Papers by Author: Renato Altobelli Antunes

Paper TitlePage

Authors: Isaac Jamil Sayeg, Renato Altobelli Antunes, Mara Cristina Lopes de Oliveira
Abstract: In this work, the corrosion resistance of passivated PIM 316L stainless steel specimens was evaluated in 1M H2SO4 + 2 ppm HF solution at room temperature during 28 days of immersion. Passivation was carried out in HNO3 and H2SO4 solutions. The electrochemical behavior of the passivated specimens was assessed through electrochemical impedance spectroscopy and anodic polarization curves. Scanning electron microscopy (SEM) was employed to observe the surface of the specimens before and after the passivation treatments. The results pointed to a strong influence of the passivation conditions on the corrosion resistance of the specimens.
Authors: Mara Cristina Lopes de Oliveira, Isolda Costa, Renato Altobelli Antunes
Abstract: Bipolar plates play main functions in PEM fuel cells, accounting for the most part of the weight and cost of these devices. Powder metallurgy may be an interesting manufacturing process of these components owing to the production of large scale, complex near-net shape parts. However, corrosion processes are a major concern due to the increase of the passive film thickness on the metal surface, lowering the power output of the fuel cell. In this work, the corrosion resistance of PIM AISI 316L stainless steel specimens was evaluated in 1M H2SO4 + 2 ppm HF solution at room temperature during 30 days of immersion. The electrochemical measurements comprised potentiodynamic polarization and electrochemical impedance spectroscopy. The surface morphology of the specimens was observed before and after the corrosion tests through SEM images. The material presented low corrosion current density suggesting that it is suitable to operate in the PEM fuel cell environment.
Authors: Renato Altobelli Antunes, Mara Cristina Lopes de Oliveira, Lucas Costa de Castro Ferraz, Letícia dos Reis Gonçales, Olandir Vercino Correa
Abstract: The aim of the present work was to study the influence of beta phase precipitates content and distribution on the corrosion behavior of the AZ91D magnesium alloy, using samples subjected to solution annealing and aging. The morphology of the beta phase was observed using optical microscopy and scanning electron microscopy. The volume fraction of each phase was also determined. Potentiodynamic polarization tests and immersion tests were carried out, indicating an increase of the corrosion resistance with the volume fraction of the beta phase and its distribution on the grain boundaries of the alpha-phase. Solution annealed samples were more susceptible to corrosion.
Authors: Renato Altobelli Antunes, Wagner S. Wiggers, Maysa Terada, Paulo A.P. Vendhausen, Isolda Costa
Abstract: The use of AISI 316L stainless steels for biomedical applications as implants is widespread due to a combination of low cost and easy formability. However, wrought 316L steel is prone to localized corrosion. Coating deposition is commonly used to overcome this problem. Ceramic hard coatings, like titanium nitride, are used to improve both corrosion and wear resistance of stainless steels. Powder injection moulding (PIM) is an attractive method to manufacture complex, near net-shape components. Stainless steels obtained from this route have shown mechanical and corrosion properties similar to wrought materials. The literature on the use of PIM 316L steel, either coated or not, as implants is still very scarce. The aim of the present work was to study the corrosion behaviour of PIM 316L in two conditions: TiN-coated and bare. Electrochemical investigations were performed using EIS and potentiodynamic polarization techniques.
Showing 1 to 4 of 4 Paper Titles