Siemens Aktiengesellschaft

Reiner Muller

Horst Kippenberg

Heinrich Hassler

Irmo Paulus

Rudiger Hess

Hannelore Schnodt

Contact pieces for vacuum switchgear comprise a base material with additives of readily vaporizable components to produce a sufficiently conductive switch path in the switch-off process. It is desired to have an overvoltage-free switching behavior for the vacuum switchgear. The additives are concentrated in a firmly adhering layer covering the switching surface of the contact piece. Such contact pieces can be manufactured in particular by direct fusing of the additives on the surface, by fusing a separate application of the additives in powder form, in granulate form or as foil or sheet on the surface or alternatively by vapor deposition of the additives on the switching surface of a given contact piece body of base material. Advantageously, a CuCr contact piece base material is used.

Contact pieces for vacuum switchgear, and method for the manufacture

A method of producing copper-chromium fusion alloys having a chromium content of at least 25% by mass and at most 60% by mass with a homogeneous macrostructure without lattice defects and without shrink holes or pipes, which can be used as contact material for vacuum power switches with breaking currents exceeding 10kA. According to the invention, during fusing of the starting material to the fusion alloy a superheating to at least 2000.degree. C. is obtained at least in a partial zone of the instantaneous melt volume. Thereafter the melt is cooled at a cooling rate such that no primary Cr precipitation or segregation occurs.

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Steinbach, Germany

Reiner Muller