Structure and properties of passivating titanium oxide films fabricated by DC plasma oxidation

Titanium oxide layers have been synthesized on commercially pure titanium and TiN using direct current plasma oxidation. X-ray diffraction analyses reveal that the titanium oxide layers have the rutile structures. Micro-hardness, nano-hardness test, ball-on-plate wear experiment, scratch adhesion test and platelet adhesion investigation were conducted to evaluate the mechanical properties and blood compatibility of the titanium oxide layers. The results show that the commercial purified titanium sample micro-hardness increased by approximately 70% and the TiN sample micro-hardness increased by approximately 30% after plasma oxidation. It is believed that the increase in the film hardness is due to the development of TiO2 phases. The nano-hardness of titanium oxide layer reached 11 GPa. The wear resistance of the titanium oxide layer increased by a factor of 200 in Hankʹs solution. The adhesion strength between the titanium oxide layer and titanium matrix was as high as 25 N. Our results thus indicate that titanium oxide layers fabricated by this method have good blood compatibility and mechanical properties.