TiAlN Thin Films Research Articles

Low-temperature formation of Ti2AlN during post-deposition annealing of reactive multilayer systems

Mn+1AXn-phase Ti2AlN thin-films were synthesized using reactive sputtering-based methods involving the deposition of single-layer TiAlN, and Ti/AlN and TiN/TiAl multilayers of various modulation periods at ambient temperature and subsequent annealing at elevated temperatures. Ex situ and in situ x-ray diffraction measurements were used to characterize the Ti2AlN formation temperature and phase fraction. During annealing, Ti/AlN multilayers yielded Ti2AlN at a significantly lower in situ temperature of 650 °C compared to TiN/TiAl multilayers or single-layer TiAlN (750 °C). The results suggest a reactive multilayer mechanism whereby distinct Ti and AlN layers react readily to release exothermic energy resulting in lower phase transition temperatures compared to TiN and TiAl layers or mixed TiAlN. With a modulation period of 5 nm, however, Ti/AlN multilayers yielded Ti2AlN at a higher temperature of 750 °C, indicating a disruption of the reactive multilayer mechanism due to a higher fraction of low-enthalpy interfacial TiAlN within the film.

Structure, mechanical properties and thermal decomposition of carbon-alloyed TiAlN thin films: A first-principle study

TiAlCN thin films have been known for their high hardness, favorable toughness and wear properties. Nevertheless, a comprehensive theoretical study conveying the mechanism for the effects of dissolved carbon on the mechanical properties, and thermal stability of TiAlN is still missing. Here, we studied the influence of carbon addition on the structure, modulus and thermal stability of TiAlN by first-principle calculations. The calculated formation energies indicate that carbon preferentially occupies nitrogen site and decreases the solubility of Al in cubic TiN. Furthermore, the enhanced ductility and decreased shear modulus by carbon addition revealed by our calculations, nicely explain the experimentally observed exceptional toughness of TiAlCN. The decomposition enthalpy calculations suggest that c-Ti(C,N) and c-AlN are the most probable decomposition products of TiAlCN. The reduced diffusion barriers of Al, the dominant diffusing atoms, indicate promoted spinodal decomposition process by carbon addition.

Cutting performance of TiAlN-based thin films in micromilling high-speed steel AISI M3:2

Micromilling high-speed steel offers high precision in shape and geometry. However, the service life greatly depends on the wear resistance of protective thin films. In comparison to TiAlN, TiAlSiN and TiAlTaN thin films offer enhanced wear resistance for difficult-to-machine materials. Employing a hybrid process that combines direct current magnetron sputtering (dcMS) and high power pulsed magnetron sputtering (HiPIMS) enhances the properties of these films. In cutting tests, it is demonstrated that TiAlSiN and TiAlTaN outperform TiAlN in micromilling of high-speed steel AISI M3:2. Notably, dcMS/HiPIMS-TiAlSiN stands out by having the lowest reduction in cutting forces combined with reduced wear.

Electrical properties and thermistor behavior of TiAlN thin films deposited by combinatorial sputtering

A combinatorial deposition was performed by direct current magnetron sputtering (DCMS) to develop Ti1-xAlxN thin films with different Ti/Al ratios and investigate the electrical response to temperature. The crystal structure as a function of the x was studied by X-ray diffraction, and sheet resistance response was measured up to 200 °C. From x = 0.16 to x = 0.56, the film shows an fcc phase with Al in solid solution in the TiN matrix, whilst, from x ≥ 0.69, a mixture of hcp (AlN) and fcc phases is observed. A negative temperature coefficient (NTC) thermistor behavior was found from x = 0.21 onwards, and a maximum sensitivity β of 1600 K was observed for x = 0.56 and 0.69. One fcc sample (x = 0.46) was selected to analyze the chemical states by X-ray photoelectron spectroscopy and the impedance behavior with the temperature by electrical impedance spectroscopy. The crystal structure, bond states and impedance analysis were compared with an AlN thin film. It is concluded that the conduction mechanism for x = 0.46 is based upon electron hopping, and the effect of the grain boundary is more relevant than the grain at low temperatures. We demonstrate that it is possible to use TiAlN as an NTC-thermistor with different crystal structures and chemical compositions.

Effect and optimization of tribological parameters upon wear responses of TiAlN coating

This study investigated the relative effects of tribological process parameters and their optimization for wear responses of a TiAlN thin film deposited on heat-treated and plasma-nitrided novel MDC-K hot work tool steel. The effects of tribological process parameters were studied by conducting a tribological test on the TiAlN thin film against a tungsten carbide (WC) counterbody. The researchers considered three tribological process parameters – namely, sliding velocity, applied load and sliding distance – to conduct the tribological test and study the effect of the parameters on five different wear responses – namely, friction coefficient, surface roughness (R a), wear depth, wear mass loss and hardness. The relative effects of the process parameters were studied using contour plots, and the individual effects and contributions were analyzed using an analysis of variance test. Further, the overall evaluation criteria method was employed to select the optimal settings of tribological process parameters based on the experimental results. Finally, the surface morphology of the worn TiAlN surface against the best and worst parametric settings was evaluated using scanning electron microscopy integrated with energy-dispersive X-ray spectroscopy to investigate the underlying wear mechanisms.

Structural, mechanical and corrosion resistance of phosphorus-doped TiAlN thin film

Structural, mechanical and corrosion resistance of phosphorus-doped TiAlN thin film

Structure and fracture toughness of TiAlN thin films deposited by deep oscillation magnetron sputtering

TiAlN thin films were deposited on Si(100) and AISI 304 austenitic stainless steel substrates at the low deposition temperature below 250℃ by the deep oscillation magnetron sputtering (DOMS), respectively. The peak sputtering power changed from 58.7 kW to 129.9 kW by adjusting the oscillation voltage on-time (τon) / off-time (τoff) ratio with 6–12 μs to 30 μs. All TiAlN thin films have a face centered cubic structure with a composition of Ti0.22Al0.28N0.50. With increasing the peak powers, a transit of the columnar morphology in Zone I with the preferred orientation of c-TiAlN(111) to a compact morphology in Zone T with c-TiAlN(200) was characterized. The hardness, residual stress, and H/E and H3/E2 ratios of TiAlN thin films increased with the maximal values obtained at the peak power of 90.2 kW, and then slightly decreased. Correspondently, the fracture toughness (KIC) of TiAlN thin films on Si(100) and AISI 304 stainless steel increased firstly from 0.56 MPa∙m1/2 to 1.10 MPa∙m1/2 and from 0.58 MPa∙m1/2 to 1.08 MPa∙m1/2 as the structure from Zone I with c-TiAlN(111) to Zone T with c-TiAlN(200), and then decreased to 0.94 MPa∙m1/2 and 0.71 MPa∙m1/2 at the structure of Zone T with c-TiAlN(200), respectively. The higher KIC values of Ti0.22Al0.28N0.50 thin films in Zone T were achieved on Si(100) and AISI 304 stainless steel at 90.2 kW. The excellent mechanical properties of TiAlN thin films on Si(100) and AISI 304 stainless steel substrates were carried out by using DOMS at the low deposition temperature.

Tribomechanical and microstructural properties of cathodic arc-deposited ternary nitride coatings

Sintered carbides are promising materials for surfaces that are exposed to extreme wear. Owing to their high service load, ceramic-based thin films are coated on carbides using different techniques. In this study, non-toxic and cobalt-free powder metallurgy-sintered carbide samples were coated with TiN, TiAlN, CrAlN, and TiSiN ceramic-based thin film coatings by cathodic arc physical vapor deposition. The microstructure (phase formation, coating thickness, surface roughness, and topography), mechanical properties (hardness, modulus of elasticity, and plasticity indices), and tribological properties (nanoscratch and wear behavior) of the thin film coatings were investigated. No cracks or defects were detected in these layers. The ceramic-based ternary nitride thin film coatings exhibited better mechanical performance than the TiN coating. The TiN thin film coating had the highest average surface roughness, which deteriorated its tribological performance. The ternary nitride thin film coatings exhibited high toughness, while the TiN thin film coating exhibited brittle behavior under applied loads when subjected to nanoscratch tests. The wear resistance of the ternary nitride coatings increased by nearly 9–17 times as compared to that of the TiN coating and substrate. Among all the samples investigated, the substrate showed the highest coefficient of friction (COF), while the TiSiN coating exhibited the lowest COF. The TiSiN thin film coating showed improved mechanical and tribological properties as compared to other binary and ternary nitride thin film coatings.

A facile synthesis of Al-doped BaTiO3 thin films by a hydrothermal-galvanic couple method on TiAlN film electrodes

Al-doped barium titanate (ABT) thin films were produced by a facile hydrothermal-galvanic couple (HT-GC) method using ternary TiAlN seeding layers. TiAlN thin films serving as the working electrode were deposited onto Si substrates by reactive unbalanced magnetron sputtering. HT-GC synthesis was conducted in the alkaline solutions consisting of 0.5 M Ba(CH3COOH)2 and 2 M NaOH. Although no external power sources were applied, substantial galvanic currents occurred during the synthesis. X-ray diffraction patterns show that cubic ABT films were formed over TiAlN. Field-emission scanning electronic microscopy revealed ABT films exhibiting hemispherical grains over the nitride surface with single-layered structures. X-ray photoelectron spectroscopy verified Al doping in the obtained ABT coatings. Reaction paths and formation mechanisms of the ABT coatings were also proposed. Moreover, the ABT thin films possessed higher residual polarization (Pr) and piezoelectricity coefficient (d33) compared with un-doped BaTiO3 (BTO), deduced from polarization–electric field loops results. The deduced Pr-value for BTO thin films was 0.8 μC/cm2 and could be enhanced to 1.6 μC/cm2 for ABT thin films, meanwhile the value of d33 for BTO films was 13 ± 1 pC/N and increased to 18 ± 1 pC/N for ABT films. Such a facile synthesis of ABT thin films may bring in more technological applications such as piezoelectric and triboelectric materials in the hybrid nanogenerator, and non-volatile ferroelectric random access memory.

Adequate Tialn Thin Films Deposited by Sputtering for Thermistor Sensors: The Study of Conduction Mechanisms and the Microstructure Role on the Electrical Properties

Adequate Tialn Thin Films Deposited by Sputtering for Thermistor Sensors: The Study of Conduction Mechanisms and the Microstructure Role on the Electrical Properties

Experimental Investigation on Mechanical Properties of TiAlN Thin Films Deposited by RF Magnetron Sputtering

The mechanical properties of TiAlN deposited on the steel are explained in this study. Thin films are deposited by RF magnetron sputtering on the steel substrates to improve the wear resistance and hardness of the samples. Due to their improved microstructure and nanograins, the nanofilms have improved the mechanical properties of the steel substrate surface. The thin film deposited has improved the wear resistance by 80% and has improved the hardness by 95%. The deposited thin films are tested for hardness by nanoindentation and wear test by the pin-on-disk test. SEM has tested films for their microstructure and adhesion by nanoscratch test.

Arc Ion Plating 법으로 형성된 TiAlN 박막의 버퍼층에 따른 특성 연구

In this study, using the AIP method, a TiAlN thin film was grown on a WC-5Co alloy using the buffer layer as TiAl, TiN, and CrN. The preferred orientation according to the XRD analysis showed a pattern with the growth directions of (111) and (110) in almost coating conditions. In the case of the thin film using TiN and CrN as buffer layers, (220) was more prominent than that of other specimens. The adhesion of the TiAlN layer showed a tendency to be affected by the buffer layer and surface roughness. The TiN buffer layer showed the highest adhesion of 130 [N], while the TiAl buffer layer showed a low adhesion of 20[N]. And to examine the high-temperature oxidation resistance, heat treatment was performed. In the case of the specimen using TiN and CrN as buffer layers and coating the TiAlN upper layer for 60 minutes, nitrogen was not replaced with oxygen even at 900[℃] and the nitride thin film was maintained as it is.

Wear and Thermal Behavior of TiAlN Thin Films onto Ti6Al4V Alloy Manufactured by Selective Laser Melting Method.

In this study, it was targeted to enhance the tribological and thermal properties of Ti6Al4V alloys, which were manufactured with three different build orientations and hatch spacing by using the selective laser melting (SLM) method and a traditional method (casting). In addition, the surfaces of the samples produced by these two methods were coated with the TiAlN thin film by using the cathodic arc physical vapor deposition (CAPVD) method. After the experimental investigations, the lowest wear rate was obtained for the 60-90° sample, and the highest microhardness value was measured as ∼1070 HV0.1 for the 90-45° sample. It was specified that the wear rate rose as the hatch spacing increased among the same build orientation Ti6Al4V alloys produced by SLM method. According to thermal analysis results, among the same hatch spacing values, it was determined that as the build orientation value increased, the specific heat capacity and thermal conductivity values decreased. Among the coated samples, the highest thermal conductivity and specific heat capacity values were obtained for casting samples as 5.63 (W/m·K) and 560.4 (J/kg·K), respectively.

An inverse problem in estimating fracture toughness of TiAlN thin films by finite element method based on nanoindentation morphology

The fracture toughness of TiAlN thin films on AISI 304 austenitic stainless steel was inversely investigated by combining nanoindentation experiment with finite element method (FEM) and extended FEM (XFEM) simulation. The TiAlN thin films were deposited by deep oscillation magnetron sputtering (DOMS) with the oscillation pulse on and off times of 12 μs and 30 μs at a peak power of 136.1 kW. A completely dense TiAlN thin film with the thickness of 1500 nm has a face-centered-cubic microstructure with (200) preferred orientation. The displacements of the nanoindenter were intentionally interrupted by 1200 nm and 1800 nm, latter is thin film-crossing to induce an apparently cracking. The cross-sectional samples of TiAlN thin films with the cracks were fabricated by focused ion beam. The experimental crack number and position in the cross-sectional samples were observed by scanning electron microscopy. The maximum damage initiating stress (σmax) and corresponding crack separation distance (δc) in the Griffith–Irwin relationships were fitted using the XFEM calculation based on the crack morphology to match the crack number and position of TiAlN thin films. The fracture toughness of TiAlN thin films on AISI 304 austenitic stainless steel was calculated to be 1.09 MPa m1/2 according to the fitted parameters of 5.5 GPa for σmax and 1.5 nm for δc. Therefore, an alternative method by the nanoindentation morphology and the inversely calculation fitting was developed to estimate the fracture toughness of thin films.

Micro-structural and bonding structure analysis of TiAlN thin films deposited with varying N2 flow rate via ion beam sputtering technique

Abstract Titanium aluminum nitride (TiAlN) thin films were deposited on Si(1 0 0 ) substrate using titanium and aluminum targets in 1:1 ratio at various N2 flow rates using ion beam sputtering (IBS) technique. The morphology, particle and crystallite size of TiAlN thin films were estimated by field emission scanning electron microscope (FE-SEM), atomic force microscope (AFM), and grazing incidence X-ray diffraction (GIXRD) technique, respectively. The SEM images of the TiAlN thin films revealed smooth and uniform coating, whereas AFM images confirmed the particle size varying from 2.5 nm to 8.8 nm, respectively. The crystallite size and lattice strain were observed to vary from 4.79 nm to 5.5 nm and 0.0916 and 0.0844, respectively, with an increase in N2 flow rate in the TiAlN thin films. The X-ray absorption near edge structure (XANES) results showed Ti L, N K and O K-edges of TiAlN coating within a range of 450 eV to 470 eV, 395 eV to 410 eV and 480 eV to 580 eV photon energy, respectively. The electronic structure and chemical bonding of state of c-TiAlN thin film of Ti L, N K and O K-edges were analyzed through semi-empirical curve fitting technique.

Electric field strength-dependent accuracy of TiAlN thin film composition measurements by laser-assisted atom probe tomography

Accurate quantification of absolute concentrations represents a major challenge for atom probe tomography (APT) since the field evaporation process is affected significantly by the measurement parameters. In the present work we investigate systematically the effect of laser pulse parameters on the accuracy of laser-assisted APT for a TiAlN thin film previously quantified by ion beam analysis, combining Rutherford backscattering spectrometry and time-of-flight elastic recoil detection analysis. The electric field strength is estimated from the Al2+/Al+ charge state ratio for all systematically varied measurement parameters. Subsequently, the absolute concentrations from laser-assisted APT are compared to ion beam analysis data. An increase of the electric field strength from approximately 25–28 V nm−1 improves the accuracy of absolute concentrations measured by laser-assisted APT from 11.4 to 4.1 at% for N, from 8.8 to 3.0 at% for Al and from 2.8 to 0.9 at% for Ti. Our data emphasize that the measurement accuracy of laser-assisted APT for TiAlN is governed by the electric field strength. It is shown that the smallest compositional discrepancies between ion beam analysis and APT are obtained for the maximum electric field strength of approximately 28 V nm−1 at 10 pJ laser pulse energy. This can be rationalized by considering the enhanced ionization of neutral fragments caused by the increased electric field strength.

Наносекундное воздействие интенсивного лазерного излучения на тонкие плёнки TiAlN

The spectral dependencies (λ = 0.35-1.0 μm) of the transmittance and reflectivity (R) of TiAlN thin films deposited on glass and Si substrates by magnetron sputtering technique have been measured. The TiAlN/Si films of 0.5 μm thickness were irradiated by single nanosecond (70 ns) ruby laser pulses in order to study the influence of laser-induced thermophysical processes in TiAlN on its R(t) dynamics at the wavelengths λ1 = 0.53 and λ2 = 1.06 μm of probing radiation, and on the state of laser irradiation zones, which was studied by optical and scanning electron microscopy. The observed in the experiment and connected with the pulsed heating dynamics changes of R - increase at λ1 and decrease at λ2 amplifies as the irradiation energy density W approaches to the threshold of laser ablation of the nitride ~ 1 J/cm2. Laser-induced thermophysical processes, occurring at W = 0.6-0.9 J/cm2, lead to a specific modification of the TiAlN layer with the formation of a net of cracks due to thermal stresses arising during the laser pulse. The increase of W leads to the formation of a more developed net/cellular structure of the film with a smaller average size of cells.

Modelling of Nanoindentation of TiAlN and TiN Thin Film Coatings for Automotive Bearing

Bearings are critical components for the transmission of motion in machines. Automotive components, especially bearings, will wear out over a certain period of time because they are constantly subjected to high levels of stress and friction. Studies have proven that coatings can extend the lifespan of bearings. Hence, it is necessary to conduct studies on coatings for bearings, particularly the mechanical and wear properties of the coating material. This detailed study focused on the mechanical properties of single-coatings of TiN and TiAIN using the finite element method (FEM). The mechanical properties that can be obtained from nano-indentation experiments are confined to just the Young’s modulus and hardness. Therefore, nanoindentation simulations were conducted together with the finite element method to obtain more comprehensive mechanical properties such as the yield strength and Poisson’s ratio. In addition, various coating materials could be examined by means of these nanoindentation simulations, as well the effects of those parameters that could not be controlled experimentally, such as the geometry of the indenter and the bonding between the coating and the substrate. The simulations were carried out using the ANSYS Mechanical APDL software. The mechanical properties such as the Young’s modulus, yield strength, Poisson’s ratio and tangent modulus were 370 GPa, 19 GPa, 0.21 and 10 GPa, respectively for the TiAlN coating and 460 GPa, 14 GPa, 0.25 and 8 GPa, respectively for the TiN coating. The difference between the mechanical properties obtained from the simulations and experiments was less than 5 %.

Reprint of “Effect of target composition on the microstructural, mechanical, and corrosion properties of TiAlN thin films deposited by high-power impulse magnetron sputtering”

Ti1−xAlxN thin films were deposited using reactive high-power impulse magnetron sputtering on silicon Si (100), tungsten carbide (WC-Co), and SUS304 substrates using three metallurgical TixAly alloy targets with Al/(Al + Ti) atomic ratios of 0.19, 0.36, and 0.57. A fixed duty cycle of 1% and a N2/Ar ratio of 15.8% was used. The current–voltage characteristics of the TixAly alloy targets were first investigated. Then, the microstructural evolution and the mechanical and corrosion properties of the as-deposited Ti1−xAlxN thin films were analysed by scanning electron microscopy, grazing incident X-ray diffractometry, X-ray photoelectron spectroscopy, transmission electron microscopy, nanoindentation, and anodic potentiodynamic polarisation tests. The power density of 1.86 kW/cm2 achieved with the square-like power output wave obtained in the constant current mode was higher than the 1.37 kW/cm2 power density obtained with the triangular-like power output wave. The deposition rates of the Ti1−xAlxN thin films increased from 13.4 to 28.6 nm/min with an increasing alloy target Al/(Al + Ti) atomic ratio due to the higher sputter yield of Al than Ti. The Al/(Al + Ti) atomic ratio of the alloy target determines the structure, which changed from a highly preferred TiN (111) orientation (Al/(Al + Ti) ratio = 0.19) to a nanocomposite structure (Al/(Al + Ti) ratio = 0.57). The nanoindentation results indicated that the highest hardness and elastic modulus values of the Ti1−xAlxN thin films were 33.3 GPa and 405.9 GPa, respectively, obtained using the Al/(Al + Ti) = 0.19 alloy target. In addition, the friction coefficients of the Ti1−xAlxN thin films were between 0.68 and 0.77. However, the potentiostatic polarisation measurements showed that the amorphous TiAlN films exhibited the highest corrosion resistance in 3.5% NaCl solution, as the corrosion resistance of the Ti1−xAlxN coatings increased as the Al/(Al + Ti) atomic ratio increased.

Bias voltage effect on magnetron sputtered titanium aluminum nitride TiAlN thin films properties

In this study, a negative substrate bias voltage is used to tune the structural, morphological, mechanical and electrochemical properties of TiAlN coatings fundamental for protective coating applications. TiAlN thin films have been deposited on glass, (001)Si and stainless steel substrates by RF magnetron sputtering at a power density of 4.41 W/cm2. The deposition rate was determined from X-ray reflectivity measurements to 7.00 ± 0.05 nm/min. TiAlN films used in this work were deposited for 60 min to yield a film thickness of 420 nm. Structural analysis has shown that TiAlN coating forms a cubic (fcc) phase with orientations in (111), (200), (220) and (222) planes. The deposited coatings present maximum hardness (H = 37.9 GPa) at −75 V. The dependence of hardness and Young's modulus and corrosion resistance on microstructure has been established. Electrochemical studies by potentiodynamic polarization in aggressive environment (3.5 wt.% NaCl) have revealed that stainless steel substrate with TiAlN coating exhibits excellent corrosion resistance.