DEVICE FOR IN SITU MONITORING OF CORROSION RATES OF POLARIZED OR UNPOLARIZED METALS

摘要

ABSTRACT OF THE DISCLOSUREA technique for electrochemical measurement of the corro-sion current (corrosion rate) is disclosed. The electro-chemical parameters that are necessary to calculate thecorrosion rate are contained in the harmonic current,response to a moderate amplitude sinusoidal voltage per-turbation applied to the corroding metallic component.The harmonic current response is analyzed at frequencies1f, 2f, 3f, 4f, 5f and the rectification current responseat DC current to the presence of a 20-50 mV AC voltageperturbation at a frequency f. The free corrosion cur-rent density, the free corrosion potential and the Tafelcoefficients are calculated. The Tafel coefficient orTafel slope is a measure of the exponential dependence atthe rate of corrosion in a material. From these data,the dissolution current is calculated, which in turn isintegrated with respect to time to yield a cumulativemass loss.A-45695