Linear-sweep voltammetric studies on iron in aqueous sulphate electrolytes between 20 and 200°C

Potentiostatic polarisation studies have been made on iron in 10% Na₂SO₄ at sweep rates of 0.3–30 mV s^?1 and at temperatures of 20–200°C using a platinum-platinum oxide reference electrode. The sweeps showed characteristic features of anodic dissolution and passivation. Oxide removal was evident on the cathodic sweeps. As noted by previous workers two anodic dissolution peaks were observed with clean electrode surfaces, but only one occurred when the surface was covered with oxide. The number of dissolution peaks was also found to depend on sweep rate. In contrast to other work which suggested that there was no passive region above 95°C, passivation was shown to occur even at 200°C.