Caracterização eletroquímica e microestrutural de espinélios mistos nanocristalinos produzidos eletroquimicamente sobre o aço AISI 304

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

2011

RESUMO

In the coloration process of stainless steels, an oxide film, which exhibits interference colors, is formed on the metal surface. In this work, nanoporous oxide films were formed on AISI 304L stainless steel by electrochemical coloring in 5 M H2SO4 and 2.5 M CrO3 with different electrolysis times, using the triangular current scan method. The nanocrystalline spinel oxide films thus obtained were electrochemically characterized by cyclic voltammetry at 1 mV/s in 0.5 M Na2SO4. Since the steel colored for 40 min exhibits three well defined anodic peaks, the effect of potentiodynamic polarization from -0.8 V to a final potential between 0.9 V and 1.4 V in 0.5 M Na2SO4 on the morphology and the composition of these films were analyzed in more detail. Scanning electron microscopy (SEM) images showed that the coloration process causes severe grain boundary attack. According to the atomic force microscopy (AFM) images, the oxide film is always nanoporous and constituted of nanometric granules. Raman spectra indicated that the oxide films consist of (Fe,Ni,Cr)(Fe,Cr)2O4 spinel. Cyclic voltammetry tests confirmed the large surface area of these films. The presence of several anodic peaks in the voltammetries, along with the X-ray photoelectron spectroscopy (XPS) results, evidenced that the ionic species in the film are not completely oxidized, thus enabling to control its chemical composition by simple polarization. The experimental results showed that the oxide films produced by coloration of stainless steel are promising for applications in electrocatalysis and ions lithium intercalation.

ASSUNTO(S)

coloração espinélio nanomateriais aço inoxidável comportamento eletroquímico

ACESSO AO ARTIGO

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