Effect Of Bias Voltage Research Articles

Microstructure, mechanical and oxygen-deficient lead-bismuth eutectic corrosion properties of FeCrAlTiMo high-entropy alloy coatings for fuel claddings

The FeCrAlTiMo high-entropy alloy (HEA) coatings were deposited on the ferritic/martensitic (F/M) steel fuel cladding tubes by magnetron sputtering technology to improve their lead-bismuth eutectic (LBE) corrosion resistance. The effects of bias voltage on the microstructure, mechanical and LBE corrosion properties of the FeCrAlTiMo coatings were systematically investigated. The LBE corrosion test shows that the coatings with a bias voltage of −150 V exhibit the best oxidation resistance after exposed to the oxygen-deficient LBE at 600 °C for 500 h, and can be used as a protective candidate coating material for lead-cooled fast reactor (LFR) application. The high-temperature LBE corrosion mechanism of the FeCrAlTiMo coatings under deficient oxygen concentration was also discussed in detail.

Effects of substrate temperature and bias voltage on mechanical and tribological properties of cosputtered (TiZrHfTa)Nx films

This study investigated the effects of substrate temperature and bias voltage on the mechanical and tribological properties of cosputtered (TiZrHfTa)Nx films. A substrate temperature ranging from room temperature to 400 °C, and a bias voltage ranging from 0 to −150 V were selected as the sputtering variables. A mixture gas with a nitrogen flow ratio (fN2 = N2/[N2 + Ar]) of 0.2 was used to fabricate nitride films. Nanoindentation and wear tests were conducted to assess the performance of the fabricated (TiZrHfTa)Nx films, which formed a single face-centered cubic structure. Increasing the substrate temperature resulted in grain growth, lattice shrinkage, and nonsignificant improvements in mechanical properties. Applying a bias voltage of −150 V to the substrate increased the hardness of the fabricated film to a peak of 32.7 GPa compared with that of 29.3 GPa for the film prepared in an electronically grounded state. The (Ti0.24Zr0.22Hf0.19Ta0.35)N0.66 film prepared at a bias voltage of 0 V and substrate temperature of 400 °C exhibited the optimal combination of mechanical and tribological properties (hardness, 30.0 GPa; elastic modulus, 325 GPa; and wear rate, 1.16 × 10−5 mm3/Nm).

Quantitative characterization on influence of surface particles on corrosion behavior of multiarc ion plated CrAlN coatings

Surface particles on multiarc ion plated coatings are common defects, and their influence on the service performance of coatings is rarely defined. The CrAlN coatings were deposited on the tungsten steel (YG8) substrates using multiarc ion plating. The effects of the substrate bias voltages and nitrogen flow rates on the quantity of the surface particles were investigated, and the influence of the surface particles on the corrosion resistance of the coatings is quantitatively characterized. The morphology of surface particles was characterized using a scanning electron microscope. The quantity of the surface particles was counted by image software. The corrosion resistance of the coatings was evaluated through an electrochemical workstation. The results show that the quantity of surface particles decreased with the increase in the substrate bias voltage and nitrogen flow rate. The corrosion resistance of the coatings showed a positive correlation with the quantity of the surface particles, and it decreased dramatically when the quantity of the surface particles exceeded 111/10 000 μm2. The corrosion mechanism of the coatings was attributed to the defect-induced pitting corrosion.

The effects of bias voltage and magnetic field on optical properties of boron phosphide monolayer

The effects of bias voltage and magnetic field on optical properties of boron phosphide monolayer

The key role in the structure and properties of a novel CrNiTiMo high-entropy alloys films prepared by magnetron sputtering: Bias voltage

In this study, CrNiTiMo high-entropy alloys films were prepared on 304 stainless steel and silicon wafer substrates by direct current magnetron sputtering and the effects of bias voltages (0 to −200 V) on microstructure, chemical composition, hardness and corrosion resistance were investigated. The results showed that the surface of the CrNiTiMo HEAs films exhibited equiaxed nanoparticles and are composed of uniformly distributed Cr, Ni, Ti, and Mo elements. Meanwhile, the films developed a columnar structure and formed a biphasic structure with body-centered cubic solid solution and amorphous phases. The roughness decreased and then increased with increasing bias voltage, and the film deposited at −50 V had the lowest roughness (1.02 ± 01 nm), which also had a maximum hardness of approximately 9.52 ± 0.2 GPa and a maximum elastic modulus of approximately 187 ± 6 GPa. In addition, all films showed better corrosion resistance compared to 304 stainless steel substrates at 3.5 wt% NaCl solution. The corrosion current density (icorr) of the films decreased and then increased with increasing bias voltages and reached the lowest icorr of about 2.49 × 10−8A/cm2, indicating that the films deposited at a bias voltage of −50 V had the best corrosion resistance. These was attributed to the formation of the passivation films mainly composed of TiO2 and Cr2O3 and the improvement of the surface quality of the film as well as the refinement of the columnar structure and particles.

Effect of bias voltage on the structure and properties of CoCrFeNi high entropy alloy thin films prepared by magnetron sputtering

In this study, CoCrFeNi high entropy alloy thin films were prepared on 304 stainless steel and single crystal Si substrates using the direct-current magnetron sputtering process under different bias voltages. The effects of these bias voltages on the film micrographs, phase structure, surface roughness, corrosion resistance, and mechanical characteristics of thin films were studied by a scanning electron microscope, transmission electron microscope, X-ray diffractometer, atomic force microscope, electrochemical workstation and nanoindentation tester, respectively. The results indicated that all films exhibited equiaxed nano-scale grains and developed a columnar structure. Fe, Co, Cr, and Ni were uniformly dispersed in all films and all films displayed face centered cubic solid solution (FCC). At a bias voltage of 0 V, the CoCrFeNi HEAs film formed a FCC single phase. With increasing bias voltage, the crystallinity decreased and then increased, reaching the worst crystalline state at bias voltage of −200 V due to the fact that the structure of the film was composed of FCC nanocrystalline and amorphous biphasic structure. Meanwhile, the surfaces of the film prepared at bias voltage of −200 V exhibited the densest structures and the least roughness, with grain sizes reaching a minimum value of approximately 10 nm. In addition, columnar grains of the film prepared at a bias voltage of −200 V displayed the densest state and had the least size, thus this film displayed the best corrosion resistance of a minimum value 1.51 × 10−7 A/cm2, a maximum hardness of approximately 11.18 ± 0.2 GPa and a maximum elastic modulus of approximately 193 ± 2.8 GPa. The passivation films of CoCrFeNi HEAs films were mainly composed of Cr2O3.

Correlation between Crystallite Characteristics and the Properties of Copper Thin Film Deposited by Magnetron Sputtering: Bias Voltage Effect

This work investigates the properties of copper thin films deposited by magnetron sputtering. The substrate is biased by a negative voltage (Vs), which controls the energy ions bombardment during the deposition of the thin films. In order to focus solely on the ions energy contribution, the power supply was fixed and the working pressure was selected at 5 Pa. This ensures energetic sputtered particles completely thermalized, by a sufficient number of collisions with the Argon gas. X-ray diffraction analysis revealed that substrate voltage Vs affects essentially the structure and size of the formed crystallites. The preferred orientation (111) and the larger crystallite size (30 nm) were achieved at Vs = - 60 V. The Cu (111)/(200) peak intensity ratio is maximal (12.55) at - 60 V, corresponding to the lowest resistivity value (6.33 mW.cm). Optimum corrosion resistance of the deposited thin film was achieved at -60 V. At high crystallite sizes, nanoindentation analysis showed a thin film that is more elastic (133 GPa) and less hard (1.96 GPa).

PECVD technology deposition of high hardness a-C:H films on micro-drill surfaces: Substrate bias voltage effects

The plasma enhanced chemical vapor deposition (PECVD) technique was utilized to produce hydrogenated amorphous carbon (a-C:H) films. The overall structure of the films consists of a Cr/WC transition layer, a WC/a-C:H transition layer, and an a-C:H functional layer. The study investigated the effects of substrate bias voltages (SBVs) of −580 V, −660 V, −740 V, −820 V, and −900 V on the microstructure, mechanical, and tribological properties of a-C:H films. The findings indicate that different SBVs influence the ionic energy during the deposition of a-C:H films, consequently affecting the film growth. In this case, when the SBV is -820 V, C+ with sufficient energy will penetrate beneath the initial layer in the form of shallow injection. Therefore, compared to other experimental groups, the a-C:H films prepared under this condition have the lowest Ra value (0.42 nm), the highest sp3 CC bond content (39.88 %), the maximum hardness (31.6 GPa), the lowest friction coefficient (0.052), and the smallest wear rate (7.48 × 10−8 mm3/(N·m)), demonstrating significantly better mechanical and tribological properties. The a-C:H films, prepared at different SBVs, are deposited on micro-drill surfaces for hole drilling tests. The experimental results indicate that a-C:H films prepared at SBV of −820 V exhibit the satisfactory drilling performance due to the better mechanical and tribological properties. This is evident not only in the minimal surface wear of the film micro-drill after different drilling quantities but also by the satisfactory quality of the corresponding machined holes. The a-C:H film micro-drill prepared at SBV of −820 V exhibited larger process capability index (CPK) values for the machined holes at 500, 1000, and 2000 hole numbers of 5.449, 3.693, and 3.263 respectively. During the 2000th drill on the printed circuit board (PCB) surface, the hole wall roughness (Rz) and nail head values of the machined hole were measured to be 10.6 μm and 1.3, respectively.

Effects of substrate bias voltage on conductivity and internal stress of TiN films

In order to make the service life of microelectronic devices longer, titanium nitride electrode films need to meet the requirements of high electrical conductivity and low internal stress. In this paper, the effect of substrate bias voltage on the properties of titanium nitride films prepared by direct current (DC) reactive magnetron sputtering was studied systematically. The changes of titanium nitride films properties were investigated in detail from the aspects of resistivity, growth rate, crystal orientation, roughness and internal stress. The results show that the introduction of substrate bias voltage is conducive to the formation of dense titanium nitride films. Considering that the resistivity and internal stress of titanium nitride film vary with substrate bias voltage, the film deposited at substrate bias voltage of -100 V is selected as the electrode film material with the best performance (resistivity of 47.5 μΩ·cm, roughness of 1.1 nm and internal stress of -5.6 GPa).

Effect and mechanism of bias voltage on microstructure and corrosion resistance of CrxNy coatings in proton-exchange membrane fuel cells

The key factor limiting the long-term commercial application of CrxNy coatings in the PEMFC is that these coatings easily grow into coarse columnar crystals with subsequent microcracks and pinholes, leading to a sharp decrease in corrosion resistance performance. In this view, a series of different substrate bias voltages were applied to deal with this problem. The results demonstrated that with applying a −120 V bias voltage on the substrate, the adhesion strength is double that of the CrxNy coating without bias voltage. In addition, the −120V-CrxNy sample exhibits the lowest corrosion current density of 0.65 μA/cm2 and a minimum ICR value of 5.87 mΩ cm2, thus highly meeting the U.S. DOE 2025 targets. Moreover, the CrxNy coatings subjected to bias voltages ranging from −100 V to −140 V exhibit excellent durability and stability, with current densities that are 1-2 orders of magnitude lower compared to the 0V-CrxNy coatings. Therefore, this work provides a novel approach to control the growth of columnar crystals in CrxNy coatings for future PEMFC manufacturing processes, and has important reference value for the regulation of columnar crystals in other coatings such as TiN, NbN, AlN, etc.

Effect of negative bias voltage on microstructure and thermal stability of Cu/Nb nano-multilayers deposited by FCVA technique

he deposition energy is a crucial factor in the preparation of nano-metallic multilayers using the physical vapor deposition method. To study the effect of deposition energy on the microstructure and performance of coatings, Cu/Nb nano-multilayers were prepared by the FCVA technique with different negative bias voltages. The surface morphology, composition, and interface structure were investigated by SEM, XRD, and TEM. The results indicated that the increased negative bias voltage leads to compressive stress and the temperature rise effect, which promotes the formation of psedo-diffuse transition zones and the transformation of columnar to equiaxed crystals. In addition, the difference in hardness is used to characterize the structural integrity of the laminate structure of the material after heat treatment. Even after one hour of annealing at 600 °C, the sample retains a highly stable laminate structure when the negative bias voltage is set to -100 V, and its hardness reduces by just 22.3%. The mechanisms of the pseudo-diffuse transition zone and crystal structure on thermal stability were discussed.

Microstructure and corrosion performance of CoCrFeNiSix coatings deposited by magnetron sputtering at various negative bias voltages

In this work, CoCrFeNiSix coatings were fabricated by magnetron sputtering at the negative bias voltage ranging from 0 to 100 V. The effect of negative bias voltage on the composition, microstructure and corrosion performance was studied. The results show that all CoCrFeNiSix coatings consisted of amorphous and nanocrystalline FCC phases. However, the ratio of both amorphous/nanocrystalline phases and Si/(Co + Cr + Fe + Ni) atoms decreased with increasing negative bias voltage. Applying negative bias voltage also led to the improved surface quality. Accordingly, the corrosion rate of CoCrFeNiSix coatings in 0.5 mol/L H2SO4 solution exhibited a decreasing trend. Meanwhile, the CoCrFeNiSix coating deposited at 100 V had the lowest passive current density, highest coating resistance and lowest carrier density. This was because that Si competed with Cr to suppress the formation of Cr2O3 in the compact inner layer, and thus the decreasing Si content caused by increasing negative bias voltage led to the improved protection effect of the passive film.

Effect of bias voltages and interlayer design on microstructure, mechanical properties, and adhesion performance of AlCrSiN coatings deposited using HiPIMS

This study fabricated AlCrSiN coatings from six alloy targets (Four Al7Cr3 targets and two Cr9Si1 targets) using high-power impulse magnetron sputtering (HiPIMS) with a focus on the effects of substrate bias voltage (−30 to −90 V) on deposition rate, microstructure, crystal orientation, residual stress, and mechanical properties. Electron Probe Microanalysis (EPMA) and X-ray Diffraction (XRD) results revealed that variations in bias voltage had little impact on the element composition or crystal structure (FCC) of AlCrSiN coatings; however, under high bias voltage (exceeding −60 V), the preferred orientation shifted from the (111) plane to the (220). Increasing the bias voltage from −30 to −90 V was shown to reduce the deposition rate (from 42.2 to 37.6 nm/min) and the thickness of the AlCrSiN coating (from 2.9 to 2.6 μm). It was also shown to increase the hardness (from 2147 to 3658 HV) and residual stress (from −0.01 to −0.59 GPa) by reducing the grain size and allowing the formation of a denser structure. Various interlayer designs (AlCr/AlCrxNy/AlCrN, CrSi/AlCrxNy/AlCrN, AlCr/CrSixNy/CrSiN, CrSi/CrSixNy/CrSiN) were assessed in terms of adhesion strength between the AlCrSiN and substrate. Under the same AlCrSiN deposition condition, with the bias voltage set to −60 V, the highest adhesion strength (from 32.28 to 45.81 N) was achieved using a CrSi/CrSixNy/CrSiN interlayer structure.

Effect of Sputtering Bias Voltage on the Microstructure and Lead-Bismuth Eutectic Corrosion Resistance of the FeCrAlY Coating

FeCrAlY coatings deposited on the outer surface of the cladding tube by the magnetron sputtering with varying bias voltages (0 V to −500 V) were corroded at 550°C to 600°C in oxygen-saturated and oxygen-poor lead-bismuth eutectic for 500 h to 1,000 h. The increased bias voltage led to the Al content decreased and the Y content increased. The coating changed from columnar crystals to equiaxed crystals with increased bias voltage. The decreased bias voltage makes an improved corrosion resistance. The fundamental process governing the evolution of microstructure and corrosion resistance in the FeCrAlY coatings was discussed.

Effect of bias voltage on the structural properties of WN/NbN nanolayer coatings deposited by cathodic-arc evaporation

In this work, WN/NbN nanolaminate coatings were synthesized by cathodic-arc physical vapor deposition (CA-PVD) technique on a stainless-steel substrate. The paper reports the microstructure, cross-sectional morphology, surface roughness, and adhesion strength changes caused by variations in the absolute values of the negative substrate bias voltage, Us , in the 50-200 V range. Synthesized coatings were analyzed by Grazing incidence X-ray diffraction (GI-XRD), scanning transmission electron microscopy (STEM), scanning electron microscopy (SEM), laser scanning confocal microscopy (LSCM), and Daimler-Benz test. The phase analysis revealed that multilayer coatings had complex polycrystalline microstructure. They consisted of face-cantered cubic (fcc) β-W2N, fcc δ-NbN, and hexagonal ε-NbN phases. The total thickness and surface roughness had a descending trend with an increase in the absolute value of the negative bias voltage. Moreover, the WN/NbN coating deposited at Us = -50 V demonstrated the best adhesion strength to the substrate, suitable for protective coatings.

Investigating the simultaneous effect of bias voltage and annealing on structural and optical properties of ZnO layer prepared by RF magnetron sputtering

In this study, the effects of different bias voltages (0, −100, −200 V) with an annealing temperature of 450 °C have been investigated on the structural and optical properties of zinc oxide (ZnO) thin film as a transparent conductive oxide (TCO) deposited by radio frequency (RF) magnetron sputtering method. The investigation on effects uniformity or the double effects of annealing on the layers prepared in different biases is the aim of this work. The prepared thin films were characterized by X-ray diffractometry (XRD), scanning electron microscopy (SEM), atomic force microscopy (AFM), UV–visible (Uv–Vis) spectroscopy, and four-point probe resistance measurement. The XRD patterns analysis confirmed the formation of crystalline c-axis (002) orientated hexagonal wurtzite structure of ZnO thin films. The transmittance spectra of ZnO thin films exhibited a transparency of nearly 90 % in the visible region. The direct optical band gap of ZnO thin films was calculated using Tauc’s plot, showing about 3.9 eV for the as-deposited (or before annealing) samples while post-annealing (or after annealing) reduced the band gap by 17 % to about 3.2 eV in all samples. Moreover, by applying a bias voltage of −100 V, not only the lowest sheet resistance was observed compared to that of the 0 V and −200 V, but also an increase in grain size and a reduction in surface roughness were observed. Moreover, annealing has shown that at a bias voltage of −100 V the structure and electro-optical properties of the thin films are improved, while the opposite occurs for −200 V.

Effects of Bias Voltages on the Tribological Behaviors of DLC Coatings

Ti/TiN/(Ti,N)-DLC/Ti-DLC/DLC coatings were deposited on 431 stainless steel using direct current magnetron sputtering technology under different bias voltages(0 V, −100 V, −200 V and −300 V). The microstructure and tribocorrosion performance of these DLC coatings in seawater was investigated. The results indicated that under the bias voltages, a denser and smoother surface of DLC coatings with a higher bonding strength between coatings and substrates was observed related to the increased incident kinetic energy of deposited ionized atoms. When the bias voltage was −200 V, the surface roughness reduced from 9.81 nm to 7.03 nm, and the bonding strength enhanced from 8.23 N to 8.86 N. What is more, the sp3 bond proportion and the disorder degree in DLC coatings both increased, which resulted in improved hardness and deformation resistance. However, when the bias voltage was −300 V, the increase of the amorphization was associated with a simultaneous rise in internal stress, which reduced the hardness and bond strength a little (8.72 N). DLC coatings can effectively improve the tribocorrosion properties of 431 stainless steel in seawater. When the voltage was −200 V, the average friction coefficient decreased from 0.35 to 0.07, with shallower wear traces and the wear loss of the DLC coating also being the smallest. The abrasive wear caused by metal oxides falling off the grinding ball, and the plastic deformation of the DLC coatings are the main wear forms. The high-density structure of DLC coatings under bias voltages can not only prevent the rapid expansion of cracks during deformation, but also provides a physical barrier to the erosion, which improves the corrosion and friction resistance in seawater. The optimization of bias voltage can improve the tribological performance of DLC coatings by regulating the carbon chain bond and microstructure. These results provide reference for DLC preparation and their potential engineering applications in stainless steel.

Influence of screen height and bias voltage on the active screen plasma nitriding of shot-peened Ti-6Al-4V titanium alloy

The effects of screen height and bias voltage on the active screen plasma nitriding (ASPN) of Ti-6Al-4V titanium alloy were investigated in this paper. Before nitriding, the Ti-6Al-4V alloy was pretreated by shot peening to allow the ASPN performed at a low temperature of 500 °C. The ASPN process variables concerned in this paper included screen height (20 and 100 mm) and bias voltage (0, 400 and 1100 V). The results show that the increase in active screen height effectively increased the yield of nitride particles transferred to the specimen surface by expanding the screen sputtering area and promoted the thickening of the nitrided layer. When the bias voltage increased from 0 V to 1100 V, the nitrided layer thickness and surface hardness of the nitrided Ti-6Al-4V showed a tendency of increasing first and then decreasing. Among the three selected bias voltages (0 V, 400 V, 1100 V), the thickest and hardest nitrided layer was obtained at 400 V, which balanced better between the deposition of nitride particles and the sputtering thinning of the nitrided layer. Meanwhile, the thickness and hardness of the nitrided layer on the shot-peened Ti-6Al-4V specimens were greatly improved compared to the original specimen. The thickest (5.30 μm) and hardest (1672 HV) nitrided layer was obtained on the shot-peened specimen at ASPN 500 °C–20 h with a bias voltage of 400 V and a screen height of 100 mm.

Regulation of π-π interactions between single aromatic molecules by bias voltage.

π-stacking interaction, as a fundamental type of intermolecular interaction, plays a crucial role in generating new functional molecules, altering the optoelectronic properties of materials, and maintaining protein structural stability. However, regulating intermolecular π-π interactions at the single-molecule level without altering the molecular conformation as well as the chemical properties remains a significant challenge. To this end, via conductance measurement with thousands of single molecular junctions employing a series of aromatic molecules, we demonstrate that the π-π coupling between neighboring aromatic molecules with rigid structures in a circuit can be greatly enhanced by increasing the bias voltage. We further reveal that this universal regulating effect of bias voltage without molecular conformational variation originates from the increases of the molecular dipole upon an applied electric field. These findings not only supply a non-destructive method to regulate the intermolecular interactions offering an approach to modulate the electron transport through a single molecular junction, but also deepen the understanding of the mechanism of π-π interactions.

Effect of bias voltage on the erosion performance of TiAlSiN coatings on TC6 substrate by high power impulse magnetron sputtering

TiAlSiN coatings were deposited on TC6 substrates by high power impulse magnetron sputtering at various bias voltages for the improvement of titanium alloy anti-sand erosion performance. The effect of bias voltage on the composition, microstructure and mechanical properties were investigated by X-ray photoelectron spectroscopy, X-ray diffractometer, transmission electron microscopy, scanning electron microscopy, Rockwell-C indentation, scratch testing and nano nanoindentation. The erosion performance was evaluated at the impingent angles of 30° and 90° respectively in a sand blasting tester. With the application and increase in bias voltage, the discharge current increases from ∼87 A to ∼210 A. The coatings exhibit face center cubic structure, mainly composed of the (Ti,Al)N nanocrystallites and Si3N4 matrix. The preferred orientation shifts from (200) to (220) in the range of 0∼−150 V, but goes back to (200) at −200 V. The surface nodular defects and deposition rate are gradually reduced, yet the sectional structure becomes much denser. The residual stress is compressive and continually grows, whereas the adhesion strength, hardness (H), Young's modulus (E) and H/E ratio gradually increase before decreasing, arriving at maximum values of ∼68 N, ∼37.53 GPa, ∼339.9 GPa and 0.11 respectively at −150 V. The erosion resistance of the TiAlSiN coatings is consistent with these mechanical changes at various bias voltages and is also optimal at −150 V, which is ∼14 times that of TC6 substrate. The failure mechanism comes from coating brittleness nature, fractured chips and microcracks, regardless sand erosion angles, yet the driving forces are different.