Method for directly joining metal pieces to oxide-ceramic substrates

DETAILED DESCRIPTION It is an object of the invention to provide an improved method for the direct joining of metal pieces to oxide-ceramic substrates, in which a substantially bubble-free joint between the metal pieces and the ceramic substrates and at the same time an oxide-free metal surface is obtained in a simple manner.
With the foregoing and other objects in view, there is provided in accordance with the invention a method for the direct joining of metal pieces to ceramic oxide substrates which comprises covering the ceramic substrate with a metal piece having an oxide coating on the side facing the ceramic substrate, heating the substrate covered by the metal piece with an oxide coating to a temperature above the eutectic temperature of the metal and the oxide but below the melting point of the metal to form a eutectic melt in an atmosphere of an inert gas and 20 to 50 volume parts per million oxygen, reducing the temperature to cool and solidify the eutectic melt and after solidification of the eutectic melt continuing cooling while maintaining the ceramic substrate with the covering metal piece in an atmosphere of an inert gas in the absence of oxygen.
Other features which are considered as characteristic for the invention are set forth in the appended claims.
Although the invention is illustrated and described herein as embodied in a method for directly joining metal pieces to oxideceramic substrates, it is nevertheless not intended to be limited to the details shown, since various modifications may be made therein without departing from the spirit of the invention and within the scope and range of equivalents of the claims.