Unbalanced Magnetron Sputtering Method Research Articles

High-temperature oxidation resistance of CrAlN thin films prepared by DC reactive magnetron sputtering

CrAlN thin films were prepared by using the reactive DC unbalanced magnetron sputtering method from the single alloy target on a silicon substrate. The effect of annealing temperature in the air which ranges from 500℃ to 900℃ for 1 h on phase structure, film composition, surface morphology, microstructure, and hardness was investigated by XRD, EDS, FE-SEM, and Nanoindentation techniques, respectively. The high-temperature (up to 900℃) oxidation resistance of the thin film was also evaluated. The result shows that solid solutions of (Cr,Al)N with (111), (200), and (220) planes for the as-deposited film and no oxide phase were found after annealing with different temperatures. The O content slightly increases with an increase in the annealing temperature with various Cr, Al, and N contents found by the EDS. From the FE-SEM result, as increased annealing temperature, the evolution of cross-sectional morphology from dense to compact columnar structure was exhibited but the oxides layer was not detected. These results concluded that the as-deposited thin film showed good oxidation resistance when annealed in air at an elevated temperature reaching 900℃. Moreover, the film’s hardness decreased from 61.19 GPa to 50.11 GPa with increasing the annealing temperature observed by the Nanoindentation technique.

Effect of thermal oxidation on structural and tribological properties of MoS2 films

AbstractThe aim of this study is to investigate the structural, mechanical and tribological behaviours of thermally oxidized MoS2 films. MoS2 coatings were deposited on D2 tool steel substrates using the closed field unbalanced magnetron sputtering method (CFUBMS). The thermal oxidation process was carried out at four different temperatures. Tribological properties were determined by pin‐on‐disc wear tests in the atmospheric environment. It was determined that thermal oxidation temperatures affected the chemical composition of MoS2 films, but did not cause any change in film thickness. The wear rates of the samples differed depending on the oxidation temperature and the applied load. The lowest wear rate was determined as 1.97 × 10−8 mm3/Nm in the oxidized film at 350°C. In addition, the highest hardness value was obtained as 655 HV in the film oxidized at 400°C, and the lowest coefficient of friction was obtained as 0.01 in the film oxidized at 350°C.

Nucleation retardation of cubic boron nitride films caused by the addition of oxygen in argon‑nitrogen sputtering gas

Cross-sectional transmission electron microscopy (TEM) was employed to study the effect of the additive oxygen gas on the microstructure of boron nitride (BN) films especially focusing on the intervening turbostratic BN (tBN) layer's behavior. Films in this study were deposited on diamond coated Si substrates, which were biased with negative voltages, using an unbalanced magnetron sputtering method with a boron carbide target. Various amounts of oxygen were added into argon‑nitrogen mixed sputtering gas. TEM showed that the tBN intervening layer was also observed to form prior to cubic BN (cBN) layer formation for all films, irrespective of oxygen addition. The tBN layer thickness increased with increasing oxygen content. This thickness increase implied that the addition of oxygen delayed cBN phase nucleation. On the other hand, the alignment of the hexagonal BN planes in the tBN layer, estimated from FTIR spectra, was observed to be enhanced with increasing oxygen content. Such alignment enhancement is considered as a result of oxygen adsorption on the tBN layer surface, which suppresses breaking sp2 bonds caused by Ar ion bombardments. The suppression of the sp2 bond breakage, consequently, causes the difficulty of forming sp3 bonds and delays the cBN phase nucleation.

Hardness, Adhesion, and Wear Performance of Duplex Treatment Coatings of Nitride/TiAlZrN with Different Zr Target Currents

The surface treatment, which includes first a thermal diffusion process, such as nitriding and then a physical vapor deposition coating process as the working layer, is called duplex treatment in the literature. In this study, the effects of the duplex treatment on the hardness, adhesion, and wear performance of TiAlZrN coatings on the hardened AISI H13 steel produced using the closed field unbalanced magnetron sputtering method with variable Zr target current (2 A, 3 A, and 5 A) were investigated. Within the scope of these investigations, scanning electron microscope, x-ray diffracrometer, optical microscope, optical profilometer, energy-dispersive spectrometer, micro- and nano-hardness, scratch, and wear tests were used. In micro- and nano-hardness tests, it was determined that the hardness of the substrate increased significantly (approximately 400%) owing to the duplex treatment. In addition, with the increase in the Zr target current, it was observed that the hardness of the coatings was in an increasing trend. Adhesion strength increased with the enhancement of both the hardness of the substrate and the coatings. It was beheld that the adhesion strength of the coatings increased with the duplex treatment. Besides, the coating produced using the highest Zr target current reached maximum adhesion strength of 79 N in relation to superior hardness. Wear performance of the samples was determined using a ball-on-disk tribometer. As a result of wear tests, TiAlZrN coatings with duplex treatment were observed to notably improve the wear performance of the substrate material by 95 times. The effects of Zr target current on the wear performance of the coatings were similar to those of hardness and adhesion strength.

Friction and wear behaviors of different DLC films sliding against SiC and Si3N4 balls under high relative humidity

In this paper, the Pure-DLC, B4C-DLC and Si-DLC films were deposited on the AISI 304 stainless steel by unbalanced magnetron sputtering method. The tribological behaviors of the films sliding against SiC and Si3N4 balls were tested by a ball-on-disc tribometer under high relative humidity (90%). The results showed that the tribological behaviors for the films sliding against SiC exhibits more excellent than the corresponding film sliding against Si3N4, mainly showing lower friction coefficients and wear rates, narrower wear widths as well as lower fluctuant friction curves. There are two main reasons for the results. On the one hand, the films sliding against SiC ball exhibit the superior graphitization degree, smaller size of microcrystalline graphite and smaller disorder and sp2 hybrid bond content. On the other hand, the films sliding against Si3N4 ball show more abrasive particles during the friction process, which leads to the adsorbate of films on the surface to be more easily desorbed so that the σ bond reacted easily with water vapor and oxygen is more exposed and forms a strong covalent bond.

Tribological investigation of multilayer CrN/CrCN/TaN films deposited by close field unbalanced magnettron sputtering

AbstractCrN/CrCN/TaN multilayer films were deposited onto the CoCrMo alloy substrates at different number layers as two, four and 8 layers by close-field unbalanced magnetron sputtering method. Microstructure and the tribo-logical properties of the films were characterized by XRD, SEM, pin-on-disk wear test, scratch test, micro hardness. CrN/CrCN/TaN multilayer coatings exhibited good adhesion properties on the CoCrMo alloy substrate. A very high hardness value of 60 GPa was obtained for 8 multilayered coating. As a result of the pin-on-disc wear tests, it was found that the tribological properties of the CoCrMo alloy were enhanced by coating its surface with this architecture by using close-field unbalanced magnetron system with used parameters.

Synthesis of Carbon Nitride Films by Unbalanced Magnetron Sputtering Method and The Sliding Characteristics under Oil Lubrication

Synthesis of Carbon Nitride Films by Unbalanced Magnetron Sputtering Method and The Sliding Characteristics under Oil Lubrication

Failure of DLC Films Caused by Cyclic Sphere Indentation and Effects of Film Structures on Failure Mode

As a new strength evaluation method for hard coatings such as diamond-like carbon (DLC), the cyclic indentation test was proposed. Then, a test rig was fabricated and used for the evaluation of DLC. DLC and a Cr/C inclined interlayer for the improvement of the adhesion strength of DLC were prepared by the unbalanced magnetron (UBM) sputtering method on heat-treated and polished JIS SCM415 substrates. Si3N4 spheres having diameters of 10 mm were used for the cyclic indentation test. 10000 cycle indentations brought about DLC fracture and detachment in the indentation impression. Also ring cracks were observed around the impression. I(D)/I(G), which is the ratio of the D to G peak intensities, decreases towards the center of the impression. It was considered to indicate decreasing sp2 cluster size in DLC. On the other hand, compressive stress increased near the surface of DLC in the contact area, as indicated by the change in its G peak position. It seemed to be the cause of the fracture and detachment of DLC in the impression.

Oxidation behavior and corrosion resistance of vacuum annealed ZrN-coated stainless steel

ZrN thin films were deposited on AISI 304 stainless steel (304SS) by unbalanced magnetron sputtering (UBMS). Afterwards, the specimens were annealed at 1000 °C in vacuum (4 × 10−6 Torr) for a duration ranging from 1 to 4 h. The purpose of this study was to investigate the oxidation behavior and corrosion resistance of the vacuum annealed ZrN-coated 304SS prepared by UBMS method. The results of X-ray diffraction indicated that ZrN remained as the major phase in the oxidized thin films even after heat treating at 1000 °C for 4 h in vacuum. The surface grain size of the oxidized film increased with heat treating duration. The oxidized ZrN thin film on 304SS formed two oxide layers, the outer layer on the film surface and the inner layer nearby the film/substrate interface, which could be attributed to the simultaneous diffusion of oxygen from film surface and the edge of film/substrate interface, respectively. The results of potentiodynamic polarization scan showed that the corrosion resistance of the oxidized ZrN-coated 304SS was excellent and increased by at least 100 times relative to that of bare 304SS, based on the decrease of corrosion current density. The oxidized ZrN-coated 304SS also showed excellent durability after 500-hr salt spray test with corrosion area less than 4% for all specimens, and the oxidized ZrN films showed better durability than the as-deposited ZrN film in salt spray test. The results suggested that the electrical conductivity of the film may be a significant factor on Icorr, and the relative corrosion resistance of ZrN and ZrO2 in NaCl solution may also play an important role in salt spray test. The fully oxidized ZrN thin film showed high corrosion resistance and remained intact on 304SS substrate after potentiodynamic polarization scan, which was associated with the enhanced adhesion by the interdiffusion layer due to heat treatment. The adhesive problem of ZrO2 on stainless steel could be solved either with or without ZrN interlayer, if the vacuum annealing could produce a large interdiffusion zone and thereby enhancing the adhesion.

Microstructures and tribological properties of GLC coated 100Cr6 bearing steels

Low friction and hard amorphous carbon films were fabricated on 100Cr6 bearing steels via the unbalanced magnetron sputtering method. This paper studied the effect of graphite-like carbon (GLC) coatings on the wear resistance of 100Cr6, which are widely used in textile rings. The microstructures of the GLC coatings were investigated using scanning electron microscope (SEM), atomic force microscope (AFM), energy dispersive Spectrometer (EDS) and Raman. A comparative analysis using a ball-on-disc tribometer was carried out on 100Cr6 bearing steels with GLC coatings and those that had chromium-electroplated coatings. It was demonstrated that the GLC films on 100Cr6 presented better tribological properties, and the corresponding wear mechanisms were investigated. The tribological properties of GLC films under cryogenic treatment (−196 °C), annealing at temperatures of 300 °C and 350 °C were characterized. It was revealed that the friction coefficients decreased after using three kinds of treatments above.

On-Chip Evaluation of DNA Methylation with Electrochemical Combined Bisulfite Restriction Analysis Utilizing a Carbon Film Containing a Nanocrystalline Structure.

This paper reports an on-chip electrochemical assessment of the DNA methylation status in genomic DNA on a conductive nanocarbon film electrode realized with combined bisulfite restriction analysis (COBRA). The film electrode consists of sp2 and sp3 hybrid bonds and is fabricated with an unbalanced magnetron (UBM) sputtering method. First, we studied the effect of the sp2/sp3 ratio of the UBM nanocarbon film electrode with p-aminophenol, which is a major electro-active product of the labeling enzyme from p-aminophenol phosphate. The signal current for p-aminophenol increases as the sp2 content in the UBM nanocarbon film electrode increases because of the π-π interaction between aromatic p-aminophenol and the graphene-like sp2 structure. Furthermore, the capacitative current at the UBM nanocarbon film electrode was successfully reduced by about 1 order of magnitude thanks to the angstrom-level surface flatness. Therefore, a high signal-to-noise ratio was achieved compared with that of conventional electrodes. Then, after performing an ELISA-like hybridization assay with a restriction enzyme, we undertook an electrochemical evaluation of the cytosine methylation status in DNA by measuring the oxidation current derived from p-aminophenol. When the target cytosine in the analyte sequence is methylated (unmethylated), the restriction enzyme of HpyCH4IV is able (unable) to cleave the sequence, that is, the detection probe cannot (can) hybridize. We succeeded in estimating the methylation ratio at a site-specific CpG site from the peak current of a cyclic voltammogram obtained from a PCR product solution ranging from 0.01 to 1 nM.

The Influence of the Negative Bias of TiAlN/ABS Film Composition

By increasing the negative bias assisted sputter deposition in an unbalanced magnetron sputtering method for the preparation of TiAlN/ABS film for improving the wear resistance, the surface hardness and gloss of the polymer material. This article focuses on the impact of the substrate negative bias the composition of the film. The results: The film contains TiAlN, TiN, AlN chemical substance. With increasing of bias the content of these types of substances gradually increased. TiAlN film contains at most when the negative bias is 60V.

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.

Characteristics of Sputtered ZnO Thin Films for an Inverted Organic Solar Cell.

Several research groups have claimed high energy conversion efficiency in organic solar cells. However, it still has low efficiency and is unstable, because organic materials are easily oxidized by atmospheric humidity and UV light. In this work, ZnO thin film as the blocking layer attributed to the interference of the injection of the hole from the P3HT and no charge carrier recombination. We obtained the maximum power conversion efficiency of 1.9% under AM 1.5 G spectral illumination of 100 MWcm(-2), when we used a ZnO film of 60 nm and the optimized P3HT:PCBM, and Au as the back electrode to solve the reaction problem of Al electrode and to control the work function between the HOMO level of P3HT and the energy level of the metal electrode. Power conversion efficiency of inverted organic solar cell (IOSC) is significantly dependent on the thickness of the ZnO thin film deposited by unbalanced magnetron sputtering method. Also, the stability of IOSC is measured under ambient conditions.

Characteristics of Nitrogen Doped Diamond-Like Carbon Films Prepared by Unbalanced Magnetron Sputtering for Electronic Devices

Synthetic diamond-like carbon (DLC) is a carbon-based material used mainly in cutting tool coatings and as an abrasive material. The market for DLC has expanded into electronics, optics, and acoustics because of its distinct electrical and optical properties. In this work, n-doped DLC (N:DLC) films were deposited on p-type silicon substrates using an unbalanced magnetron sputtering (UBMS) method. We investigated the effect of the working pressure on the microstructure and electrical properties of n-doped DLC films. The structural properties of N:DLC films were investigated by Raman spectroscopy and SEM-EDX, and the electrical properties of films were investigated by observing the changes in the resistivity and current-voltage (I-V) properties. The N:DLC films prepared by UBMS in this study demonstrated good conducting and physical properties with n-doping.

Oxidation behavior of amorphous boron carbide film deposited using the unbalanced magnetron sputtering method

The oxidation behavior of amorphous boron carbide thin film, deposited using the unbalanced magnetron sputtering method, was investigated. Weight change was measured using thermo gravity analysis under the condition of dry flowing air (100 mL/min), with increasing temperature of up to 1200 ℃ as well as at constant temperature. For the isothermal oxidation experiment, dry Ar gas was used until the oxidation temperature was stabilized; then, the Ar gas was replaced with dry air. The weight gain was negligibly small under 600 ℃ and then increased rapidly with increasing temperature. The isothermal oxidation curves show decreasing weight gain rate with oxidation time. At 1000 ℃, the weight gain was shown to become negative after a certain period. This isothermal weight change behavior can be ascribed to diffusional oxidation and weight loss due to the evaporation of liquid boron oxide. The possibility of the transition of boron oxide to boric acid at room temperature under an ambient atmosphere was also discussed.

Thickness Effects of TiC Interlayer on Tribological Properties of Diamond-Like Carbon Prepared by Unbalanced Magnetron Sputtering Method.

We investigated the tribological properties of diamond-like carbon (DLC) films prepared with TiC interlayer of various thicknesses as the adhesive layer. DLC and TiC thin films were prepared using unbalanced magnetron (UBM) sputtering method using graphite and titanium as targets. TiC films as the interlayer were deposited under DLC films and various physical, tribological, and structural properties of the films fabricated with various TiC interlayer thicknesses were investigated. With various TiC interlayer thicknesses under DLC films, the tribological properties of films were improved with increasing thickness and the DLC/TiC layer fabricated by unbalanced magnetron sputtering method are exhibited maximum high hardness over 27 GPa and high elastic modulus over 242 GPa, and a smooth surface below 0.09 nm.

Wear and Friction Characteristics of AlN/Diamond-Like Carbon Hybrid Coatings on Aluminum Alloy

The use of diamond-like carbon (DLC) coatings has the potential to greatly improve the wear resistance and friction of aluminum alloys, but practical application has so far been limited by poor adhesion due to large difference in hardness and elasticity between the two materials. This study investigates the deposition of DLC onto an Al-alloy using an intermediate AlN layer with a graded hardness to create a hybrid coating. By controlling the hardness of the AlN film, it was found that the wear life of the DLC film could be improved 80-fold compared to a DLC film deposited directly onto Al-alloy. Furthermore, it was demonstrated through finite element simulation that creating a hardness gradient in the AlN intermediate layer reduces the distribution of stress in the DLC film, while also increasing the force of adhesion between the DLC and AlN layers. Given that both the DLC and AlN films were deposited using the same unbalanced magnetron sputtering method, this process is considered to represent a simple and effective means of improving the wear resistance of Al-alloy components commonly used within the aerospace and automotive industries.

Silicon carbide thin film deposited by unbalanced magnetron sputtering method

Silicon carbide thin film deposited by unbalanced magnetron sputtering method

Effect of deposition pressure on the electrical properties of nitrogen-doped amorphous carbon films

In this study, we investigate the effect of the deposition pressure on the electrical properties of nitrogen-doped amorphous carbon (a-C:N) films deposited by using an unbalanced DC magnetron sputtering method. As the deposition pressure is decreased from 9 to 1 mTorr, the resistivity decreases from 7.88 to 2.68 × 10 −2 Ω·cm while the deposition rate increases from 3.5 to 4.4 nm/min. The decrease in resistivity is caused by increases in both the carrier concentration and mobility. As the pressure is decreased, the carrier concentration increases from 1.9 × 1014 to 7.8 × 1020 cm −3, and the mobility increases from 0.01 to 0.3 cm2/V·sec. X-ray photoelectron spectroscopy and Raman spectroscopy reveal that the improved electrical properties of the film deposited at a lower pressure are the result of a higher fraction of sp2 bonding.