contact arrangements in the vacuum contactors. The invention shows a whole new, unsuspected range of application for the above fused materials. Up to now, contactors normally used material based on tungsten and copper which were first sintered and then immersed. It has now been experimentally shown that fused materials of copper and chrome, particularly after being reshaped, are very well suited as a contact material for vacuum contactors. Furthermore, in contact pieces of said fused material, methods are provided for additional additives to be precisely inserted by localized alloying, diffusion, or related techniques.

Use of a fusion material of copper and chrome as the contact material

Contact arrangement for vacuum switch in which one of two contacts is movable relative to the other in the axial direction of the contacts and is designed as a recessed contact. According to the invention, a condensation plate with a diameter greater than the inside diameter at the rim of the recessed contact is provided between the other contact and its current lead. The sidewall of the recessed contact forms a guide ring for the metal vapor, a substantial part of which condenses on the condensation plate.

Contact arrangement for vacuum switches

In the method according to the invention, Cr powder is poured into a degased mold, which can be made of graphite. On this Cr powder a piece of low-oxygen copper is placed. Subsequently, the mold is closed with a porous cover, which can also be made of graphite. Then the mold is degased in a high-vacuum furnace at room temperature until a pressure of better than 10.sup.-4 mb is reached. Thereafter, the furnace temperature is increased to as high as possible a temperature below the melting point of copper. This furnace temperature is maintained constant until an internal pressure in the furnace of better than 10.sup.-4 mb is reached. Subsequently, without intermediate cooling, the furnace temperature is further increased slowly to a final value of 100 degrees K. to 200 degrees K. above the melting temperature of the copper. This temperature is then maintained until the porosity contained in the Cr powder is completely filled up by the liquid copper.

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Wendelstein, Germany

Heinrich Haessler