Investigation of Properties and Thermochemical Mechanisms of the Aging of RAB-Ceramic-to-Metal-Joints

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Ceramic-to-Metal-Joints can be brazed in air with silver based fillers by the Reactive Air Brazing Process. During the first period of this project (BO 1979/19-1 PAK 524) the reactions between fillers and base materials were analyzed in detail und new fillers and processes were developed successfully. Beyond the brazing process itself the long term behavior of the brazed joints is a critical aspect. The growth of the reaction layers between the filler and the steel occurring in standard fillers at typical operating conditions can lead to failure of the joint. Consequently the aim is to investigate, understand and influence the aging behavior of the RAB joints. The influence of the different parts of the joint respectively the brazing gap (steel, metal oxides, reaction zones, silver matrix, ceramic) on the aging at service conditions has to be analyzed. It has to be clarified how the growth of the reaction layers can be controlled by varying the filler metals and/or the brazing process. Furthermore the mechanical properties of joints brazed with new developed fillers and processes will be determined.