Comportamento em fadiga da liga Ti-6Al-4V para uso biomédico com superfícies modificadas

Abstract

Surface modification in implants is used, basically, to improve osseointegration, which is defined as the intimate contact between bone and implant material, without a soft tissue layer in the bone/implant interface. Titanium alloys, which are the most commonly used materials in the fabrication of hip stem, have an excellent biocompatibility. The surface modification of these materials can lead to a better osseointegration. The developments and studies of new modification processes are very dynamic and often related to biological aspects, for example, cellular growth on the modified surface. Studies regarding engineering and properties of the implant with modified surface are not up to date with the quickness of new processes developments and evaluation of these processes on cellular response. Since fatigue is a determinant property of implants, this study aims to evaluate the fatigue behavior of Ti-6Al-4V alloy with modified surfaces by laser and anodic oxidation. Thus, axial fatigue tests were performed to obtain SxN curves (Stress x number of cycles) of cylindrical specimens, in the polished and surface treated conditions. Roughness measurements and scanning electron microscopic (SEM) were used to characterize the features of the modified surface. As a result, the modification by anodic oxidation, for the parameters used, did not affect the fatigue behavior of Ti-6Al-4V alloy. Unlike anodic oxidation, the laser surface modification performed in this work decreases by about 30% the limit of fatigue strength of the alloy.