TiZrN Coatings Research Articles

Phase Formation, Residual Stress, and Surface Energy of Carbon-Doped TiZrN Coatings

Phase Formation, Residual Stress, and Surface Energy of Carbon-Doped TiZrN Coatings

The Bonding State and Surface Roughness of Carbon-Doped TiZrN Coatings for Hydrogen Permeation Barriers

We doped carbon into a TiZrN coating to reduce hydrogen permeability, and investigated the phase formation, bonding state, microstructure, and surface roughness of the carbon-doped TiZrN. The laser output for laser carburization was limited to a range of 20–50%. The grain size of the TiZrN coatings decreased from 26.49 nm before carburization to 18.31 nm after carburization. For XPS analysis, the sp2/sp3 ratio was 1.23 at 20% laser output, but it showed 2.64 at 40% laser output, which means that amorphous carbon was formed. As the grain size decreased with the formation of amorphous carbon, the surface microstructure of the carbon-doped TiZrN coatings transitioned to an intergranular structure, indicating the creation of amorphous carbon-embedded (Ti, Zr)(C, N) in the coating. The surface roughness (Ra) of the carbon-doped TiZrN coating was decreased to a maximum of 7.12 nm, and the hydrogen permeability correspondingly decreased by 78% at 573 K.

Improving tribological behavior of titanium nitride (TiN) hard coatings via zirconium (Zr) or vanadium (V) doping

This research expounds on the influence of zirconium (Zr) or vanadium (V) doping on titanium nitride (TiN) coatings deposited via magnetron sputtering technique. The study focuses on microstructure analysis, tribological properties, and the implications of these doping. Previous research has shown that doping can modify the microstructure, coating substrate adhesion, friction, and wear resistance of TiN coatings. However, further investigation is required to understand the specific effects of doping levels and the underlying mechanisms. This study addresses the need to enhance TiN coating performance by exploring the potential of Zr and V doping. It fills a gap in knowledge by examining the influence of specific doping levels on coating properties and contributes to resolving disputes in the literature. Analytical methods, including GI-X-ray diffraction, energy dispersive X-ray spectroscopy, scanning electron microscopy and atomic force microscopy, were used to analyze the coatings microstructure, morphology, chemical composition, phase composition, and roughness. The findings reveal that Zr-doped TiZrN coatings outperform TiVN and TiN coatings in terms of mechanical and tribological properties. TiZrN coatings exhibit higher texture coefficients, elastic modulus, and hardness. Moreover, Zr or V doping enhances the anti-wear properties of the coatings, shifting the dominant wear mechanism from adhesive to abrasive. The implications of this research are significant for industries seeking improved wear resistance and durability in coatings. This study expands knowledge on the microstructural and tribological characteristics of doped TiN coatings, contributing to advancements in the field.

Corrosion and tribocorrosion behaviors of ternary TiZrN coating on 304 stainless steel prepared by HiPIMS

In this work, the wear- and corrosion-resistant binary TiN and ternary TiZrN coatings were deposited severally on 304 stainless steel (304SS) though high-power impulse magnetron sputtering (HiPIMS) technology. The microstructure, composition, surface roughness, corrosion and tribocorrosion performance of the bare and coated substrates were investigated, respectively. The results revealed that the binary TiN coating presents a rough surface and higher O concentration while the ternary TiZrN coating possessed higher surface hardness and elastic modulus. Both of the coatings exhibited better anticorrosion properties after immersion for 0.5 h in a neutral medium. However, the long-term soaking results indicated that the ternary TiZrN coating can effectively hinder coating degradation in reducing acidic electrolyte, and its Rct value was approximately 5.5 × 105 Ω cm2, which was almost 10 times that of the binary TiN coating. Furthermore, the as-prepared coatings also maintain the lower coefficient of friction (CoF) values as well as leading to a decrease in the wear rate by approximately 55.4–77.3%, compared to 304SS. These results provide insights into the positive effect of co-deposited Zr and Ti particles in improving the corrosion and tribocorrosion behaviors.

Grain boundary strengthening of carbon-doped TiZrN coatings by laser carburization

ABSTRACT The improved mechanical properties of carbon-doped TiZrN coatings were investigated in terms of the microstructure and bonding state. The carbon incorporation and structural change were confirmed as a shift to lower degree of the diffraction pattern and the decreased grain size from 24.64 to 22.19 nm. The clear grain boundaries (GBs) were observed in the carbon-doped coating, and its fast Fourier transform (FFT) exhibited a diffused ring pattern. Edge dislocations were also observed in the inverse FFT image, indicating the formation of an amorphous phase due to laser carburization. From the X-ray photoelectron spectroscopy depth profile analysis, the carbon concentration decreased to 37.26 at.% after carburization, which is non-stoichiometric behavior that suggests the formation of the amorphous carbon (a-C) rather than carbides. Both sp2- and sp3-hybridized bonds were detected in the C 1s spectrum of the carbon-doped coating, indicating that the diffused carbon atoms were trapped in the GBs as a-C. The change in the GB structure increased the compressive residual stress from 3.97 to 4.63 GPa. In addition, the hardness, elastic strain to failure (H/E), and plastic deformation resistance (H3/E2) of the carbon-doped TiZrN increased by 19.22%, 12.64%, and 49.59%, respectively, demonstrating the effect of GB strengthening.

Solid particle erosion behavior and failure mechanism of TiZrN coatings for Ti-6Al-4V alloy

Arc-plasma deposition technique was used to prepare coatings on a Ti–6Al–4V alloy surface due to its high coating deposition rate and superior coating-substrate bonding strength. The effects of the coatings on the erosion resistance of the alloy to solid-particle erosion at low- (30°) and high- (90°) impact angles were investigated. The results indicated that all coatings significantly improve the erosion resistance of the titanium alloy at an impact angle of 30°. It was attributed to the high microhardness and excellent bonding strength of the coatings. However, at a high-impact angle (90°), the thin monolayer coating was worn off after the erosion test and the failure mechanism of this coating was shear fracture and interface cracking of columnar crystals. With increasing of the coating thickness, the failure mechanism changed to single shear fracture and the thick monolayer coating retained the protection capability for the titanium alloy surface after this erosion. Moreover, compared with the monolayer coating, the multilayer coating as thick as the thick monolayer coating had a superior erosion resistance and slighter shear fracture under this erosion test condition. It was mainly due to the good toughness and strength, sufficiently high dynamic loading capability of the multilayer coatings.

Hydrogen permeation barrier of carbon-doped TiZrN coatings by laser carburization

Hydrogen impermeability of carbon-doped TiZrN coatings was investigated in terms of carbon diffusion behavior and bonding states. The FFT pattern of a ring pattern and the inverse FFT with edge dislocations indicated formation of an amorphous phase and change in intergranular structure due to carbon diffusion through the grain boundaries of TiZrN. The diffused carbon followed Harrison Type-B behavior, because of localization at near-surface and increased compressive residual stress. The formation of amorphous carbon suggested the trapping at boundaries. The impermeability of the carbon-doped coatings was enhanced by 80 %, showing the contribution of amorphous carbon as a repellent.

Phase Formation and Wear Resistance of Carbon-Doped TiZrN Nanocomposite Coatings by Laser Carburization

Carbon-doped TiZrN nanocomposite coatings were investigated for phase formation and wear behavior. They were prepared by laser carburization using carbon paste, and the thermal energy of the pulsed laser was limited to the range of 20 to 50%. X-ray photoelectron spectroscopy analysis revealed that the ratio of carbide (TiC, ZrC) increased as the thermal energy of the laser increased. The sp2/sp3 ratio increased by approximately 16% when the laser thermal energy was raised from 30 to 40%, and the formation of amorphous carbon was confirmed in the carbon-doped TiZrN coatings. As a result of microstructural analysis, the carbon-doped TiZrN nanocomposite was formed by an increase of hybrid bonds in expanded localized carbon clusters. Wear resistance was evaluated using a ball-on-disc tester, which showed that the friction coefficient decreased from 0.74 to 0.11 and the wear rate decreased from 7.63 × 10−6 mm3 (Nm)−1 to 1.26 × 10−6 mm3 (Nm)−1. In particular, the friction coefficient and wear rate improved by 71 and 66%, respectively, owing to the formation of carbon-doped TiZrN nanocomposite with amorphous carbon while the thermal energy was increased from 30 to 40%.

Effect of Ti interlayer thickness on mechanical properties and wear resistance of TiZrN coatings on AISI D2 steel

In the tool industry, adding a soft metallic interlayer to enhance the adhesion of hard coatings is a common practice. This study investigated the effect of Ti interlayer thickness on the residual stress, adhesion strength and wear resistance of TiZrN coatings. The feasibility of using stored elastic energy as an index of wear resistance of the coatings was also studied. The effect of Ti interlayer thickness was evaluated by comparing the mechanical properties of TiZrN films with different Ti interlayer thickness, ranging from 50 to 250 nm. The results showed that the increase of interlayer thickness from 50 to 250 nm reduced the stress of the TiZrN coatings from −5.67 to −3.75 GPa. The optimal Ti interlayer thickness to enhance the adhesion strength of the TiZrN coatings with about 2 μm thickness on D2 steel was 150 nm; however, the adhesion was insignificantly improved compared with the specimen without interlayer. Introducing 250 nm Ti interlayer could slightly increase the wear resistance of the TiZrN coating about 16%, but the adhesion strength of the coating decreased about 6%. The insignificant improvement on mechanical properties and wear resistance of the TiZrN coatings by the Ti interlayer were mainly attributed to the high residual stress of TiZrN top layer. For the coatings with high residual stress (>−4.0 GPa), the stress relief by adding a metal interlayer is limited and insufficient to enhance adhesion strength or wear resistance. Other approaches that can directly lower the intrinsic growth stress in hard coatings may be more effective.

Test method for degradation of TiZrN coatings on metal substrate using electrical resistance measurement

A test method was devised to evaluate the degradation level of TixZr1-xN (x = 0.1, 0.5) coatings on SUS304 under thermo-mechanical stress. A pulsed laser ablation system was employed to apply repetitive local stress. A system was designed to determine the degradation from the electrical conductivity differences between the TiZrN coating and the substrate. The electrical resistance between the stress loaded area and the stress un-loaded area was measured using a multimeter. The resistance gradually decreased by more than 60% as the number of laser ablations increased. The resistance displayed the convergence value, which was considered the failure point of the coating layer. SEM-EDS and GIXRD analysis of the coating layer showed an increase in the element concentration of substrate components under laser ablation, which indicated that the decrease in resistance was due to the diffusion of the substrate elements.

Atomic structure and residual stress of carbon-doped TiMeN (Me = Zr, Al, and Cr) coatings on mechanical properties

The hardnesses of carbon-doped TiMeN (Me = Zr, Al, and Cr) coatings were investigated in terms of lattice distortion and residual stress according to the difference in the ionic radii of the transition metal. TiMeN coatings were deposited on SUS304 by sputtering, and laser carburization was carried out for carbon doping. The scratch test showed that the delaminations of TiZrN, TiAlN, and TiCrN coatings were occurred about 13 N, 19 N, and, 16 N before and after carbon doping. The rate of hardness increase rate of TiZrN with carbon doping was the highest at 15.1%, and that of TiAlN and TiCrN were at 8.8% and 10.7%, respectively. The difference in hardness was analyzed by Rietveld refinement using HR-XRD, and the change in the lattice constant for TiZrN was 0.18 Å, which was larger than that of TiAlN (0.10 Å) and TiCrN (0.07 Å). The expansion distortion was confirmed by the increase in lattice constant, and the doped carbon affected the lattice distortion differently depending on the ionic radius of the transition metal. The variation in residual stress through the lattice distortion was identified by the sin2Ψ method using HR-XRD with parallel beam and tilting of the specimen. The TiZrN coating showed the largest residual stress variation at 22%, and TiAlN and TiCrN showed similar tendencies at 11% and 13%, respectively.

Surface graphitization of carbon-doped TiZrN coatings

Surface graphitization was induced to improve the wear characteristics of carbon-doped TiZrN coatings (C-TiZrN) and was investigated in terms of bonding state. The C-TiZrN were prepared by laser carburization using pulsed laser ablation and were annealed to transform the carbon hybridization state from sp3 to sp2. The amorphous phase of the doped carbon was identified by detecting a mixture of hybrid bonds (sp2 and sp3). The variation of the sp2/sp3 ratio from 2.16 to 5.44 implied the transformation from sp3 to sp2 after heat treatment. The transformation of sp2 bond was confirmed by the shift of the G peak to lower wavenumbers and the fluctuation of the ID/IG ratio, in the Raman spectra. The formation of graphitized atomic layers during the transformation was verified by the presence of a 2D peak at 500 °C. The change in lattice constants from 4.47 to 4.45 displayed the effect of the sp3 to sp2 structural transformation. The friction coefficient of the annealed C-TiZrN (500 °C) in the wear test decreased by 12% owing to the suppression of adhesive wear by the graphitized surface.

Surface amorphisation of TiZrN coatings by laser carburisation

ABSTRACTThe enhancement of wear resistance by laser carburisation on TiZrN coatings was investigated in terms of bond state. Graphite paste was used to cover the TiZrN coatings and then pulsed laser ablation was used to solidify the carbon. Tribometer test showed that the friction coefficient was reduced from 0.64 to 0.17 after laser carburisation. The doped carbon was analysed as a mixture with sp2C and sp3C bonds using an X-ray photoelectron spectroscopy depth profile. The sp2/sp3 ratio was 2.29 at the surface and increased up to 2.91 in the depth direction. To verify the effect of the hybrid bonds on the atomic order, annealing was carried out to the carburised specimens. As the ratio increased to 3.28, graphitisation resulting in transition from sp3 to sp2 was confirmed, and variation in the lattice structure was demonstrated by a reduction in the lattice constant (4.45 Å to 4.40 Å) using Rietveld refinement.

Effect of Ti interlayer on mechanical properties of TiZrN coatings on D2 steel

The objective of this study was to investigate the effect of Ti interlayer on the stress relief and mechanical properties of TiZrN coatings with thickness up to 3 μm. TiZrN coatings with 250-nm Ti interlayer (TiZrN/Ti) were deposited on AISI D2 steel substrate using unbalanced magnetron sputtering. In addition to TiZrN/Ti specimens, two more sets of specimens were prepared for comparison, namely, TiN and TiZrN monolayer coatings. The results showed that Ti interlayer can enhance the (111) preferred orientation of the thinner TiZrN coatings (≤1 μm); however, the preferred orientations of the thicker coatings (>1 μm) showed weak dependence on the Ti interlayer. The stresses in the TiZrN top layer, Ti interlayer and steel substrate were respectively measured using cos2αsin2ψ X-ray diffraction method. The results indicated that the stress in the top TiZrN layer was relieved by both Ti interlayer and the steel substrate for most of the TiZrN/Ti specimens, except for the specimen with 0.53 μm TiZrN, where the stress in the top TiZrN layer was mainly relieved by Ti interlayer. The stress relief reached a maximum in sample with 1.46 μm TiZrN. Then, the stress in TiZrN increased with the film thickness up to 3 μm, where the stress relief was mainly by the steel substrate. The results of scratch test showed that Ti interlayer could increase the adhesive strength. The wear resistance cannot be evaluated by individually considering residual stress or coating thickness. Instead, the elastic stored energy (Gs) combining the residual stress and coating thickness is a better index for evaluating the wear resistance of hard coatings. Adding a Ti interlayer may increase the wear resistance for coatings ≤1 μm; however, the wear resistance may decrease for thicker TiZrN coatings (>1.5 μm) due to the increase of Gs which decreases the capacity in absorbing the external input energy.

Antimicrobial activity of Ti-ZrN/Ag coatings for use in biomaterial applications

Severely broken bones often require external bone fixation pins to provide support but they can become infected. In order to reduce such infections, novel solutions are required. Titanium zirconium nitride (Ti-ZrN) and Ti-ZrN silver (Ti-ZrN/Ag) coatings were deposited onto stainless steel. Surface microtopography demonstrated that on the silver containing surfaces, Sa and Sv values demonstrated similar trends whilst the Ra, average height and RMS value and Sp values increased with increasing silver concentration. On the Ti-ZrN/Ag coatings, surface hydrophobicity followed the same trend as the Sa and Sv values. An increase in dead Staphylococcus aureus and Staphylococcus epidermidis cells was observed on the coatings with a higher silver concentration. Using CTC staining, a significant increase in S. aureus respiration on the silver containing surfaces was observed in comparison to the stainless steel control whilst against S. epidermidis, no significant difference in viable cells was observed across the surfaces. Cytotoxicity testing revealed that the TiZrN coatings, both with and without varying silver concentrations, did not possess a detrimental effect to a human monocyte cell line U937. This work demonstrated that such coatings have the potential to reduce the viability of bacteria that result in pin tract infections.

Friction and Wear Studies of Uncoated and TiZrN Coated Brass Substrates

Objectives: Investigation of enhancement in tribological properties of TiZrN coated brass substrate. Methods/Statistical Analysis: The magnetron sputtering was used to develop TiZrN coating on brass substrate by varying titanium (Ti) target power. X-ray diffraction (XRD) and Scanning Electron Microscopy (SEM) was used to do structural characterization of TiZrN coatings. Tribological properties of TiZrN coatings such as friction and wear were investigated by a pin on disc tribometer. Findings: The evolution of well intense (200) and (311) peaks of TiZrN coatings was observed with rise in power of titanium target. Increase of titanium power has a negligible effect on average crystallite size of TiZrN coatings and average crystallite size is around 4-5nm. TiZrN coatings are uniform, smooth and crack free as observed from SEM images for all samples. Tribological properties of TiZrN coatings were examined with testing parameters such as load and sliding distance. Application/Improvements: This coating may be useful for applications where low friction and wear is required such as gears, bearings, and electrical applications.

Antibacterial activity and cell compatibility of TiZrN, TiZrCN, and TiZr-amorphous carbon coatings

A cathodic-arc evaporation system with plasma-enhanced duct equipment was used to deposit TiZrN, TiZrCN, and TiZr/a-C coatings. Reactive gases (N2 and C2H2) activated by the Ti and Zr plasma in the evaporation process was used to deposit the TiZrCN and TiZr/a-C coatings with different C and nitrogen contents. The crystalline structures and bonding states of coatings were analyzed by X-ray diffraction and X-ray photoelectron spectroscopy. The microbial activity of the coatings was evaluated against Staphylococcus aureus (Gram-positive bacteria) and Actinobacillus actinomycetemcomitans (Gram-negative bacteria) by in vitro antibacterial analysis using a fluorescence staining method employing SYTO9 and a bacterial-viability test on an agar plate. The cell compatibility and morphology related to CCD-966SK cell-line human skin fibroblast cells on the coated samples were also determined using the 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay, reverse-transcriptase-polymerase chain reaction, and scanning electron microscopy. The results suggest that the TiZrCN coatings not only possess better antibacterial performance than TiZrN and TiZr/a-C coatings but also maintain good compatibility with human skin fibroblast cells.

Corrosion, haemocompatibility and bacterial adhesion behaviour of TiZrN-coated 316L SS for bioimplants

TiZrN coating was deposited on 316L stainless steel (SS) by the reactive magnetron co-sputtering technique. Cubic phase of TiZrN with uniform surface morphology was observed by X-ray diffraction and atomic force microscopy. Bacterial adhesion, haemocompatibility and corrosion behaviour of TiZrN coating were examined in order to evaluate the coating’s compatibility for ideal implant. Results revealed that TiZrN coatings exhibited less bacterial attachment against Staphylococcus aureus and Escherichia coli bacteria, negligible platelets activation and superior corrosion resistance than the uncoated 316L SS.

Microstructures, mechanical properties and oxidation behavior of vacuum annealed TiZrN thin films

The purpose of this study was to investigate the effects of vacuum heat treatments on microstructures, associated mechanical behavior and oxidation behavior of TiZrN films. The films with three Zr/(Zr + Ti) ratios of 0.3, 0.5 and 0.7 were prepared using a DC reactive unbalanced magnetron sputter system. The annealing temperatures ranged from 700 to 1000 °C. X-ray diffraction (XRD) and microstructural examination revealed that both the as-deposited and heat-treated films exhibited a single TiZrN phase with columnar grains at the annealing temperature below 900 °C. At 1000 °C, ZrO2 phase appeared. In a temperature range from 700 to 900 °C in vacuum for 3 h, the heat-treated films showed a 15% drop in hardness, as compared with the as-deposited films. The slight decrease in hardness suggested that the heat-treated TiZrN films with a hardness level of application interest could be attributed to solid solution strengthening. Stress state of the films was found to be compressive. Substantial decrease in the magnitude of the residual compressive stresses could be achieved via heat treatment. At 1000 °C, the volume expansion arising from the oxidation of zirconium within the film may lead to an increase in residual compressive stresses of the films. The Ti0.7Zr0.3N film exhibited a lowest oxidation rate in the TiZrN coatings at 1000 °C in vacuum.

Interfacial stability and diffusion barrier ability of Ti1−xZrxN coatings by pulsed laser thermal shock

Interfacial characteristics and diffusion behavior of Ti1−xZrxN coatings under thermomechanical stress were investigated, in terms of morphologies and depth profiles, after pulsed laser ablation. TiZrN coatings were deposited on SUS304 substrates, using TiZr compound targets with Ti:Zr wt.% ratio of 90:10, 70:30, and 50:50. XRD patterns showed the same growth orientations of TiN and ZrN as (111), (200), and (220) in all coating specimens. The lattice parameters and the microhardness increased through solid solution with the substitutions of Zr to the Ti sites. Spalling of the coating layer was observed in the specimen of 10% wt.% Zr ratio after laser ablation. Delamination was suppressed as the substitution of Zr increased, and it could be attributed to the formation of ZrN which can promote heat transfer in the coating layer faster than TiN. SIMS depth profiles revealed that the diffusion distance of the coating (Ti, Zr) and the substrate (Cr, Fe) atoms decreased, due to diffusion path reduction by the solid solution effects.