Accelerated tests for prediction of cut edge corrosion of coil-coated architectural cladding. Part II: cyclic immersion

A cyclic immersion apparatus has been constructed for the evaluation of edg e corrosion of coil-coated cladding. In this method, edge corrosion is acce lerated by coupling each coil-coated specimen to an external stainless stee l cathode in order to increase the cathode to anode area ratio, thereby inc reasing the rate of undercutting of the metal coating. Comparisons with out door results reveal that the cyclic immersion test produces realistic edge corrosion and blistering morphologies and has significantly less variabilit y than conventional cabinet tests. Furthermore, it has the distinctive abil ity amongst accelerated tests to potentially control the acceleration of un dercutting at the cut edge by varying the size of the cathode. A limitation of the test at present is the relatively small acceleration factor for the simulation of industrial environments. This limitation is explained with t he aid of polarisation test results and methods for increasing the accelera tion of the test are discussed. (C) 1999 Elsevier Science S.A. All rights r eserved.