The Corrosion Behavior of Cu and Naval Brass in 0.5M NaCl Solutions at Ambient Temperature

The rotating ring‐disk technique was used to obtain insight into the corrosion mechanisms of pure Cu and naval brass in deaerated 0.5 M NaCl at ambient temperature. The potential regions for the reactions: Cu 2 + → Cu + , Cu 2 + → Cu , Cu + → Cu 2 + , and Zn 2 + → Zn have been explored to permit analysis of the products of dissolution processes occurring during galvanostatic corrosion of these materials. Pure Cu corrodes only via Cu + over the range ∼ 2.5 × 10 − 6 to ∼ 900 × 10 − 6 A / cm 2 corrosion current (0.19 cm 2 area). No evidence is found for Cu 2+ species or for film forming reactions. Naval brass [60.54 w/o (weight per cent) Cu, 38.70 w/o Zn, and 0.76 w/o Sn] corrodes solely via Cu + and Zn 2+ up to ∼ 450 × 10 − 6 A / cm 2 corrosion current. No Cu 2+ species are found. Experiments indicate that selective dissolution of Zn does not occur. No evidence can be found for a Cu redeposition mechanism. Data suggest the occurrence of a homogeneous solution reaction in which soluble Cu + species produced on corrosion of the alloy undergo hydrolysis before reaching the zone of the ring electrode. No evidence is found for formation of CuOH or Cu 2 O directly on the corroding surface.