Oxynitride Coatings Research Articles

PVD decorative coatings on polycarbonate and polyamide substrates for the automotive industry

Utilizing magnetron sputtering to incorporate metal onto polymer surfaces as a substitute for metal parts in the automobile industry offers an eco-friendly alternative. In this work, decorative titanium oxynitride (TiNxOy) coatings were sputter deposited over polycarbonate and polyamide 12 substrates using a low-temperature pulsed deposition method. In order to improve coating adhesion, all substrate surfaces were pre-treated for 30 s by reactive plasma etching. Four different film thicknesses were investigated to achieve various colours. The TiNxOy coatings were quasi-amorphous, and the oxygen content decreased with increasing film thickness. Overall, four distinct colours - green, purple, magenta, and blue - were produced, and all coatings showed excellent adhesion to the polymeric substrates. Colour fastness was assessed using adapted pin-on-disk tests to evaluate the film's applicability as decorative coatings for automotive parts, with all films achieving high ratings for colour fastness. This study provides insights into the deposition of thin films on polymeric substrates, showcasing successful approaches to achieve desired colours while preserving the film's optical properties after color fastness testing.

Structure and mechanical properties of multi-principal AlCrNbSiTiON oxynitride coatings

The multi-principal AlCrNbSiTiON oxynitride coatings were deposited by pulsed arc ion plating under different oxygen flow. The structure and mechanical properties of the coatings were systematically investigated. The surface of all coatings is smooth and flat. The cross section is compact and smooth. The coatings transform from FCC solid solution crystal structure with (200) preferred orientation to amorphous/nanocrystalline nanocomposite structure with increasing oxygen flow. Upon increasing oxygen flow from 0 to 150 SCCM, their hardness decreases from 43.4 to 15.6 GPa. The hardness of the coatings increases to 26.4 GPa with increasing oxygen flow again. The Cr2O3 oxides are formed on the surface of the coatings during the friction process.

Study of the Effectiveness of Corrosion Resistance Growth by Application of Layered AlN–TiO2 Coatings

The work is devoted to the study of the use of AlN–TiO2 coatings as protective materials against corrosion and natural aging, as well as a rise in wear resistance of the steel surface under long-term mechanical influences. The choice of oxy-nitride coatings obtained by magnetron sputtering by layer-by-layer deposition of layers of aluminum nitride and titanium oxide with layer thicknesses of the order of 50 nm and 100 nm as objects of study is due to their high resistance to external influences, which can have a significant impact on growth in the resistance to degradation processes associated with hydrogenation during the operation of steel structures. During determination of the hydrophobicity/hydrophilicity of AlN–TiO2 coatings, it was found that the applied coatings, regardless of the conditions for their preparation, have hydrophobic properties (the contact angle is ~125–130°), which are preserved both during corrosion tests (except for TiO2 coatings, for which the change in the contact angle after corrosion tests is ∆ ~ 10°) and when modeling natural aging processes. During the tribological tests of coating samples, it was found that a growth in the number of spray layers (when alternating them) leads to a rise in wear resistance, both in the case of the initial samples and for samples subjected to corrosion in a model solution of 0.1 M NaCl and when simulating natural aging processes.

Effect of deposition conditions on the structural and mechanical properties of oxynitride TaON coatings for biomedical applications

A thorough evaluation was conducted of the structural and nano-mechanical characteristics of oxynitride coatings with TaOxNy structures formed by reactive magnetron sputtering at different flows of the reactive oxygen/nitrogen gasses. Tantalum oxynitrides exhibit a broad range of modifications in their structure and elemental content depending on the conditions of deposition. The TaON structures combine the characteristics exhibited by tantalum nitride, used as a hard material for tribological and mechanical applications, with the excellent dielectric properties of the tantalum oxide. The results discussed point to the deposited tantalum oxynitrides being promising candidates for biomedical applications.

Efficiency of using nitride and oxy-nitride coatings for protection against high-temperature oxidation and embrittlement of the surface layer of steel structures

Efficiency of using nitride and oxy-nitride coatings for protection against high-temperature oxidation and embrittlement of the surface layer of steel structures

Characterization of Reactive Sputtered Chromium Oxynitride Coatings Developed on Glass Substrate

In this study, we investigate how changing the nitrogen flow rate, the length of time during deposition, and the intensity of pressure have an impact on the resulting chromium oxynitride coatings. Depending on the sputtering conditions, the X-ray diffraction analyses reveal different textures in the Cr2O3 and Cr2N phases. Films deposited with varying nitrogen flow rates and deposition durations experience compressive strains, whereas films produced with varying sputtering pressures witness tensile stresses. Film surface energies and contact angles were measured with a contact angle goniometer. Because of their hydrophobic properties, chromium oxynitride coatings may find use as water-repellent, self-cleaning surfaces. Chromium oxynitride films’ absorption and transmission curves were recorded using a UV-Vis-NIR spectrophotometer. The band gap of chromium oxynitride coatings reduces with a rise in the flow of nitrogen and sputtering time but widens with increasing deposition pressure.

Characterization, mechanical and biomedical properties of titanium oxynitride coating

In this study, a titanium oxide-nitride coating was applied to 12Cr18Ni10Ti stainless biomedical steel through reactive magnetron sputtering deposition. The microstructure and chemical bond evolution during film sputtering was tested using different flow rates of oxygen and argon, namely N2/O2 ratios of 1, 1.5, and 2. The obtained samples were analysed by IR spectroscopy, SEM, XPS, and XRD. In addition, the nanoindentation procedure measured the hardness and elastic modulus of each coating. Oxynitride coatings exhibit nanocrystalline structures, where the nitride and oxide phases are in the unbound state. A nitrogen-rich sample demonstrated the crystalline structure of (110)-oriented rutile with 124 nm large clusters. However, with increased oxygen gas flow, the mixed rutile-anatase (111)-oriented phase became more pronounced with fragmented grains 25–27 nm in diameter. The nanoindentation test shows that titanium oxide hardness and deformation resistance depend on its microstructure and orientation. Cell culture experiments show that a coating deposited at regime N2/O2 = 1 allows efficient cell proliferation on pristine steel and other oxynitride samples. The findings of this work benefit understanding the mechanisms of oxynitride barriers in coronary stent modification.

Integral Algorithms to Evaluate TiO2 and N-TiO2 Thin Films’ Cytocompatibility

Titanium oxide (TiO2) and oxynitride (N-TiO2) coatings can increase nitinol stents' cytocompatibility with endothelial cells. Methods of TiO2 and N-TiO2 sputtering and cytocompatibility assessments vary significantly among different research groups, making it difficult to compare results. The aim of this work was to develop an integral cytocompatibility index (ICI) and a decision tree algorithm (DTA) using the "EA.hy926 cell/TiO2 or N-TiO2 coating" model and to determine the optimal cytocompatible coating. Magnetron sputtering was performed in a reaction gas medium with various N2:O2 ratios and bias voltages. The samples' morphology was studied by scanning electron microscopy (SEM) and Raman spectroscopy. The cytocompatibility of the coatings was evaluated in terms of their cytotoxicity, adhesion, viability, and NO production. The ICI and DTA were developed to assess the cytocompatibility of the samples. Both algorithms demonstrated the best cytocompatibility for the sample sputtered at Ubias = 0 V and a gas ratio of N2:O2 = 2:1, in which the rutile phase dominated. The DTA provided more detailed information about the cytocompatibility, which depended on the sputtering mode, surface morphology, and crystalline phase. The proposed mathematical models relate the cytocompatibility and the studied physical characteristics.

Engineering High-Performance SiOx Anode Materials with a Titanium Oxynitride Coating for Lithium-Ion Batteries.

Micron-sized silicon oxide (SiOx) has been regarded as a promising anode material for new-generation lithium-ion batteries due to its high capacity and low cost. However, the distinct volume expansion during the repeated (de)lithiation process and poor conductivity can lead to structural collapse of the electrode and capacity fading. In this study, SiOx anode materials coated with TiO0.6N0.4 layers are fabricated by a facile solvothermal and thermal reduction technique. The TiO0.6N0.4 layers are homogeneously dispersed on SiOx particles and form an intimate contact. The TiO0.6N0.4 layers can enhance the conductivity and suppress volume expansion of the SiOx anode, which facilitate ion/electron transport and maintain the integrity of the overall electrode structure. The as-prepared SiOx-TiON-200 composites demonstrate a high reversible capacity of 854 mAh g-1 at 0.5 A g-1 with a mass loading of 2.0 mg cm-2 after 250 cycles. This surface modification technique could be extended to other anodes with low conductivity and large volume expansion for lithium-ion batteries.

Biocompatibility of Titanium Oxynitride Coatings Deposited by Reactive Magnetron Sputtering.

Titanium oxynitride coatings deposited by reactive magnetron sputtering improve biocompatibility of vascular stents by increasing NO production, viability, and adhesion of EA.hy926 cells. Thus, the application of titanium oxynitride coatings is a promising strategy for increasing the biocompatibility of nitinol stents.

The antibacterial properties and corrosion behavior of silver-doped niobium oxynitride coatings

It takes a long physical, psychological, and costly period to treat implant-associated infections. 316 L Stainless Steel (SS) is commonly used in orthopedic prostheses and cardiovascular implants. However, it has been reported that 316 L stainless steel corrodes due to the high chloride concentration in physiological body fluid, thus releasing metal ions such as Ni and Cr.Our previous study revealed that niobium oxynitride coatings are non-cytotoxic. In this study, 316 L SS were coated with silver (Ag)-doped niobium oxynitride to prevent surgical site infections. Next, the microstructure, morphology, hardness, and wettability of the coatings were analyzed using scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), nanoindentation, and an optical tensiometer, respectively. Then, corrosion tests were done in lactated Ringer’s solution to simulate the body environment. Its antibacterial properties were detected through the bacterial growth and spread of Staphylococcus aureus and Escherichia coli bacteria. Furthermore, the ion release from the coated and uncoated samples were evaluated through inductively coupled plasma mass spectrometry (ICP-MS).Ag-doped NbOxNy coatings have a dominant amorphous structure, and the surface roughness of the coatings increased with the addition of silver. Besides, the contact angles of the Ag-doped NbOxNy coatings decreased compared to undoped ones, thus increasing their wettability with the addition of Ag. The Ag maintained a metallic form in the coating. Ag-doped coatings demonstrated antibacterial activity toward E.coli and S.aureus bacterial strains. The antibacterial test results show that Ag-doped niobium oxynitride structures effectively reduce S. aureus, which often causes surgical site infections, and inhibit the release of Cr and Ni ions from the stainless steel into the corrosive environment.

Radiofrequency Plasma‐Assisted Pulsed Laser Deposited Pt/TiOxNy Coatings on Multi‐Walled Carbon Nanotubes as Gas Diffusion Electrodes for the Oxygen Reduction Reaction

AbstractThis study reports on the fabrication and characterization of novel multilayered electrocatalyst nanostructures for the oxygen reduction reaction (ORR). Thin titanium oxynitride (TiOxNy) coatings are deposited on a forest of multi‐walled carbon nanotubes (MWCNTs), directly grown on a stainless‐steel mesh, by capacitively coupled radiofrequency plasma‐assisted pulsed laser deposition (RF‐PAPLD) in a N2 environment. The resulting high‐surface‐area binder‐free electrode is further coated with a low quantity of well‐dispersed Pt nanoparticles (NPs) by PLD in an inert atmosphere. High‐speed imaging of the laser‐induced plasma expansion provided evidence of a higher kinetics of the expanding plume at higher RF plasma powers, changing the morphology of the TiOxNy coatings. X‐ray photoelectron spectroscopy demonstrated that the coatings are homogeneous throughout their thickness, where the TiN, TiON, and TiO bonds exist in all samples. The oxygen content of the coating increases with the RF plasma power. Both TiOxNy/MWCNT and Pt/TiOxNy/MWCNT nanostructures are tested in a gas diffusion electrode setup to evaluate their activity in the ORR. The results showed the superior activity of the Pt/TiOxNy‐0.03 Torr‐30 W/MWCNT, reaching the highest current density of 180 mA cm−2, while the commercial Pt/C electrode with the same Pt loading yielded 105 mA cm−2 at the potential of 0.5 V.

Surface modification of PLLA scaffolds via reactive magnetron sputtering in mixtures of nitrogen with noble gases for higher cell adhesion and proliferation

Despite the widespread use of bioresorbable electrospun poly-L-lactic acid scaffolds in tissue engineering, a significant drawback is the high hydrophobicity of their surface. A proper solution for this problem is the surface modification with titanium oxynitride coatings using reactive magnetron sputtering. However, this method is characterized by a low deposition rate and the difficult selection of suitable working parameters. A feasible solution to this problem is the addition of a noble gas to the working gas nitrogen, which increases the deposition rate and thus the coating thicknesses, even with gentle magnetron sputtering process parameters. In this study, the results of surface modification of poly-L-lactic acid scaffolds using direct current reactive magnetron sputtering of a titanium target in the presence of a mixture of the working gas nitrogen with one of the following noble gases: helium, neon, argon, krypton, and xenon. Due to this modification, depending on the composition of the gas mixture, a thin nitrogen-containing titanium coating forms on the scaffold surface, represented by titanium oxide and titanium oxynitrides of different stoichiometry. At the same time, the modification process does not significantly affect the morphology, crystallinity and molecular conformation of the poly-L-lactic acid scaffold backbones, while an increase in the surface wettability is observed. Another biomedical important effect of this surface modification is an observed increase in the adhesion and proliferative activity of fibroblast culture applied to the investigated poly-L-lactic acid scaffold samples. The poly-L-lactic acid scaffold samples surface-modified via direct current reactive magnetron sputtering of a titanium target in a mixture of the working gas nitrogen and the noble gas argon shows the highest number of adhered fibroblasts.

On the chemistry, photocatalytical, and corrosion behavior of co-sputtered tantalum and titanium oxynitride thin films

Direct current magnetron co-sputtered titanium and tantalum based oxynitride coatings (TaTiON) were analyzed in terms of their chemistry, surface morphology, surface energy, photocatalytic activity, and corrosion resistance. The variable parameter for the deposition was the applied current on each target, changing between 0.75A and 0.25A for the Ta target, and from 0.25A to 0.75 A for the Ti target, to obtain a total current of 1A. Reference single-sputtered samples (TaON and TiON) were deposited under identical conditions. It was observed that a higher degree of oxidation occurred in the samples deposited with higher current on the Ti target, while nitriding and oxynitriding processes occurred only on the surfaces of the films containing Ta. In terms of surface roughness, the co-sputtered coatings exhibited significantly smaller values, compared to the single-sputtered coatings. The highest photodegradation efficiency was registered for the co-sputtered sample which contains the highest N concentration. The corrosion rate, obtained from electrochemical tests, varies in a rather large domain, as function of the chemical species in the coatings.

Influence of oxygen content on structure, thermal stability, oxidation resistance, and corrosion resistance of arc evaporated (Cr, Al)N coatings

(CrxAl1-x)(OyN1-y)ε coatings with different oxygen fractions were prepared by cathodic arc evaporation through variation of injected oxygen flux, and elaborated concerning structure, mechanical properties, thermal stability, oxidation resistance, and electrochemical properties. A moderate addition of O into (Cr, Al)N coatings generates a (Cr, Al)(O, N) solid solution with a face-centered cubic structure, whereas an additional corundum-structured (Cr, Al)2O3 solid solution is formed with superfluous oxygen introduced. The addition of O effectively improves the thermal stability by retarding the formation of w-AlN as well as the dissociation of the CrN bond, allowing the oxynitride coatings to maintain higher hardness after annealing. Notably, a small fraction of O-addition (e.g. 8 or 21 at.% in non-metal sublattice) enhances significantly the resistance against oxidation to above 1100 °C by facilitating the formation of a protective Al-rich oxide scale. Further incorporation of O gives rise to a development of oxide scale with unity elemental distribution and hence results in inferior oxidation resistance. Nevertheless, the O-rich oxynitride coatings provide better protection against electrochemical corrosion while the N-rich coatings exhibit higher corrosion current as well as lower polarization resistance compared to the CrAlN coating.

Experimental Investigation of oxygen gas variation on wettability properties of chromium oxynitride coatings

In present work, the coating of chromium oxynitride were developed on substrate of glass and silica by reactive RF magnetron sputtering. Investigation of the influence of oxygen gas variation on the structural and wettability properties of chromium oxynitride thin films. The structural properties of the deposited films were studied using X-Ray diffraction (XRD) and Atomic Force Microscopy (AFM). While the wettability studies were carried out on automated goniometer to measure the contact angle of deposited films. The contact angle of deposited coatings was found to increase from 92.4° to 98.4°, when the oxygen gas flow rate was varies from 0.5 sccm to 6 sccm. The deposited films were thus found to be of hydrophobic nature.

Titanium oxide– and oxynitride–coated nitinol: Effects of surface structure and composition on interactions with endothelial cells

Titanium oxynitride (TiOxNy) coatings increase the bio- and hemocompatibility of stainless steel and Co-Cr vascular stents, possibly by directly releasing NO. Herein, to examine the applicability of this approach to nitinol (NiTi) devices, we coated NiTi samples with TiOx or TiOxNy by reactive magnetron sputtering using different reaction gas compositions and bias voltages. One side of the samples was preliminarily abraded, while the other remained in its original state. Samples morphology, composition and structure were studied by atomic force microscopy (AFM), X-ray diffraction (XRD) and field emission scanning electron microscopy (FE SEM). We investigated how various types of TiOx and TiOxNy coatings interact with EA.hy926 endothelial cells. None of the tested samples exhibited cytotoxicity, and an N2:O2 ratio of 3:1 regardless of the bias voltage was found to be optimal for NO production and cell adhesion, spreading, and viability, which was ascribed to a cumulative positive effect of the composition and nanoroughness of TiOxNy coatings formed under these conditions. Thus, the deposition of TiOxNy coatings was concluded to be a promising strategy of increasing the biocompatibility of NiTi stents.

Evaluation of in Vitro Corrosion Behavior of Titanium Oxynitride Coated Stainless Steel Stents

Coronary artery disease (CAD) affects every fifth person in the world. The gold-standard treatment for CAD is stent implantation, however, the existing therapy is not sufficient. In recent years, titanium oxynitride (TiOxNy) coatings on bare metal stents (BMSs) attracted the attention of many researchers around the world due to their promising results and improved surface properties. However, good coating adhesion and coverage of the inner surface in stent applications is still a challenging task. Moreover, enhanced corrosion resistance and durability over a longer period under the influence of an aggressive biological environment is one of the main requirements while developing novel coatings for bare-metal stents. In this work, the titanium oxynitride (TiOxNy) coated stainless steel stents were fabricated by magnetron sputtering and the corrosion behavior of coated and uncoated stents has been studied using immersion, fluid dynamic, and electrochemical corrosion tests. For the first time, the entire stent surface has been used for quantitative corrosion tests on stents. We discuss and compare the in vitro biostability and corrosion behavior of bare stainless steel (316L) and titanium oxynitride films (TiOxNy) coated stents.TiOxNy coatings provide valuable stability to the BMS against harsh environments or conditions. The coated stents are remarkably more stable when compared with the reference uncoated stents (316L BMS), regardless of the ratio of O2 and N2. The variation of stent coating parameters is still possible to get more anticorrosive and biostable behavior; therefore, the results could provide the basis for further research.

Investigating the Effects of Lithium Phosphorus Oxynitride Coating on Blended Solid Polymer Electrolytes

Solid state electrolytes are very promising to enhance the safety of lithium ion batteries. Two classes of solid electrolytes, polymer and ceramic, can be combined to yeild a hybrid electrolyte that can syngergistically combine the properties of both materials. Chemical stability, thermal stability, and high mechanical moduli of ceramaic electrolytes against dendrite penetration can be combined with the flexibility and ease of processing of polymer electrolytes. By laminating a polymer electrolyte with a ceramic electrolyte, the stability of the solid electrolyte is expected to improve against lithium metal, and the ionic conductivity could remain close to the value of the original polymer electrolyte as long as an appropriate thickness of the ceramic eletrolyte is applied. Here we report a bilayered lithium-ion conducting hybrid solid electrolyte consisting of a blended polymer electrolyte (BPE) laminated with a thin layer of the inorganic solid electrolyte lithium phosphorous oxynitride (LiPON). The hybrid system was thoroughly studied. First, we investigated the influence of polymer chain length and lithium salt ratio on the ionic conductivity of the BPE based on poly(ethylene oxide) (PEO) and poly(propylene carbonate) (PPC) with the salt lithium bis(trifluoromethanesulfonyl)imide (LiTFSI). The optimized BPE consisted of 100k molecular weight PEO, 50k molecular weight PPC, and 25(w/w) % LiTFSI, (denoted as PEO100PPC50LiTFSI25) which exhibited an ionic conductivity of 2.11x10-5 S/cm, and the ionic conductivity showed no thermal memory effects as the PEO crystallites were well distrupted by PPC and LiTFSI. Secondly, the effects of LiPON coating on the BPE were evaluated as a function of thickness down to 20 nm. The resulting bilayer structure showed an increase in the voltage window from 5.2 to 5.5V (vs Li/Li+) and thermal activation energies that approached the activation energy of the BPE when thinner LiPON layers were used, resulting in similar ionic conductivities for 30nm LiPON coatings on PEO100PPC50LiTFSI25. Coating BPEs with a thin layer of LiPON is shown to be an effective strategy to improve the long-term stability against lithium.

Niobium-oxynitride coatings for biomedical applications: Its antibacterial effects and in-vitro cytotoxicity

316L Stainless Steel (SS) has been widely used in many medical applications, such as orthopedic prostheses and cardiovascular implants due to its good mechanical properties and resistance to corrosion. Despite its superior features, SS has bio-functionality problems. In this study, niobium oxynitride coatings were deposited onto 316L SS substrates to improve their biocompatibility using a reactive radio frequency (RF) magnetron sputtering technique. The nitrogen flow was fixed, and the nitrogen to oxygen flow ratio was set to 2, 5 and 10 to investigate the effect of oxygen concentration on biocompatibility and the antibacterial behavior of the oxynitride films. The microstructure, morphology and wettability properties of the coatings were analyzed by scanning electron microscopy (SEM), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and an optical tensiometer. The antibacterial activities of coated and uncoated 316L substrates were tested against S. aureus and E. coli bacterial strains. The cytotoxic effects of NbOxNy-coated and uncoated substrates were evaluated on human fibroblast cells. The results showed that niobium oxynitride coatings were not cytotoxic and exhibited more antibacterial activity in comparison to the uncoated ones.