Effects of Dimple Surface Texturing on Wear Characteristics of Commercially Pure Ti in Comparison with Ti-6Al-4V ELI and Ti-29Nb-13Ta-4.6Zr Alloys for Dental Applications

We investigated the effects of surface texturing dimple-shaped patterns via picosecond pulsed laser processing on the wear behaviors of titanium alloy discs in contact with zirconia (ZrO2) ball by comparing three different alloy types. As an α-type titanium alloy, commercially pure titanium (CP-Ti) was used in the present study, and the results were compared with those obtained using an α+β- and β-type titanium alloy, Ti-6Al-4V ELI (Ti64) and Ti-29Nb-13Ta-4.6Zr (TNTZ), in the previous study. The wear behaviors of these alloys were dominated by different wear modes depending on the alloy type. Abrasive and adhesive wear modes were dominant in Ti64 and TNTZ, respectively. Conversely, adhesion of wear debris was observed in CP-Ti but the amount of adhered wear debris was smaller than that in TNTZ. In Ti64, the wear debris acted as abrasive particles. By contrast, the wear debris easily adhered to the TNTZ disc surface and formed a hard wear-protective layer. The wear debris adhered to the CP-Ti disc surface too but the amount was smaller, and the protective effect was weaker than that observed for TNTZ. These differences in wear debris characteristics lead to different impacts of surface texturing on the wear behavior of titanium alloys. As the dimples fabricated on the surface can trap wear debris, they effectively reduce wear in Ti64 but are detrimental to TNTZ. Both these effects on wear appeared for the dimples on CP-Ti because its wear debris was adhesive just after its generation, due to its low proof stress, similar to that of TNTZ. However, the wear debris was more prone to oxidation and hardened more easily, resulting in its transition to abrasive particles, similar to those of Ti64.