Effect of Dissolved Ozone on the Corrosion Behavior of Monel 400, Monel K-500, CDA 706, and CDA 715 in Seawater

摘要

Ozone is being considered as an alternative to chlorine based biocides for use in marine heat exchange systems. Ozone has several advantages over chlorine based biocides: including stronger oxidizing power, the ability to be produced on site, and degradation to oxygen. Before ozone is used in heat exchange systems it is important to understand its impact on the corrosion behavior of the metals used in these systems. Two separate studies were carried out: the first at the Corrosion Lab, Rensselaer Polytechnic Institute in Troy, NY comparing ozonated and aerated seawater for thirty, sixty, and ninety days, and the second, at the LaQue Center for Corrosion Technology, Inc. in Wrightsville Beach, N.C. which compared ozonated and chlorinated seawater environments for sixty days. Electrochemical experiments were performed and compared with crevice coupon immersion tests to determine effects of dissolved ozone on the corrosion behavior of Monel 400, Monel K-500, 90Cu/10Ni (CDA 706), and 70Cu/30Ni (CDA 715). Studies in-lab correctly predicted the morphology of crevice corrosion in ozonated seawater but, did not predict the extent of corrosion seen in the North Carolina tests.