Tribological behavior of micro/nano structured tantalum surfaces by anodization method

• Autor(a) principal: Khalid, Ayesha
• Data de Publicação: 2016
• Tipo de documento: Dissertação
• Idioma: eng
• Título da fonte: Repositório Científico de Acesso Aberto de Portugal (Repositórios Cientìficos)
• Texto Completo: http://hdl.handle.net/10316/36921
• topic: Tântalo; Anodização; Nano-texturização; Domínio/Área Científica::Engenharia e Tecnologia::Engenharia Mecânica

Tantalum is a metal which has shown to have excellent biocompatibility and bioactivity, making it a potential material for dental implant. Nano texturing can improve the performance of Ta dental implant as it promotes faster osseointegration. Nano texturing changes surface roughness which affects the tribological behavior. An electrochemical process called anodization was used to modify the surface of tantalum by introducing highly ordered nano pores on its surface. Anodization is a process that involves several parameters which can be easily modified to produce controlled surface texturing. The applied potential has a propotional relationship to pore diameter and Ta2O5 film thickness. Higher applied potential leads to larger pore diameters and thicker oxide layer. For the purpose of this thesis, tantalum was anodized at three different potentials, namely 15, 25 and 50 V. The purpose of this thesis was to test the effect of surface roughness induced by anodization, on the tribological properties of Ta, particularly its static friction behavior. The surface roughness parameter used for this study was the mean peak to valley height of profile (Rz). Reference samples used for comparison were polished Ta metal and chemically etched Ta. Structural analysis of the prepared Ta samples was performed by optical microscopy, surface morphology was characterized by scanning electron microscopy (SEM), the crystal structure was examined by X-ray diffraction (XRD), hardness was measured using Vickers hardness method and surface roughness measurements were made by a 3-D profilometer. Friction tests were performed using a standard tensile testing machine with electronic control of cross head motion. Highly ordered nano porous surface was formed by the anodization process. The size of pores increased when higher anodization potentials were used. The anodization process caused a change in surface roughness. The relationship between surface roughness and the static friction coefficient was studied and it was found that static friction coefficient showed a propotional relationship to surface roughness. Dynamic friction coefficient did not show a clear relation to surface roughness.