Abstract
The corrosion of St 37, StE 36, Al 99,5 and AlβMg 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 Β°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 70Β°C to 80Β°C the corrosion of steel and aluminium was low (wall losses in the order of 1 mΜm/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 Β± 0,18 eV for steel, and AE~Al~ = 1, 07 Β± 0,07 eV for aluminium.
A corrosion treatment on aluminum fatigue specimens after 1000β1500 hours at 110 Β°C caused a notable decrease in fatigue strength; no such behaviour was noted for steel, even when corroded at 170 Β°C.