Corrosion speed measurement method - determining transfer resistance of electrodes in corrosive soln. in 10 to 2000hz range

摘要

The procedure is based on the measurement of the relation existing between weak perturbations (dv) of the metal-solution potential and the induced variations (di) of the current density circulating between the metal and the solution. The corrosion speed V=K/R where K is a constant and R, the transfer resistance =dv/di. The resistive part of the impedance is measured of the highest frequency for which the reactive part of the impedance passes through a minimum in the range 10-2000Hz. The appts. has a variable frequency voltage generator (1) connected to a potentiostat (3) supplying current to measuring electrodes (5) in the corrosive solution in such a way that they present on electric voltage equal to the delivered voltage supplied by the generator. The potentiostat is then connected via a current current-voltage converter (6) to an adjusting circuit connected to display (8) and comprising a phase comparator (7) and on output conditioner (9). The phase shift between the delivered voltage and the voltage supplied to the current-voltage converter is measured and displayed. The transfer resistance (R) is then measured at the frequency where the phase shift is a minimum and converted to a corrosion speed.