Impedance Measurement by Laplace Transformation of Microprocessor Obtained Data from Corrosion Cells

Data obtained by a microprocessor devised to automate frequency response analysis of electrode systems have been treated by the Laplace transformation method. The method was applied to three corrosion systems. After checking the system with standard circuits and overcoming the problem of noise, the polarization resistance values so obtained for two of the systems, one activation and one diffusion controlled, compared closely with those from least-squares computer-fitting the polarization data about the corrosion potential. As expected, the diffusion controlled cathodic process at a rotating electrode did not result in a Warburg impedance. A 70:30 copper-nickel alloy in sea water produced a frequency response diagram which did not have a simple low frequency limit.