Metal Corrosion Associated with Thermal Cycling of Inhibited and Uninhibited Propylene Glycol/Water Solution in Solar DHW Systems

摘要

As part of the Solar Reliability and Materials Program at Argonne National Laboratory, metal corrosion associated with thermal cycling at 82 exp 0 C circulating and 176 exp 0 C stagnating temperatures of propylene glycol and ASTM corrosive water mixture (50% v/o) was investigated. Preliminary data indicate that in a mixed metal system of copper, steel, and aluminum specimens stagnating together in a glycol solution, the copper randomly pits and the pitting stops when the pit depth extends to about 1-1/2 mil. The addition of 1% molybdate as an inhibitor to the glycol solution is slightly beneficial for steel, but the added expense of adding and maintaining the concentration of an inhibitor may not be warranted. Dissolved copper rapidly deposits on the aluminum surface and promotes severe galvanic corrosion. (ERA citation 08:040527)