Papers by Author: A.V.C. Sobral

Abstract: The present work describes the studies on corrosion of powder injection molded 316L stainless steel potentiostatically coated by poly{trans[RuCl2(vpy)4]} where vpy (4- vinylpyridine) acts as ligand. Scanning Electron Microscopy (SEM) coupled to an Energy Dispersive X-Ray Analysis (EDAX) characterized the coated electrodes. Anodic polarization tests were performed in 3% NaCl to estimate the anodic dissolution current density of the electrode coated by the polymeric material. In addition, the specimens were exposed to salt spray and acid rain simulated environment. The microestrutural analysis indicated that the films were approximately 58 μm thick. Cyclic voltammetry experiments were carried out in 0.1M HTBA/methyl isobutyl ketone solution. The results revealed a scan rate dependent wave corresponding to a Ru2+/Ru3+ redox reaction, thus confirming the presence of ruthenium as metallic center in the polymer backbone. Pitting corrosion was observed in coated specimens only after thirty days of exposure to salt spray and after two days of exposure to acid rain simulated environment.

Abstract: The use of generated coated polymeric films by electrochemistry means in the sintered metallic surfaces has been being the focus of our research aimed at the corrosion protection of small mechanical components obtained from powder metallurgy. The sintered alloys Fe- 2%Ni, Fe-5%Ni and 10%Ni with polymeric coating were tested using electrochemistry methods in corrosive solutions of NaCl 3%, KNO3 1.25M, H2SO4 0.5M, HNO3 0.5M, acetic acid 1%, oxalic acid 1% and lactic acid 1%. The electrochemistry corrosion tests were performed using two techniques, Eocp vs. Time and Potentiodynamic and they proved the efficiency of the polymeric coating on the corrosion protection of sintered alloys.