Electrode Radius Research Articles

Effect of Liquid Metal Embrittlement Indent Cracks on Zinc Coated 3rd Generation AHSS Mechanical Performance

Third-generation advanced high-strength steels (3G-AHSS) are typically galvanized to prevent corrosion of the outer body structure. However, the zinc coating on the surface, combined with the locally elevated temperatures generated during the resistance spot welding (RSW) process, can provide the prerequisites for liquid metal embrittlement (LME). This work uses two strategies to control LME crack formation: current pulsation and varying the electrode geometry. These two methods were compared to a baseline welding schedule for a 3G-980-GI coated AHSS. The effectiveness of each method was discussed in terms of the overall weld cracking index and local cracking index. The results showed that increasing the current pulses results in a slower energy input into the weld, which can help to reduce LME crack formation. Introducing more pulses (five to seven pulses) reduced LME crack formation while maintaining the same welding time. Regarding the electrode geometry, the results showed an increase in LME cracking index for currents below the expulsion level Imax-10% when the electrode face diameter increased, whereas at the current level Imax-200A, the electrode radius was the most important factor to control LME crack index. For the current level above the expulsion, Imax+10%, a drastic decrease in the LME cracking index was observed when a large electrode surface diameter was used. The electrode radius was not a significant factor in controlling LME. The mechanical properties of selected conditions were examined using the lap shear test and the results showed no significant effect of LME cracks on the shear tensile strength. The location of the failure indicated that most of the cracks are located in the indented area (type A), which does not influence the lap shear strength.

State and Prospects of Unbalanced, Compositionally Symmetric Flow Battery Cycling and Steady-State Amperometry Techniques for Electrolyte Stability Assessment: The Case of Methyl Viologen

An increasing number of redox-active substances with improved electrochemical stability is currently being reported in the literature for potential applications in redox flow batteries (RFBs). Consequently, the demand for methods capable of estimating the long-term stability of redox couples is increasing as well. It seems to be of particular importance to understand the limitations of existing stability assessment techniques. In this work, two recently established and highly promising stability assessment techniques are directly compared for the first time to measure the capacity fade rate of a N,N′-dimethyl-4,4′-bipyridinium dichloride (methyl viologen or MV) molecule as a benchmark anolyte substance. These two methods are the unbalanced, compositionally symmetric flow cell cycling (symmetric cycling or UCSFCC) and the steady-state amperometric state of health (ASOH) measurement. The results of the symmetric cycling indicate a 3-fold higher stability for MV compared to a previous literature report as well as a high standard deviation for the measured capacity fade rate. More comprehensive investigations of the technique revealed that the influence of the MV purity, electrolyte leakage, and membrane cross-over could not cause the difference between the measured and earlier reported capacity fades and, thus, indicated insufficiency of the technique’s accuracy for the measurement of highly stable redox species. ASOH as the second technique exhibited similar capacity fade rates like the symmetric cycling as well as comparably high standard deviations. Furthermore, it is prone to temperature fluctuations and variations of the electrode radius. Thus, we demonstrate an approach for a temperature correction in this method, which enables significantly higher accuracy and reliability. Despite this, the variation of the electrode radius remains the main concern for this technique. Based on the obtained results for the MV anolyte, the state and prospects of both techniques for the stability assessment in RFB research are discussed in detail.

Modeling soil ionization effect based on experimental data

• Measurements of Soil Ionization. • Modeling Soil Ionization effect based on experimental data. • Means for estimating soil ionization on the response of grounding electrodes. • Ionization of soils subjected to uniform electric field. • Ionization of soils subjected to non-uniform radial electric field. Results of a huge number of experimental tests involving soil ionization developed by the authors were used in this paper for analyzing the phenomenon and developing means for predicting the effect on the response of grounding electrodes subjected to lightning currents. These results refer to samples of fifteen different soils (from about 100 to 10,000 Ωm at natural moist content) subjected to impulsive current waves exhibiting front times similar to those of first and subsequent return stroke currents. The tests considered conditions of uniform and radial non-uniform electric fields with intensities comparable to those resulting from the impression of real lightning currents on grounding electrodes. A curve was suggested for taking the effect of ionization on the lightning response of electrodes into account for soils in general, by means of an equivalent increase of the electrode radius as a function of the linear density of current dispersed to the soil.

Sterilization mechanism of helium/helium–oxygen atmospheric-pressure pulsed dielectric barrier discharge on membrane surface

Pulsed dielectric barrier discharge (PDBD) exhibits several applications in different fields; however, the interaction of its components with substances remains a key issue. In this study, we employed experimental and numerical modeling to investigate the interactions between different PDBD components and substances in pure helium and a helium–oxygen mixture. A membrane comprising a Staphylococcus aureus strain was utilized as the treatment object to demonstrate the trace actions of the evolutions and distributions of certain components on the surface of the substance. The results revealed that the shapes and sizes of the discharging area and inhibition zone differed between groups. Under a pure helium condition, a discharge layer existed along the membrane surface, lying beside the main discharging channel within the electrode area. Further, an annulus inhibition zone was formed at the outer edge of the electrode in the pure helium group at 30 s and 1 min, and this zone extended to a solid circle at 2 min with a radius that was ∼50% larger than that of the electrode radius. Nevertheless, the discharging channel and inhibition zone in the helium–oxygen mixture were constrained inside the electrode area without forming any annulus. A 2D symmetrical model was developed with COMSOL to simulate the spatiotemporal distributions of different particles over the membrane surface, and the result demonstrated that the main components, which formed the annulus inhibition zone under the pure helium condition, contributed to the high concentration of the He+ annulus that was formed at the outer edge of the electrode. Moreover, O+ and were the main components that killed the bacteria under the helium–oxygen mixture conditions. These results reveal that the homogenization treatment on a material surface via PDBD is closely related to the treatment time and working gas.

Impact of electrode conductivity on mass sensitivity of piezoelectric resonators at high temperatures

Abstract. High-temperature stable piezoelectric Ca3TaGa3Si2O14 and La3Ga5SiO14 resonators with keyhole-shaped Pt electrodes are coated with metal oxide films such as TiO2−δ and SnO2 that overlap the Pt electrodes. The resonators are exposed to reducing atmospheres in order to increase the electrical conductivity of the oxide film and then act as extended oxide electrodes. The resulting increase in the effective electrode radius causes an increase in the mass sensitivity of the resonators and, thereby, resonance frequency shifts. In other words, the effective mass of the Pt electrode becomes higher. An electrical circuit model is presented to describe the increase in the effective electrode radius of the resonator, which is used to calculate the related resonance frequency shift. Additionally, an electromechanical model is presented, which subdivides the resonator into two coupled oscillators. One is representing the resonator volume underneath the Pt electrode and the other underneath the oxide electrode at increased electrical conductivity. The model reflects how the oxide electrodes affect the resonance frequency. Furthermore, the impact of increasing oxide electrode conductivity on the resonance frequency is discussed with respect to the application of oxide electrodes and for gas sensing.

Continuum model for converse flexoelectricity in a thin plate

Flexoelectricity – the effect where inhomogeneous polarization causes deformation – substitutes symmetry-forbidden piezoelectricity in nano-scale centrosymmetric materials. Its mathematical treatment in terms of continuum mechanics represents a challenge: correct models are subjects of debates during the past decades. In the present article we formulate a model with reasonable approximations for converse flexoelectric effect in a plate. Except for very specific boundary conditions the theory inevitably include nonclassical higher order terms. These are treated using variational calculus and are essentially reduced to a modification of the boundary conditions for the elastic variables. Analytical solutions are obtained for a circular plate with round electrodes, where deflections are proportional to the inverse square of plate thickness. For mechanically free boundary conditions at plate’s edges deflection grows monotonically with the electrode radius. In contrast, a plate with clamped edge does not deform at all when fully electroded, an optimal electrode size is found rendering maximal deflection.

Effect of Non-Specific Ion Adsorption and Parallel Faradaic Reactions on the Nucleation of H2 Nanobubbles

We report voltammetric experiments of single H2 nanobubble nucleation at Pt nanodisk electrodes (radius < 100 nm) in the presence of highly-charged species: Ru(NH3)6 3+, La3+, Fe(CN)6 3−, and Fe(CN)6 4−. The highly charged cations are expected to be non-specifically adsorb at electrode potentials sufficiently negative for the H2 evolution reaction (HER) to proceed, thus affecting the thermodynamics and kinetics of bubble formation through alterations in interfacial solution structure. Conversely, anions are not expected to be non-specifically adsorbed during H2 evolution. We observed a more highly complex behavior than expected: (i) the presence of the two redox ions that are simultaneously reduced at potentials where HER occurs (i.e., Ru(NH3)6 3+ and Fe(CN)6 3−) results in a large overpotential for HER and bubble nucleation as well as a decrease in the H2 supersaturation required for nucleation; (ii) the presence of the electroinactive cation, La3+, results in a decrease in H2 supersaturation but no increase in HER overpotential; and (iii) Fe(CN)6 4− has only a minor effect on both HER kinetics and H2 supersaturation. We infer that the driving force of nucleation decreases in the presence of highly-charged ions. The results also suggest that the HER rate is significantly decreased when parallel redox reactions are operative.

Design and Analysis of Quartz Crystal Microbalance with a New Ring-Shaped Interdigital Electrode.

In this paper, a new type of ring-shaped interdigital electrode is proposed to improve the accuracy and repeatability of quartz crystal microbalance. The influence of different types of single finger, dot finger, dot double-finger electrodes on mass sensitivity distribution as well as the optimal proportion of finger and gap width are obtained through multi-physical coupling simulation. The results show that the design criteria of interdigital electrodes will not change with the increase in the number of fingers. The gap width should obey the decrease order from central to edge and be about twice the width of finger. The width of the outermost finger and the radius of the middle dot electrode should be maintained at about 0.4 and 0.2 times of the total electrode radius. An experiment was carried out to verify that the quartz wafer with a dot double-finger electrode has high quality factors and less modal coupling, which can satisfy the engineering application well. As a conclusion, this study provides a design idea for the electrode to maintain a uniform distribution of quartz crystal microbalance mass sensitivity.

Simulation and Optimization of Piezoelectric Micromachined Ultrasonic Transducer Unit Based on AlN

The relatively low piezoelectric constant of aluminum nitride (AlN) piezoelectric film limits the development and application of the acoustic field performance of AlN-based micromachined ultrasonic transducers; thus, in this study we establish a mid- to low-frequency transducer unit model to address this problem. The transducer operates at 4.5 MHz, and the construction of a clamped structure is first investigated to ensure the feasibility of performance analysis. Secondly, the effectiveness of the optimized upper electrode distribution proposed in this paper in improving the acoustic field radiation of the array element is also compared with the original structure. Finally, the influence of the optimized electrode geometry parameters on the acoustic wave direction is analyzed. The finite element simulations are performed in the COMSOL Multiphysics (COMSOL) software and post-processing results are analyzed. Based on the simulation results, the proposed optimal distribution of the upper electrode makes the radiation beam uniform and symmetrical in the case of both the clamped model and the optimized structure model. In the case of the upper electrode radius of 28 µm, this electrode division operation makes the unit vibration mode switching in the frequency range more moderate. The sound field radiation improvement of the proposed optimized structure model is better than that of the clamped structure.

Theoretical and Experimental Study of the Effect of Plasma Characteristics on the Mechanical Properties of Ihram Cotton Fabric.

Theoretical and experimental investigations of the radial distribution function of the electron temperature (RDFT), for the abnormal glow region in a low-density plasma fluid and weakly ionized argon gas, are provided. The final proved equation of RDFT agrees with the experimental data for different low pressures ranging from 0.2 to 1.2 torr, confirming that the electron temperatures decrease with an increasing product of radial distance (R) and gas pressures (P). A comparison of the two configurations: for the axial distance (L), from the tip of the single probe to the cathode electrode, and the cathode electrode radius (R), shows that, in both cases, the generated plasma temperatures decrease, and densities increase. The RDFT accurately depicts a dramatic decrease for L < R by 60% compared with the values for L > R. This indicates that, when L < R, the rate of plasma loss by diffusion is reduced. Under this investigation, the mechanical characteristics of treated and pre-treated Ihram Cotton Fabric Samples were compared under the Influence of the different two configurations of Plasma Cell discharge: . These characteristics included resiliency, strain hardening, tensile strength, elongation percentage, yield strength, ultimate tensile strength, toughness, and fracture (breaking) point. Furthermore, the mechanism parameters of plasma interaction with textile membrane will be discussed, such as: process mechanism, interaction, and gas type.

Study on the Electrochemical Deburring for the External Surface of the Microhole Caused by Mechanical Drilling Process

To improve the performance of electrochemical deburring for microhole drilling (MD-ECD), the distribution and dynamic change of the current density in the machining area during the electrolysis process were analyzed, and the synchronous change relationship between the current density and the burr profile was studied. The effects of process parameters, such as machining voltage U, initial machining gap d, electrolyte concentration C, and electrode radius r1 on the deburring process, were studied. The results show that the magnitude of the current density value in the burr area reflects the MD-ECD’s deburring performance. The current density near the burr tip is high, and the material is preferentially removed. The non-processed area has a low current density and slow material removal. As the machining progresses, the burr tip becomes blunt and the current in the burr area gradually transfers to the non-machining area, resulting in the transfer of the material removal area from the burr area to the adjacent non-machining area. Then, a chamfer is formed at the orifice; the chamfer width is larger than the chamfer height. When U = 4 V, d = 0.35 mm, C = 12%, and r1 = 0.4 mm, the burr removal efficiency and accuracy can be guaranteed. The chamfer width and chamfer height obtained from the test are 29 μm and 17 μm, and the burr removal effect is good.

The Effect of the Distance between the Cylindrical Poles of the Electrostatic Quadrupole Deflector on the Trajectory of Charged Particles

The impact of the electrostatic quadrupole deflector diameter (E.Q.D.D) on the image characteristics and efficiency of the 90°quadrupole deflector was explored. For electrostatic quadrupole deflectors (E.Q.D) of various diameters, a comparison of aberration figures, electron beam kinetic energy, and fight time was done. The results revealed that when the E.Q.D.D of the E.Q.D was two and a half times greater than the electrode radius, the best image could be created at the image plane (r).

Electroanalytical measurements of lanthanum (III) chloride in molten calcium chloride and molten calcium chloride and lithium chloride

Cyclic voltammetry (CV), square wave voltammetry (SWV) and other electroanalytical methods have been applied to molten chloride salts to study metal ion behavior. These studies have been useful for understanding and optimizing the electrowinning of metals. Notable ions that have been studied are rare earth and actinide metal ions in LiCl-KCl salts. However, the behavior of lanthanum (La3+) ions in some molten chlorides or chloride mixtures (e.g., CaCl2) has not been studied. CV experiments were conducted to evaluate La3+ behavior in CaCl2-LiCl and CaCl2 and were compared to La3+ behavior in LiCl-KCl and CaCl2-NaCl eutectics from other studies. The electrochemical reaction was checked for reversible, quasi-reversible, and irreversible transitions in scan rate by examining the relationship between the scan rate applied and the peak current and potential for La3+ reduction. Properties such as diffusion coefficient (Do) and electrons exchanged (n) were calculated from data. The electrochemical setup was also checked for radial diffusion based on the calculated La3+ diffusion coefficient and electrode radius, which led to the observation that natural convection possibly affected the La3+ reduction peak at low scan rates. For more accurate electroanalytical measurements of La3+ reduction, CV curves with and without LaCl3 added to CaCl2 and CaCl2-LiCl were compared to establish baselines for the La3+ reduction peak. The impact of resistance (IR) compensation on the La3+ reduction peak was also explored. Techniques and practices that improved electroanalytical measurements include placing the electrolytic cell in a Faraday cage, distancing electrodes from the heating coils, and melting the chlorides twice prior to measurements.

Implementing intermittent current interruption into Li-ion cell modelling for improved battery diagnostics

A novel electroanalytical method, the intermittent current interruption (ICI) technique, has recently been promoted as a versatile tool for battery analysis and diagnostics. The technique enables frequent and continuous measurement of battery resistance, which then undergoes statistical analysis. Here, this method is implemented for commercial Li-ion cylindrical cells, and combined with a physics-based finite element model (FEM) of the battery to better interpret the measured resistances. Ageing phenomena such as solid electrolyte interphase (SEI) formation and metallic Li plating on the surface of the negative graphite particles are considered in the model. After validation, a long-term cycling simulation is conducted to mimic the ageing scenario of commercial cylindrical 21700 cells. The large number of internal resistance measurements obtained are subsequently visualized by creating a ‘resistance map’ as a function of both capacity and cycle numbers, providing a straight-forward image of their continuous evolution. By correlating the observed ageing scenarios with specific physical processes, the origins of ageing are investigated. The result shows that a decrease of the electrolyte volume fraction contributes significantly to the increase of internal resistance and affect the electrolyte diffusivity properties. Additionally, effects of porosity and particle radius of the different electrodes are investigated, providing valuable suggestions for battery design.

Solid-liquid phase change subjected to unipolar charge injection from a circular wire electrode

A numerical investigation of isothermal melting of a dielectric phase change material in a square cavity subjected to unipolar charge injection from a circular wire electrode is reported. Governing equations for the solid-liquid phase change under the influence of an electric field include the Navier–Stokes equations for fluid flow, energy equation for thermal transport, Poisson equation for electric potential, and the Nernst-Planck equation for charge conservation. An enthalpy source-term based fixed grid approach is adopted to model the melting process. The governing equations that consider the coupled interactions between flow, thermal and electric fields are solved using the finite volume framework of OpenFOAM®. Time evolution of the melting rate, maximum flow velocity, mean Nusselt number, and mean Coulomb force in the electrohydrodynamic flow assisted melting process is mapped. The mechanism and role of electrohydrodynamic forces on influencing the net flow and melt interface morphology is studied. The competing viscous, buoyancy, and electric forces result in an altered flow pattern that aids the melting process. The enhancement in the rate of melting at different strengths of buoyancy and electrostatic forces is quantified. Furthermore, the effects of the radius of the circular wire electrode in relation to the cavity size are highlighted. A maximum of 63% enhancement in melting rate is observed within the considered parameter space.

A modified expression for breakdown voltage of Townsend discharge in a non-uniform electric field and uniform axial magnetic field

Townsend breakdown mechanism for direct current discharge in argon gas by considering the effects of the non-uniformity of electric field, the loss of electrons due to radial diffusion, and the applied axial magnetic field has been discussed and an analytical expression has been derived for the breakdown voltage. It was Shown that the non-uniformity of electric field, between two parallel disc electrodes with radius R and separation of d, significantly affects the electron multiplication for d≥2.7R and that effect was disappeared for the gas pressure higher than 0.35 Torr. The loss coefficient δ was used to quantify the effects of the electron radial diffusion and axial magnetic field and the PIC-MCC numerical simulations were used to determine it. The results show that increasing the gap size above the electrode radius leads to dramatic increase of the δ coefficient while applying an axial magnetic field can effectively decrease it.

Research on Characteristics of Copper Foil Three-Electrode Planar Spark Gap High Voltage Switch Integrated with EFI

In view of the low-energy explosion foil detonation system’s requirements for the integration technology of high-voltage switches and technical overload resistance technology, a magnetron sputtering coater is used to sputter copper film on the surface of the substrate. The thickness is 4.0 μm, the radius of the main electrode is 4 mm, the trigger electrode is 0.6 mm and 0.8 mm, and the main gaps are 0.8 mm, 1.0 mm, 1.2 mm mm, 1.8 mm, 2.0 mm, 2.2 mm, and 2.6 mm. Copper foil three-electrode planar spark gap high voltage switches are designed and manufactured; and the static self-breakdown characteristics, dynamic operating characteristics, and discharge life characteristics of the three-electrode planar spark gap high voltage switch based on copper foil are studied in this paper. The test results show that with the increase of the main electrode gap from 0.8 mm to 2.6 mm, the self-breakdown voltage of the planar spark gap switch increases, and the working voltage also increases. When the main electrode gap is a maximum of 2.6 mm, the self-breakdown voltage of the switch can reach 3480 V, which indicates that the maximum operating voltage of the switch is 3480 V. When the charging voltage is 2.0 kV, with the increase of the main electrode gap from 0.8 mm to 2.6 mm, the minimum trigger voltage value of the planar spark gap switch increases from 677 V to 1783 V (a = 0.6 mm), and from 685 V to 1766 V (a = 0.8 mm), the switch on time is 16 ns, 22 ns, 28 ns, 48 ns, 64 ns, 77 ns, 93 ns (a = 0.6 mm), and 26 ns, 34 ns, 51 ns, 67 ns, 81 ns, 102 ns (a = 0.6 mm). With the increase of the gap between the two main electrodes of the switch, the maximum static working voltage of the three-electrode plane spark gap high-voltage switch increases, the minimum trigger voltage value also increases, and the on-time of the switch gradually becomes longer. The peak current of the discharge circuit decreases and the dynamic impedance and inductive reactance of the switch also increase; as the width of the trigger electrode increases, the minimum trigger voltage decreases, the dynamic impedance and inductance decrease, and the switch operating voltage with the same parameters is higher. The easier the switch is to turn on, the lower the minimum trigger voltage. The electrode thickness of the three-electrode plane spark gap switch has a certain influence on the field strength and the service life of the switch. The results of this study provide useful references for promoting the research and development of LEEFIs.

Performance of Grounding Electrodes Under Lightning Strokes in Uniform and Two-Layer Soils Considering Soil Ionization

This article presented the characteristics of the grounding electrodes in uniform and two layer soils when subjected to lightning including the impacts of soil ionization with frequency, soil resistivity, and permittivity variations. The critical breakdown field strength of two layer soils with different values of the reflection factors was presented. The transient probabilistic grounding potential rise and the transient impedances of the horizontal and vertical electrodes were investigated in uniform and two layer soils including the effect of soil ionization with frequency. Finally, the influences of resistivity and permittivity variations which have substantial impacts on the electric field at the occurrence of the soil ionization were considered. Moreover, transmission line approach (TL) with the aid of ATP has been used to compute the transient grounding voltages. The results indicated that the reflection factor has a significant impact on the equivalent radius of the grounding electrode. It is also observed that the peak values of the lightning induced voltages decreases sharply when the soil ionization phenomenon considering the variations in soil resistivity and permittivity with the stroke frequency changes. Furthermore, the impedances of the burial electrodes that have negative reflection factors were lower than that in case of positive reflection factors.

The Effect of Corona Wire Position and Radius in a Duct-Type ESP with Wavy Collecting Plates

Electrostatic precipitators (ESPs) have become one of the most effective methods for removing harmful particles from various industries. Many investigations in this subject are constantly developing due to the inherent benefits of using an ESP, and there are many robust initiatives taking place today all over the world. Different configurations of collection and discharging electrodes must be investigated to improve the ESP performance of ESPs. Many studies are working to enhance existing models in different ways. The geometry of the electrodes and the collecting plates is one area that could be improved. This paper investigates the wavy designs of collecting electrodes with varied corona electrode radius (range of variable corona radius (0.07-0.6 mm)) and position in a single-stage ESP. Wavy plates (WPs) and Inverted wavy plates (InvWPs) are compared to flat plates (FPs) using a numerical simulation tool. The results of this work show the impact of changing the corona radius when wavy and inverted wavy collecting electrodes are used on the electric potential, electric field strength, current density, and space charge density distribution, and particle collection efficiency. When compared to InvWPs and FPs, WPs show the highest performance in this range of particles. Although InvWPs can be utilized to reduce current density or space charge density, they do not increase particle collection efficiency.

Modelling the Role of the Inner Electrode Radius on the Oxygen Negative Corona Discharge in Coaxial Electrode Geometry

The charge species plays a vital role in changing the field in direct current discharge (DC). This article introduces a numerical modeling in one dimension of the inner electrode diameter of oxygen-fed negative corona discharge in coaxial electrodes geometry. The properties of negative corona plasma in a concentric cylindrical electrodes (wire-cylinder) were simulated by COMSOL Multiphysics software. Various diameters of negative corona electrode, namely 0.01, 0.025, 0.05, 0.075, and 0.125 mm, were applied, ​​where the diameter of the outer cylindrical electrode was taken as 15 mm. The model was run at atmospheric pressure and the applied negative voltage was -10 KV. Moreover, oxygen gas was used to fill the inter-electrodes distance. Furthermore, the spatial distribution of electrons, positive ions, and negative ions as a function of the diameter of negative electrode of the negative corona discharge were investigated. The study also tested the effects of the electrode diameter of the negative corona discharge on ozone generation. The observed decrease in ozone density with the increase in negative electrode diameter was reasonable and consistent with other results provided by researchers in this field.