The corrosion of steel and aluminium in calcium chloride/ammonia, magnesium chloride/methylamine and magnesium chloride/methylamine/decane

The corrosion of St 37, StE 36, Al 99,5 and Al‐Mg 3 in the chemical pairs of substances calcium chloride/ammonia, magnesium chloride/methylamine and magnesium chloride/methylamine/decane was investigated. The corrosion tests were performed in autoclaves at room temperature to 180 °C. The nominal duration of the experiments was 1000 hours. Rod shaped fatigue specimens with polished surfaces served as test specimens; these were fatigue tested after the corrosion treatments. All materials tested were compatible with calcium chloride/ammonia under the experimental conditions employed. Steel and aluminium showed similar behaviour against magnesium chloride/methylamine and magnesiumchloride/methylamine/decane, respectively. At room temperature and 70°C to 80°C the corrosion of steel and aluminium was low (wall losses in the order of 1 m̈m/a). Corrosion increased with increasing temperature. The activation energy for the reaction, which determined the rate of weight loss in magnesium chloride/methylamine/decane, was AE st = 0, 60 ± 0,18 eV for steel, and AE Al = 1, 07 ± 0,07 eV for aluminium. A corrosion treatment on aluminum fatigue specimens after 1000‐1500 hours at 110 °C caused a notable decrease in fatigue strength; no such behaviour was noted for steel, even when corroded at 170 °C.