Tribocorrosion Behavior of Ti6Al4V Machined and Burnished Components for Biomedical Application

Abstract

Nowadays, the increased average age of patients and the decreased age at which arthroplasty is carried out represents a reason for the necessity of higher quality standards for prostheses. In particular, tribocorrosion generates an irreversible transformation of the materials and the release of particles and metal ions in toxic concentrations in the biological environment in which the systems are implanted. One of the most used materials for prosthetic implants is the Ti6Al4V alloy but its tribological behavior is still challenging for the application. Employing and optimizing severe plastic deformation processes represents a way to obtain prostheses with superior performance improving patients’ quality of life and reducing the burden on National Health Cares. Ti6Al4V bars have undergone machining with semi-finishing parameters and burnishing processes. Tribocorrosion tests have been performed in a custom-made cylinder-on-disk configuration employing Al2O3 counterparts and phosphate buffer solution with the addition of albumin as simulated body fluid. The effects of sole machining and its combination with burnishing on surface quality and specific wear rate (SWR) have been assessed with respect to as received surface conditions. Optical microscopy, stylus profilometry and sample weighing before tests and at specific intervals during the tests have been employed for characterization. As a main result, it has been found that burnishing process is able to improve SWR of Ti6Al4V samples with respect to both as received and machined samples. Furthermore, the overall behavior of tribological system is gradually improved first employing sole machining and then combining machining and burnishing, reducing SWR of counterparts as well.