Unbalanced Magnetron Sputtering Technique Research Articles

Nb-doped hydrogenated diamond-like carbon coated biodiesel injectors material: Synthesis, structure and properties

Despite the economic and environmental benefits of biodiesel, it poses significant challenges, including coking on metal surface and increased wear on diesel engine injector nozzles. Therefore, this study investigates the synthesis of niobium-doped diamond-like carbon (Nb-DLC) coatings on two types of injector nozzle materials (viz. H13 steel, AISI 420 stainless steel) using the Closed-Field Unbalanced Magnetron Sputtering (CFUBMS) technique. Comprehensive characterizations, including microstructural analysis, crystal structure evaluation, hardness assessment, and tribological property assessment, were conducted. The Nb-DLC coatings demonstrated a stable friction coefficient, with values four times lower than that of the substrate materials. The present findings demonstrate significant enhancements in terms of structural composition, crystalline phase, hardness, friction coefficients, and adhesion properties due to the Nb-DLC coatings. Therefore, Nb-DLC coated materials could be the promising candidate material for biodiesel engine injector nozzle applications. This emphasizes their potential to contribute significantly to the sustainable consolidation of biodiesel within automotive engine.

Effect of deposition parameters on structural and mechanical properties of Novel h-BN doped TiCrNbN coatings

In this paper, the novel h-BN doped TiCrNbN thin films was deposited on the DIN 1.2714 steel using closed field unbalanced magnetron sputtering (CFUBMS) technique with variable working pressure, bias voltage, and LaB6 target voltage. The main goal is to determine the contribution of degrees of these parameters on structural and mechanical properties using Analysis of Variance (ANOVA). The deposition parameters were leveled based on L9 (33) orthogonal Taguchi design method. Microstructural and thickness of coatings were investigated using SEM. The coatings had granular and flawless surface properties. The thickness of the coatings was determined in the range of 874 nm and 1.69 μm. The deposition parameter that has the highest contribution to coating thickness is working pressure. Hardness and adhesion strength of coatings were determined employing nanohardness and scratch tester, respectively. The highest hardness among the coatings was 24.67 GPa, obtained with the 3x10-3 Torr working pressure, 100 V bias voltage and 600 V LaB6 target voltage parameters. The deposition parameter that has the highest contribution to hardness is working pressure. The coating conditions with the highest hardness exhibited the highest adhesion strength. The superiority of the contribution of working pressure on the adhesion strength was prominent compared to other parameters.

Combined magnetron sputtering and laser annealing process for the fabrication of proton conducting thin films

Acceptor doped barium zirconates are known for their exceptional protonic conductivity and the challenges in their fabrication. Within this work, BaZr0.8Y0.2O3-δ (BZY20) films were successfully deposited on a BaZr0.7Ce0.2Y0.1O3-δ/Ni (BZCY72/Ni) substrate using a combination of closed-field unbalanced magnetron sputtering and various annealing techniques such as conventional furnace annealing and laser annealing. Thin films could be tempered at only 800 °C with an additional laser annealing step and exhibit a heigh density as well as a sufficient protonic conductance. The highest measured ionic conductivity was 1.11*10−3 S/cm. The provided synthesis could pave the way for employing metallic supports in protonic ceramic fuel cells by using lower sintering temperatures than normally required.

The effect of different annealing temperatures on the mechanical and tribological properties of the Ti2AlN MAX phase films

Ti2AlN MAX phase films produced at different N2 flow rates and different annealing temperatures were deposited on 52100 steel substrates using the closed-field unbalanced magnetron sputtering technique. N2 flow rates were changed to 2, 3.5, and 5 sccm. Due to the increasing N2 flow rate, film thickness decreased from 2 to 1.3 µm. Then the produced films were subjected to annealing at temperatures of 700, 750, and 800°C. After the film produced at a flow rate of 2 sccm was annealed at 750°C, the presence of the Ti2AlN MAX phase was determined. The binding energies of Ti 2p, Al 2p, and N 1s determined in the XPS analysis confirmed the existence of the Ti2AlN film. The friction coefficient measured for Ti2AlN MAX phase films was calculated as 0.53, the hardness value as 22.8 GPa, the elastic modulus as 291.4 GPa, and the wear rate as 2.96 × 10−4 mm3/(N·m).

Corrosive behavior and interfacial conductivity of stampable a-C film on titanium bipolar plate in proton exchange membrane fuel cells

Titanium bipolar plates coated with amorphous carbon films are considered to combine good electrical conductivity and corrosion resistance in proton exchange membrane fuel cells. However, there is a lack of research on the post-forming surface properties of coated bipolar plates. In this study, a-C film was deposited on the surface of titanium foil using unbalanced magnetron sputtering technique. The film displayed strong adhesion and no obvious post-formation peeling. The chemical composition, interfacial conductivity, surface and cross-sectional morphology and corrosion resistance of the deposited films were all thoroughly examined. The results showed that the specimens exhibited good corrosion resistance and significantly improved interfacial conductivity under a simulated fuel cell cathode environment. In comparison to titanium substrate, the corrosion current density and contact resistance of the specimens were orders of magnitude lower, and the excellent stability of the a-C films led to almost no change in contact resistance following corrosion. Additionally, a-C film corrosion under cathodic condition was investigated. These results offer strong justification for the practical use of stampable a-C film on titanium bipolar plates in PEMFCs.

A new strategy for enhancement of structural ordering and H-diamond formation in (Mo: a-C) overcoats through substrate temperature: Microstructure, mechanical and tribological performances

In the present study, molybdenum-amorphous carbon coatings were prepared using an unbalanced magnetron sputtering technique with substrate temperatures between 0 and 200 °C. Microstructural examinations confirmed the formation of crystalline hexagonal diamond and graphite-like carbon as well as amorphous molybdenum-carbon phases. This study enabled the formation of a crystalline hexagonal diamond phase under the appropriate combination of unbalanced magnetron configuration and substrate temperature. It was concluded that a balance between sp2 domain size and the amount of crystalline hexagonal diamond phase was key to achieving coatings with hardness values of up to 36 GPa. In addition, it was found that increasing the substrate temperature decreased the coefficient of friction and wear rate of the coating.

A facile strategy to synthesis nanocrystalline H-Diamond (H-D) phase in MoCx (H-D/a-C) composite coatings using a reactive sputtering system: The role of Mo content

In the magnetron sputtering system, using an unbalanced magnetic field configuration in the cathode is a privileged strategy for designing protective coatings on metal substrates for the specific application. In the present study, A105 carbon steel substrates coated with MoC x (H-D/a-C) composite films (H-D: hexagonal diamond, a-C: amorphous carbon) utilizing an unbalanced magnetron (UBM) sputtering technique. The effects of (Mo/C+H) ratio on microstructure, mechanical and tribological characteristics of MoC x (H-D/a-C) composite coatings were investigated. MoC x (H-D/a-C) coated A105 carbon steel substrates showed enhanced mechanical and tribological performance. The Mo content strongly affected the bonding structure of MoC x (H-D/a-C) composite coatings. The results from Raman spectroscopy showed that the coatings contain a high value of sp 2 carbon bonding, and its affluence increases with increasing (Mo/C+H) ratio. For the first time, the H-Diamond phase was successfully formed in all the UBM sputtered MoC x (H-D/a-C) composite coatings, while Mo acted as a catalyst for the nucleation and growth of H-Diamond phase. The MoC x (H-D/a-C) composite coatings with more H-Diamond phase and higher Mo content showed higher hardness and plasticity index, lower coefficient of friction (COF) and wear rate. The results confirmed that MoC x (H-D/a-C) coated A105 carbon steel substrates can be potentially applied to protect the surface of the perforated spherical ball of ball valves.

ZrN-ZrOxNy vs ZrO2-ZrOxNy coatings deposited via unbalanced DC magnetron sputtering

ZrN-ZrO{ }_{x}N{ }_{y} and ZrO{ }_{2}-ZrO{ }_{x}N{ }_{y} coatings were deposited on 316L stainless steel substrates via the unbalanced DC magnetron sputtering technique in order to improve their corrosion resistance and evaluate their possible use as a coating biocompatible with bone cells. The composition, structure, morphology, and corrosion resistance were studied by sum means of x-ray photoelectron spectroscopy (XPS), x-Ray diffraction (XRD), scanning electron microscopy (SEM), and atomic force microscopy (AFM). The corrosion resistance was evaluated in 3.5 wt.% NaCl using potentiodynamic polarization (PL) and electrochemical impedance techniques (EIS). The ZrN-ZrO{ }_{x}N{ }_{y} and ZrO{ }_{2}-ZrO{ }_{x}N{ }_{y} coatings exhibited barrier-type protection of the substrate against corrosion. The growth of mouse osteoblast cells was evaluated in the coating that exhibited the greatest resistance to corrosion, ZrO{ }_{2}-ZrO{ }_{x}N{ }_{y}, finding that the cell viability was maintained, so this material can be considered to be a candidate for use in osteosynthesis processes.

TiN/NbN Nanoscale Multilayer Coatings Deposited by High Power Impulse Magnetron Sputtering to Protect Medical-Grade CoCrMo Alloys

This study describes the performance of nanoscale multilayer TiN/NbN coatings deposited on CoCrMo medical-grade alloys by utilising novel mixed high power impulse magnetron sputtering (HIPIMS) and direct current unbalanced magnetron sputtering (UBM) technique in an industrial size vacuum coater. Scanning electron microscopy analysis showed that these coatings were extremely dense without any intercolumnar voids. The coating exhibited high hardness of 28 GPa, as well as low friction and wear coefficient of 0.7 and 1.4 × 10−14 m3·N−1·m−1, respectively, as compared to the bare material. Scratch tests revealed superior coating to substrate adhesion due to the HIPIMS etching prior to coating deposition. Energy-dispersive X-ray analysis of the wear debris generated during the impact test together with focused ion beam cross-section analysis in different locations of the impact crater revealed the coating failure mechanism and further confirmed the excellent coating to substrate bonding strength. Potentiodynamic polarisation tests in NaCl and Hank’s solutions revealed the clear passivation behaviour, several orders of magnitude lower corrosion currents, and high pitting potentials of the coating, which guarantee excellent protection to the base alloy in such aggressive environments. Inductively coupled plasma mass spectrometry analysis of Hank’s solution containing corrosion debris of the coated sample revealed that the leaching of harmful metal ions from the base material was reduced to below the detection limit of the technique, thus demonstrating the high barrier properties of the coating.

Accidental damaged diamond-like carbon coating by prefabricated scratches: Experimental exploration on anticorrosion and tribological performances

Accidental damage on the diamond-like carbon (DLC) coating can have a great influence on the anticorrosion and tribological performances. In this study, DLC coating was deposited by a DC unbalanced magnetron sputtering technique. The scratch tests with different damage loads of 2, 10, 20, 30, 40 and 50 N were used to imitate the different types of accidental damage. The influence of different types of surface damage states on anticorrosion performance and scratch damage structures on tribological performance were studied and compared with those of the coating without damage. Cracking or spalling of the coating promotes the corrosion failure of the coating system and pitting corrosion of the stainless steel substrate, resulting in the deterioration of the corrosion protection effectiveness. With the damage increases from fine crack to complete failure, the corrosion resistance decrease obviously and the corrosion rate increases from 1.796 × 10−9 to 2.880 × 10−8 (A/cm2). The coating with an appropriate scratch structure as the sample S2 (scratch width of 0.012 mm and the ratio of the scratch width to the contact width is 0.033) can effectively avoid the softening of the coating surface caused by graphitization and collect the wear debris particles, resulting in the excellent tribological behaviors with the lowest wear rate of 1.848 × 10−16 m3/(N·m).

Investigating the structure, adhesion and tribological properties of Al and Zr-doped TiN coatings with various substrate bias voltage and working pressure

In this study, TiAlZrN films were coated on the hardened 1.2344 (X 40 CrMoV 5 1) steels using DC power supplied closed field unbalanced magnetron sputtering (CFUBMS) technique. Structural investigations of coatings were carried out using scanning electron microscope and X-ray diffraction. The thickness of coatings was measured from the cross-sectional scanning electron microscope images, and the grain size value and residual stress were calculated by using X-ray diffraction data in the Scherrer formula. Nano indentation method was used to investigate the surface hardness for reducing the substrate effect due to very thin coating thickness (∼2–3 µm). Scratch test was performed for determining the adhesion strength of the coatings. As a tribo-test, a ball-on-disk system was used. From the results, it was understood why TiAlZrN coatings were attractive. The highest hardness was observed as 50.67 GPa, and the highest scratch resistance was reached to 56 N. Also, it was determined that the coating having the highest tribological properties (5.46 × 10−5 mm3/Nm) increased the wear resistance of the substrate six times (3.06 × 10−4 mm3/Nm).

Quantification of the Effects of Coating Parameters on the Properties of TiAlZrN Coatings

In this study, TiAlZrN layer was coated on AISI H13 substrate surface with variable substrate bias voltage, Zr target current, and ambient pressure deposition parameters by using closed field unbalanced magnetron sputtering (CFUBMS) technique. The main goal of this paper is to determine the effect percentages of these variable parameters on the properties of TiAlZrN coatings by Analysis of Variance (ANOVA). These coating properties include average grain size, thickness, hardness, adhesion strength and wear resistance. The numerical data obtained as a result of this study will shed light on the select of parameters which have a direct effect on coatings to the researchers who will work on this topic. The parameters used as variables in the deposition process were leveled with Taguchi experimental (33) design method. Average grain size and thickness of coatings were established by SEM images. The average grain sizes of coatings were between 290 and 440 nm and the most effective parameter was substrate bias voltage with 58.4 %. The hardness, adhesion strength and wear properties of the coatings were determined using micro hardness tester, scratch test and ball on disc wear device respectively. The maximum hardness of coatings was 1674 HV, while the wear resistance was increased by 37 times compared to the substrate material. The maximum adhesion strength value of the coatings was reached 56N. The superiority of the effect of substrate bias voltage on the hardness, adhesion strength and wear resistance of the coatings compared to other deposition parameters was again prominent (respectively 86.15%, 53.63% and 70.86%). Also, the hardness and wear resistance properties were found to be directly related to each other. The sample with the highest coating hardness also showed the highest wear resistance performance. In the sample with the lowest hardness, this situation found to be similar.

Surface blistering in ZrSiN nanocomposite films irradiated with He ions

In the present work, the influence of silicon content on the surface blistering of ZrSiN nanocomposite films after He ion irradiation (energy of 30 keV and doses up to 8 × 1016 cm−2) and post-radiation annealing at the temperature of 600 °C was investigated. Using SEM, TEM and AFM methods, the influence of amorphous/crystalline boundaries on the formation of blisters in the n-ZrN/a-Si3N4 nanocomposites was studied. ZrSiN nanocomposite films (~300 nm thick) were deposited at 600 °C onto (001) Si wafers by reactive unbalanced magnetron sputtering technique. Silicon concentration was varied from 7.1 to 23.1 at.%. While helium ion irradiation (at the dose of 8 × 1016 cm−2) did not change the surface morphology of the nanocomposite films, the alteration of the surface was observed after vacuum annealing. It was revealed that post-radiation annealing (600 °C) of ZrN and Si3N4 mononitride films resulted in surface blistering at the dose of 5 × 1016 cm−2. Rather low blister density (0.017 μm−2) after post-radiation annealing at the dose of 5 × 1016 cm−2 was also observed for the nanocomposite film with 7.1 at.% Si content. As the irradiation dose increased up to 8 × 1016 cm−2, the surface density of blisters raised significantly (0.53 μm−2). It was found that increasing of Si concentration in the nanocomposite films was beneficial for their radiation resistance. The ZrSiN nanocomposite film with maximum Si content of 23.1 at.% was the most stable, with no sign of surface blistering being detected.

Structure evolution and stress transition in diamond-like carbon films by glancing angle deposition

In this article the diamond-like carbon films have been prepared by the strategy of the glancing angle deposition using unbalanced magnetron sputtering technique. It is found that the structure and the residual stress of the films are strongly dependent on the deposition angle. Of particular interest is that the stress of the films significantly transforms from compressive to tensile state as a function of the deposition angle, which is attributed to the result of the competition and mediation between compressive stress due to surface capillary forces of the island surface and tensile stress due to the coalescence of the islands during Volmer-Weber growth of the films. Based on this mechanism, the nearly stress-free film with desirable performance can be prepared at the proper deposition angle. The correlation between the residual stress and the atomic-bond structure also reveals that the stress transition is not only related to the sp2-bonded carbon content, but also closely to the changes of the heptatomic and pentatonic rings in the carbon network. This work demonstrated herein will provide a promising route to prepare the stress-free diamond-like carbon films with desirable performance.

Characterization of the structure and electrochemical behavior of Ag-TaN nanostructured composite coating for biomedical applications

This work presents the development of a new Ta/TaN/TaN-Ag/TaN (hereinafter referred as Ag-TaN) multilayer coating system deposited by unbalanced magnetron sputtering technique on AISI 316L steel. The microstructure and electrochemical behavior of the coating in relation to the bias voltage (−30 V and −120 V) applied during the formation of the upper layer of TaN were studied. It was found that the structure, mechanical properties and silver release depend on the bias voltage applied, as this affects the degree of densification of the TaN diffusion layer. The multilayer coating exhibited high values for mechanical properties due, among other factors, to the obtained nanometric structure obtained and to the stress relief caused by the minimization of the defects, whereas doping with silver nanoclusters reduced the hardness of the coating. The Ag-TaN coatings presented superior electrochemical activity to the steel substrate and the TaN matrix coating, and consequently exhibited greater corrosion current densities. This behavior is correlated mainly with the dissolution of silver to the surrounding medium. The Ag-TaN(−30 V) composite coating provided the best mechanical properties and highest electrochemical activity and silver release, the last of these with maximum values of 0.23 μg/mL, lower than those reported as cytotoxic, making this multilayer useful for biomedical applications.

A study for anticorrosion and tribological behaviors of thin/thick diamond-like carbon films in seawater

The thin and thick diamond-like carbon (DLC) films were prepared by unbalanced magnetron sputtering technique on 304L stainless steels and (100) silicon wafers. Microstructure, mechanical, corrosion and tribological properties were systematically investigated by SEM, Raman, nanoindenter, scratch tester, modulab electrochemical workstation and R-tec multifunctional tribological tester. Results showed that the adhesion force presented a descending trend with the growth in soaking time. The adhesion force of the thin DLC film with high residual compressive stress (−3.72 GPa) was higher than that of the thick DLC film (−2.96 GPa). During the corrosion test, the thick DLC film showed a higher impendence and a lower corrosion current density than the thin DLC film, which is attributed to the barrier action of large thickness. Compared to bare 304L substrate, the friction coefficients and wear rates of DLC films in seawater were obviously decreased. Meanwhile, the thin DLC film with ideal residual compressive stress, super adhesion force and good plastic deformation resistance revealed an excellent anti-wear ability in seawater.

Cellulose Fiber-Based Hierarchical Porous Bismuth Telluride for High-Performance Flexible and Tailorable Thermoelectrics.

Porous modification is a general approach to endowing the rigid inorganic thermoelectric (TE) materials with considerable flexibility, however, by which the TE performances are severely sacrificed. Thus, there remains an ongoing struggle against the trade-off between TE properties and flexibility. Herein, we develop a novel strategy to combine Bi2Te3 thick film with ubiquitous cellulose fibers (CFs) via an unbalanced magnetron sputtering technique. Owing to the nano-micro hierarchical porous structures and the excellent resistance to crack propagation of the Bi2Te3/CF architectures, the obtained sample with a nominal Bi2Te3 deposition thickness of tens of micrometers exhibits excellent mechanically reliable flexibility, of which the bending deformation radius could be as small as a few millimeters. Furthermore, the Bi2Te3/CF with rational internal resistance and tailorable shapes and dimensions are successfully fabricated for practical use in TE devices. Enhanced Seebeck coefficients are observed in the Bi2Te3/CF as compared to the dense Bi2Te3 films, and the lattice thermal conductivity is remarkably reduced due to the strong phonon scattering effect. As a result, the TE figure of merit, ZT, is achieved as high as ∼0.38 at 473 K, which competes with the best flexible TEs and can be further improved by optimizing the carrier concentrations. We believe this developed technique not only opens up a new window to engineer flexible TE materials for practical applications but also promotes the robust development of the fields, such as paper-based flexible electronics and thin-film electronics.

Minimizing the Adhesion Effects in Food Packages Forming by the Use of Advanced Coatings

The metal packaging industry used for food application has undergone drastic changes in the demands of its final consumers. The raw material for these packages, is a low carbon steel coated with a thin layer of tin (2,0 g/m2), also known as tinplate. The stamping process of these packages occurs at room temperature and is critically influenced by the tin transfer from the steel surface to the tool surface, mainly due to the tin softness. This problem is easily solved using lubrification but the purpose of this study will be the reduction or even absence of lubricants during the process in order to comply with costumers’ requirements. A successful way to minimize the consumption of lubricants is to use tools which are coated with PVD (Physical Vapour Deposition) advanced coatings deposited with unbalanced magnetron sputtering technique. Thin WC (Tungsten Carbide) and CrCN (Chromium Carbonitride) coatings were deposited using PVD on tool stamping steel – AISI D2. Block on ring tribological tests were performed on the coatings against tinplate counterface in order to investigate their wear performance, with particular emphasis on the material transfer (tin) phenomena during the sliding tests. The results allowed for selecting the best coating tested with a view to avoid the tin adhesion to the die.

Study of the mechanical properties of Ti-and Cr-based multicomponent hard coatings

TiCrAlN and CrTiAlN multicomponent coatings have been developed using closed-field unbalanced magnetron sputtering technique (CFUBMS) in a gas mixture of Ar + N2. The nitrogen level was varied by using the feedback control of plasma optical emission monitor (OEM). An investigation into the effect of the CFUBMS process parameters on the properties of the coatings was undertaken. The main coatings parameters such as thickness, surface morphology, nanohardness, strength of adhesion and wear resistance were studied by means of ball-cratering method, atomic force microscopy, scanning electron microscopy, scratch tests and nanoindentation measurements. The study revealed strong dependency of the mechanical properties on the nitrogen flow rate. Analysis of the experimental results showed that Cr-based multicomponent coatings possess better mechanical properties than Ti-based coatings at a nitrogen flow rate of 21 sccm: higher value of hardness (≤ 31GPa) and higher scratch resistance (> 30 N).

Improved wear resistance at high contact stresses of hydrogen-free diamond-like carbon coatings by carbon/carbon multilayer architecture

Diamond-like carbon (DLC) coatings are widely used in tribological applications because it can provide high hardness and low friction coefficient. However, hydrogen-free DLC coatings tend to fracture and delaminate where high contact stresses (>1 GPa) are required. We proposed that the carbon/carbon (C/C) multilayer may have the potential for tribological applications under high contact stresses. In this study, C/C multilayer coatings consisting of alternate soft-layer and hard-layer were deposited using unbalanced magnetron sputtering technique. The effect of multilayer architecture (the ratio of hard-layer to soft-layer and bilayer thickness) on tribological behavior was investigated. The tribological performance at different high contact stresses (1.82 GPa, 2.30 GPa, 2.89 GPa and 3.65 GPa) was evaluated by a ball-on-disc tribometer. The C/C multilayer coatings can withstand the maximum contact stress of ∼3.65 GPa with low wear rate. In contrast, the single layer hard DLC failed when the stress is higher than 2.30 GPa. The 50% hard multilayer with 61 nm bilayer thickness shows the best overall wear resistance, especially at a stress of 3.65 GPa. The wear rate of our C/C multilayer (∼10−8 mm3/Nm) is 10 times lower than that of DLC coatings (∼10−7 mm3/Nm) from the current literature. The excellent wear resistance of the multilayer DLC can be explained by the combination of good toughness and the lubrication effect of the transfer layer. Such C/C multilayer structure offers an alternative to deposit DLC coatings for high stress applications without introducing other elements.