Closed Field Unbalanced Magnetron Sputtering Research Articles

Influence of Ti content on the corrosion properties and contact resistance of CrTiN coating in simulated proton exchange membrane fuel cells

CrTiN coatings with different Ti content are deposited on stainless steel 316L (SS316L) substrate as bipolar plates for proton exchange membrane fuel cells (PEMFCs) by close field unbalanced magnetron sputter ion planting (CFUBMSIP). The effect of Ti incorporation on the surface morphology, phase structure, electrochemical properties, interfacial contact resistance (ICR) and contact angle with water are investigated. Scanning electron microscope (SEM) results indicate that Ti doped coatings are compact and dense. X-ray diffraction (XRD) and nanoindentation hardness results show that Ti incorporated coatings have grain refinement and solid solution phase. From electrochemical test results, CrTiN-4A coating has the highest corrosion potential of 0.1825 V in the anodic PEMFCs environment. It also has the most stable and lowest current density both in simulated anodic and cathodic environments after potentiostatic polarization. Furthermore, electrochemical impedance spectroscopy (EIS) studies reveal that the corrosion resistance of CrTiN-4A coating is higher than other coatings and bare SS316L. ICR results show that CrTiN-4A coating has the lowest ICR of 4.57 mΩ cm2 at a compaction of 1.4 MPa before potentiometric polarization. In addition, the contact angles of CrTiN-4A coating before and after potentiostatic polarization are 109.0° and 99.5°, respectively.

Adhesion and tribological properties of gradient designed a-C film on ultrahigh molecular weight polyethylene

Amorphous carbon (a-C) film is deposited with a gradient designed bias voltage on the ultrahigh molecular weight polyethylene (UHMWPE) substrates and Si3N4 balls via a closed field unbalanced magnetron sputtering. The designed bias voltage continuously increases from −40V to −80V with two different increasing rate. The film with a thickness of approximately 1000nm is made up of equiaxed grains with size of around 20nm. Nanoindentation tests show that the hardness of the UHMWPE increases from 44MPa to 2.16GPa after deposition of a-C film with gradient designed bias voltage. The wear rate and friction coefficient of the a-C film sliding against a-C films coated on Si3N4 balls is tested in air and Hank's solution by means of a reciprocating tribometer. The a-C film deposited with gradient bias voltage exhibits superior adhesion and tribological performance, compared with those deposited with balanced bias voltage. The a-C film wearing against Si3N4 balls with a-C film coating shows a lower wear rate, compared with a-C films wearing against uncoated balls, decreasing from 1.95×10−15m3N−1m−1 to 1.23×10−15m3N−1m−1. There is a further enhancement of the anti-wear performance in Hank's solution.

The influence of plasma nitriding on microstructure and properties of CrN and CrNiN coatings on Ti6Al4V by magnetron sputtering

In this paper, the CrN and CrNiN coatings were deposited on the non-nitrided and nitrided Ti6Al4V alloys with the method of closed-field unbalanced magnetron sputter ion plating (CFUBMSIP). The influence of plasma nitriding treatment on microstructure, mechanical and tribological properties of Physical Vapor Deposition (PVD) films was evacuated by means of SEM (EDS), XRD, Rockwell-C indentation testing, nanoindentation testing, and ball-on disc tribotesting. With the addition of Ni, the preferred orientation changes to CrN (200) and the grain is refined. The indentation tests indicated that the duplex treated samples exhibited the best combined properties. The nanoindentation testing results showed that the hardness of the coatings increased, the plastic deformation reduced and they had higher H3/E2 values than PVD coatings with the plasma nitriding before PVD treatment due to the increase of substrate's load bear capacity after plasma nitriding process. The friction and wear tests demonstrated that the tribological performance of the PVD coatings improved after plasma nitriding which is attributed to the enhanced the mechanical compatibility between the hard PVD coating and soft substrate and the resistance of CrN coating is better than that of CrNiN coating because of the transfer layer (constituted of TiN and Ti2N) deposited by nitriding.

Effect of Ni content on the electrical and corrosion properties of CrNiN coating in simulated proton exchange membrane fuel cell

In this paper, CrNiN coatings with various Ni content are deposited on 304ss bipolar plates by closed field unbalanced magnetron sputter ion plating from CrNi alloy targets. Simulative working environment of proton exchange membrane fuel cell (PEMFC) is applied to test the electrical and corrosion properties of uncoated 304ss and CrNiN-coated samples. The influence of Ni content on microstructure, phase structure, contact angle with water and electrochemical performance is investigated. Results show that all the coated samples significantly enhanced the corrosion resistance of the 304ss, and the CrN-coated 304ss sample without Ni has the best corrosion resistance of 153.8 and −141.9 mV in the simulated anodic and cathodic environments, respectively. Electrochemical impedance spectroscopy (EIS) studies reveal that the resistance of CrN coating is higher than that of other coated samples and 304ss in the cathodic environment. Furthermore, Interfacial contact resistance (ICR) studies revealed that CrN coating has a superior ICR of 11 mΩ cm2 at a compaction force of 160 N cm−2. In addition, the contact angle of the CrNiN coatings with water is approximately 114°, which is beneficial for water management in PEMFC. Analysis result indicates that the enhanced performance of the coated 304ss bipolar plates is related to the high film density determined by closed field unbalanced magnetron sputter ion plating, and the synergistic function of the CrNiN layered structure.

Structure and mechanical properties of graded Cr/CrN/CrTiN coatings synthesized by close field unbalanced magnetron sputtering

Abstract Graded Cr/CrN/CrTiN coatings were deposited onto M42 HSS tool steel substrates by close field unbalanced magnetron sputtering (CF-UBMS). The effects of varying Ti sputtering current, I Ti , on the chemical composition, crystal structure, morphology and mechanical properties of the graded Cr/CrN/CrTiN coatings were investigated via XPS, XRD, AFM, electron microscopy techniques and nanoindentation tests. XPS and XRD results indicate that the CrTiN layer had formed as a solid solution nitride with fcc B1 type phase. The layers in the coatings were distinct and all the coatings exhibited a columnar microstructure, which decreased in size as the Ti content increased due to the increase in the Ti sputtering current. The mechanical properties of these coatings were determined by nanoindentation tests, which revealed an increase in hardness and modulus as the Ti content increased. However, the damage resistance of the coatings decreased with increasing Ti concentration. Furthermore, deformation behaviour of the coatings at high loads revealed a good resistance to plastic deformation and good adhesion strength for all coatings. These improvements, and the increase in hardness, are attributed to a combination of a decrease in grain size and a formation of solid solution nitride.

Characterization and Electrochemical Properties of Oxygenated Amorphous Carbon (a-C) Films

Amorphous carbon (a-C) films with varying oxygen content were deposited by closed-field unbalanced magnetron sputtering with the aim to understand the effect of oxygen on the structural and physical properties of the films and subsequently correlate these changes with electrochemical properties. The a-C films were characterized by transmission electron microscopy, helium-ion microscopy, atomic force microscopy, Raman spectroscopy, X-ray photoelectron spectroscopy and time-of-flight elastic recoil detection analysis. The electrochemical properties were studied by electrochemical impedance spectroscopy and cyclic voltammetry with several redox systems (Ru(NH3)62+/3+, Fe(CN)64−/3−, dopamine and ascorbic acid). The results indicated that the carbon films are amorphous with an ID/IG ratio near 2.6. The oxygen content of the films seemed to saturate at around 11 at. %, whereas the amount of surface oxygen functional groups increased steadily with increasing oxygen inflow during deposition. O/C ratio increased from 0.09 to 0.19. A significant increase in film resistivity was observed with increasing oxygen content. Lightly oxygenated a-C films showed a low charge transfer resistance (Rct) and reversible electron transfer for Ru(NH3)62+/3+ whereas both Rct and ΔEp increased considerably for heavily oxygenated films. The inner sphere redox systems were significantly affected by the surface oxygen functional groups with dopamine and ascorbic acid showing a linear increase in ΔEp and Epa, respectively, with increasing oxygen content. Fe(CN)64−/3− did not show a clear trend but was still clearly affected by the increase in oxygen content. The double layer capacitance was about 1μF/cm2 for all the oxygenated a-C films.

The Tribological Performance of Surface Treated Ti6A14V as Sliding Against Si3N4 Ball and 316L Stainless Steel Cylinder

Closed field unbalanced magnetron sputtering was used to deposit diamond-like carbon (Ti-C:H) coatings on Ti6Al4V alloy and gas nitrided Ti6Al4V alloy. Four different specimens were prepared, namely untreated Ti6Al4V alloy (Ti6Al4V), gas nitrided Ti6Al4V alloy (N-Ti6Al4V), Ti-C:H-coated Ti6Al4V alloy (Ti-C:H/Ti6Al4V) and Ti-C:H-coated gas nitrided Ti6Al4V alloy (Ti-C:H/N-Ti6Al4V). The tribological properties of the four specimens were evaluated using a reciprocating wear tester sliding against a Si3N4 ball (point contact mode) and 316L stainless steel cylinder (line contact mode). The wear tests were performed in a 0.89 wt.% NaCl solution. The results showed that the nitriding treatment increased the surface roughness and hardness of the Ti6Al4V alloy and improved the wear resistance as a result. In addition, the Ti-C:H coating also improved the tribological performance of Ti6Al4V. For example, compared to the untreated Ti6Al4V sample, the Ti-C:H coating reduced the wear depth and friction coefficient by 340 times and 10 times, respectively, in the point contact wear mode, and 151 times and 9 times, respectively, in the line contact wear mode. It is thus inferred that diamond-like carbon coatings are of significant benefit in extending the service life of artificial biomedical implants.

Structures and Properties of C-Doped NiCr Thin Film Deposited by Closed-Field Unbalanced Magnetron Sputtering

The structures and properties of C-doped NiCr thin film as embedded thin film resistor (ETFR) materials were studied by closed-field, unbalanced magnetron sputtering method. The C-doped NiCr (NiCrC1) thin film had more stable electrical performance, better corrosion resistance, and higher hardness than NiCr thin film. The temperature coefficient of resistance (TCR) of NiCrC1 thin film deposited at room temperature (from 19.73 ppm/K to 173.7 ppm/K) was lower than that of NiCr thin film (from 157.8 ppm/K to 378.9 ppm/K), and the sheet resistor (154.25 Ω/Sq) was higher than that of NiCr thin film (62.84 Ω/Sq). The preferred orientations of C-doped NiCr thin film was Ni (111), while that of NiCr thin film was Ni (011). The carbon-doped NiCr thin film can reduce the defects and stress and change the preferred orientations. The dominant carbon in C-doped NiCr thin film had a graphite-like structure.

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.

Corrosion and tribocorrosion performance of M (M Ta, Ti) doped amorphous carbon multilayers in Hank's solution

Amorphous carbon (a-C) and Ta- or Ti-doped a-C multilayer films are deposited onto Ti6Al4V alloy by an industrial closed field unbalanced magnetron sputtering. The corrosion and tribocorrosion performances of these films are investigated in Hank's solution at 37 °C. The a-C film exhibits enhanced wear and corrosion resistance compared with the bare Ti6Al4V alloy, but the cracks propagate during the tribocorrosion process, which leads to serious breakage. Interestingly, the tribocorrosion resistance of a-C film is improved by introducing Ta- or Ti-doped multilayered structure. The high mechanical properties (high hardness and low residual stress), good corrosion, and wear resistance of Ta- and Ti-doped a-C multilayer films make them excellent protective materials for artificial joints.

Effects of Ti-C:H coating and plasma nitriding treatment on tribological, electrochemical, and biocompatibility properties of AISI 316L.

Ti-C:H coatings were deposited on original, nitrided, and polished-nitrided AISI 316L stainless steel substrates using a closed field unbalanced magnetron sputtering system. Sliding friction wear tests were performed in 0.89 wt.% NaCl solution under a load of 30 N against AISI 316L stainless steel, Si3N4, and Ti6Al4V balls, respectively. The electrochemical properties of the various specimens were investigated by means of corrosion tests performed in 0.89 wt.% NaCl solution at room temperature. Finally, the biocompatibility properties of the specimens were investigated by performing cell culturing experiments using purified mouse leukemic monocyte macrophage cells (Raw264.7). In general, the results showed that plasma nitriding followed by Ti-C:H coating deposition provides an effective means of improving the wear resistance, anti-corrosion properties, and biocompatibility performance of AISI 316L stainless steel.

Mechanical and Tribological Properties of TiTaBN Graded-Composite Coatings Deposited Using the CFUBMS Technique

ABSTRACTIn this study, TiTaBN graded-composite coatings were deposited utilizing different process parameters on D2 steel and glass substrates using pulsed DC closed-field unbalanced magnetron sputtering (CFUBMS). The morphology and structure of the coatings were analyzed using scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray photoelectron spectroscopy (XPS), and Raman spectroscopy. The hardness and critical load values of the coatings were determined using a microhardness tester and scratch tester, respectively. The tribological properties of the coatings were analyzed in different testing environments using a pin-on-disc tribometer. The properties of the coatings were found to be strongly affected by the coating parameters. The maximum thickness and hardness were obtained at the lowest nitrogen flow rate and highest frequency. Critical load values of coatings were increased with increased nitrogen flow rate. The low nitrogen flow rate and high frequency across the coatings resulted in enhanced tribological properties.

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.

Effect of N2 flow rate on the microstructure and electrochemical behavior of TaNx films deposited by modulated pulsed power magnetron sputtering

Modulated pulsed power magnetron sputtering (MPPMS) technology offers the possibility to grow high performance coatings compared to the ones developed by conventional dc magnetron sputtering. The high degree of ionization of sputtered particles developed during MPPMS can be usefully utilized to precisely tailor the properties of the growing films. One of the main advantages of such a high metal ion flux is related to the densification of the coatings due to enhance ion bombardment towards the growing film. The development of extremely dense and low-defect microstructure coatings can have a positive effect on the corrosion resistance of tantalum nitride (TaNx) films.In this study, TaNx thin films have been deposited by MPPMS in a closed field unbalanced magnetron sputtering system. Structure, surface morphology, hardness and corrosion resistance of the developed coatings have been analyzed as a function of different N2-to-Ar ratios (0, 0.25, 0.625, 1). X-ray diffraction and scanning electron microscopy analysis reveal high dependence of the grown crystal phases and the microstructure on N2-to-Ar ratio. The hardness of the TaNx coatings increases when increasing N2-to-Ar ratio up to a maximum value of 25GPa (N2-to-Ar ratio of 0.625). The corrosion behavior was investigated using electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry. EIS measurements registered at different immersion times show high impedance values (in the order of 10MΩcm2) and corrosion resistance enhancement with time, indicating the formation of a passive protective oxide layer on the top of their surfaces. TaNx film grown at 0.25N2-to-Ar ratio exhibits the highest corrosion resistance of 103.53MΩcm2 and low porosity of 1.63×10−3 and is characterized by columnar-free microstructure.

EFFECTS OF Mo CONTENT ON THE MICRO-STRUCTURE AND TRIBOLOGICAL PROPERTIES OF CrMoAlN FILMS

In recent decades, CrAlN coatings have been widely used for cutting tools due to their high hardness, good wear resistance, especially excellent thermal stability and oxidation resistance. However, the rapid development in high speeds and dry cutting applications demands further improvement in hardness and wear properties of CrAlN coatings. Mo nitrides coatings are commonly used as protective surface layers against wear and corrosion. The combination of CrAlN and Mo may lead to the development of new composite coatings with superior wear properties. In this study, the CrMoAlN multilayer coatings with different Mo contents were deposited on M2 tool steel and silicon wafers substrates by closedfield unbalanced magnetron sputtering ion plating (CFUMSIP) technique in a gas mixture of Ar+N2. The chemical composition, surface and cross sectional morphologies, microstructure, mechanical and tribological properties of coatings were studied by EDS, SEM, XRD, XPS, nano-indentation and pin-on-disk tribometer, respectively. The results indicate that the CrMoAlN coatings exhibit fcc structure. Mo atoms substitute Cr and/or Al atoms in CrAlN lattice forming the solid solution CrMoAlN coatings. The surface and cross-sectional morphologies of the CrMoAlN coatings show that the grain size and the column width decrease with the increasing of Mo content. Nano-indentation result reveals a promoted hardness and elastic modulus *浙江省自然科学基金资助项目Y15E050060 收到初稿日期: 2015-09-21,收到修改稿日期: 2016-03-09 作者简介:楼白杨,女, 1958年生,教授,博士 DOI: 10.11900/0412.1961.2015.00493 第727-733页 pp.727-733

Characterization and tribocorrosion behavior of sputtered NiTi coatings

Abstract In this study, NiTi coatings were deposited onto AISI 316L stainless steel substrates by closed field unbalanced magnetron sputtering. The microstructure and properties of the coatings were characterized by means of X-ray diffraction, scanning electron microscopy, and nano-indentation. The tribocorrosion resistance and corrosion behavior of the stainless steel substrates and NiTi coatings were investigated in Hanks' solution. The experimental results indicated the NiTi coatings show higher corrosion polarization resistance and a more stable corrosion potential in the Hanks' solution than the uncoated stainless steel substrate. The NiTi coatings also exhibited excellent wear resistance and chemical stability in sliding tests with an Si3N4 ball in the Hanks' solution. The tested samples showed different wear mechanisms in the sliding tests. Compared to the SS substrates, the NiTi coatings were more compatible with the Si3N4 ball.

Erratum to: Fabrication of UV photodetector from nickel oxide nanoparticles deposited on silicon substrate by closed-field unbalanced dual magnetron sputtering techniques

Erratum to: Fabrication of UV photodetector from nickel oxide nanoparticles deposited on silicon substrate by closed-field unbalanced dual magnetron sputtering techniques

Microstructure and tribological properties of MoS2+Zr composite coatings in high humidity environment

MoS2+Zr composite coatings with different Zr contents and their pure MoS2 counterparts were deposited on silicon wafers and steel substrates by closed field unbalanced magnetron sputtering system. The microstructure, mechanical and tribological properties of as-prepared coatings were systematically investigated using a number of analytical techniques and the effect of different Zr contents on tribological behaviors in humidity conditions of these as-deposited composite coatings was discussed. It is clearly uncovered from the present results that the MoS2+Zr composite coatings were amorphous nature embedding some nanocrystallites. Doping of MoS2 coatings with Zr can remarkably improve the mechanical and tribological properties of pure MoS2 coating in high humidity (68% RH) environment, rendering the coefficient of friction (COF) decreases with increasing Zr content. Additionally, MoS2+Zr composite coatings exhibit much more stable and lower friction coefficients with increasing applied load. The lowest friction coefficient of as-deposited MoS2+Zr composite coating was about 0.04 with an applied load of 20N (at 68% RH), where the friction coefficient of pure MoS2 coating was around 0.7. The improved tribological property of the MoS2+Zr composite coatings in high humidity environment was discussed in terms of the obtained lower friction coefficient, higher hardness and better adhesion of the composite coatings combined with inhibition of MoS2 oxidation.

Seed layer effect on the (0 0 2) texture and piezoelectric properties of pulsed-DC sputtered AlN thin films

Piezoelectric aluminium nitride (AlN) thin films were deposited by reactive sputtering of Al metal target in nitrogen atmosphere using a pulsed closed field unbalanced magnetron sputtering system on various substrates using different underlayers (seed layer) such as Pt and Mo. The texture, orientation and piezoelectric properties of AlN films were characterised by means of X-ray diffraction, field emission scanning electron microscopy and laser interferometry. A Michelson laser interferometer was designed to obtain the converse piezoelectric response of the deposited AlN thin films. It was found that the incorporation of different seed layers at various working pressure in the sandwiched structure, significantly affected the (0 0 2) orientation and the piezoelectric response of AlN thin films.

Influence of CrB2 target current on the microstructure, mechanical and tribological properties of Cr–B–C–N coatings in water

Cr–B–C–N coatings with different boron contents (24.6–27.2 at%) were deposited on Si(100) wafers and 316L stainless steels by using closed-field unbalanced magnetron sputtering via adjusting the CrB2 target current.