Titanium Carbide Films Research Articles

Influence of composition and structural properties in the tribological behaviour of magnetron sputtered Ti–Si–C nanostructured thin films, prepared at low temperature

Within the frame of this work, low temperature Ti–Si–C films were deposited on high-speed steel and stainless steel substrates by combined dc/rf magnetron co-sputtering. Composition analysis revealed the existence of two distinct regions: (i) a silicon doped sub-stoichiometric titanium carbide zone and (ii) a titanium rich zone. Structural analysis confirmed the different nature of the prepared films within each of the two zones. The residual stress states (σr) were relatively low, and the hardness values ranged between 11 and 27GPa, with a dependence on the composition as well as on the structural features. The tribological results showed quite similar trends, with both friction coefficients and wear revealing a straight correlation with the composition, and consequently, the different structural arrangements. In general terms, the obtained results showed that the friction coefficient of the samples tended to decrease with increasing CC/CSi atomic ratio, indicating an improvement in tribological behaviour for the samples with the highest carbon contents. In terms of wear resistance, the films with a stoichiometry very close to TiC, Si doped sub-stoichiometric titanium carbide films, presented the best behaviours, revealing that a compromise between the best friction and wear, must be made in order to select the optimum coating.

The effect of carbon content on the microstructure of hydrogen-free physical vapour deposited titanium carbide films

Titanium carbide (TiC) coatings for tribological applications were deposited on high speed steel. Several coatings with different titanium to carbon ratio were deposited by means of physical vapour deposition in which titanium was evaporated and carbon was sputtered. The coatings were characterised using analytical electron microscopy. It was observed that the change in titanium to carbon ratio significantly changed the microstructure of the coatings. The low carbon containing coatings consisted of columnar grains exhibiting a preferred crystallographic orientation whereas the coating with highest carbon content consisted of randomly ordered TiC grains in an amorphous carbon matrix. Energy filtered transmission electron microscopy revealed a change in Ti/C ratio as the distance from the substrate increased. The titanium to carbon ratio was observed to increase with distance from the substrate until a stable level was reached. This is due to a variation in the titanium evaporation during the early stages of film growth. This change of the titanium to carbon ratio affected the columnar growth in the initial stage of coating growth for the coatings with low carbon content.

Growth and Characterization of High Surface Area Titanium Carbide

High surface area, porous titanium carbide (TiC) films have been synthesized employing physical vapor deposition of titanium at glancing angles under high vacuum within an ethylene ambient. The composition, surface area, and morphology of the TiC films were studied as a function of deposition conditions including ethylene pressure, titanium deposition angle, substrate temperature during growth, and postdeposition annealing temperature. At high or glancing deposition angles (∼80−85°) synthesis produces films composed of arrays of porous nanocolumns of TiC, while deposition at more moderate angles, less than 70°, results in continuous, reticulated films. The maximum specific surface area (840 m2/g) is obtained by growth with an incident titanium deposition angle of 65°, an ethylene pressure of 1.5 × 10−7 Torr, and a substrate growth temperature of ∼350 K. This result is in contrast to previous investigations using related physical vapor deposition techniques which have generally shown that films with the gr...

Electron-emission properties of titanium carbide-coated carbon nanotubes grown on a nano-sized tungsten tip

Thin films (< 30 nm) of titanium carbide (TiC) are coated on carbon nanotubes (CNTs), directly grown on nano-sized (~ 500 nm in diameter) conical-type tungsten (W) tips, by employing an inductively coupled plasma chemical vapor deposition (ICP-CVD) technique. Modifications to structural properties (such as length to diameter ratio, crystal quality, and growth behavior) of CNTs due to TiC-coating are monitored using high-resolution TEM, field-emission SEM, and Raman spectroscopy. The driving voltage required to obtain the same level of emission current in CNTs-emitter is significantly reduced by TiC-coating. It is also noted that the degradation of emission current due to prolonged operation (up to 30 h) is remarkably suppressed by TiC-coating.

Bias effect on microstructure and mechanical properties of magnetron sputtered nanocrystalline titanium carbide thin films

Nanocrystalline titanium carbide (TiC) thin films were prepared by magnetron sputtering deposition at 473 K. The effect of substrate bias on microstructure and mechanical properties was studied in details using X-ray photoelectron spectroscopy, X-ray diffraction, field emission scanning electron microscopy, indentation and scanning microscratch. The TiC films exhibit a (111) preferential orientation. Substrate bias decreases grain size and deposition rate of the TiC films. The TiC films have columnar structure which becomes finer at high substrate bias. Nanoindentation hardness, Young's modulus, and toughness of the films are increased as the substrate bias goes up. However, the adhesion peaks at substrate bias of − 100 V and drops when bias is increased further.

Nanocomposite TiC/a-C:H film prepared on titanium aluminium alloy substrates by PSII assistant MW-ECRCVD

Thin films of titanium carbide and amorphous hydrogenated carbon have been synthesized on titanium aluminium alloy substrates by PSII assisted MW-ECRCVD with a mirror field. The microstructure, chemical composition and mechanical property were investigated. Using XPS and TEM, the films were identified to be a-C:H film containing TiC nanometre grains (namely, the so-called nanocomposite structure). The size of TiC grains of nanocomposite TiC/DLC film is about 5 nm. The nanocomposite structure has obvious improvement in the mechanical properties of DLC film. The hardness of a-C:H film with Ti is enhanced to 34 G Pa, while that of a-C:H film without Ti is about 12 G Pa, and the coherent strength is also obviously enhanced at the critical load of about 35N.

Investigation of processing parameters for pulsed closed field unbalanced magnetron sputtered titanium carbide thin films

Titanium carbide is a well established wear resistant coating owing to its excellent tribological properties including high hardness and elastic modulus, good wear resistance, low coefficient of friction against steel and high temperature stability. Recent advances in sputtering technology have resulted in improvements in the properties and performance of wear resistant coatings. Closed field unbalanced magnetron sputtering and pulsed magnetron sputtering have greatly improved the structure and properties of titanium carbide films by increasing ion bombardment at the substrate. However, film quality is highly dependent on the placement of the substrate relative to the sputtering targets. Titanium carbide films were deposited using a cosputtering configuration from one graphite target and one titanium target. At short substrate to target distances films exhibited an open, porous structure with low hardness and a high coefficient of friction. As the substrate to target distance was increased, along with the angle of incident particles, improvements were seen in both the microstructure and tribological properties.

Investigation of processing parameters for pulsed closed-field unbalanced magnetron co-sputtered TiC–C thin films

Titanium carbide is a well-established wear resistant coating due to its excellent tribological properties including high hardness and elastic modulus, good wear resistance, low coefficient of friction against steel, and high temperature stability. Recent advances in sputtering technology have resulted in improvements in the properties and performance of wear resistant coatings. Closed-field unbalanced magnetron sputtering and pulsed magnetron sputtering have greatly improved the structure and properties of titanium carbide films by increasing ion bombardment at the substrate. The goal of this research was to investigate how processing ties into the structure–property–performance relationship for these types of films. An electrostatic quadrupole plasma analyzer was used to measure the energy of ions at the substrate position. Energy ranges from 0.5 to 280 eV were observed under different pulsing conditions. Excessively high ion energy during deposition was found to erode the tribological performance of films.

Rolling contact fatigue and mechanical properties of titanium carbide film synthesized on bearing steel surface

The effect of plasma immersion ion implantation and deposition (PIII&D) titanium carbide (TiC) film on the rolling contact fatigue (RCF) life of coated on AISI52100 bearing steel surface is studied experimentally. Testing include plan-view optical microscopy (OM), X-ray diffraction (XRD), friction and wear behaviors, rolling contact fatigue life and nano-indentation measurements. XRD patterns show that titanium carbide phase is formed in the film, and the microhardness of treated samples is higher than that of substrate. Rolling contact fatigue failure tracks were observed using conventional light microscope. Surface wear and adhesive delamination existed. Results indicate that the maximum RCF life of the treated sample prolong by 6.5 times at a Hertzian stress level of 5.1 GPa and 90% confidence level, respectively. Comparison with the substrate, the maximum microhardness of treated specimen is increased by 28.4%. The friction coefficient decreased from 0.95 to 0.15 under identical wear conditions. This remarkable fatigue performance appears to be due to a combination of improved microstructure, adhesion, hardness and surface topography. Therefore, the PIII&D is regarded as one of the promising technologies for improving the RCF life of bearing.

Titanium carbide films obtained by conversion of sputtered titanium on high carbon steel

One the most important limitations to the industrial use of hard coatings in severe conditions is associated with their limited adhesion to the substrate. A number of research works have been done in various directions in order to improve the adhesion by post treatments such as laser remelting or thermal treatments. The aim of this work is to evaluate the possibility of using the substrate itself as a carbon source, in order to create very adherent hard titanium carbide coatings by means of a diffusion/precipitation process. A film of pure titanium was prepared by magnetron sputtering on a high carbon content steel substrate. Coated samples were then annealed in vacuum for 1 h at temperature ranging from 500 to 1100 °C. It was observed that the film was totally, partially or not transformed into titanium carbide, depending on heat treatment temperature. The transformation of titanium layer in titanium carbide takes place firstly at the interface between the film and the substrate, then it expands through the whole film thickness, toward the outer surface, by diffusion of carbon coming from the substrate. As a result, complete conversion of the titanium film in titanium carbide is obtained when an annealing temperature of 1100 °C is used. A higher adhesion, measured by means of a scratch tester, is found for this coating if compared to the one obtained on samples treated at lower temperatures and to other literature data on coatings having similar thickness and composition.

KrF laser deposition combined with magnetron sputtering to grow titanium–carbide layers

Titanium–carbide films were grown using a magnetron assisted pulse laser deposition combining KrF pulsed laser deposition and DC magnetron sputtering (PLDMS). Plasma streams produced by magnetron and laser ablation were intersected on the substrate surface. Films' properties were characterized by GDOES, AFM, XRD, XPS as well as by Raman spectroscopy. The adhesion and microhardness were also studied. Crystalline TiC films were fabricated at room temperature.

Titanium carbide film deposition on silicon wafers by pulsed KrF laser ablation of titanium in low-pressure CH4and C2H2atmospheres

We report on the deposition of thin titanium carbide films on 60 mm and 100 mm Si wafers by KrF laser ablation of titanium targets in low-pressure (0.1 Pa) CH 4 and C 2 H 2 atmospheres, and on their characterization. The targets were titanium foils (purity 99.6%). Si (111) wafers, 60 and 100 mm in diameter, were used as substrates. Film characteristics (thickness, composition and crystalline structure) were studied as a function of the carbon-containing gas (C 2 H 2 or CH 4 ), laser fluence (4 or 6 J/cm 2 ), substrate temperature (20 or 250 °C) and target-to-substrate distance (70–120 mm). Continuous, well adhesive polycrystalline TiC films were deposited even without any heating of the substrate. Films deposited in C 2 H 2 ambient atmosphere are better crystallized and less prone to surface oxidation with respect to films deposited in CH 4 atmosphere, in otherwise identical conditions.

Fabrication and characterization of anatase TiO 2 thin film on glass substrate grown by pulsed laser deposition

Titanium dioxide (TiO 2) films were prepared on glass substrates by pulsed laser deposition using a titanium carbide (TiC) target. The effects of substrate temperature on the crystal structures, surface morphologies and chemical states of the thin films were examined by the X-ray diffraction (XRD), atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), respectively. The results of XRD and XPS indicated that TiC film was grown at substrate temperature of 293 K, whereas the anatase TiO 2 film was formed at that of 773 K, which had round grains with 11–28 nm and surface roughness was 0.5–1.1 nm.

Fabrication of titanium carbide film on bearing steel by plasma immersion ion implantation and deposition

Titanium carbide films have been synthesized by plasma immersion ion implantation and deposition (PIIID) on 9Cr18 bearing steel. During the experiments, acetylene (C 2H 2) and titanium plasmas were generated simultaneously. Acetylene plasma was produced by a radio-frequency plasma source, and titanium plasma was generated by cathodic arc plasma source. Influences of gas pressure and pulse width of the bias voltage on properties of the thin film were investigated. The as-deposited films were characterized by X-ray diffraction (XRD), micro-hardness tester, pin-on-disc tribological facility and electrochemistry corrosion equipment. XRD pattern proves that TiC phase is formed in the film. Compared with uncoated substrates, micro-hardness results reveal that the maximum micro-hardness is increased by 70.8%. In addition, the friction coefficient decreases to about 0.1, and the corrosion resistance of coated substrate surfaces is improved significantly.

Spectroscopic characterization of TiCx films produced by pulsed laser deposition in CH4 environments

Titanium carbide (TiCx) thin films were grown on (1 0 0)-Si substrates by a pulsed laser deposition (PLD) method using a Ti target in methane gas. The films are characterized in situ by Auger (AES), electron energy loss (EELS) and X-ray photoelectron spectroscopies (XPS). It was found that the reaction between the ablated Ti species and CH4 in the plasma plume influenced the C:Ti ratio. XPS numerical fitting for the C 1s transition revealed three Gaussians components. The main component, binding energy of 282.8 eV, is assigned to C making bonds with Ti, like in stoichiometric TiC. The second component, binding energy of 284.9 eV, is assigned to CC bonds. A third component is found for films deposited at pressures higher than 25 mTorr at 286.5 eV. A post-deposition thermal treatment demonstrates that the TiC and CC peaks are very stable, whereas, the third peak tends to decrease for temperatures higher than 200 °C. It is assumed that this last component is due to carbonyl complexes remnant in films. Finally, it can be concluded that the titanium carbide films processed by PLD is a chemically inhomogeneous material; mostly composed of sub-stoichiometric TiC and particulates of segregated carbon.

Spectroscopic characterization of TiC x films produced by pulsed laser deposition in CH 4 environments

Titanium carbide (TiC x ) thin films were grown on (1 0 0)-Si substrates by a pulsed laser deposition (PLD) method using a Ti target in methane gas. The films are characterized in situ by Auger (AES), electron energy loss (EELS) and X-ray photoelectron spectroscopies (XPS). It was found that the reaction between the ablated Ti species and CH 4 in the plasma plume influenced the C:Ti ratio. XPS numerical fitting for the C 1s transition revealed three Gaussians components. The main component, binding energy of 282.8 eV, is assigned to C making bonds with Ti, like in stoichiometric TiC. The second component, binding energy of 284.9 eV, is assigned to CC bonds. A third component is found for films deposited at pressures higher than 25 mTorr at 286.5 eV. A post-deposition thermal treatment demonstrates that the TiC and CC peaks are very stable, whereas, the third peak tends to decrease for temperatures higher than 200 °C. It is assumed that this last component is due to carbonyl complexes remnant in films. Finally, it can be concluded that the titanium carbide films processed by PLD is a chemically inhomogeneous material; mostly composed of sub-stoichiometric TiC and particulates of segregated carbon.

Hardness of electron beam deposited titanium carbide films on titanium substrate

Increased use of titanium and titanium-base alloys in medicine is occurring due to their relatively low elasticity modulus and enhanced corrosion resistance as compared to more convenient alloys intended for implantation into the human body [1]. However, the properties of oxides present in the near-surface region of Tibase materials deserve special attention. The titanium oxides from TiO to Ti3O5 can exist in a stable state at the harsh conditions of the body fluids surrounding the implant. Tribo-chemical reactions during use can modify the oxidized surface of the implant producing wear debris accumulation, which results in an adverse cellular response and implant loosening. To improve bone response and reliability of implanted device, the surface modification by coating of implants with various substances can be used. In particular, titanium carbide on titanium can provide protection against oxidation, excellent corrosion resistance, enhanced hardness, and superior wear resistance of the implant. To cover a substrate with a thin carbide film, different methods are commonly used, e.g., chemical vapor phase deposition, pulsed laser ablation deposition (PLAD), magnetron sputtering [2–4]. The present study is aimed at the study of the hardness of electron beam deposited (EBD) titanium carbide films onto Ti substrates. To prepare the targets for EBD, titanium carbide powder (Aldrich, 98% pure) was pressed into 18 mm diameter pellets. The pellets were placed into a crucible made of titanium diboride/boron nitride composite (Advanced Ceramics Corp. Europe, UK). The crucible was then inserted into a water-cooled electron beam gun (EVI-8, Ferrotec, Germany), which has been positioned into a stainless-steel chamber evacuated by a turbomolecular pump supported by a rotation pump. The electron beam gun was controlled by a joypad that permits a complete control of the accelerating voltage in the range between −3.05 and −10 kV, the shape, pattern and position of the beam. The maximum operation power was 5 kW. The gun has a magnetic lenses system that allows a 270 ◦ deflection of the beam for avoiding contamination of the evaporating material with tungsten of the emitting filament. The substrates were heated under vacuum of 5.10−2 mbar in the chamber with a high-power halogen lamp. The deposition process was performed at the accelerating voltage −3.5 kV and the emission current of 130 to 200 mA. The pattern of electron beam was circular and slow, to ensure uniform consumption of the evaporating material. The deposition was performed at the substrate pre-heating temperature 200 or 800 ◦C for several minutes. After the cooling and venting with N2, the samples were of metallic luster and dark grey colored. The thickness of film was evaluated by scanning electron microscopy observation of the cross-sections of the samples (a LEO 1530 SEM apparatus, Carl Zeiss, Germany). An absolute error of the thickness measurement was ±10 nm. The hardness was measured with the use of a Leica VMHT apparatus (Leica GmbH, Germany) equipped with a standard Vickers pyramidal indenter (square-based diamond pyramid of face angle 136 ◦). On each sample indentations were made with 5 to 7 loads ranging from 0.01 to 5 N. Both diagonals were measured to diminish the effects of asymmetry on the imprint. Standard deviation of the diagonal measurements was about 5 to 9% of the diagonal length. The measured hardness was that of the film-substrate composite system. To separate the hardness of the film-substrate system on its constituents from the film and the substrate, a model based on an area “law-of-mixtures” approach was applied [5], where the composite hardness Hc of the film-substrate system is expressed as

Electrochemical behavior of p-Si/TiC in aqueous HF

The electrochemical behavior of p-Si in HF solution by modification of the silicon electrolyte interface is studied. For this purpose, the samples were coated with titanium carbide (TiC) deposited by RF pulverization of titanium under methane/argon atmosphere. The current–potential characteristics of TiC-coated electrodes in 5% HF are similar to the ones obtained with silicon. The scanning electron microscopy observation of the Si/CH x surface structures shows that the coating is stable in HF environment but it can be destroyed upon flowing of an anodic current. The results presented suggest that a TiC film layer can be used as a potential tool for low-thickness masking and patterning. In addition, a promising class of optical filters is introduced, based on a p-Si/porous silicon/TiC.

ＣＶＤ法で被覆したＴｉＣ膜の残留応力と強度評価に関するＸ線的研究

Thin films of titanium carbide (TiC) were coated on various substrates such as cemented carbide (WC-Co) with different cobalt contents, ferritic and austenitic steels by the chemical vapor deposition (CVD) method. Thin films did not have strong texture. The residual stress in thin films was measured by the sin2Ψ method of X-ray stress measurement. The residual stress was tensile for WC-Co substrates, while compressive for steel substrates. The residual stress was nearly uniform within the film thickness for the cases of WC-Co substrates, while it had rather steep distribution for the cases of steel substrates. The magnitude of the residual stress increased in proportion to the mismatch of the coefficient of thermal expansion (CTE). The measured stress was more compressive than the prediction by CTE mismatch. Under the uniaxial applied stress, the stress in the thin film was biaxial because of the mismatch of Poisson's ratio, and increased in proportion to the applied strain as predicted from the elasticity relation of coated layers. At high applied strains, the stress in the thin film measured by X-rays did not increase because of cracking. The tensile fracture strength of TiC films on WC-Co substrates was found to be around 750 to 800MPa. This value is about twice the fracture strength of bulk materials.

Preparation of crystalline TiC thin films grown by pulsed Nd:YAG laser deposition using Ti target in methane gas

Titanium carbide (TiC) thin films that are smooth and pinhole-free have been synthesized on Si(100) substrates by a pulsed neodymium:yttrium–aluminum–garnet (Nd:YAG) laser deposition method using titanium and TiC targets in methane gas. Glancing angle X-ray diffraction (GXRD) showed that polycrystalline films with components of TiC and Ti can be prepared using a Ti target. Single-phase TiC films can be synthesized using a TiC target. It was found that the methane gas pressure can control the crystallinity and composition. The root-mean-square (RMS) roughness of the film, as measured by an atomic force microscope (AFM), was lower than 2 nm in all the deposition areas. The film thickness, measured by α-step, was about 92 nm and the growth rate was approximately 3.1 nm/min. Measurements of optical emission spectra were performed to estimate the processing plasma state.