STUDY OF THE ELECTROCHEMICAL NOISE GENERATED BY THE MILD-STEEL ZINC-RICH PAINT NACL SOLUTION SYSTEM

The electrochemical noise generated by the mild steel/zinc-rich paint/sodium chloride solution system has been investigated under free corrosion potential conditions. The electrochemical noise was characterized as spontaneous potential fluctuations. The potential-time record has been analyzed and transformed from the time domain into the frequency domain by means of the fast Fourier transform (FFT) method. The results show that the noise spectra exhibit a 1/f relationship at high frequency, with the standard deviation of the potential fluctuations showing a minimum value at the start of the test. The 'roll-off' slope was -20 dB per decade while the 'roll-off' frequency increased at advanced exposure stages. Ethyl silicate zinc-rich paints with 84, 72 and 60% zinc content and containing 0, 12 and 24% of the conductive extender Fe2P were used in this study. © 1990.