Closed-field Unbalanced Magnetron Sputtering System Research Articles

Application of honeycomb pattern to Ti2AlN MAX phase films by plasma etching

The honeycomb pattern possesses a distinctive hexagonal structure capable of seamless repetition on a flat surface, leaving no gaps. Moreover, all arm thicknesses and angles are equal to one another. This remarkable configuration is deemed biomimetic, with numerous examples found in nature. Notably, it exhibits remarkably low density and exceptional mechanical strength. MAX phase films have gathered significant attention due to their exceptional capacity to amalgamate the essential properties of both metals and ceramics. Additionally, they possess the unique ability to effectively mend surface cracks that may arise as a result of friction-wear, restoring the material to a certain degree of integrity. In this study, Ti2AlN MAX phase thin films were deposited on M2 steel substrates by a closed field unbalanced magnetron sputtering system (CFUBMS). 750 °C heat treatment was applied to obtain the produced films in crystalline form. In addition, plasma etching parameters suitable for the phase structure of the deposited film were determined. With the inductive coupling plasma etching (ICP) process, the honeycomb pattern was given to the Ti2AlN MAX phase films with a continuous and smooth geometry at a depth of 2 μm. This study gives ideas for the development of multi-coating systems in which patterns of different geometries are included in a single layer.

Pulsed-dc bias magnetron sputtered TiB2 ceramic coating

Titanium diboride, TiB2, is well known as a ceramic material with a hexagonal structure which presents various attractive properties, such as high hardness and excellent corrosion, thermal oxidation, and wear resistance. However, one drawback of TiB2 coatings is their poor adhesion to substrate materials due to high compressive residual stress after deposition. The present study aimed to assess whether a PVD-TiB2 coating with both high hardness and sufficiently good adhesion to the substrate and good wear properties can be developed by a closed-field unbalanced magnetron sputtering system using pulsed-dc biasing. The TiB2 coating deposited on AISI M2 steel substrates was characterized in terms of the structural, mechanical and tribological property. From the experimental results, it can be concluded that a closed-field unbalanced magnetron sputtering system using pulsed-dc biasing can be used to produce a TiB2 coating with sufficiently good adhesion (82 N), and high hardness (2300 HK0.01), and low friction (0.34) under given deposition conditions. The deposition conditions, particularly substrate biasing and rotation, which inhibited the formation of (001) orientation, played a role in the coating's lack of superhardness.

Effect of Nb and V doped elements on the mechanical and tribological properties of CrYN coatings

One of the most promising approaches to enhancing the tribological properties of engineering coatings is to add transition elements to the structure. In this study, Nb-doped CrYN and V-doped CrYN thin films were deposited by pulsed DC reactive sputtering in a closed-field unbalanced magnetron sputtering (CFUBMS) system. The deposition parameters examined were target current (1, 1.5 and 2 A), deposition pressure (0.15, 0.25 and 0.35 Pa), pulse frequency (100, 200 and 350 kHz) and duty cycle (85 %, 70 % and 50 %). A Taguchi L9 orthogonal design was used to define the deposition process parameters for each doped film. The Nb and V-doped CrYN thin films were characterized in terms of their microstructure, thickness, composition, hardness and tribological properties by X-ray diffraction (XRD), scanning electron microscopy (SEM), Energy dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), nanohardness and pin-on-disc testing, respectively. The bond strength between the substrate and the films (adhesion) was analyzed by scratch testing. For the Nb-doped thin films, a maximum hardness value of 21.4 GPa and the lowest friction coefficient of 0.36 were obtained. On the other hand, in the V-doped thin films, the maximum hardness value was 16.1 GPa, while the lowest friction coefficient obtained was 0.11. In addition, Nb-doped and V-doped CrYN thin films exhibited extraordinary adhesion properties. The effect of the selected deposition parameters (target current, pulse frequency, and duty cycle) in relation to the film thickness, hardness, and coefficient of friction properties of the Nb and V-doped CrYN thin films were investigated using the Taguchi approach and optimum operating conditions were identified and confirmed.

High-Temperature Oxidation Behaviour of CrSi Coatings on 316 Austenitic Stainless Steel.

In this study, a closed-field unbalanced magnetron sputtering system, which is environmentally friendly and has high deposition efficiency, was used to deposit CrSi coatings on 316 austenitic stainless steel. This system utilised separate Cr and Si targets, and the appropriate content of Cr and Si of the coatings was adjusted by changing the currents applied to the targets. A series of CrSi coatings with different Si/Cr ratios were produced, and their oxidation behaviour at elevated temperatures was investigated. By analysing the weight gain, surface morphology and microstructure, composition and phase constituents, the oxidation behaviour at 600 °C, 700 °C and 800 °C was investigated and the optimized coating to protect the stainless steel has been identified. The outcome of the research indicated that a small amount of Si (between 4-7 at.%) in Cr coatings is effective in protecting the austenitic stainless steel against oxidation at high temperatures, while a high Si content (around 10 at.% or more) makes the coating more brittle and prone to cracking or delamination during oxidation at 800 °C.

Comprehensive effect of grain size and original target morphology on sputtering behavior of magnetron sputtering target

In this paper, the etching morphology, surface roughness, target voltage, and light emission line intensity of the copper target were investigated using a closed-field unbalanced magnetron sputtering system equipped with optical emission spectroscopy monitor (OEM). The results show that the morphology of the sputtering zone, the target voltage value, the surface roughness, and the OEM value are significantly correlated with the grain size of the target. After sputtering, the original target's morphology dramatically influences the surface roughness and OEM value.

Effect of helium incorporation on plasma parameters and characteristic properties of hydrogen free carbon films deposited using DC magnetron sputtering

The present work investigates the effects of helium (He) gas mixing with Ar on plasma parameters and examines its effect on film properties of C films. We used a closed-field unbalanced magnetron sputtering system for the deposition of C thin films at a direct current power density of 30 W/cm2 and an operating pressure of ≈3 mTorr. On the basis of systematic analysis, we present an attempt to enhance the electron temperature and investigate the high-energy electron tail, which is required for the efficient ionization in the plasmas, by incorporating He gas in the Ar background. This approach also promotes the plasma density to become high, which is more than two times at a mixing ratio of 80%. Moreover, the present study utilizes these plasma conditions to prepare hydrogen-free highly conductive nanostructured carbon films. Systematic plasma diagnostic and film analysis reveal that a high content of He incorporation is accountable for the fabrication of a highly conductive nanocrystalline carbon film in a high-density plasma environment.

Erosion and Abrasion Resistance, Mechanical Properties, and Structure of the TiN, Ti–Cr–Al–N and Cr–Al–Ti–N Coatings Deposited by CFUBMS

The results of structural studies and mechanical, abrasion, and erosion tests of single-layer and multi-layer TiN, Ti–Cr–Al–N, and Cr–Al–Ti–N coatings deposited on a closed-field unbalanced magnetron sputtering (CFUBMS) system using the ion-plasma technique are reported. It is demonstrated that, despite their low level of hardness (17–18 GPa versus 40 GPa for TiN), Ti–Cr–Al–N and Cr–Al–Ti–N coatings are superior to single-layer titanium nitride coatings in terms of their abrasive wear resistance and erosion resistance due to their structural features.

Effect of gas mixing ratio on structural characteristics of titanium dioxide nanostructures synthesized by DC reactive magnetron sputtering

In this work, high-quality and highly pure titanium dioxide nanostructures were synthesized by a homemade dc closed-field unbalanced reactive magnetron sputtering system. The operation parameters of the magnetron sputtering system were optimized to prepare TiO2 nanostructures as thin films on glass substrates. These nanostructures were characterized by x-ray diffraction, atomic force microscopy and Fourier-transform infrared spectroscopy. Both anatase and rutile phases were identified. The mixing ratio of argon and oxygen (Ar:O2) gases was found very important to control the structural characteristics of the prepared nanostructures.

Effect of load and sliding speed on the tribological properties of graphite-like carbon film under different aqueous environments

Closed field unbalanced magnetron sputtering system (CFUBM) was employed to prepare graphite-like carbon (GLC) film during deposition process. Structure and morphology of GLC film were measured by Raman spectrum and atomic force microscopy (AFM). Friction and wear properties of GLC film in different test conditions (applied load, sliding frequency, aqueous environment) were evaluated through multifunctional tribometer. The morphology of wear track was investigated by optical microscopy. Results indicated that the GLC film owned vast amounts of sp2-bonding clusters and displayed a flat surface. By friction and wear test, the GLC film presented relatively low COF and wear rate. Meanwhile, the applied load, sliding frequency and aqueous environment were crucial factors to influence the friction and wear behaviors of GLC film. Combined with the Hertzian contact theory, the micro-meshing regime might rationally explain the tribological mechanism of GLC film in this work.

Investigation of high temperature wear resistance of TiCrAlCN/TiAlN multilayer coatings over M2 steel

In this study, TiCrAlCN/TiAlN multilayer coatings were deposited on M2 high speed steel substrates by the Closed-Field Unbalanced Magnetron Sputtering system. The chemical composition, microstructure, morphology, mechanical and high temperature wear resistance properties of the coatings were characterized, analyzed and compared to the substrate. The high temperature wear tests were carried out under a load of 2 N at the lap (wear test distance) of 50 m and in dry sliding condition at Room Temperature (RT), 150, 300, 450, and 600 °C on atmospheric conditions. It has been found that the TiCrAlCN/TiAlN multilayer coatings have a higher wear resistance than the M2 substrate. The stable friction behavior and low friction tendency was determined at 600 °C. When the test temperature increased, the wear rates decreased. Narrow and smooth wear tracks and also the lowest wear rate were obtained at 600 °C.

Tribological Behaviour of Ti:Ta-DLC Films Under Different Tribo-Test Conditions

Diamond-like carbon (DLC) films are suitable applicants for cutting tools due to their high hardness, low friction coefficient and wear rate. Doping metals in DLC films have been improved its tribological properties. In this study, titanium and tantalum doped hydrogenated DLC films were deposited by closed-field unbalanced magnetron sputtering system onto M2 high speed steels in Ar/N2/C2H2 atmosphere. The friction and wear properties of Ti:Ta-DLC film were investigated under different tribo-test conditions including in atmospheric pressure, distilled water, commercial oil and Ar atmosphere. The coated specimens were characterized by SEM and X-ray diffraction techniques. The bonding state of C-C (sp3) and C=C (sp2) were obtained with XPS. The tribological properties of Ti:Ta-DLC were investigated with pin-on-disc wear test. Hardness measurements performed by micro-indentation. Our results suggest that Ti:Ta-doped DLC film shows very dense columnar microstructure, high hardness (38.2 GPa) with low CoF (µ≈0.02) and high wear resistance (0.5E-6 mm3/Nm).

Effects of Duplex Nitriding and TiN Coating Treatment on Wear Resistance, Corrosion Resistance and Biocompatibility of Ti6Al4V Alloy

Ti6Al4V alloy substrates were nitrided at 900 °C. TiN coatings were then deposited on the nitrided substrates using a closed-field unbalanced magnetron sputtering system. The microstructure, hardness and adhesion properties of the TiN-N-Ti6Al4V substrates were evaluated and compared with those of an untreated Ti6Al4V sample, a nitrided Ti6Al4V sample and a TiN-coated Ti6Al4V sample, respectively. The tribological properties of the various samples were investigated by means of reciprocating sliding wear tests performed in 0.9 wt.% NaCl solution against 316L, Si3N4 and Ti6Al4V balls, respectively. In addition, the corrosion resistance was evaluated using potentiodynamic polarization tests. Finally, the biocompatibility of the samples was investigated by observing the attachment and growth of purified mouse leukemic monocyte/macrophage cells (Raw 264.7) on the sample surface after culturing periods of 24, 72 and 120 h, respectively. Overall, the results showed that the duplex nitriding/TiN coating treatment significantly improved the tribological, anti-corrosion and biocompatibility properties of the original Ti6Al4V alloy.

Effect of deposition method on tribological performance and corrosion resistance characteristics of CrxN coatings deposited by physical vapor deposition

CrxN thin film coatings are technologically attractive due to their desirable wear and corrosion resistance attributes. However, the tribological and corrosion performances of these coatings greatly depend upon their material properties and deposition processes. Environmental regulations concerning electro-deposited and electro-less chromium have motivated the development of PVD CrxN coatings as a replacement for electroplated hard chrome. In this study, two types of PVD processes were used to apply the CrxN coatings on bearing grade AISI 52100 steel specimens: a closed-field unbalanced magnetron sputtering system (CFUMS) and an ion beam assisted e-beam deposition (IBAD) system. Tribological performances of coated specimens were evaluated under boundary layer lubrication in sliding contact tribometers, and corrosion resistance properties were determined by Electrochemical Impedance Spectroscopy (EIS) and salt spray (ASTM B117) tests. CFUMS deposited CrxN coating provided superior corrosion protection to the substrate in both salt spray and EIS testing, whereas IBAD deposited CrxN outperformed CFUMS CrxN coating in the tribological tests.

Effect of deposition method on the RCF performance of Cr x N thin film ball coatings

Abstract Cr x N thin films are of interest due to their wear and corrosion-resistant attributes. However, the tribological and functional performance of these coatings greatly depends upon their material properties and deposition processes. In this study, the tribological and functional performance of Cr x N coatings on AISI 52100 spherical rolling elements were evaluated. Two types of deposition processes were used to apply the coatings: a closed-field unbalanced magnetron sputtering system (CFUMS) and an ion beam assisted e-beam deposition (IBAD) system. Whereas the mechanical and compositional properties of the coatings obtained from the two deposition processes were found to be similar, the topographical and microstructural properties of the coatings differed. The tribological performance of the coated specimens was evaluated under boundary layer lubrication in a rolling (three ball-on-rod) contact tribometer, and the functional performance of these coatings on spherical rolling elements was examined in thrust ball bearings. The L 5 0 fatigue life of M50 rods paired with IBAD-coated balls was four times greater than that obtained with the 52100 balls. Significantly, the L 5 0 fatigue life of the M50 rods paired with the IBAD-coated balls was comparable to the fatigue life of M50 rods when paired with high-quality ceramic (Si 3 N 4 ) balls. Finally, bearings with IBAD-coated balls were observed to operate with lower torque than those with CFUMS-coated balls.

Effect of Diamond-Like Carbon Coatings on Ball Bearing Performance in Normal, Oil-Starved, and Debris-Damaged Conditions

ABSTRACTIn this study, a process was developed to deposit wear-resistant metal-doped diamond-like amorphous hydrocarbon and carbon coatings onto spherical rolling elements. Nanocomposite WC/a-C:H, TiC/a-C, and Ti/a-C:H coatings were applied in a closed-field unbalanced magnetron sputtering system and their mechanical, compositional, and microstructural properties were examined. The ability of the coated spherical rolling elements to affect bearing performance in normal, oil-starved, and debris-damaged conditions was evaluated in thrust bearing tests. WC/a-C:H-coated spherical rolling elements (balls) exhibit the ability to improve bearing performance in normal, oil-starved, and debris-damaged conditions.

CHARACTERISTICS OF TiNi THIN FILMS DEPOSITED BY MAGNETRON SPUTTERING SYSTEM WITH OPTICAL EMISSION SPECTROSCOPY MONITOR

TiNi composite thin films were fabricated using a closed-field unbalanced magnetron sputtering system equipped with optical emission spectroscopy monitor (OEM). The thin films were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), and nanoindentation. Results show that the TiNi films are amorphous, and their composition varies approximately linearly with the OEM value. Thus, the film composition could be controlled by in situ real-time OEM. The structure of the single B2 parent phase was observed in the annealed TiNi film. The hardness and elastic modulus of the films increased because of the precipitation of the Ti 3 Ni 4 phase in the single B2 parent phase.

The tribological properties of Zr/a-C:Zr/Zr-C:H-x films with various pulsed-direct current power frequency sliding against various normal loading

In this research, Zr/a-C:Zr/Zr-C:H-x films with various pulsed-direct current power frequency in the range of 30–110 kHz (x in the term Zr-C:H-x is the pulse frequencies in the deposition process) are deposited on AISI M2 substrates by a closed-field unbalanced magnetron sputtering system. The tribological properties of the films are investigated under rod-on-disc line contact wear modes using a reciprocating tribometer. The tribological behaviour of various wear pairs is discussed based on hardness (H), elastic modulus (E), adhesion property, initial Hertzian pressure and transformed layer on various contact surfaces of wear pairs. The experimental results display that the Zr-C:H-70 film with the maximum hardness and plastic deformation resistance (H3/E2) exhibits excellent tribological properties under line contact wear mode.

Microstructure and tribo-mechanical properties of Ti–B–C nanocomposite films prepared by magnetron sputtering

Ti–B–C nanocomposite films synthesized by magnetron sputtering are systematically studied with respect to the effect of composition and structure on their tribo-mechanical properties. The Ti–B–C films were deposited using a pilot-scale closed-field unbalanced magnetron sputtering system equipped with one graphite target, one TiB2 target, and two boron targets. The microstructure of the Ti–B–C films is represented by TiB2 nanocrystallites embedded in an amorphous boron carbide matrix. The film hardness varies in the range from 33 to 42GPa in relation to the composition and microstructure. The change in the mechanical properties depends upon the nanostructure, particularly the concentration and size of the TiB2 nanocrystallites in the amorphous boron carbide matrix. The tribological properties are closely related to the surface chemical states of the films. The lowest friction coefficient of 0.37 and the lowest wear rate of 3.3×10−6mm3/Nm are obtained for the Ti–B–C film with the highest titanium content, due to the formation of an oxide layer developed in the wear track. This layer acts as a solid lubricant during the tribological solicitation. The corrosion resistance of the M2 steel substrate is significantly enhanced by applying the Ti–B–C films, yielding a reduction of the corrosion current density by two orders of magnitude.

Controlling conductivity of carbon film for L-929 cell biocompatibility using magnetron sputtering plasmas.

As a material of current interest compatible with many living organisms, carbon has received considerable attention for applications in medicine. To improve and investigate the performance and applications of diamond-like carbon (DLC) films for implantable bio-organs, it is important to optimize the synthesis process from the original deposition conditions to control the characterization of DLC. Simultaneously, it is necessary to develop new techniques and processes that yield DLC films with stronger adhesion to the substrate and better biocompatibility. This work investigates the suitability of sputtering plasmas for application of carbon film biocompatibility in cell growth. This work also reports an approach to the study of the biomedical response of the well-characterized carbon films deposited by a DC unbalanced magnetron sputtering system (UBMS). Conductive carbon films are prepared at a working pressure of 3 mTorr, and their properties are studied under different operating conditions by varying the target power density. In the present work, we have used L-929 cells as the biomaterial. The influence of L-929 cells on the carbon films fabricated using closed field UBMS is studied. The data reveal that the change in L-929 cell growth with 1-5 day's proliferation is caused by the decreasing electrical resistivity with increasing sp2 bonding structure.

Tailoring the mechanical and tribological properties of sputtered boron carbide films via the B1 − xCx composition

Boron carbide films are very attractive due to their high hardness and interesting tribological properties. In the present work, the compositional effect of boron carbide B1−xCx (0<x<1) films is systematically studied to tailor mechanical, tribological and corrosion properties of the films. The B1−xCx layers were deposited on Si (100) and M2 high speed steel substrates using a pilot-scale closed-field unbalanced magnetron sputtering system equipped with one graphite and two boron targets. Different compositions were obtained by tuning the electrical power applied to the graphite target. The hardness of the B1−xCx films decreases from 28 to 20GPa as the carbon content [C] rises from 19 to 56at.%, but thereafter it increases again up to ~25GPa when [C] reaches 76at.%. The hardness variation is explained by changes in the film microstructure, namely formation of either a nanocrystalline boron carbide in the case of boron-rich films, or boron carbide nanocrystals dispersed in an amorphous boron carbide/a-C matrix in the case of carbon-rich films as deduced from the combined XPS, micro-Raman and XRD measurements. The friction coefficient of the B1−xCx films reduces from 0.66 to 0.13, and the wear rate against alumina ball drops from 6.4×10−5mm3/Nm to 1.3×10−7mm3/Nm with increasing the [C]. Raman analyses indicate that improvement of the tribological properties of the B1−xCx films is primarily caused by the presence of the amorphous carbon phase that leads to the formation of a graphitic tribolayer acting as a solid lubricant during the wear process. Deposition of the B0.81C0.19 film with high hardness (28GPa) improves the corrosion resistance of the M2 steel substrate by four orders of magnitude, documented by the decrease of the corrosion current from 3×10−6A/cm2 to 8×10−10A/cm2. We demonstrate that adjustment of the x-portion in the B1−xCx system allows one to tailor the tribo-mechanical properties over a large range from high hardness/high friction to high hardness/low friction structures.