Controlled Release of Inhibitors for Extended Protection of Aluminum in Engine Cooling Systems

A method of controlled release of inhibitors (CRI) is described, by which inhibitors in a depleting engine coolant can be automatically replenished. A corrodible diaphragm is used to separate an inhibitor reserve from the coolant; inhibitor release is achieved by corrosive rupture of the diaphragm when the coolant becomes depleted.

Electrochemical and simulated service tests were used to demonstrate the effectiveness of the method. The CRI diaphragm corroded in less depleted coolants than were required to initiate corrosion on 3003, 7072 and cast 355 aluminum. Inhibitor release prevented aluminum corrosion in depleted coolants.