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Junqueira R.M.R.,Instituto Senai Of Inovacao Em Engineering Of Superficies | De Andrade Manfridini A.P.,Rede Tematica em Engineering de Materiais REDEMAT | De Oliveira Loureiro C.R.,Instituto Senai Of Inovacao Em Engineering Of Superficies | De Mendonca R.,Rede Tematica em Engineering de Materiais REDEMAT | And 2 more authors.
Surface Engineering | Year: 2013

Anodic interference films were grown on stainless steel by an electrochemical process in a 70 g L-1 CrO3+500 g L -1 H2SO4 solution at temperatures of 25-75°C. The aim of this research was to assess the influence of temperature on characteristics of this coating. The morphology of the films was assessed through atomic force microscopy, the chemical composition was assessed by X-ray photoelectron spectroscopy, while the mechanical characteristics were assessed by resistance to abrasion wear and nanohardness. The roughness of the films grown at 25°C is less than that of the other temperatures. No significant difference regarding the porosity of the films was detected. A chromium hydroxide was observed on the top of the oxide layer grown on stainless steel. The steel coloured at 75°C presented a lesser hardness compared to the samples grown at 25, 35 and 55°C. The wear resistance increased as the temperature of the film's growth rose, which was inversely proportional to the hardness. © 2013 Institute of Materials, Minerals and Mining. Source


Lopes I.M.F.,Instituto Senai Of Inovacao Em Engineering Of Superficies | Loureiro C.R.O.,Instituto Senai Of Inovacao Em Engineering Of Superficies | Junqueira R.M.R.,Instituto Senai Of Inovacao Em Engineering Of Superficies
Materialwissenschaft und Werkstofftechnik | Year: 2014

The chemical and structural complexity of soils, coupled with their heterogeneity, contributes to the increase in soil aggressiveness, which can in turn result in severe corrosion of underground materials. The understanding of corrosive processes of underground structures is important in aiding the development of methods, as well as in monitoring and maintenance, in an attempt to minimize environmental, social, and economic impacts. In this work, electrochemical impedance spectroscopy (EIS) was used to monitor the corrosive process of galvanized steel when in contact with soil extracts, aimed at evaluating the potentiality of applying electrochemical impedance spectroscopy when monitoring underground structures. To accomplish this, the behavior of the galvanized steel when undergoing corrosion was studied for 105 days, examining the variations in the eletrochemical parameter values obtained through EIS assays over this period. EIS proved to be effective in the study of corrosive processes of galvanized steel when in contact with soil extracts, identifying the different stages of the corrosive process, controlled by mass and/or charge transfer reactions. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim. Source

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