Tribological Properities Of TiO₂Nanotubes And The Copper-Nanotubes Layers On Ti Surface By Electrophoretic Deposition

Surface nanocrystallization is a new concept proposed in recent years. It showed a good scene that improving the tribological properties. Titanium and titanium alloy is widely used in metal materials, but it have poor wear resistance. In this paper, the TiO2nanotube layers on titanium were fabricated by electrochemistry anodic oxidation to study the tribological properties.A series of nano-tube/hole layers on Ti with three different thickness (～500nm、1200nm、～2000nm) and four different inner diameter (～50nm、～100nm、～170nm、400nm) were fabricated by anodic oxidation and microarc oxidation. Copper deposition on TiO2film surface with different diameters were carried out via electrochemical pulses method. By using scanning electronic microscope (SEM), X-ray diffraction (XRD), roughness testing machine, angle of contact testing machine and hardness testing machine, investigate the surface properties of pure titanium treated by anodic oxidation process such as microappearance, microstructure, surface roughness, surface free energy, surface hardness and so on.The friction properties of it TiO2nanotube layers has an important influence on its functionality in clinics. While the sliding friction is a common form in material tribology. T1O2nanotube layers with different thickness were fabricated on titanium surfaces by anodization. and some of specimens were heat-treated at450℃.The sliding friction tests of specimens against GCrl5steel ball were carried out in ball/plat approach under the10N normal load in dry friction conditions. Results indicated that friction coefficients and wear scar decreased with the increase of nanotube thickness. The existence of the TiO2nanotube layers reduced the wear and friction coefficients, which would become even lower after heat treatment. The wear mechanism of the specimens involved abrasive wear, fatigue and adhesive wear.The TiO2nanotube layers could improve wear-resistant of Ti, while copper and its alloys had been widespread concern because of self-lubricity, excellent mechanical properties and corrosion resistant and other features. The sliding fretting wear tests under the5N tangential load was proceeded in dry friction and lubrication conditions respectively. The results show that samples have self-lubricity after copper deposition. The surface modification method can control inherent adhesive wear of pure Ti to an extent, which can reduce wear and friction coefficient. Under dry friction condition the specimens coated with copper have reduce wear and wear depth, Sample with copper deposition under dry wear condition have lower wear depth when compared with the samples without copper deposition. The wear and friction coefficient of hole interlayer sample reach lowest value under dry friction and lubrication, which indicates copper film can reduce friction and copper with larger diameter have better results. The difference between frication coefficient curve exist in dry frication and lubrication, and friction coefficient has large fluctuation in dry wear, while it remains stable under lubrication. The TiO2nanotube specimen with the largest diameter have lowest friction coefficient which imply that copper film on samples have effects on wear in different wear situations.