CORROSION BEHAVIOR OF THE SYSTEM ELECTROGALVANIZED-NANOPARTICULATE PROCESS-ORGANIC COATING

F.M. QUEIROZ; P.R. SERÉ; C. I. ELSNER; A.R. DI SARLI; C. R. TOMACHUK; I. COSTA

Milan

Congreso; INTERFINISH 2012 -XVIII World Interfinish Congress & Exhibition; 2012

Politécnico de Milan

Finding environmentally friendly process with the same performance of those ones that already exists has been the great challenge for researchers of surface treatment Field. A successful example is chromium III based salts treatments as a substitute of hexavalent chromium that, so far, is the best alternative. In the last years, studies in nanotechnology are increasing and nanoparticulate systems based on silica, titanium and zirconium have been evaluated. In this work was studied the corrosion behavior of an electrogalvanized-nanoparticulate process-organic coating system by means evaluation of the open corrosion potential (Ecorr) and electrochemical impedance spectroscopy (EIS), besides accelerated corrosion tests. The samples were obtained from electrogalvanized steel prepared in an alkaline cyanide free bath. After this, they were immersed in a nanoparticulate system containing trivalent chromium salts and zirconium. Finally, part of the samples received an organic coating solvent based and the other one organic coating water based. After curing, samples were exposed to salt spray and humid chamber. Periodic inspections were performed measuring the open circuit potential, the impedance of the system. Moreover, visual observation to detect the corrosion degree and blistering with photographic register were carried out. In order to compare the new system, samples treated with trivalent chromium and hexavalent chromium were also evaluated. The results showed superior protection when the electrogalvanized-nanoparticulate process/organic coating was applied compared to the trivalent chromium and hexavalent chromium, indicating that is a promising process as an alternative to hexavalent chromium.