Tribocorrosion Behavior of Ti6Al4V Coated with a Bio-absorbable Polymer for Biomedical Applications

The modification of titanium-based surfaces has been recently studied to accelerate the osseointegration process of endosseous implants. Indeed, bioabsorbable polymer veneers carrying antimicrobials or bone growth factors to the implant–bone interface could enhance such osseointegration process. The main aim of this work was to study the tribocorrosion behavior of veneering biodegradable poly(d,l-lactide) on titanium surfaces in an artificial saliva solution. Cylinders of Ti6Al4V were prepared by grit-blasting with 250-µm alumina particles followed by HF/HNO3 etching technique to increase the roughness of the top surface. After surface modification and cleaning, the rough surface was covered with poly (d,l-lactic acid) (PDLLA) by spin-coating technique. Reciprocating sliding tests were performed against an alumina ball at a normal load of 0.5 N, a sliding frequency of 1 Hz, and linear displacement amplitude of 3 mm using a tribometer. The sliding tests associated to open-circuit potential (OCP) measurements were performed in artificial saliva solution to mimic the oral conditions for 60 min. After tribocorrosion tests, the worn surfaces were inspected by scanning electron microscopy. The results revealed a lower coefficient of friction (COF) on PDLLA than that recorded on Ti6Al4V. A protective effect of PDLLA against wear and corrosion of Ti6Al4V was noticed on the reciprocating sliding under OCP measurements for 60 min. Furthermore, a gradual degradation of PDLLA was detected, which could be useful in situ to release of therapeutic substances to be incorporated into the bioabsorbable polymer.