The corrosion behavior and hemocompatibility of TiNi alloys coated with DLC by plasma based ion implantation

Diamond-like carbon (DLC) films have been successfully deposited on Ti-50.8 at.% Ni alloys using plasma based ion implantation (PBII) technique. The influence of the pulsed negative bias voltage applied to the substrate from 12 eV to 40 eV on the surface characteristics and corrosion resistant property as well as hemocompatibility has been investigated. The results show that the RMS values firstly decrease from 7.202 nm (12 kV) to 5.279 nm (20 kV), and then increase to 6.991 nm (30 kV) and 7.060 nm (40 kV). With the voltage increasing the value of I(D)/I(G) ratio firstly decreases, and reaches a minimum value at 20 kV, and then increases. Combined with the Tafel measurement and SEM observation, we found that the uncoated TiNi alloy shows severe pitting corrosion, which could be due to the presence of Cl− ions in the solution. On the contrary, the coated sample shows very little pitting corrosion and behaves with better corrosion resistant property especially for the specimens deposited at 20 kV bias voltages. The platelet adhesion test shows that the hemocompatibility of DLC coated TiNi alloy is much better than that of the bare TiNi alloy, and the hemocompatibility performance of DLC coated TiNi alloy deposited at 20 kV is superior to that of the other coated specimens.