Most coolant formulations designed for cast iron engines are unsatisfactory for aluminum head/block use because of excessive heat-transfer corrosion, resulting in heavy corrosion product deposition and loss of cooling efficiency in the radiator.
The effect of inhibitor and buffer additives, singly and in combination, on the heat-transfer corrosion rates for cast aluminum alloys was investigated. It was shown that some tetraborate and phosphate mixtures can be excessively corrosive. Silicate, in contrast, effectively protects the heat-transfer surfaces.
In addition, the effects of heat-transfer surface temperature, nucleate boiling, and variations in glycol, dissolved oxygen and chloride concentrations on the heat-transfer corrosion rate were investigated.