The relationship between structural behaviour of sputtered TiC / amorphous C (TiC /a:C) thin films and corrosion properties was measured in three various pH solutions (0.5 M NaCl (pH=6); 0.1 M HCl (pH=1); 0.1 M NaOH (pH=13). The ~ 400 nm thick nanocomposites were deposited by DC magnetron sputtering on different substrates (Ti6Al4V alloy and CoCrMo alloy) in argon at 25 C° and 0.25 Pa with 150 W input power of carbon target and 50 W input power of titanium target. The structure and composition of nanocomposites were investigated by Transmission and Scanning Electron Microscopy. In both samples the structural investigations confirmed columnar structure of TiC /a:C films with 25-50 nm sized cubic TiC. These columns were separated by 2 -3 nm thin amorphous carbon layers. TiC /a:C /Ti6Al4V alloy implant material showed better corrosion resistance than the TiC /a:C /CoCrMo alloy in 0.5 M NaCl solution based on results of the Electrochemical Impedance Spectroscopy. For both samples, the 0.1 M NaOH solution was the most corrosive media.

a b s t r a c tThe relationship between the structure, elemental composition, mechanical and tribological properties of TiC/amorphous carbon (TiC/a:C) nanocomposite thin films was investigated. TiC/a:C thin film of different compositions were sputtered by DC magnetron sputtering at room temperature. In order to prepare the thin films with various morphology only the sputtering power of Ti source was modified besides constant power of C source. The elemental composition of the deposited films and structural investigations confirmed the inverse changes of the a:C and titanium carbide (TiC) phases. The thickness of the amorphous carbon matrix decreased from 10 nm to 1-2 nm simultaneously with the increasing Ti content from 6 at% to 47 at%. The highest hardness (H) of $ 26 GPa and modulus of elasticity (E) of $ 220 GPa with friction coefficient of 0.268 was observed in case of the film prepared at $ 38 at% Ti content which consisted of 4-10 nm width TiC columns separated by 2-3 nm thin a:C layers. The H3/E2 ratio was $ 0.4 GPa that predicts high resistance to plastic deformation of the TiC based nanocomposites beside excellent wear-resistant properties (H/E ¼0.12).