Siemens Aktiengesellschaft

Manfred Huehnlein

Horst Kippenberg

Heinrich Haessler

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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Nuremberg, Germany

Manfred Huehnlein