Filmes de diamante-CVD sobre substrato de titânio puro poroso: uma proposta para aplicação como eletrodo / CVD-diamond films on tridimentional porous pure titanium substrate: an electrode application proposal

AUTOR(ES)
DATA DE PUBLICAÇÃO

2008

RESUMO

A novel composite material formed from nanocrystalline and/or microcrystalline diamond films grown on pure porous titanium substrate was extensively studied taking into account their morphological, structural and electrochemical properties. The films were deposited by chemical vapor deposition technique, using a hot filament reactor, while the powder metallurgy showed to be the more suitable technique to obtain the titanium substrate, mainly due to the required control of the compact porosity and their mechanical properties. This work is presented considering important stages to obtain and to characterize the substrates and diamond films. The titanium compacts, the diamond films as well as their interfaces were analyzed by scanning electron microscopy, X-ray diffraction, Raman scattering spectroscopy and energy dispersive X-ray spectroscopy. Particularly, these tridimensional composite electrodes, formed from boron doped microcrystalline and nanodiamond films, were also characterized by cyclic voltammetry technique. A systematic study revealed that the substrate hydrogenation was the determinant factor in the fissure formations on the titanium matrix. Therefore, the importance to control the deposition parameters, such as pressure, growth temperature, filament distance, and growth time showed to be relevant to minimize the negative effects caused in titanium matrix by atomic or molecular hydrogen present in the gas phase during the film growth. These suitable experimental parameters optimized the diamond film formation covering the entire substrate in its surface and deeper planes as well as in its pore walls. In this sense, the interface characterization, formed between the film/substrate, allowed to identify the hydride and carbide phase formations, as the main phases present in this interface, in addition to their strong dependence with the growth temperature and with the argon concentration in the mixture used to grow nanocrystalline films, mainly associated to the TiC(111), TiC(200) e TiH2 phase evolutions.

ASSUNTO(S)

filmes finos hot filament chemical vapor deposition (hfcvd) deposição química a partir da fase vapor assistida por filamento quente (hfcvd) porous titanium engenharia e tecnologia espacial diamante-cvd mecanismo de deposição space technology and engineering deposition mechanism chemical vapor deposition diamond (cvd) thin films titânio poroso

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