Volume 4, Issue 4 (April 2007)
Accelerated Oxidation and Corrosion Testing of Engine Coolants Using a Rotary Pressure Vessel Oxidation Test
Today’s modern engines are exposing engine coolants to more severe operating conditions involving higher coolant temperatures, greater heat rejection requirements, greater metal to coolant heat fluxes, higher coolant flow rates, higher cooling system pressures, and slower deaeration. These conditions will have a tendency to accelerate oxidation/thermal degradation, reduce corrosion protection, and shorten coolant life. In efforts to simulate the increased severity in operating conditions, an accelerated oxidation and corrosion test, using a rotary pressure vessel oxidation test, was developed and evaluated to assess the oxidation/thermal stability and corrosion protection of conventional, hybrid, and extended life coolants. The test involves exposing the coolant to a high temperature oxygen rich environment under pressure with six different metal corrosion coupons. The test allows a quantitative assessment of corrosion protection of the coupons and the effects on coolant chemistry. Test results are provided on conventional, hybrid, and extended life coolants. The test has also been found to be a promising predictive tool to screen satisfactory versus unsatisfactory coolant formulations, including recycled coolants.