45 research outputs found
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