Theory 25/Corrosion Science
Corrosion Is an Area Ratio
The claim
Galvanic corrosion rate is set by the ratio of cathodic to anodic area rather than by potential difference alone.
01The mechanism
The galvanic current is fixed by the potential difference and the resistance, but the anodic current density depends on how much cathodic area collects it; a small anode coupled to a large cathode dissolves fast.
02Predictions
- P1Rate should track the area ratio.
- P2Potential difference alone should mispredict.
03Refutation
Rate tracking potential difference would remove the area term.