Growth Of TiN Research Articles

Corrosion protective double layer hard coatings

Abstract A Cr + TiN double layer was coated on an SS-420 substrate using a hollow cathode discharge gun. The compositional analysis of the samples carried out by glow discharge optical emission spectroscopy confirmed the Cr/TiN constituents. X-ray diffraction pattern studies showed that due to the presence of chromium in the TiN matrix, preferential growth of TiN was changed from (200) to (111) reflection plane, leading to formation of a Cr + TiN double layer hard composite. However, at the same time, the hard coating layers exhibited unavoidable defects exposing them to corrosive environments. In this work, the corrosion protective behaviour of the Cr + TiN double layer was examined by potentiodynamic measurements in sodium chloride solution. It was inferred from this study that the increase in corrosion potential from −505 mV to −452 mV corresponding to the bare substrate and Cr + TiN coatings, respectively, led to the formation of more corrosion protective layers. The electrochemical impedance spectra analysis of the SS-420 substrate, TiN and Cr + TiN layers revealed that corrosion resistance increased and the electrochemical impedance of the Cr + TiN layer decreased. This is attributed to the corrosion protective properties of the resultant coating and its reduced permeability to the corrosive environment.

Tin-Oxide Nanotubes for Gas Sensor Application Fabricated Using SWNTs as a Template

We develop a simple method to synthesize nano tube or wire structure of tin-oxide for gas sensor application. It is realized by the rheotaxial growth and thermal oxidation (RGTO) of tin on porous single-wall carbon nanotubes (SWNTs) as a template. The morphology and chemical property of thus formed nanostructures are examined. The electrical and NO(x) gas sensing properties are also investigated. The sensor exhibits a fast response time of less than 100 seconds and a good recovery. A sensing response of 23,400% to 10 ppm concentration at 200 degrees C is observed.

Performance of tin doped titania hollow spheres as electrocatalysts for hydrogen and oxygen production in water electrolysis

The electrocatalytic activity of tin doped TiO 2 hollow sphere particles has been examined in acid solution. Titania hollow spheres have been synthesized by using poly(styrene-methacrylic acid) latex particles as a template, and tin was doped over spheres with the appropriate amount of SnCl 2·2H 2O solution in HCl. The surface characteristics have been evaluated by XRD, SEM and TEM analysis. XRD analysis has shown the presence of rutile SnO 2 and TiO 2 phase in the catalysts; and the peak intensity for SnO 2 phase increased with rise in the calcination temperature indicating the critical growth of tin on the surface of the catalysts. Diameter of pure TiO 2 hollow spheres and Sn doped samples were found from SEM and TEM images in the range of 1–1.2 and 0.4–0.6 μm, respectively. TGA has been performed with the uncalcined 40 wt% Sn doped TiO 2 catalyst. The peaks for hydrogen and oxygen production are present significantly for all the hollow sphere samples in cyclic voltammograms; but peaks for hydrogen production is more prominent in 20 and 40 wt% Sn/TiO 2 catalysts. The performances of the hollow sphere electrocatalysts were evaluated up to current densities of 50 mA cm −2 during anodic polarization measurement. Sn/TiO 2 electrocatalysts have also shown long time electrochemical stability in acidic media.

Atomistic nitriding processes of titanium thin films due to nitrogen-implantation

Nitrogen ions (N 2 +) with 62 keV were implanted into the as-deposited Ti film composed of mainly (1 1 0)-oriented TiH x and (0 3 · 5)-oriented hcp-Ti at room temperature, which results in the epitaxial formation of (1 1 0)-oriented and (0 0 1)-oriented TiN y , respectively. The electron energy loss spectroscopy experiments elucidate that in the early N-implanting stage the release of hydrogen constituting TiH x gives rise to the shift of the loss peak due to plasmon excitation to lower loss energy side. On the other hand, the energy loss peaks due to plasmon excitation for nitriding of hcp-Ti gradually shifted to higher energy side with increasing dose. Through the N-invasion into the octahedral sites of hcp-Ti with larger space and lower electron density, the hcp–fcc transformation of Ti sublattices is induced by the shift of the (0 0 · 1)-plane in the 0 1 ⋅ 0 direction of hcp-Ti promoted by the forming of the strong Ti–N bonds including the π-type covalent bonds, and by the weakening of the Ti–Ti bonds. Furthermore, the inheritance of square atomic arrangement and the movement of the N atom to other neighboring O-site in the transformed fcc-Ti sublattice are responsible for the epitaxial growth of TiN y . The atomistic processes of the epitaxial growth of TiN y are discussed with the aid of the molecular orbital calculations.

Modelling the growth of transition metal nitrides

Due to its unique physical properties, and its wide use in industrial applications, the growth of TiN has been extensively investigated and reported in literature. Since the final film properties are known to be influenced by the film microstructure and crystallographic orientation, much effort has been made to understand the fundamental phenomena determining the film growth process. However, several controversial growth models have been published. As an attempt to gain more insights in the growth of TiN and to have a better control on the development of the microstructure and crystallographic orientation, a general growth model is discussed. It will be shown that this growth model enables to understand the influence of several deposition parameters such as the film thickness, ion-to-atom ratio, and N2-flow on the resulting microstructure and orientation of TiN films deposited by reactive magnetron sputtering.

Ion-beam assisted pulsed laser deposition of textured transition-metal nitride films

AbstractIon-beam assisted deposition (IBAD) offers the possibility to prepare thin textured films on amorphous or non-textured substrates. It was shown within the last decade that the ion beam influences the nucleation in material with a rocksalt structure leading to a strong cube texture already within the first 10 nanometres. Among these materials, transition metal nitrides exhibit interesting physical properties as superconductivity, metallic behaviour or superior hardness. Therefore, a reactive IBAD process was applied for the preparation of highly textured transition metal nitride layers using pulsed laser deposition of pure metals in combination with a nitrogen-containing ion beam. The results on the in-plane textured growth of TiN are promising for the development of conducting buffer layer architectures for YBCO coated conductors based on the IBAD approach. Furthermore, this approach was used to prepare other highly textured transition metal nitride thin films like NbN and ZrN.

Growth and characterization of free-standing single crystalline tin and tin oxide nanobelts

Free-standing single crystalline tin nanobelts have been synthesized from tin foil by a novel selective etching process in NaOH solutions under hydrothermal conditions at low temperatures. The process requires neither catalysts nor templates to yield single crystalline tin nanobelts which are oriented and aligned on tin substrate. The crystal structure and morphology of these nanobelts were characterized by X-ray diffraction, scanning electron microscopy and transmission electron microscopy, showing that oriented, single crystalline tin nanobelts were formed and grew along [101] crystal direction. These single crystalline tin nanobelts were easily converted into single crystalline tin oxide nanobelts by a shape-preserving oxidation process.

Study of the gradual interface between hydroxyapatite thin films PLD grown onto Ti-controlled sublayers

Hydroxyapatite thin films were grown on layered structures by Pulsed Laser Deposition with the goal of investigating the interface of the ceramic film with the substrate. The latter consisted of Si/TiN/Ti sandwich structures. This multilayer substrate was also prepared by laser ablation earlier in the same experimental session. This particular type of structure was chosen in order to induce the in situ growth of hydroxyapatite directly onto freshly deposited Ti. We tried this way to avoid previous direct Ti exposure to air, hence its oxidation. The subsequent depositions of multilayers were performed with the aid of a carousel multi-target system mounted inside the irradiation chamber. This allowed for selecting in order the respective TiN, Ti and HA targets without opening the chamber between individual depositions. X-ray diffractometry, transmission electron microscopy and selected area electron diffractometry studies revealed the formation at the interface of a transition complex phase, 2 to 25 nm thick, consisting of a mixture of TiO 2 and CaP phase. The specific growth of TiN and Ti phases was also investigated.

Effects of Interfacial Organic Layers on Nucleation, Growth, and Morphological Evolution in Atomic Layer Thin Film Deposition

Atomic layer deposition (ALD) of titanium nitride, TiN, from the reaction of Ti[N(CH3)2]4 and NH3 on silicon dioxide, and silicon dioxide modified by interfacial organic layers with different structures (straight-chain vs branched) and functional terminations (−OH, −NH2, and −CH3), has been investigated employing molecular beam techniques, atomic force microscopy (AFM), X-ray photoelectron spectroscopy, and scanning transmission electron microscopy (STEM). We find that the interfacial organic layers have a profound effect on subsequent growth of TiN via ALD. For organic layers possessing unreactive end groups (−CH3), the initial rate of growth (thickness deposited per cycle) is strongly attenuated, and growth on these surfaces is 3-D and severely islanded, emanating from defects in the adlayer. Roughness builds quickest on the organic layers that are the thickest. For organic layers that possess reactive end groups (−NH2 and −OH), growth is also attenuated, but less so, and the degree of attenuation is es...

Microstructure and tribological properties of Cu–Zn/TiN multilayers fabricated by dual magnetron sputtering

Metal/nitride multilayers have attracted much interest due to their superior features such as high hardness and good wear resistance. In this work, the microstructure and tribological properties of Cu–Zn/TiN multilayers with nm and sub-μm bilayer periods fabricated by magnetron sputtering are investigated. Delamination occurs when the individual TiN layers are too thin and the Cu–Zn sublayers are thick. Cu (111) and TiN (002) growth orientation have been found in the multilayers. The wear results show that Cu–Zn/TiN multilayers can offer good wear resistance. The wear resistance is improved with larger Cu–Zn content and bilayer periods. When the t Cu–Zn: t TiN ratios are 6:1, the wear resistance of the multilayers is improved significantly with increasing the periods and the film shows longer punch through time than that with t Cu–Zn: t TiN ratios of about 1:1. The hardness of multilayers is better than that of the steel substrate, but little influence has been found on the hardness with changing the t Cu–Zn:t TiN ratios or the bilayer periods.

Hard nanocomposite Ti–Si–N films prepared by DC reactive magnetron sputtering using Ti–Si mosaic target

Hard nanocomposite Ti–Si–N films were deposited on 321 stainless steel substrates by direct current (DC) reactive magnetron sputtering using a Ti–Si mosaic target consisting of a Ti plate and Si chips. The composition, microstructure, and mechanical properties were investigated using EDX, XRD, XPS, nano-indentation, and scratch tests. The results indicate that the hardness of the Ti–Si–N film gradually rises with increasing Si contents in the layer until the peak value of 42 GPa appears corresponding to a Si content of 11.2 at.%. The hardness then decreases with further increase in the Si content. XRD and XPS reveal that the hardest Ti–Si–N film consists of fine TiN crystallites (approximately 8 nm in size) in an amorphous Si 3N 4 matrix. Preferential growth of TiN is indicated by the XRD patterns. All the Ti–Si–N films show high adhesive strength as indicated by the scratch tests. The strengthening mechanism of the nanocomposite films is also discussed.

Growth of TiN∕GaN metal/semiconductor multilayers by reactive pulsed laser deposition

Ti N ∕ Ga N metal/semiconductor multilayers were grown by reactive pulsed laser deposition in an ammonia ambient on sapphire and MgO substrates for potential application in solid-state thermionic direct energy conversion devices. Crystallographic analysis of the multilayers by high-resolution x-ray diffraction and cross-sectional transmission electron microscopy revealed that, despite the difference in the crystal structures of rocksalt TiN and wurtzite GaN, it is possible to grow thick (micron scale) uniaxially textured columnar-grained multilayers with nanoscale periods and without agglomeration. X-ray scattering suggests that epitaxial growth of TiN∕GaN multilayers on (100) MgO substrates stabilizes ultrathin (1–2nm) GaN layers in the high-pressure rocksalt polymorph yielding (100) oriented rocksalt TiN∕GaN superlattices. The challenges in growth and the chemical and morphological stability of lattice- and structure-mismatched multilayers are discussed on the basis of kinetic and thermodynamic factors.

Effect of TiN inclusions on the impact toughness of low-carbon microalloyed steels

Microalloying with various elements, including titanium, coupled with thermomechanically controlled processing, has become a major technology for the manufacture of high-quality steel plate. In this research, the influence of TiN inclusions on the impact toughness of low-carbon plate steels microalloyed with titanium, vanadium, and boron was investigated. The three experimental steels had Ti/N ratios of 2.44, 3.5, and 4.2, and all three had a granular bainite microstructure. However, Charpy V-notch testing showed that steel A had very high toughness at both room temperature and -20 degrees C, whereas steels B and C showed very low toughness at -20 degrees C and moderate toughness at room temperature. Scanning electron microscope fractography revealed that coarse TiN inclusions had acted as cleavage fracture initiation sites in steels B and C. The effect of Ti and N levels on TiN formation and growth is analyzed using alloy thermodynamics. It is shown that not only is the Ti/N ratio important, but also the product of total Ti and N plays a most important role in TiN formation and growth. It is concluded that the product of the total Ti and N contents should not be greater than the solubility product of TiN at the solidus temperature to prevent the precipitation of TiN particles before solidification. Furthermore, the ratio of Ti to N should also be maintained lower than the stoichiometric ratio of 3.42 to ensure a low coarsening rate for the TiN inclusions during soaking before rolling.

Microstructure evolution and grain growth of nanocomposite TiN–TiB 2 films: experiment and simulation

Titanium–boron–nitride (TiN–TiB 2) films deposited onto Si (100) at room temperature with different boron contents by reactive unbalanced magnetron sputtering have been analyzed by a combination of high-resolution transmission electron microscopy, X-ray photoelectron spectroscopy, and X-ray diffraction. Microstructure studies revealed that at low boron incorporation (up to about 9 at.%), the film microstructure was basically TiN with a [111] preferred orientation. As the B content increased to about 19 at.%, a two-phase nanocomposite structure was formed, showing nanocrystalline (nc-) solid solution Ti(N,B) grains within amorphous (a-) TiB 2 matrices. Simultaneously, their preferred orientations gradually transformed from [111] to a mixture of [111] and [200]. When the B content reached about 27 at.% or above, nc-Ti(N,B) grains, embedding into matrix consisting of a-TiB 2 and a-BN, became smaller and separate. These grains existed in either round or elliptical shape. Using Monte Carlo simulations, the effects of the mixed amorphous TiB 2-BN phase on the microstructure evolution and grain growth in nanocrystalline Ti(N,B) were also studied. The results indicated that the formation of such an amorphous phase at the grain boundary could hinder the growth of Ti(N,B) grains and the mean grain size showed an exponential decay with boron concentration, in good agreement with our experimental observations.

Atomic force microscopy study of growth kinetics: Scaling in TiN–TiB 2 nanocomposite films on Si(1 0 0)

We used the reactive unbalanced close-field dc-magnetron sputtering growth of TiN–TiB 2 on Si(1 0 0) at room temperature to determine if scaling theory provides insight into the kinetic mechanisms of two-phase nanocomposite thin films. Scaling analyses along with height-difference correlation functions of measured atomic force microscopy (AFM) images have shown that the TiN–TiB 2 nanocomposite films with thickness ranging from 70 to 950 nm exhibit a kinetic surface roughening with the roughness increasing with thickness exponentially. The roughness exponent α and growth exponent β are determined to be ∼0.93 and ∼0.25, respectively. The value of dynamic exponent z, calculated by measurement of the lateral correlation length ξ, is ∼3.70, agreeing well with the ratio of α to β. These results indicate that the surface growth behavior of sputter-deposited TiN–TiB 2 thin films follows the classical Family-Vicseck scaling and can be reasonably described by the noisy Mullins diffusion model, at which surface diffusion serves as the smoothing effect and shot noise as the roughening mechanism.

Coating and near‐surface modification design strategies for protective and functional surfaces

AbstractThis paper discusses strategies for controlling the surface chemistry and microstructure of materials to form protective and functional surfaces through controlled gas‐metal reactions. Potential applications range from oxidation, corrosion, and wear resistance to electrochemical devices such as fuel cells to catalysts. Phenomenological examples are presented for coatings designed to self‐grade under oxidizing conditions, and for the growth of simple and complex (binary and ternary) nitride and carbide phase surface layers by nitridation and carburization reactions. Specific systems discussed include environmental barrier coatings (EBCs) for Si‐based ceramics such as Si3N4 and SiC, the growth of continuous, protective CrN/Cr2N, TiN, VN, NiNbVN, and related simple nitride layers on Fe‐ and Ni‐base alloys, the possible formation of ternary nitride and carbide surface phases (e.g. Ti3AlC2 and related MAX‐phases) on intermetallic surfaces to improve oxidation resistance, and the formation of composite near‐surface structures in Ag‐SiO2 and Co(Mo)‐Co6Mo6C2 systems.

Investigation of TiN Seed Layers for RABiTS Architectures With a Single-Crystal-Like Out-of-Plane Texture

Sharpening of the substrate texture is key to obtain critical current densities approaching single crystal values in coated conductors. In particular, great improvements in J/sub c/ are obtained by narrowing the substrate texture down to values of 3-4/spl deg/ for both phi-scan and omega-scan FWHM. The best Ni-alloy substrates used today for RABiTS show FWHM's of 6-5/spl deg/. Although the majority of buffer layers deposited on these tapes by various techniques approximately duplicate the substrate's grain alignment, some materials have been found to develop much sharper out-of-plane texture. Here we report on growth and structural characterization of TiN seed layers on various textured metal tapes. TiN seed layers deposited by PLD have consistently shown tilting of the c-axis toward the direction of the sample's surface normal. We address the extent of such tilt and discuss feasibility of alternative RABiTS architectures that use a TiN seed layer to provide very sharp out-of-plane texture and serve as an effective metal-ion diffusion barrier.

Nucleation kinetics versus nitrogen partial pressure during homoepitaxial growth of stoichiometric TiN(0 0 1): A scanning tunneling microscopy study

We grow homoepitaxial stoichiometric TiN(0 0 1) layers by ultra-high vacuum reactive magnetron sputtering in Ar/N 2 mixtures and use scanning tunneling microscopy to study nucleation as a function of the N 2 gas fraction f N 2 and growth temperature T s. The characteristic island size R c necessary to nucleate a new layer decreases continuously with f N 2 , varying from 18.0 nm at T s = 740 °C with f N 2 = 0.10 to 11.2 nm with f N 2 = 1.00 . Over the temperature range 600 ⩽ T s ⩽ 860 °C, nucleation is diffusion limited with an activation energy E s of 1.1 ± 0.1 eV for TiN(0 0 1) growth with f N 2 = 0.10 and 1.4 ± 0.1 eV in pure N 2. We attribute the increase in E s to a higher steady-state N coverage resulting in an increase in the average x-value of the primary surface-diffusing species, TiN x admolecules.

Real time in situ diagnostics of PVD growth using synchrotron radiation

For specific applications of hard coatings, the microstructure (or nanostructure) has to be tailored for optimum performance. This requires information about the mechanisms of growth and the connection between the microstructure and the deposition parameters. In order to obtain this knowledge, in situ real time growth studies of magnetron-sputtered thin films were carried out. A growth chamber, equipped with two magnetrons and Kapton windows for X-ray diffraction and reflectivity, was mounted on a six-circle goniometer at a synchrotron beam line at ESRF in Grenoble. As an example, X-ray diffraction measurements were carried out in situ during growth of TiN to follow the development of the microstructure. Recrystallization was identified as the mechanism which controlled the development of texture. The driving force for these texture changes arose from minimalization of the sum of the surface energy and the strain energy of the individual grains. As another example, the heteroepitaxial growth of TiN on MgO(001) was studied. Bragg–Brentano as well as grazing-incidence in-plane wide angle scattering was used to establish the pseudomorphic growth of TiN to the underlying MgO(001). Using real-time specular X-ray reflectivity, layer-by-layer growth was observed, with the surface roughening decreasing with an increase in the deposition temperature. The growth of nanocrystalline Au was also investigated. Among the results we found that changes in the (111) fiber texture arose from grain rotations.

Growth mechanism of TiN film on dielectric films and the effects on the work function

We have investigated the growth mechanism of ALD-TiN film on different dielectrics and the resulting effective work function value. TiN nucleation rate and growth rate are found to be dependent on the dielectric films. TiN growth mechanism changed from 3-D type on SiO 2 to layer-by-layer type on HfO 2. The minimum TiN thickness required for a complete surface coverage varies according to the growth mechanism. Capacitor (MOSCAP) characterization revealed that the effective work function of TiN is dependent not only on dielectric films but also on the TiN thickness. The behavior of work function and fixed charge correlated with the growth mechanism of TiN on dielectric films.