Transporte atômico e reação química em nanoestruturas TiN e TiN/Ti em aço nitretado a plasma

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

The use of cutting tools in progressively more severe conditions in the metal-mechanics industry and the requirement to increase tool life against friction, wear and high temperature corrosion made of surface treatments an important protection method. One of the most modern treatments is the so-called duplex, that consists of plasma nitriding and deposition of hard coatings, as TiN. In duplex coatings, the adhesion is increased, probably due to the diffusion of nitrogen through the interface of these structures, most probably by decreasing interface stresses originated in abrupt composition changes in this region. To investigate this hypothesis, structures like TiN/Ti/nitrided steel and TiN/nitrided were produced. Samples of high speed steel M2 were plasma nitrided and thin films were deposited by magnetron sputtering. An isotopic tracer (15N) was used to observe eventual nitrogen migration. The results revealed effectively nitrogen migration through the TiN/nitrided steel and TiN/Ti/nitrided steel interfaces, as well as migration of Ti to steel. Other chemical species existing in the nitrided region of the steel, such as, Fe, Cr, Si, migrated to the surface of the films. The presence of an intermediate layer of Ti between the protective coating of TiN and the nitrided steel seems to be an additional contribution to adhesion, because it increases the migration of atoms through the interface, without increasing the interface stress. This is proven by the fact that during the deposition process, all the intermediate layer of Ti has been converted into nitride and oxynitrides.

ASSUNTO(S)

filmes finos engenharia de materiais e metalurgica engenharia de superfície tratamentos superficiais revestimentos protetores

ACESSO AO ARTIGO

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