Magnetron Sputtering Ion Plating System Research Articles

The corrosion behavior and mechanical properties of CrN/Ni[sbnd]P multilayer coated mild steel as bipolar plates for proton exchange membrane fuel cells

This research mainly studies on the interfacial conductivity and corrosion resistance of mild steel (MS)/electroless plating nickel (EN)/CrN composite coating. The MS/EN/CrN composite coating is deposited on a mild steel substrate using a combination of electroless nickel plating process and closed field unbalanced magnetron sputter ion plating system. The simulative working environment of proton exchange membrane fuel cell (PEMFC) is implemented to test the electrical and corrosion properties of uncoated mild steel and coated samples. Results show that the performance of the MS/EN/CrN coated samples was greatly improved. The SEM results indicate that the surface of MS/EN/CrN is dense and smooth. CrN (111) and Ni (111) are observed in the MS/EN/CrN coating by XRD. The potentiodynamic polarization and EIS tests show that the incorporation of electroless nickel deposits into the CrN coating can provide better corrosion resistance. Potentiostatic polarization tests reveal that MS/EN/CrN coating has the lowest current density both in anodic and cathodic environment. The Interfacial contact resistance (ICR) results show that the ICR of MS/EN/CrN coated sample reduces to 3.3 mΩ cm2 at a compaction force of 140 N/cm2. Moreover, after potentiostatic polarization, the ICR values of the MS/EN/CrN coating are still less than DOE's 2020 target. In addition, compared with other samples, the hardness and adhesion property of the MS/EN/CrN multilayer coating were greatly improved, which is beneficial for resisting the shock and wear during the assembly process of fuel cell stacks.

Mechanisms of growth, properties and degradation of amorphous carbon films by closed field unbalanced magnetron sputtering on stainless steel bipolar plates for PEMFCs

Stainless steel bipolar plates possess good manufacturability, low costs, but inadequate interfacial conductivity and corrosion resistance in proton exchange membrane fuel cells (PEMFCs). Amorphous carbon films have been deposited on stainless steel as a function of bias voltage through closed field unbalanced magnetron sputtering ion plating system (CFUMSIP) to enhance the interfacial conductivity and corrosion resistance. Surface and cross-section morphologies, hybridization, interfacial conductivity, corrosion resistance and degradation mechanisms of a-C films were systemically investigated and results are very sensitive to the substrate bias voltage. The compactness and hybridization sp2/sp3 ratio have parabolic relation with the substrate bias voltage and the a-C film deposited with 120V has the densest cross structure and maximum sp3 percentage. Various electrochemical corrosion tests in the simulated PEMFCs cathode environment confirm the fact corrosion resistance is closely related to the film compactness and hybridization. Then a-C film prepared at bias voltage 120V has the lowest corrosion current density. The initial interfacial contact resistance (ICR) of a-C is a combination result of sp2 percentage and film compactness and the samples deposited with bias voltage 60V and 300V have much lower ICR values than DOE target. Afterwards, the ICR increase mechanism of a-C film after electrochemical corrosion tests is illustrated through Raman and XPS detection, and the results reveal that increased oxygen content adsorbed on the film surface contributes to the increase of ICR value.

Synthesis, characterisation and wear performance of W–Al coatings

W, W–15 at-%Al, W–30 at-%Al and W–45 at-%Al coatings were synthesised by using a reactive four-target DC closed field unbalanced magnetron-sputtering ion plating system. Structure, morphology, composition, hardness and adhesion were studied by using an X-ray diffractometer, an energy dispersive spectrometer, a scanning electron microscope, a scanning transmission electron microscope and nanohardness and scratching testers. Wear performance was evaluated by using a pin-on-disk wear tester. The sputtering deposition of this binary system led to the formation of single-layer W–Al coatings as a result of complete dissolution of the Al atoms into the W lattice during the depositing process. The W–15 at-%Al coating showed improved wear resistance as compared with the W coating.

Flexibility and frictional behaviour of DLC and Si-DLC films deposited on nitrile rubber

The flexibility and frictional behaviour of DLC and Si-DLC films with and without Si–C interlayers were studied in this paper. The films were deposited onto nitrile rubber using a combination of a closed field unbalanced magnetron sputtering ion plating system and plasma enhanced chemical vapour deposition in Ar/C4H10 plasma. Flex tests were used to determine the film flexibility. The frictional and wear characteristics of these films were investigated using a pin-on-disc tribometer for applied loads of 1N and 5N under conditions of dry and wet sliding with a stainless steel counterpart. The induced temperature rise during tribo-testing was used to determine the effect of frictional heating on the frictional behaviour of these films. Lateral cracking was observed for DLC film and Si-DLC film with and without Si–C interlayer after flex tests. More de-bonding was observed for Si-DLC film. The films generally showed excellent frictional results for dry sliding under a normal load of 1N and for wet sliding under normal loads of 1N and 5N. The improved film flexibility was related to enhanced adhesion as a result of the Si–C interlayer. Frictional heating was significant for tribo-testing performed under a normal load of 5N under dry sliding conditions. The induced surface temperature suggests that the influence of frictional heating of the structural transformation taking place within the wear track is minimal compared to the formation of wear debris.

Development of Zr-Ti-N Coatings for Micro Drills for Machining of PCBs

A group of Zr-Ti-N coatings was prepared and studied to access their potential as a protective layer for micro drills to obtain cutting tool wear improvement. The coatings were grown using an industrial-scale four-target closed-field unbalanced magnetron sputtering ion plating system, employing one Ti and three Zr targets working in residual N2 atmosphere. To achieve Zr-Ti-N coatings with varying Ti doping content, the current applied to the Ti target was subjected to change from 0A to 3.6A while those to the Zr targets were kept constant. The coatings were characterized using GDOES, XRD, SEM, Vickers microhardness tester, scratch tester and Rockwell C indentation tester. Evaluation of wear improvement by Zr-Ti-N coatings for microdrills was conducted by machining of FR4 print circuit boards. It was found that the coatings with 16.5 at.% Ti doping content showed the highest microhardness and wear improvement for microdrills. Wear of microdrills with this coating could be reduced by a factor of two as compared with traditional TiN coated ones.

Adhesion and composite micro-hardness of DLC and Si-DLC films deposited on nitrile rubber

Thin films of hydrogenated diamond-like carbon (DLC) and silicon (Si) doped diamond-like carbon (Si-DLC) have been deposited on acrylonitrile butadiene rubber (NBR) using a closed field unbalanced magnetron sputtering ion plating system. A sputter cleaning process was integrated into the deposition process so as to reduce the likelihood of re-contamination between the cleaning and deposition stages. The deposited coatings showed excellent adherence with an adhesion rating of 4A for films with a Si-C interlayer. The composite micro-hardness was highest for DLC films at 15.5GPa for indentation load of 147.1mN using a Vickers micro-hardness tester. Tribological tests undertaken under normal load of 5N using a pin-on-disc tribometer for all of the samples of DLC and Si-DLC films, with and without Si-C interlayer, show a friction increase between 0.25 and 0.4 to between 0.45 and 0.6. This friction increase has been related to the micro-hardness of the films.

Characteristics and tribological performance of DLC and Si-DLC films deposited on nitrile rubber

The characteristics and tribological performance of DLC and Si-DLC films with and without Si–C interlayers were studied in this paper. The films were deposited on nitrile rubber using a closed field unbalanced magnetron sputtering ion plating system. The film properties and characteristics were determined by scanning electron microscopy (SEM), hydrophobicity studies, Raman spectroscopy and tribological investigations. Tribological performance of these films was investigated using a pin-on-disc tribometer under applied loads of 1N and 5N under conditions of dry and wet sliding. The effect of immersing the films in water on tribological performance was also examined. The results show that the morphology of the films had a crack-like network. At a substrate bias of −30V, the coatings were characterised by a very dense non-columnar microstructure. The highest value of the ratio of intensities of the D and G peaks (ID/IG) was 1.2 for Si-DLC film with Si–C interlayer. The lowest value of 0.7 was observed for DLC film. The contact angle (CA) of water droplets showed that the films were hydrophobic. These results are interpreted in terms of hybridisation of carbon in these coatings. The tribological investigation showed a dependence on both the tribological condition under investigation and the atomic percentage of Si in the films. At 5N normal load the lowest wear depth was observed for DLC films.

Effect of Additional Elements on Microstructure and Properties of CrN Coatings

Abstract CrMoN and CrWN coatings were deposited using closed field unbalanced magnetron sputter ion plating system. The microstructure, preferred orientation, and morphology of coatings were determined by x-ray diffraction analysis and SEM observation. The influences of additional elements on the microstructure, adhesion, mechanic, and tribological properties have been investigated. XRD Results showed that preferred orientation of CrMoN and CrWN coatings obviously changed compared with that of the pure CrN coating. All of the new hard coatings exhibited excellent adhesion due to the gradient interface layer design. By introducing Mo and W elements into the CrN-based structure, the coating hardness had an obvious improvement in comparison with pure CrN coatings. Results also showed the wear resistance of CrMoN and CrWN coatings increased clearly. The steady-state dry friction coefficients of the new coatings measured against a WC–6% Co ball are about 0.3, which were significantly decreased from 0.5 of pure CrN coaing. It is expected that these advantageous properties can enable these new hard coatings for a wide range of applications such as dry high-speed machining.

Performance of nanolayer CrN/Ag coated cutting tools

A nanolayer CrN/Ag coating comprising a lamination of hard transition metal and soft metal was synthesised using an industrial scale four target dc closed field unbalanced magnetron sputtering ion plating system (CFUBMSIPS). For comparison, a monolayer CrN coating was also grown on the same deposition system. Characterisation was conducted using SEM, TEM, XRD and Vickers microhardness and scratch testers. Wear behaviour was studied on an SRV wear tester. Performance of coated cutting tools was evaluated via two kinds of machining tests: one was using the coated microdrills to continuously make through thickness holes on FR4 printed circuit boards and the other using the coated turning cutters to machine S45C steel bars. The structural analysis showed that the nanolayer CrN/Ag coating with bilayer thickness λ 30 nm was composed of alternative stacking layers of pure Ag and CrN phases. The nanolayer CrN/Ag coating, in spite of having lower hardness than the monolayer CrN coating, showed great improvements in the wear resistance and microdrilling and turning performance, which could be attributed to the combination of multilayer structure and lubricating function of Ag.

Deposition of nano-scaled CrTiAlN multilayer coatings with different negative bias voltage on Mg alloy by unbalanced magnetron sputtering

In a magnetron sputtering system, the negative substrate bias voltage has been used as a basic process parameter to modify the deposition structure and properties of coatings. In this paper we report the effect of bias voltage ranging from −40 V to −90 V on nano-scaled CrN/TiN/CrN/AlN (CrTiAlN) multilayer coatings synthesized on a Mg alloy by a closed-field unbalanced magnetron sputtering ion plating system in a gas mixture of Ar + N 2. The technological temperature and atomic concentration in the multilayer coatings were controlled by adjusting the current density of different metal magnetron targets and the plasma optical emission monitor. The composition, crystallographic structure, deposition model and friction coefficient of multilayer coatings were characterized by X-ray photoelectron spectrometry (XPS), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM) and ball-on-disc testing. The experimental results show that the deposition model and friction coefficient of nano-scaled CrTiAlN multilayer coatings were significantly affected by the negative bias voltage ( V b). The nitride species in multilayer coatings mainly involve CrN, AlN and TiN, and XRD analysis shows that the crystallographic structure was face-centered cubic. Under different bias voltage conditions, the multilayer coating composition shows a fluctuation, and the Al and Cr concentrations respond in the opposite sense to the bias voltage, attaining their greatest values at V b = −70 V. The surface and cross-sectional morphology shows deposition model change from a columnar model into non-columnar model with the increase in negative bias voltage. The friction coefficient of the nano-scaled multilayer coatings at V b = −55 V stabilize after 10 000 cycles.

Nanolayer CrN x/WN y coatings used on micro drills for machining of printed circuit boards

A series of CrN x/WN y nanolayer coatings were synthesized using an industrial-scale four-target DC closed-field unbalanced magnetron sputtering ion plating system (CFUBMSIPS™), employing one W target and three Cr targets. For comparison, a monolayer CrN coating was also grown on the same deposition system. Characterization was conducted using EDX, SEM, TEM, AFM, XRD, nanohardness indentation tester, and scratch tester. Performance of cutting tools with the nanolayer coatings was carried out via machining tests using the coated micro drills to continuously make through-thickness holes on printed circuit boards. The results showed that nanolayer CrN x/WN y coatings with various modulation period ( λ) could be obtained on an industrial-size deposition machine by means of control in the current applied to the W target. Of the studied nanolayer CrN x/WN y coatings, the one with λ = 27 nm showed the highest nanohardness and best micro drilling performance. This nanolayer coating showed significant improvements in cutting performance as compared with the referred monolayer CrN coating.

A wear-resistant coating—Oxidized graded multilayer TiN/W coating

Combining sputtering technology using an industrial-scale four-target DC closed-field unbalanced magnetron sputtering ion plating system (CFUBMSIPS™) with post heat treatment, a graded multilayer TiN/W coating, consisting of five layers, was synthesized and its outmost W layer was transformed to lubricious WO 3 successfully. The coatings were characterized by using GDOES, GXRD, a Rockwell C indentation tester, a nanoindentation tester, and a scratching tester. Wear behavior of coatings was evaluated by using a pin-on-disc tribometer. Through proper post heat treatment, the multilayer TiN/W coating, in spite of having a lower nano-hardness, showed good adhesion, much better wear performance and lower friction coefficient compared with the reference monolayer TiN coating.

Microstructure and wear behaviour of silicon doped Cr –N nanocomposite coatings

Hard Cr–N and silicon doped Cr–Si–N nanocomposite coatings were deposited using closed unbalanced magnetron sputtering ion plating system. Coatings doped with various Si contents were synthesized by changing the power applied on Si targets. Composition of the films was analyzed using glow discharge optical emission spectrometry (GDOES). Microstructure and properties of the coatings were characterized using X-ray diffraction (XRD), transmission electron microscopy (TEM), and nano-indentation. The harnesses and the elastic modulus of Cr–Si–N coatings gradually increased with rising of silicon content and exhibited a maximum at silicon content of 4.1 at.% and 5.5 at.%. The maximum hardness and elastic modulus of the Cr–Si–N nanocomposite coatings were approximately 30 GPa and 352 GPa, respectively. Further increase in the silicon content resulted in a decrease in the hardness and the elastic modulus of the coatings. Results from XRD analyses of CrN coatings indicated that strongly preferred orientations of (111) were detected. The diffraction patterns of Cr–Si–N coatings showed a clear (220) with weak (200) and (311) preferred orientations, but the peak of CrN (111) was decreased with the increase of Si concentration. The XRD data of single-phase Si 3N 4 was free of peak. The peaks of CrN (111) and (220) were shifted slightly and broadened with the increase of silicon content. SEM observations of the sections of Cr–Si–N coatings with different silicon concentrations showed a typical columnar structure. It was evident from TEM observation that nanocomposite Cr–Si–N coatings exhibited nano-scale grain size. Friction coefficient and specific wear rate (SWR) of silicon doped Cr–N coatings from pin-on-disk test were significantly lower in comparison to that of CrN coatings.

Microstructure and Properties of Low Temperature Deposit Cr<sub>x</sub>N Using Unbalanced Magnetron Sputtering

CrxN coatings are deposited on the substrates with low temperature using a Teer UDP 550 Close Field Unbalanced Magnetron Sputter Ion Plating system (CFUBMSIP). The effect of applied power on Cr targets related to sample temperature is studied. When the applied power of Cr targets is lower than 1.1KW, the depositing temperature could be controlled at about 180°C. Scratch test shows no coating detachment at the end of scratch track up to 85N load. All results of Rockwell-C indentation indicate that CrxN coating holds good bonding strength. Pin-on-disc tests are performed to evaluate wear resistance of the coatings and no any wear loss can be detected after 6000s and 1800s of running. XRD profile demonstrates that the coating deposited in this study is CrxN.

Microabrasive Wear Resistance of CrN and CrSiN Coatings

Evaluation of the wear resistance for tools and dies, particularly for coated components, is a challenging task in surface engineering testing. Pin-on-disc is a widely employed method in the literature; its result is rather associated with the friction aspect of the samples than wear resistance for components. A microabrasive test has been suggested recently to assess the wear resistance of hard coatings. The key point in that is to simulate the aspect which is close to the factor of the industrial performance for most of the components. This paper aims to compare pin-on-disc tests and microabrasive methods. Two hard coatings of CrN and CrSiN were deposited using a closed field unbalanced magnetron sputter ion plating system. SiC was used as the abrasive particle in the slurry. Results show that the abrasive wear rates of the CrN coatings changed sensitively with the depositing parameters. At the same time, the specific wear rate from pin-on-disc test was not able to pick up the change of wear endurance of the coatings. A hole drilling test indicates that the number of holes increases significantly when the abrasive wear rate is lower than a certain critical value. It is concluded that the microabrasive test is an appreciable method in practice to evaluate the wear resistance of hard coatings.

Effect of crystallographic orientation on the friction and wear properties of Mo xS y–Ti coatings by pulsed-dc in nitrogen and humid air

This work reports on the structural and wear properties of Mo x S y –Ti films, deposited on D2, 52100, and 440C steel substrates by pulsed-dc magnetron sputtering. A closed field unbalanced magnetron sputter ion plating system was used for the deposition process. The mechanical and tribological properties of Mo x S y –Ti coated composites onto selected steel substrates were characterized using microhardness test, friction–wear test in atmospheric conditions and in dry nitrogen. The X-ray diffraction (XRD) was used to determine the phase structure. Structural analysis was performed using SEM-EDS. Mo x S y –Ti films showed a very dense structure with pronounced basal plane (0 0 2) orientation, which showed the lowest friction coefficient (0.022) in dry nitrogen. The coefficient of friction can be attributed to the oxidation of MoS 2 at the wear track to form MoO x that is known to cause an increase in the friction coefficient. In humid air, an oxidative environment, the films had higher coefficient of friction (0.07), and lower wear life (142 500 passes with 2.11 × 10 −6 mm 3/N m wear rate) than in dry nitrogen, where the wear life was over 250 000 passes with the lowest wear rate of 3 × 10 −8 mm 3/N m.

Ion beam analysis and Raman characterisation of coatings deposited by cosputtering carbon and chromium in a closed field unbalanced magnetron sputter ion plating system

A novel non-hydrogenated a-C coating has been deposited by sputtering carbon and chromium targets in a closed field unbalanced magnetron sputter ion plating system, with a metallic adhesion layer between the substrate and the cosputtered layer. The properties of these new carbon coatings have been previously compared with those of more conventional hydrogenated metal-containing DLC. Reciprocating and pin-on-disk friction and wear tests have shown that the new carbon coatings have a lower friction coefficient and that their wear resistance is more than one order of magnitude higher than metal-containing hydrogenated DLC coatings.This paper presents an initial study of the composition and structure of these new coatings. Rutherford and Non-Rutherford backscattering of alpha particles and protons are used for studying the stoichiometry and for the determination of impurities. Elastic recoil detection analysis (ERDA) is used for depth profiling of hydrogen. Raman spectroscopy is used to investigate the structure of the different carbonaceous layers.

A study of the structural and mechanical properties of Ti=MoS2 coatings deposited by closed field unbalanced magnetron sputter ion plating

The closed field unbalanced magnetron sputter ion plating system has been used to produce MoS2 coatings by co-deposition of Ti and MoS2. Previous results have shown that the coatings are harder than pure MoS2 coatings and that they show very low coefficient of friction and longer lifetimes. These Ti=MoS2 coatings show excellent wear resistance at high loads. The coefficient of friction is as low as 0.02 at a relative humidity of 40%, and conventional adhesion scratch tests indicate critical loads in excess of 120 N. This paper presents a study of the composition, structure and mechanical properties of these metal=MoS2 composite coatings using several analytical techniques (RBS, ERDA, XRD, scratch test, SEM and EDS). The analytical results are discussed and related to the mechanical properties of the coatings.

Mechanical and microstructural changes of magnetron sputtered TiN films with various magnetic field configurations

TiN coatings were deposited in a single magnetron sputter ion plating system in “balanced” and unbalanced mode with a closed magnetic field configuration. The film microhardness, thickness, adhesion, microstructure, preferred orientation and topography were analyzed as a function of the substrate position inside the deposition volume. In the static deposition mode and under the limitations of the experimental set-up used, no real homogeneous deposition conditions were achieved, but a significant possibility of controlling the spatial distribution of deposition conditions was demonstrated. The variation of the coating microhardness over the target-to-substrate distance, d S–T, ranging from about 80 to 210 mm was acceptable for practical applications, while the critical load for adhesive failure was found to decrease significantly with increasing d S–T in a balanced magnetron configuration. The variation of magnetic field configuration provided a relatively homogeneous distribution of the bias current density over the deposition volume, but the preferred orientation of the coating was changed from (200) to (111) with increasing d S–T. The energy delivered per unit volume of growing film, S E, and bombarding ion to deposited metal atom flux ratio j i/ j m were considered. It was found that j i/ j m can be used to describe qualitatively the change of preferred crystalline orientation of coatings.

Preparation of a new tetragonal copper oxynitride phase by reactive magnetron sputtering

Cu–O–N layers were deposited on Si-〈100〉 wafers at a temperature of 90°C in a reactive magnetron sputtering ion plating system (R-MSIP). For this, a Cu-target was sputtered by a nitrogen/oxygen plasma, and the influence of the oxygen partial pressure on composition, structure, and texture of the Cu–O–N layers was investigated. The analyses of the films with EPMA, XRD, and HEED yielded the following results: with an appropriate setting of the oxygen partial pressure, the oxygen content of the Cu–O–N layers could be controlled between 2.4 and about 50 at. %. Structure analyses have shown changes in the crystal structure of the films with increasing oxygen and decreasing nitrogen content from the simple cubic (sc) structure of Cu 3N, followed by a two phase region, where the sc structures of Cu 3N and Cu 2O appear, to a single phase film with the sc structure of Cu 2O. With an oxygen content of 43.6 at. % a new Cu–O–N phase with the tetragonal structure of paramelaconite (≈Cu 12 2+Cu 4 +O 14) and the composition Cu 27O 22N was grown. The film with an oxygen content of about 50 at. % consists of monoclinic CuO.