Electrochemical Investigation of the Corrosion Mechanism of Chromium Plated Panels in Aerated Solutions of Acidic Calcium Chloride

Corrosion of chromium plated components on cars in areas using calcium chloride for snow melting instead of sodium chloride is becoming a serious concern for the automotive industry. The use of calcium chloride is becoming more widespread because it is more effective than sodium chloride and is readily available. It is also used as an antidust treatment on dusty roads due to its hygroscopic nature. Compared to sodium chloride, the main differences are that (as already mentioned) it is hygroscopic and so components which are in contact with calcium chloride tend to remain damp, and the fact that calcium chloride solutions tend to readily absorb carbon dioxide from the air so the pH tends to fall [4]. In countries which have severe winters, cars are often not washed for several months at a time and the mixture of mud and calcium chloride which adheres to the chromium plating is very corrosive to the chromium which often results in severe corrosion of the plating. We have discovered that chromium deposited from trivalent electrolytes gives better results in accelerated tests developed by the automotive industry than chromium deposited from hexavalent electrolytes over microporous nickel. It is the objective of this paper to investigate the mechanism of chromium corrosion in acidic calcium chloride solutions.