On Area Ratio of Anode to Cathode for Iron in Neutral Solution

We have succeeded in making a corrosion cell which separates the anodes from the cathodes for iron in a neutral solution. In the corrosion cell, two test pieces are faced, or put back to back, and immersed in the condition of electrical short circuit. The corrosion behavior was measured by the amount of galvanic current with a zero impedance ammeter and by weight loss. After the test, it was found that the corrosion cell of horizontally opposed electrodes could almost perfectly separate the anodes from the cathodes in the differential aeration cell formed. The galvanic current density of the anode (that is, the anodic dissolution rate) is proportional to the area ratio of anode to cathode; while the galvanic current density flowing in the cathode is not related to the area ratio and approaches the limiting current density for oxygen reduction. It is concluded that this corrosion cell can be useful for corrosion mechanism studies.