In situ analysis utilizing electrical resistance measurements when brazing cemented carbides

Abstract

Abstract Usually it is not possible to observe a high temperature brazing process such as joining cemented carbides to steel with copper as filler metal. The process takes place in a vacuum chamber at high temperatures and an analysis of the joint formed is only possible in a subsequent step. In this investigation, a novel setup has been introduced to allow for an in situ measurement of the brazing process via its electrical resistance. For this, a 4wiretechnique has been applied to the specimen to precisely measure the low resistance of the joint within a range of µΩ. By choosing two different holding times at a process temperature of 1150 °C and by analyzing the ensuing joint structures, it was possible to correlate the signal measured with the on-going diffusion and bonding process. Finally, the authors have revealed that the applied current of the measurement system had a distinct effect on the joint structure formed, which could be used additionally to improve the quality of the joint.