AVALIAÇÃO DA PROTEÇÃO CONTRA CORROSÃO DE AÇO ELETROGALVANIZADO, PASSIVADO COM CROMO TRIVALENTE E PINTADO

MARTINS QUEIROZ, F.; C. I. ELSNER; A. R. DI SARLI; C. R. TOMACHUK; I. COSTA

San Pablo

Congreso; 66° Congresso da Associacao Brasileira de Metalurgia, Materiais de Mineracao (ABM); 2011

ABM

The passivation of eletrogalvanized steel to prevent the corrosion process is widely known and studied. Regarding to Cr VI-based treatments, in the last two decades researchers have been trying to find out alternatives to replace these salts once they must be banned in accord to environmental and industrial guidelines. In this context, several studies indicated new passivation treatments, especially Cr III-based conversion coatings, which has shown performance compatible to Cr VI-based treatments. The aim of this work was evaluate the corrosion behavior of electrogalvanized steel covered with Cr III-based treatment and an organic coating. Steel samples were electroplated in a cyanide-free alkaline zinc bath, then they were immersed in a Cr III-based solution and finally painted with three different organic coatings. EIS measurements were performed in NaCl 0,05 M and Na2SO4 0,1 M, during the immersion time. The organic coatings were characterized by their adherence and blistering. The results showed a similar behavior for the three coatings and, despite a second constant time has been pointed by the EIS fitting, the R2 values indicated a low corrosion rate. The system Zn-Cr III-organic coating was compatible to the system Zn-Cr VI-organic coating, for the immersion period considered.