Wear and Corrosive Behaviors of Electroless Ni-LaCl3 Composites on Nanoporous ATO Surface of Ti Substrate

Abstract

Ti and its alloys, because of its poor wear and oxidation resistance, have seriously restricted its industrial applications in the dry friction conditions. Herein we reported an easy-handling and effective approach for electroless Ni-LaCl3 nanocomposite films on nanoporous ATO surface of Ti substrate to modify its surface properties. Anodized titanium oxide, shorted as ATO, was designed as a template to deposit Ni-LaCl3 films on Ti surface with superior bonding interface. By adjusting the anodizing voltage from DC 60 to 240 V, the surface of ATO templates was manipulated to achieve a suitable diameter of nanopores using high voltage with low-current density state. The as-received Ni-LaCl3 film with a leaflike surface was successfully formed on to ATO surface. With an increase in LaCl3 addition from 0 to 4.0 g L−1 in bath, results indicated that the diversified orientations of Ni crystals along Ni (111), (200), (220) and (311) were detected for Ni-LaCl3 films, rather than preferred directions of Ni (111) and (200) for pure Ni sample. As expected, the specific wear rate was ~ 10−5 mm3 (N m)−1 for Ni-4.0 g L−1 LaCl3 films, which was two times lower than that of the un-coated Ti substrate. Besides a lower microhardness of ~ 629 HV0.2 was detected for pure Ni, which was much lower that of ~ 752 HV0.2 for Ni-LaCl3 films, but higher than that of ~ 336 HV0.2 for Ti substrate. In addition, a superior corrosion resistance was obtained for Ni-LaCl3 composites relative to pure Ni, which was ascribed to the coexistence of La3+ ions and its La-rich insoluble products on its corroded surfaces for completing the pitting holes. In view of these, the as-deposited Ni-LaCl3 films on the surface of Ti substrate could guide an available proposal for surface modifying of Ti alloys against the wear corrosive failures, further intensifying their servicing life as subjected to harsh conditions.