Caracterização de filmes finos de coloração por interferência em aços inoxidáveis

AUTOR(ES)
FONTE

IBICT - Instituto Brasileiro de Informação em Ciência e Tecnologia

DATA DE PUBLICAÇÃO

13/02/2004

RESUMO

In this work, various experimental techniques were employed to study colored interference films deposited on the surface of AISI 304 stainless steel by an electrochemical pulsed current process developed at Fundação Centro Tecnológico de Minas Gerais Cetec. The influence of the film thickness on the mechanical properties of the coating-substrate system, of the current and pulse size applied during electrodeposition, on the morphology of the film and of its porosity on the mechanical properties of the composite layer, were evaluated. The effects of heat treatment on the colored steel at 150 °C for 256 hours were also evaluated, in terms of the physical, chemical and morphological characteristics of the interference film and of the mechanical properties of the composite systems. It has been observed that colored interference films are constituted mainly by hydrate chromium oxide exhibiting characteristics of an amorphous structure containing nanometric pores. The electrodeposition of the interference films on the surface of stainless steels modifies the mechanical behavior of the substrate, giving rise to composite systems that are softer than it. The coated system formed by thicker films are the softest, but present higher wear resistance. The morphology of the interference films is affected mainly by the pulse duration in the coloring process, more compact films being formed by shorter pulses. It has also been observed that the hardness of the composite system decreases linearly with the percentage of porous area and the average pore diameter of the interference film. Heat treatment at 150 °C leads to a loss water in the interference film, a decrease in the porous area and on the average pore diameter and an increase in the wear resistance of the composite system. After 256 hours at 150 °C, an increase in hardness and a decrease in the elastic modulus of the composite system were observed, leading to a decrease of their plasticity index (H/E).

ASSUNTO(S)

engenharia metalúrgica teses.

ACESSO AO ARTIGO

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