The influence of structure changes in the properties of TiCxOy decorative thin films

Abstract

The main purpose of this work consists in the preparation of titanium oxycarbide, TiC x O y , thin films, in which the presence of oxygen changed the film properties between those of titanium carbide and those of titanium oxide. Varying the oxide/carbide ratio allowed to tune the structure of the films between titanium oxide and carbide and consequently electronic, mechanical and optical properties of the films. The depositions were carried out from a TiC target by direct current, dc, reactive magnetron sputtering, varying the oxygen flow rate. The obtained results showed that the film's properties can be divided into 3 different regimes -i) carbide, ii) a transition zone and iii) an oxide one. X-ray diffraction results revealed the occurrence of a face-centered cubic phase (TiC-type) for low oxygen content, also obtained in the TiC 1.6 (O) film, with a clear tendency towards amorphization with the increase of the oxygen flow rate. For the highest oxygen contents, the results revealed the development of a mixture of poorly crystallized TiO 2 phases. The colour results indicated a strong dependence on the O/Ti ratio. A progressive reduction of hardness and residual stresses with the increase of the O/Ti ratio was also observed. The residual stresses, as well as the film structure, seem to play an important role on the adhesion of the coatings. The static friction coefficient revealed also some correlation with the mechanical properties, but mainly with the surface roughness.

Multifunctional titanium oxycarbide films fabricated by filtered cathodic vacuum arc technique using CO2 as a precusor

“…The similar variation tendency of internal stress and nano-hardness observed in Fig. 7a has been also reported by Fernandes et al [10]. According to their analysis, it is observed that internal stress plays an important role in hardening factor.…”

“…Various methods have been used to prepare titanium oxycarbide films, including magnetron sputtering [5][6][7], sol-gel, electrophoretic deposition [8] and pulsed laser [9]. Because of the high affinity of O with Ti, phase transition usually occurs through tuning experimental parameters, such as reactive gas pressure [6,10] and substrate negative bias [11] to control the O/Ti ratio in films, It's worth mentioning that FCVA technique is a superior method equipped with several controllable experimental parameters, such as reactive gas flow rate, substrate negative bias, filtered coil current, in order to obtain a high quality film. The high ionization rate and ion drift energy properties of FCVA are beneficial for the preparation of compact films [12].…”

Metalorganic chemical vapor deposition of Ti–O–C–N thin films using TBOT as a promising precursor

“…It is clear that in addition to the spherical-like shape particles of TiO 2 (anatase), fiber-like shape structures observe in the sample deposited at 600 • C. By increasing the substrate temperature to 750 • C, size of anatase particles decreased to about 200 nm. It was claimed that the tendency to the decrease of TiC grain size with the increase of oxygen flowrate was accompanied by a significant peak broadening as a result of transformation of TiC to Ti-oxycarbide [20]. Also, at that temperature (750 • C) we observed disappearance of fiber-like shape structures which appeared at 600 • C and the morphology of the deposited film was mainly spherical-like shape particles.…”

“…The formation of TiN phase can be also confirmed in the deposited film as osbornite with a cubic NaCl structure (JCPDS card no. 65-0970) with preferred orientation (2 0 0), (1 1 1) and (2 2 0) [5,20] for the films deposited at 750 • C. Also, a little shift in TiC peak positions to a higher 2 theta values are observed. This indicates the formation of Ti-oxycarbide phase, Fig.…”

“…This decrease in hardness resulting from the increase in the oxide phases amount as a result of formation and anatase transformation to rutile phase and oxidation of TiC. Fernandes et al [20] observed that TiC has higher hardness value than that of Ti-oxycarbide with increasing oxygen flowrate. High hardness value at 600 • C also may be related to the amorphous carbon existed at the grain boundaries of the TiC grains.…”