Perturbation solutions for steady direct and inverse electrochemical machining problems

The steady state electrochemical machining process gives rise to both the direct problem which consists of determining the anode shape resulting from a specified cathode shape, and the inverse problem in which the cathode shape required to produce a given anode shape is sought. These two problems are solved by a perturbation scheme in which the perturbation parameter is the square of the ratio between the “wavelength” of the variation in the anode or cathode surfaces and the inter-electrode gap.     

Operating characteristics of the hollow anode glow discharge ion source

In this work, a new shape of a glow discharge ion source with axial extraction has been designed and constructed. High output ion beam current can be extracted axially in a direction normal to the discharge region without using extraction system. Optimization of the distance between the anode and the cathode has been determined using argon gas. It is found that the optimum gap distance between the anode and the cathode is equal to 3.5 mm, where stable discharge current and maximum output ion beam current can be obtained. The discharge characteristics of the ion source at different operating gas pressures have been measured at this optimum distance between the anode and the cathode. A disk of Teflon insulator has been put between the anode and the cathode. This disk was covering the cathode area and reducing the discharge area on the cathode surface for discharge confinement, therefore, a higher output ion beam current could be obtained.     

Two-Dimensional Model of Plasma Cathode with an Open Plasma Boundary

The paper deals with the solution of two problems for which a two-dimensional distribution is found of the current density and of the electric field in the hollow-cathode plasma. In the first one of these problems, the anode surface of the cavity represents two concentric flat anodes separated by an insulator. This system is used to study the problem of switching the current over from the external to internal anode, with the anode drop being a nonlinear function of current density. The distribution of the current density and of the anode voltage drop on the surfaces of both anodes is calculated for different potentials of the external and internal anodes. In the second problem, the function of internal anode is served by the open boundary of plasma with zero anode drop. The shape of the plasma boundary is determined depending on the plasma cathode geometry and parameters. The singularities are discussed that characterize the extraction of current from the open plasma boundary for different forms of electric discharges.     

圆锥形阴极真空微三极管的计算机模拟

利用有限元法对圆锥形场致发射阴极的真空微三极管进行了计算机模拟。改变真空微三极管的各项结构参数及阳极和栅极电压 ,得到一系列模拟数据。然后对模拟结果进行分析讨论 ,总结出圆锥形阴极有效发射、阳极电流与真空微三极管的结构尺寸、阳极电压和栅极电压之间的关系 ,对于真空微三极管的实际设计和制作有一定的参考价值     

钛基二氧化铅作为阳极电解制备羟基氧化镍的研究

使用钛基二氧化铅作为阳极,不锈钢作为阴极进行了电解制备羟基氧化镍(NiOOH)的研究,并和以泡沫镍为阴阳极的体系在氧化机理,氧化效率,产品型貌等方面进行了比较,结果说明钛基二氧化铅作为阳极电解法制备羟基氧化镍是一种更为高效、绿色的制备方法.     

Mathematical modeling of the electron beam formatting systems on the basis of field emission cathodes with various shapes

In the present paper we solve some problems of field emission cathodes mathematical modeling and the electron guns for vacuum electronics. The supposed shape of the field emission cathode was either “sphere-on-cone” or “sphere-on-spindle” (as a cathode) on the sphere substrate and the spherical segment (as an anode).     

Martensitic Transformation of TiNi Shape Memory Alloy Fiber Reinforced Ni Matrix Composites

In this paper, a TiNi shape memory alloy fiber Ni matrix composite was fabricated by an electroplating method using TiNi alloy as the cathode and Ni as the anode. The constrained martensitic transformation behaviors of the TiNi alloy were studied by differential scanning calorimeter (DSC), and the results showed that two endothermic peaks appear on the DSC heating curves and the reverse transformation temperatures increase with increasing prestrain levels. Moreover, comparing to the free transformation, the temperature window of the constrained reverse transformation is widely expanded due to the influence of recovery stress.     

镓酸镧基陶瓷燃料电池电极材料研究进展

综述了镓酸镧基陶瓷燃料电池电极材料的研究进展,对目前广泛研究的Ni负极材料研究中存在的问题和改进研究进行了详细的介绍,评述了掺杂LaMnO3等正极材料与镓酸镧电解质的化学相容性以及今后电极材料的发展方向.     

Hollow Carbon Nanobelts Codoped with Nitrogen and Sulfur via a Self‐Templated Method for a High‐Performance Sodium‐Ion Capacitor

Sodium‐ion capacitors (SICs) have attracted enormous attention due to their high energy density and high power density. In this work, N and S codoped hollow carbon nanobelts (N/S‐HCNs) are synthesized by a self‐templated method. The as‐synthesized carbon nanobelts exhibit excellent performance in pseudocapacitance and electric double layer anions adsorption. After pairing the N/S‐HCNs cathode with a tin foil anode in a carbonate electrolyte, the obtained SIC achieves a high specific capacity of 400 mAh g^?1 at 1 A g^?1 (based on the mass of cathode material) and energy density of 250.35 Wh kg^?1 at 676 W kg^?1 (based on the total mass of cathode and anode materials). Besides, the presented SIC also demonstrates high cycling stability with almost 100% capacity retention after 10 000 cycles, which is among the best results of the reported SICs, suggesting the potential for high‐performance energy storage applications.     

Special features of mechanisms of formation of transverse nanosecond discharge with slot cathode, confined by dielectric walls

Experiments are performed and comparison is made of the electrical and optical characteristics of open and confined transverse nanosecond discharges with a slot cathode. It is found that the duration and shape of current pulse under conditions of open and confined discharges are significantly different and, under some conditions, the current density of confined discharge exceeds that of open discharge by more than an order of magnitude. Estimates are obtained of the coefficient of electron emission from cathode plasma, which significantly exceed the coefficient of electron emission in an abnormal discharge. It is demonstrated that the beam mode of primary electrons in the cathode layer during motion in the anode direction gradually transforms to hydrodynamic mode. The free paths of accelerated electrons in plasma are determined, and it is demonstrated that they reach the anode and have a significant impact on the dynamics of development and on the structure of optical radiation of transverse nanosecond discharge with a slot cathode.     

A Multifunctional Organic Electrolyte Additive for Aqueous Zinc Ion Batteries Based on Polyaniline Cathode

The practical applications of aqueous zinc ion batteries are hindered by the formation of dendrites on the anode, the narrow electrochemical window of electrolyte, and the instability of the cathode. To address all these challenges simultaneously, a multi-functional electrolyte additive of 1-phenylethylamine hydrochloride (PEA) is developed for aqueous zinc ion batteries based on polyaniline (PANI) cathode. Experiments and theoretical calculations confirm that the PEA additive can regulate the solvation sheath of Zn²⁺ and form a protective layer on the surface of the Zn metal anode. This broadens the electrochemical stability window of the aqueous electrolyte and enables uniform deposition of Zn. On the cathode side, the Cl⁻ anions from PEA enter the PANI chain during charge and release fewer water molecules surrounding the oxidized PANI, thus suppressing harmful side reactions. When used in a Zn||PANI battery, this cathode/anode compatible electrolyte exhibits excellent rate performance and long cycle life, making it highly attractive for practical applications.     

Calculation of the derivative of interpolation shape function for three-dimensional natural element method

The natural element method (NEM) is a special meshless method. Its shape functions are constructed using natural neighbor node interpolations based on the concepts of Voronoi tessellation. The NEM interpolation is linear between adjacent nodes on the boundary of the convex hull, which facilitates imposition of essential boundary conditions. However, for a three-dimensional problem, the computation of shape function derivative of NEM is still very complicated even with the non-Sibson interpolation function, which makes the NEM an unpopular numerical method. In this paper, we adopt the direct mathematical derivative technique, and after some rigorous deduction, finally obtain the shape function derivative expression of three-dimensional NEM. Compared with the Lasserre algorithm, this algorithm is more intuitionistic and can be conveniently programmed. The NEM numerical results for cantilever beams verify the correctness of the shape function derivative expression of NEM derived in this paper.     

Laser-Monitor-Assisted Investigation of the Regions of Closure of Current on the Electrodes of an Atmospheric-Pressure Low-Current Carbon Arc

The results are given of observations of regions of closure of current on the electrodes of an atmospheric-pressure low-current carbon arc, performed using a laser monitor immediately during the time of burning of the arc. It is found that the time of existence of a cathode crater on a graphite cathode is 0.2–0.3 s. An analysis of images of the region of closure of current on a pyrographite cathode reveals evidence of melting of pyrographite. A comparison of images of the region of closure of current on the electrodes of a carbon arc with the available literature data on the conditions of closure of current on the anode and cathode enables one to establish the origins of the various details of images of the region of closure of current on the cathode and anode of a low-current carbon arc. The results of this comparison further lead one to conclude that a low-current electric arc is an arc with liquid cathode and anode spots, and that the melting process is a stabilizing factor as regards the current density in those spots.     

Etching‐Assisted Crumpled Graphene Wrapped Spiky Iron Oxide Particles for High‐Performance Li‐Ion Hybrid Supercapacitor

From graphene oxide wrapped iron oxide particles with etching/reduction process, high‐performance anode and cathode materials of lithium‐ion hybrid supercapacitors are obtained in the same process with different etching conditions, which consist of partially etched crumpled graphene (CG) wrapped spiky iron oxide particles (CG@SF) for a battery‐type anode, and fully etched CG for a capacitive‐type cathode. The CG is formed along the shape of spikily etched particles, resulting in high specific surface area and electrical conductivity, thus the CG‐based cathode exhibits remarkable capacitive performance of 210 F g^?1 and excellent rate capabilities. The CG@SF can also be ideal anode materials owing to spiky and porous morphology of the particles and tightly attached crumpled graphene onto the spiky particles, which provides structural stability and low contact resistance during repetitive lithiation/delithiation processes. The CG@SF anode shows a particularly high capacitive performance of 1420 mAh g^?1 after 270 cycles, continuously increases capacity beyond the 270th cycle, and also maintains a high capacity of 170 mAh g^?1 at extremely high speeds of 100 C. The full‐cell exhibits a higher energy density up to 121 Wh kg^?1 and maintains high energy density of 60.1 Wh kg^?1 at 18.0 kW kg^?1. This system could thus be a practical energy storage system to fill the gap between batteries and supercapacitors.     

Phenomenological features of diaphragm discharge

Flame formations of relatively little-studied diaphragm discharge in water at low energy of discharge (up to 10 J) are investigated. Its particular features show up in the fundamental difference in shape between the anode and cathode flames on both sides of the diaphragm, in the difference in variation of their shape and size with the variation of electrical conductivity of the medium, in polar development of flames from the diaphragm to their electrodes, in the possibility of existence of “half-breakdowns”, and in the difference between them depending on polarity, in a special form of cathode breakdown.     

基于标准阴极特性的面齿轮阴极设计方法

目的 解决电解加工过程中,简单曲面阴极设计方法不能保证面齿轮加工精度的问题。方法 利用标准阴极进行正交试验,得出钢制面齿轮的最优电解工艺参数。利用该工艺参数对阴极重新设计,加工试件,根据试件的测量结果对原始阴极进行修形,得出最终阴极形状。结果 通过对正交试验数据进行处理,得出钢制面齿轮的最优电解工艺参数为K=20, U=10 V, v=0.6 mm/min;根据试件的误差测量结果,推导出最优修形数为0.4602。结论 此阴极设计方法所设计的阴极能保证面齿轮的加工精度,而且能够加工出IT7级精度制件,同时为复杂型面的高精度电解加工方案提供了一种可行的阴极设计方法。     

The Disappearing Anode Myth

The goal of this paper was to simply demystify the disappearing anode problem. Three key concepts for anode control were presented. First, anode / cathode area ratio, second, magnetron ejection angle and, lastly, the concept of aspect ratio / acceptance angle were introduced. Examples of the application of these principles were demonstrated. Finally, tradeoffs associated with dual magnetron sputtering and DC pulsed deposition were discussed.     

等离子喷涂制造固体氧化物燃料电池三合一电极

采用大气等离子喷涂法在阳极支撑上制备了电解质与阴极.利用X射线衍射分析了阴极与阳极喷涂前后的成分和相结构,用扫描电镜观察了SOFC( solid oxide fuel cell)三合一电极的截面形貌以及阳极、电解质与阴极的表面形貌.结果表明:喷涂前后阴极的化学成份未发生改变,阴极为单斜相、钙钛矿型的(La0.8Sr0.2MnO3)LSM;阳极在喷涂前为Ni/YSZ(Y2O3稳定ZrO2),在喷涂后Ni被氧化成NiO.由阳极、电解质与阴极构成的三合一电极界面不明显,其中电解质致密,阳极与阴极有一定孔隙.     

Application of the BEM to chromium electroplating simulation and to identification of experimental polarisation laws

Two challenges in electrochemical plating analysis are taken up in this paper: (i) numerical simulation of depositing thickness on industrial parts to cover; and (ii) numerical identification of experimental polarisation laws for the electrodes submerged in electrolyte and used for electroplating.Consideration of the first one leads to a formulation based on the Boundary element Method (BEM) in a three-dimensional space to solve the ionic migration problem in the electrolyte. The electroplating system convergence is monitored by an algorithm to satisfy experimentally the global and dual quantities between the two electrodes (anode and cathode). Our model has been validated by electrolyser outfits modelisations. Numerical simulation of these industrial applications shows numerical results and deposit measurements are in good correlation.Additionally, in order to confirm or to improve the experimental polarisation laws we have developed a numerical identification model. The numerical model is adjusted at the geometric point of measurement, to respect the experimental measurements realised with accuracy away from the disturbed point, and after that the real polarisation law on electrode is determined. This new development allows us to access to not really measurable quantities needed to simulate electrolytic deposits.     

Plasma cathode for a broad-beam electron accelerator

We propose a grid-stabilized plasma cathode based on a slit-contracted low-pressure glow discharge with hollow anode. The area of the plasma cathode is one order of magnitude higher than that in systems where electrons are extracted immediately from plasma in the cathode cavity. Conditions for the discharge initiation, the current switching to the hollow anode, and the obtaining of uniform emission from the plasma cathode are determined. At an accelerating voltage of 160 kV, an electron beam with a 1000 × 180 mm cross section, a total current of several amperes, and a current pulse duration of up to 10⁻³ s was obtained. The plasma cathode operates under technical vacuum conditions (air, 0.1 Pa) and ensures high stability and reproducibility of the beam current pulses.