Corrosion of Cu under highly corrosive environments

Cu corrosion in mixed flowing gases (MFG) has been widely studied. However, most of these studies have been carried out using conditions which were designed for accelerated tests simulating North America and Western Europe. More and more equipment are being deployed to emerging markets such as Asia Pacific and China, Eastern Europe, and the Middle East, where they are subjected to much more corrosive environments than those typically seen in North America and Western Europe. There is a need to understand the corrosive conditions in the emerging markets and come up with an accelerated test for products to be deployed in those conditions. In this work, we investigated the corrosion products on test Cu coupons exposed to harsh conditions by a combination of several analytical techniques. This work allowed us to establish a procedure for quantifying corrosion products and led to insights about corrosion mechanisms for copper in highly corrosive environments. Results showed that the corrosion of copper in the highly corrosive MFG testing condition (containing H ₂S, SO₂, C_l2, and NO₂) leads mainly to the formation of copper sulfide (Cu₂S) at the exposed surface, with the presence of a thin, buried cuprous oxide (Cu₂O) layer sandwiched between Cu₂S and copper substrate. The thickness of the corrosion products increases linearly with the exposure time.