Cathodic Arc Plasma Research Articles

Optimization and Analysis of Dry Sliding Wear Behavior of AlCrTiSiN Coated SKD61 Steel Using Response Surface Methodology

The aim of this research is to investigate the wear behavior of SKD61 steel coated with AlCrTiSiN using the Filtered cathodic arc plasma deposition coating method while adhering to VDI 3198 standards for coating adhesion assessment. Dry sliding wear tests, conducted according to ASTM G133-05. The experiment is designed using response surface methodology (RSM) to determine the response parameter as the wear rate, with independent parameters of interest including load, sliding velocity, and sliding distance ranging from 5 to 11N, 0.1 to 0.2 m/s, and 250 to 550 m, respectively. Additionally, wear characteristics are analyzed using SEM-EDS analysis. The wear test results demonstrate that load had the most significant impact on the wear rate, followed by distance and speed, respectively. The target of achieving minimal wear rate was attained with a load of 5 N, a sliding velocity of 0.11 m/s, and a sliding distance of 550 m. Model significance testing revealed that the determination coefficient (R2) and adjusted determination coefficient values, indicating the accuracy of the model, were equal to 93.96% and 88.53%, respectively.

High-efficiency ZnO:Al/p-GaN epitaxial heterojunction photocatalysts for antimicrobial application

Highly efficient ZnO:Al (AZO) thin-film-type photocatalysts with thicknesses of approximately 400 nm are deposited on (0001) p-GaN at deposition temperature of 400 °C via cathodic arc plasma evaporation to develop epitaxial heterojunction photocatalysts for antimicrobial applications. AZO films with a multidomain structure are deposited on (0001) sapphire to compare their antimicrobial performances. Their microstructural and electrical properties, depth-resolved cathodoluminescence spectra, and antibacterial activity are investigated. The results of antimicrobial activity analysis indicate that the AZO/p-GaN heterojunction photocatalysts exhibit better antibacterial activity against Staphylococcus aureus than the multidomain AZO films deposited on (0001) sapphire. The improvement in antibacterial activity is attributed to the built-in electric field formed by the AZO/p-GaN heterojunction, which results in enhanced separation between photogenerated electrons and holes under ultraviolet A irradiation. In addition, the AZO/p-GaN heterojunction photocatalysts possess higher concentrations of oxygen vacancies, defect levels, conductivities, and carrier mobilities than the multidomain AZO films. Therefore, they exhibit better antibacterial activity by inhibiting the growth of S. aureus. An excellent antimicrobial thin film-type AZO/p-GaN epitaxial heterojunction photocatalysts is successfully developed in this study for application in the microbial control field.

Sustainable super-hard and thick nanodiamond composite film deposited on cemented carbide substrates with an interfacial Al-interlayer

Super-hard nanodiamond composite (NDC) films, synthesized via cathodic arc plasma deposition on unheated WC − Co substrates, offer an eco-friendly solution for cutting tools. A 100 nm-thick Al-interlayer mitigates Co catalytic effects, improving adhesion and yielding smooth and dense 10 µm-thick films at a deposition rate of 3.3 μm/hr. These grain-boundary-rich nanostructured films, with an impressive 58 GPa hardness attributed to a substantial 70 % C sp3 fraction, prove optimal for hard coatings. The Al-interlayer effectively suppresses Co catalytic effects, forming a dense Al-oxide layer, enhancing film hardness and adhesion (Lcr = 18.6 N). NDC films present a promising eco-friendly option for high-performance hard coatings.

Facilely Fabricated Zero-Bias Silicon-Based Plasmonic Photodetector in the Near-Infrared Region with a Schottky Barrier Properly Controlled by Nanoalloys.

Plasmonic Schottky devices have attracted considerable attention for use in practical applications based on photoelectric conversion, because they enable light to be harvested below the bandgap of semiconductors. In particular, silicon-based (Si) plasmonic Schottky devices have great potential for useful photodetection in the near-infrared region. However, the internal quantum efficiency (IQE) values of previously reported devices are low because the Schottky barrier is excessively high. Here, we are the first to develop AuAg nanoalloy-n-type Si plasmonic Schottky devices by cathodic arc plasma deposition. Interestingly, it is found that a novel nanostructure, which leads to the improvement of responsivities, is formed. Moreover, these plasmonic nanostructures can be fabricated in only ∼1 min. The fabricated AuAg nanoparticle-film structure enables proper control of the Schottky barrier height and increases the area of the Schottky interface for electron transfer. As a result, the considerably enhanced IQE of our device at a telecommunication wavelength of 1310 nm (1550 nm) without external bias is 4.6 (6.5) times higher than those in previous reports, and these responsivities are a record high. This approach can be applied to realize efficient photodetection in the NIR region and extend the use of light below the bandgap of semiconductors. This paves the way for future application advancements in a variety of fields, including photodetection, imaging, photovoltaics, and photochemistry.

Formation Processes of a Solid Electrolyte Interphase at a Silicon/Sulfide Electrolyte Interface in a Model All-Solid-State Li-Ion Battery.

Understanding the electrochemical reactions at the interface between a Si anode and a solid sulfide electrolyte is essential in improving the cycle stabilities of Si anodes in all-solid-state batteries (ASSBs). Highly dense Si films with very low roughnesses of <1 nm were fabricated at room temperature via cathodic arc plasma deposition, which led to the formation of a Si/sulfide electrolyte model interface. Li (de)alloying through the model interface hardly occurred during the first cycle, whereas it proceeded stably in subsequent cycles. Hard X-ray photoelectron spectroscopy and neutron reflectometry directly revealed that the reduction or oxidation of the interfacial component or Li3PS4 electrolyte occurred during the first cycle. Consequently, an interfacial layer with a thickness of 13 nm and primarily composed of Li2S, SiS2, and P2S5 glasses was formed during the first cycle. The interfacial layer acted as a Li-conductive, electron-insulating solid electrolyte interphase (SEI) that provided reversible (de)lithiation. Our model interface directly demonstrates the electrochemical reaction processes at the Si/Li3PS4 interface and provides insights into the structures and electrochemical properties of SEIs to activate the (de)lithiation of Si anodes using a sulfide electrolyte.

Interfacial structure changes between amorphous silicon anode/liquid electrolyte using a highly dense and flat model electrode

Changes in the interfacial structures of the amorphous silicon (a-Si) anode/organic electrolyte interfaces in lithium-ion batteries were investigated using highly dense a-Si films fabricated by cathodic arc plasma deposition as a model electrode. Raman spectroscopy, transmission electron microscopy (TEM), and X-ray reflectivity revealed that the Si films were grown in an amorphous state with an atomically flat surface. The a-Si films exhibited lithium alloying and de-alloying reactions, with a large irreversible capacity during the first cycle. The irreversible capacity was derived from the formation of a solid electrolyte interphase (SEI) along with an incompletely de-alloyed Li-Si phase, as confirmed by ex situ TEM and X-ray photoelectron spectroscopy observations. The discharge and charge capacities of the Si films gradually decreased in the subsequent cycles, despite the fact that no further SEI formation or cracking of the Si layer occurred. Scanning electron microscopy observations combined with energy-dispersive X-ray spectroscopy revealed the miniaturization of the a-Si film in the surface region to generate domains measuring less than a few hundred nanometers. These results suggest that delamination and miniaturization of the a-Si nanodomains from the electrode surface are partly responsible for degradation of the a-Si anode.

EFFECT OF PULSED SUBSTRATE BIAS ON THE STRUCTURE AND PROPERTIES OF NITRIDE COATINGS DEPOSITED BY FILTERED CATHODIC ARC PLASMA

The results of studies of nitride coatings deposited using a cathodic vacuum arc plasma source with a rectilinear type filter are presented. The effect of parameters of high voltage substrate bias pulses on the deposition rate, composition, structure and mechanical properties of coatings based on TiN and CrN, including multi-component ones with the additions of Al, Si, Zr, Y, Re, Nb, Hf, was analyzed. With different regimes of bias potential the formation of coatings with a nanocrystalline cubic structure (of the NaCl type) and close to stoichiometric nitrogen content and high hardness of 25…36 GPa is ensured. It was found that changing the amplitude, duration and frequency of pulses allows to effectively controlling the morphology, size of crystallites, texture and stress level in coatings, which effects their mechanical properties. The use of a pulse bias potential with an amplitude of 1…2 kV, a frequency of 10…20 kHz and duty cycle of 10…15% makes it possible to form a homogeneous dense nanostructure with a [110] or [100] texture, an optimal stress level 4…5 GPa and a smooth surface in coatings of different compositions. It is shown that such a structure provides improved resistance of coatings to various types of wear. Unequivocal correlations were not found between the hardness of the coatings, the modulus of elasticity and their wear.

Catalytic NH3 oxidation affected by the nanometric roughness of the platinum overlayer.

Pulsed cathodic arc-plasma deposition was employed to create a few nanometre-thick Pt overlayer on a 50 μm-thick Fe-Cr-Al metal (SUS) foil, resulting in an effective NH3 oxidation catalyst fabrication. This catalyst exhibited a turnover frequency (TOF) exceeding 100 times that of Pt nanoparticles. In this study, Pt overlayer catalysts with varying degrees of surface roughness were fabricated using different metal foil substrates: mirror-polished (Pt/p-SUS), unpolished (Pt/SUS) and roughened by the formation of a surface oxide layer (Pt/Al2O3/SUS). The nanoscale roughness was comprehensively analysed using electron microscopy, laser scanning confocal microscopy and chemisorption techniques. NH3 oxidation activity, measured at 200 °C, followed an increasing trend in the order of Pt/Al2O3/SUS < Pt/SUS < Pt/p-SUS, despite a decrease in the apparent Pt surface area in the same order. Consequently, the calculated TOF was markedly higher for Pt/p-SUS (267 min-1) compared to Pt/SUS (107 min-1) and Pt/Al2O3/SUS (≤22 min-1). The smooth Pt overlayer surface also favoured N2 yield over N2O at this temperature. This discovery enhances our fundamental understanding of high-TOF NH3 oxidation over Pt overlayer catalysts, which holds significance for the advancement and industrial implementation of selective NH3 oxidation processes.

Optical emission spectroscopy of vanadium cathodic arc plasma at different nitrogen pressure

Optical emission spectroscopy studies of vanadium plasma in a cathodic-arc discharge in a nitrogen atmosphere have been carried out. Spectral lines of neutral atoms and ions of the cathode material V, V1+, and V2+, and nitrogen N2 and N2+ were observed in the discharge plasma. Analysis and comparison of the intensity of vanadium and nitrogen spectral lines as a function of nitrogen pressure showed that in vacuum excited ions V2+ and V+ are registered, with increasing pressure, the lines V+*, N2*, and N2+* are observed, and at pressures above 0.5 Pa, the neutral vanadium lines are additionally registered. The electron temperature of Te decreases from 5.9 to 3–4 eV with increasing pressure. Studies of cross-sectional scanning electron microscopy images of VN coatings deposited at different nitrogen pressures have shown that a dense, homogeneous, fine-grained microstructure is formed in the coating when the number of neutral V in the plasma is low, while in the presence of a large number of neutrals, the coating structure changes to a dense structure with columnar growth.

New Anodic Discoloration Materials Applying Energy-Storage Electrochromic Device.

We have assessed new anodic coloring materials that can be used as ion storage layers in complementary energy storage electrochromic devices (ESECDs) to enhance their electrochromic storage performance. In our study, we fabricated counter electrodes (ion storage layers) using an IrO2-doping NiO (Ir:NiO) film through cathodic arc plasma (CAP) with varying surface charge capacities. We have also investigated the influence of a MoO3-doped WO3 (Mo:WO3) film using various Ar/O2 gas flow ratios (1/4, 1/5, and 1/6, respectively). The ESECDs used in the demonstration were 10 × 10 cm2 in size and achieved an optical transmittance modulation of the Ir:NiO ESECDs (glass/ITO/ Mo:WO3/gel polymer electrolytes/ Ir:NiO/ITO/glass), with ΔT = 53.3% (from Tbleaching (66.6%) to Tcoloration (13.1%)). The ESECDs had a quick coloration time of 3.58 s, a rapid bleaching time of 1.24 s, and a high cycling durability. Furthermore, it remained at a 45% transmittance modulation level even after 3000 cycles. New anodic materials can thereby provide an alternative to traditional active materials for bi-functional electrochromic batteries.

Topography of high-speed steel substrates sputter cleaned by an Ar/Ti cathodic arc plasma

Hard coated high-speed steels are often used for tooling applications and consist of three different microstructural constituents: a martensitic matrix, M6C and MC carbides. The behavior of these three during the various tool manufacturing steps has a detrimental effect on the final tool performance. The focus of the current work is the surface topography change due to variation of the substrate bias voltage applied during the Ar/Ti arc plasma sputter cleaning process which changed the sputtering behavior of the high-speed steel's microstructural constituents and the appearance of droplets on the sputtered surface. The surface topography was characterized by laser confocal and scanning electron microscopy. Furthermore, microstructural analysis was carried out on cross-section lamellae prepared by a focus ion beam technique and analyzed by transmission electron microscopy. At each of the three investigated substrate bias voltages (Ub) of −600, −800 and −1000 V during the Ar/Ti arc plasma sputter cleaning process, the mentioned microstructural constituents behaved differently. At an Ub threshold of −600 V, sputter erosion starts at M6C carbides in an inhomogeneous material erosion pattern. At −800 V, a homogeneous sputter behavior was established for the entire sample. M6C carbides showed the highest sputter erosion rate, on MC carbides Ti deposition occurred instead of sputter erosion, and the martensitic matrix was smoothened, as peaks and exposed features were sputtered preferentially. As of Ub = −1000 V, the sputter erosion behavior of the martensitic matrix changed and exposed features were preserved. The reason for this change was identified to be Ti+ ion implantation indicated by Monte Carlo simulations and the associated increase of the matrix' cohesive strength, calculated using Density Functional Theory. The published results in this study will help to further utilize Ar/Ti arc plasma sputter cleaning processes for intentional surface topography design.

Determination of Cooling Rate and Temperature Gradient during Formation of Cathode Spot Craters in a Vacuum Arc

Due to the extreme thermal conditions and short lifetimes, experimental exploration of cathode spots in vacuum arcs is very difficult. The intensive heat in the cathode spot is believed to be generated by ion bombardment and by Joule heating. However, thermal conditions occurring inside the re-melted material in craters created by cathode spots are not accurately known. During the exposure to cathodic arc plasmas, an Al-Cr cathode’s surface was locally melted by successive ignition and extinction of cathode spots. The melted layer, that quickly solidified, was characterized by the formation of several thin layers with a thickness of a few micrometers that were stacked on top of each other. The corresponding solidification patterns displayed cellular and dendritic microstructures. A phase field-based model was used to simulate and determine the thermal process conditions that led to the dendritic structures observed within the re-melted layer. Different combinations of cooling rates and temperature gradients were numerical explored to determine the most probable thermal conditions under which the cathode material re-solidifies. The results showed that the material in the vicinity of the cathode spot crater re-solidified under the condition of a cooling rate of about 3 × 105 K/s and a temperature gradient of about 6 × 107 K/m. These results constitute valuable data for the validation of numerical models dedicated to cathode spot formation.

Structure and Properties of CrN/TiN Multilayer Coatings Produced by Cathodic Arc Plasma Deposition on Copper and Beryllium-Copper Alloy

Structure and Properties of CrN/TiN Multilayer Coatings Produced by Cathodic Arc Plasma Deposition on Copper and Beryllium-Copper Alloy

Applied IrO2 Buffer Layer as a Great Promoter on Ti-Doping V2O5 Electrode to Enhance Electrochromic Device Properties.

Electrochromic devices (ECDs) are a promising material for smart windows that are capable of transmittance variation. However, ECDs are still too expensive to achieve a wide market reach. Reducing fabrication cost remains a challenge. In this study, we inserted an IrO2 buffer layer on Ti-doped V2O5 (Ti:V2O5) as a counter electrode using various Ar/O2 gas flow ratios (1/2, 1/2.5, 1/3 and 1/3.5) in the fabrication process. The buffered-ECD resulted in a larger cyclic voltammetry (CV) area and the best surface average roughness (Ra = 3.91 nm) to promote electrochromic performance. It was fabricated using the low-cost, fast deposition process of vacuum cathodic arc plasma (CAP). This study investigates the influence of the IrO2 buffer/Ti:V2O5 electrode on ECD electrochemical and optical properties, in terms of color efficiency (CE) and cycle durability. The buffered ECD (glass/ITO/WO3/liquid electrolyte/IrO2 buffer/Ti:V2O5/ITO/glass) demonstrated excellent optical transmittance modulation; ∆T = 57% (from Tbleaching (67%) to Tcoloring (10%)) at 633 nm, which was higher than without the buffer (ITO/WO3/liquid electrolyte/Ti:V2O5/ITO) (∆T = 36%). In addition, by means of an IrO2 buffer, the ECD exhibited high coloration efficiency of 96.1 cm2/mC and good durability, which decayed by only 2% after 1000 cycles.

Sliding wear performance of TiAl-based nitride coatings deposited on ADI by cathodic arc deposition and plasma based ion implantation and deposition

ABSTRACT This work studied the sliding wear performance of TiAl-based nitride coatings synthesized on austempered ductile iron (ADI) by cathodic arc deposition (CAD) and plasma-based ion implantation and deposition (PBIID). Monolayer CAD TiAlN films and bilayer CAD and PBIID TiAl/TiAlN films deposited on an experimental device were analyzed and benchmarked against a commercial bilayer CAD film. Sliding wear was evaluated in a pin–on–disc tribometer. Two test conditions were employed, one intended to prevent damage (low load, short distance) and another intended to promote damage (higher load, longer distance). Regarding low load tests, all coated samples showed friction coefficients of 0.40–0.45 and negligible wear. Regarding high load tests, all coated variants exhibited lower or equal disc and pin wear rates with respect to uncoated ADI. In addition, coated samples displayed steady-state friction coefficients between 0.2 and 0.6 while uncoated ADI steady-state coefficients between 0.6 and 0.85.

Ti–6Al–4V alloy deposition characteristics at electrode-negative polarity in the cold metal transfer–gas metal arc process

Although wire arc additive manufacturing (WAAM) of Ti alloys using gas metal arc yields a high deposition rate, cathode spots exhibit unstable behavior. In this study, the cold-metal-transfer process and an electrode-negative (EN) polarity were used in the WAAM process of the Ti–6Al–4V alloy. High-speed imaging was performed to investigate the mechanisms to stabilize cathode plasma jets, arc plasma, and molten metal transfer in the EN polarity. Arc plasma and cathode jets had the same direction, and sound cathode jets were shrouded by arc plasma in the EN mode. The metal transfer was also stabilized by balanced plasma formation under the EN mode, and inconsistent wire melting under the electrode-positive (EP) mode was mitigated. In the deposition test using the EN mode, distributed heating of the substrate and depressed molten pool were observed, which resulted in a 21.0% increase in the bead width and 27% decrease in the wetting angle compared with the EP mode. This study demonstrated that the instability of the gas metal arc WAAM process of Ti alloys can be overcome with the EN-mode cold metal arc process.

The Properties of Zr, Ti, Al and Si Nitride-Based Multilayer Coatings Obtained By Cathodic Arc Plasma Deposition

The Properties of Zr, Ti, Al and Si Nitride-Based Multilayer Coatings Obtained By Cathodic Arc Plasma Deposition

Investigation of the plasma composition of a discharge with a self-heating hollow cathode and an active anode in a gas mixture with titanium and hexamethyldisilazane vapors

The analysis of composition of low-pressure (~0.1-1 mTorr) hollow cathode arc plasma in Ar+N2 gas mixture with Ti+hexamethyldisilazane vapors was carried out by optical emission spectroscopy. The influence of HMDS flow rate (1-10 g/h), discharge current (10-50 A) and Ti-vapors flow on hexamethyldisilazane decomposition degree and plasma composition and was investigated. The proposed plasma activation method provides both an intense flow and a high activation degree of metal vapors, and a sufficient decomposition degree of precursor vapors for the formation of solid TiSiCN coatings at a high deposition rate. Test coatings with a thickness of 6 microns and a hardness of 31 GPa were obtained in 1 hour at 400ºC.

Low-Temperature Deposition of Transparent Conducting Films Applied to Flexible Electrochromic Devices.

Here, we compare two different transparent conducting oxides (TCOs), namely indium tin oxide (ITO) and indium zinc tin oxide (IZTO), fabricated as transparent conducting films using processes that require different temperatures. ITO and IZTO films were prepared at 230 °C and at room temperature, respectively, on glass and polyethylene terephthalate (PET) substrates using reactive magnetron sputtering. Electrochromic WO3 films deposited on ITO-based and IZTO-based ECDs using vacuum cathodic arc plasma (CAP) were investigated. IZTO-based ECDs have higher optical transmittance modulation, ΔT = 63% [from Tbleaching (90.01%) to Tcoloration (28.51%)], than ITO-based ECDs, ΔT = 59%. ECDs consisted of a working electrochromic electrode (WO3/IZTO/PET) and a counter-electrode (Pt mesh) in a 0.2 M LiClO4/perchlorate (LiClO4/PC) liquid electrolyte solution with an active area of 3 cm × 4 cm a calculated bleaching time tc of 21.01 s and a coloration time tb of 4.7 s with varying potential from −1.3 V (coloration potential, Vc) to 0.3 V (bleaching potential, Vb).

Preparation of High-Performance Metal-Free UV/Near Infrared-Shielding Films for Human Skin Protection.

A series of metal-free UV/near infrared (NIR)-shielding coatings are successfully fabricated by shielded cathodic arc plasma evaporation (CAPE) and substrate-biased RF magnetron sputtering processes. The UV/NIR-shielding coatings comprising quarter-wave stacks of TiO2/SiO2 multilayers and high-conductivity sputter-deposited ITO films with a thickness in the range of 200–600 nm could block IRA and IRB radiations, respectively. The total thicknesses of UV/near infrared-shielding films are in the range from 375 nm to 1513.8 nm. The anatase-phase TiO2 films with absorption edge located at ~375 nm were deposited by shielded CAPE at ~100 °C. Further, the well-crystallized ITO films were found to have high free-electron concentrations (1.12 × 1021 cm−3), resulting in strong absorption of IRB due to the plasmon resonance absorption. The optimal optical design and ITO film thickness were investigated, and the TiO2(SiO2/TiO2)3 multilayer combined with an ITO film thickness of 400 nm was found to provide a high NIR-shielding rate of 94.8%, UVB to UVA-shielding rate of 92.7%, and average visible light transmittance of 68.1%. Further, human skin cells protected by a UV/NIR-shielding coating showed significantly decreased reactive oxygen species generation and inflammatory cytokine expression as compared to those of unprotected cells. The results demonstrate that the development of multifunction coatings have potential for transparent heat insulation windows and human skin protection against UV/IR radiations.