Electrochemical Noise Generation During Stress Corrosion Cracking of Alpha-Brass

An investigation of the electrochemical noise generation during the stress corrosion cracking (SCC) of alpha-brass was conducted in Mattsson1 solution (ammoniacal copper sulfate solution) of pH 7.2 under free corrosion potential. The electrochemical noise was observed as spontaneous potential fluctuations. The analysis of the readings obtained are made using the Burg’s maximum entropy method2. The measured parameters which appeared to give the clearest indication of the results were the standard deviation (essentially the average noise power) and the roll-off slope. The observed corrosion behaviors as obtained from the results are related to the existing known SCC mechanisms. All of the spectra appeared as a low frequency plateau with a roll-off at high frequencies. In addition, plastic replicas are made from specimen’s surface and subsequently examined by scanning electron microscopy (SEM) to follow the progress of the crack initiation and growth.