Corrosion and wear behavior of thermally sprayed nano ceramic coatings on commercially pure Titanium and Ti-13Nb-13Zr substrates

摘要

Surface treatments and coatings are the practical approaches used to extend the lifetime of components and structures especially when the surface is the most solicited part of the considered engineering com-ponent. Hard thermally sprayed coating is one of the most wear resistance coating widely used in many practical mechanical applications. In the construction of articulating parts of medical devices, titanium and its alloys have to be surface coated to improve their tribocorrosion behavior. In this way, the use of porous thermal coatings is known to be a strategy for better binding bone or tissue on femoral stem for example. It is, thus, important to evaluate the corrosion and the wear behaviors of such materials for biosecurity considerations in the human body. In this study, we investigate the behavior of new nano ZrO_2 and Al_2O_3-13 wt. percent TiO_2 thermal sprayed coatings on commercially pure (cp)-Ti (grade 4) and tita-nium alloy substrates. Friction and wear tests against Al_2O_3 balls showed that the wear resistance of Al_2O_3-13 wt. percent TiO_2 is better than that ZrO_2 coating. Both plasma sprayings have similar abrasive wear behavior; however, the average friction coefficient is higher for alumina-titania coating. Electrochemical tests, open circuit potential monitoring and potentiodynamic polarization, were performed in simulated body conditions (Hank's solution, 37 deg C). Results showed that corrosion resistance was appreciably higher for alumina-titania coating.