Analysis of corrosion of joints brazing copper matrix composites

ABSTRACT This work presents an electrochemical corrosion study in synthetic seawater of the dissimilar joint of TiC/Cu composite by brazing technique. Composites were machined by liquid infiltration without external pressure. This composite were joined with copper using a filler material constituted by an alloy of silver - copper and titanium powder. The composite joined shown a good adhesion forming a dissimilar assembled and coherent. In order to carry out the corrosion studies, two different techniques were used, potentiodynamic polarization curves (PCs) and electrochemical noise (EN). In addition, the corrosion potential measures as a function of the time were carried out to get the stabilization time of the anodic and cathodic reactions in the corrosion process. Electrochemical measurements were made at different exposure times with a total exposure time of 24 hours. A typical three-electrode electrochemical cell was used; where the working electrode (WE) was a sample of composite joined, the reference electrode was the saturated calomel electrode (SCE) and a sintered graphite rod was used as auxiliary electrode. The electrochemical results shown that the susceptibility to localized corrosion of the composite joined sample was higher than the based metal (copper). The corrosion mechanism of the composite joined sample is a differential aeration cell, where it can produce pitting and crevice corrosion form. The results shown a good correlation between the superficial analysis and the results obtained by the EN and CPs.