Multi-scale mechanical analysis of thin titanium layer on UHMWPE substrates for biomedical applications

Abstract

We present a multi-scale scratch resistance analysis of thin titanium layer with thickness varying between 0.5 and 1μm, deposited on two biomedical polymeric substrates (UHMWPE). Using different experimental set-ups with specific tip radii, we have performed scratch experiments at various testing conditions. First, nano scratch tests have been performed with a spherical indenteur (tip radius R=22μm) with increasing progressively the normal applied load between 1 and 100 mN. Then, macro-scratch tests have been realized with a spherical indenter (tip radius R=200μm) with the same experimental procedure by applying normal load in the range of 0.5 to 15N. Finally, experimental results about multi-pass scratch tests at low average contact pressure are presented. Scratch experiments have been performed using a specific built-in microvisioscratch device that allows in situ observations of the contact area and of the residual groove during tests. About 100 repeated scratch experiments have been realized in the same track with a glass spherical indenter (tip radius R=3.3mm) at a constant normal load of 5N. Friction coefficient evolutions are studied as function of the scratching conditions and some correlations have determined with damage mechanisms observed by SEM and chromatic confocal microscopy.