Sputtered nanocrystalline ceramic TiC / amorphous C thin films as potential materials for medical applications

The relationship between structural behaviour of sp uttered TiC / amorphous C (TiC /a:C) thin films and corrosion properties was measured in thre e 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 s ubstrates (Ti6Al4V alloy and CoCrMo alloy) in argon at 25 C° and 0.25 Pa with 150 W inp ut power of carbon target and 50 W input power of titanium target. The structure and composi tion of nanocomposites were investigated by Transmission and Scanning Electron Microscopy. I n 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 amorp hous carbon layers. TiC /a:C /Ti6Al4V alloy implant material showed better corrosion resi stance than the TiC /a:C /CoCrMo alloy in 0.5 M NaCl solution based on results of the Electro chemical Impedance Spectroscopy. For both samples, the 0.1 M NaOH solution was the most corrosive media

Mechanical properties of pulsed laser deposited nanocrystalline SiC films

The mechanical properties of nanocrystalline SiC thin films grown on (100) Si at a substrate temperature of 1000°C under a CH4 atmosphere using the pulsed laser deposition (PLD) technique were investigated. Nanoindentation results showed that films exhibited hardness values around 36GPa and Young modulus values around 250GPa. Scratch tests found that films were adherent to the substrate, with critical load values similar to those recorded for other hard coatings deposited on significantly softer Si substrates. Wear tests performed at a temperature of 900°C showed that films exhibited friction coefficients and wear rates very similar to those measured at room temperature, due to the presence of C-C bonds as evidenced by X-ray photoelectron spectroscopy investigations. These results recommend such coatings for demanding high temperature applications such as nuclear fuel encapsulation

Examination of nanocrystalline TiC/amorphous C deposited thin films

The relationship between structural, chemical and mechanical properties of nanocrystalline TiC / amorphous C thin films was studied. Thin films were deposited by DC magnetron sputtering on oxidized silicon substrates in argon at 25 C° and 0.25 Pa. The input power of the carbon target was 150 W, the input power of the titanium target was varied between 15 and 50 W. It was found that all thin films consist of a few nanosized columnar TiC crystallites embedded in carbon matrix. The average size of TiC crystallites and the thickness of the carbon matrix have been found to correlate with Ti content. The mechanical properties of the films have been strictly dependent on their structure. The highest values of the nanohardness (~ 66 GPa) and Young's modulus (~ 401 GPa) were observed for the film with the highest TiC content which was prepared at 50 W of Ti target