CHARACTERIZATION OF THE CORROSION BEHAVIOR OF ZN AND ZN ALLOY ELECTRODEPOSITS - ATMOSPHERIC AND ACCELERATED TESTS

The corrosion behaviour of unchromated Zn, Zn-Co (0.6%), Zn-Fe (0.4%) and Zn-Ni (12%) coatings deposited from alkaline cyanide free solution was studied in a humid tropical climate and in accelerated chloride a nd sulfur dioxide cabinet tests. The presence of Ni or Co in the Zn ma trix increases Zn coating corrosion resistance, while Fe does not chan ge it. The statistical analysis of the data obtained showed that the s pecimens corrosion losses can be represented as an exponential equatio n as a Function of time of wetness. In such case the corrosion losses in one year of wetness can be approximated as a linear function of acc umulated CL-and SO, pollutant deposition. The data indicate a more sig nificant SO2 influence on the coating corrosion rate that is due to Cl -. (C) 1998 Elsevier Science Ltd. All rights reserved.