Electrochemical Discharge Research Articles

Superior discharge performance of Mg-air battery: The influence of anodic intermetallic compounds Mg41Nd5 in Mg–4Li-3Nd-0.2Zn alloy

The impact of the anodic second phase, Mg41Nd5 in as-extruded Mg–4Li-3Nd-0.2Zn alloy was first reported as a candidate anode material for primary Mg-air batteries. Solid solution treatment of Mg–4Li-3Nd-0.2Zn was conducted at 400, 450, and 500 °C for 8 h. The electrochemical behaviour and discharge performance were investigated using microstructural characterization, electrochemical measurements, and discharge tests. The results indicated that solid solution treatment led to increased grain size and reduced volume fraction of the anodic second phase (Mg41Nd5) with a uniform distribution. In turn, the anode electrochemical activity was promoted, and the bulk effect was reduced. The anode efficiency and comparison capacity were significantly improved. At 5 mA cm−2, the average discharge voltage reached as high as 1.45 V with a utilization efficiency of 61.29%, and a discharge capacity of 1358.98 mAh·g−1 for the solid solution-treated sample at 450 °C, making it the excellent candidate anode material for Mg-air batteries.

A study of electrolyte effect during machining of non-conducting material on WECDM process

The demand of glass is increasing day by day due to their attractive properties such as transparency, heat resistance, and high corrosion resistance. Glass is used in many applications especially in micro electromechanical systems. Machining of glass material is a big challenge for manufacturers. It is difficult to achieve part of complicated shapes of these materials by conventional machining techniques. Electro Chemical Discharge Machining (ECDM) is found most appropriate technique for shaping these materials. The material removal process in ECDM depends on parameters like applied voltage, electrolyte nature, combination and concentration, Duty cycle, wire speed, and tension.In the present work, role of electrolyte has been examined by investigating the effect of electrolyte types, concentration, and the addition of abrasives in electrolytic solution. The quality of the machined surface was examined by an optical microscope, which shows the sallow and micro-cracks with the use of higher concentration of electrolytes. Results reveals that a better surface finish is obtained with abrasives mixed electrolyte which reflects the abrasives played important role for getting better surface finish. By comparing the performance of different electrolyte, the higher material removal rate (MRR) was obtained by using mixed solution of KOH (Potassium Hydroxide) and NaOH (Sodium Hydroxide).

Enhancement of Electrochemical Discharge Machining Process with Pressurized Tool Feeding Mechanism

In the present era, Microfluidic devices play a vital role in the field of pharmaceutical and bio-medical industry. The Electrochemical Discharge Machining (ECDM) process is a promising micromachining process for fabricating microfluidic devices using a micro subtractive material removal process on highly transparent material such as glass. A microfluidic device consists of microchannels, which are interconnected with the help of microholes. The feeding mechanism in the ECDM process plays a vital role in the fabrication of micro features with desired geometry. Therefore in the present research, authors have introduced a novel method for feeding mechanism, i.e. Pressurized Tool Feeding Mechanism (PTFM). The authors have discussed the design and development of PTFM with designed details and compared the machining features with the Pressurized Work Feeding Method (PWFM). In PTFM, a zero working gap is maintained throughout the machining process with the help of spring back pressure. Using present PTFM, the major limitation of PWFM was minimized significantly and fabricated straight holes without undesired hole deviations. A provision has also been made in the PTFM attachment to drill an inclined hole with a desired angle in any direction. This technique will be helpful in the fabrication of microfluidic devices in a one-go for microfluid mixing and separation in a single chip.

Ultrasonic-assisted electrochemical discharge grinding and broaching for machining quartz square microholes

A novel hybrid technology that ultrasonic-assisted electrochemical discharge grinding combined with in-situ ultrasonic broaching was used to process an array of square microholes on quartz glass. Diamond abrasive particles were directly added to the electrochemical discharge electrolyte to simultaneously perform electrochemical discharge machining and grinding. Because the diamond abrasive particles were added to the electrolyte, it could be used for both processes and replacing the slurry or electrode was unnecessary. This method removes material through simultaneous melting, etching, and impact grinding. The proposed method was successfully used to machine a 2 × 2 array of square microholes in quartz glass. The hole inlet size was 20 μm, and the difference between the maximum and minimum average size of the array holes was only 6 μm. After the final step of ultrasonic vibration broaching using the same electrolyte, the difference between the maximum and minimum average inlet size was reduced to 3 μm, and the hole taper angle was 1.77°.

Overview of Electric Discharge Machining of MachineTooled Ceramics and Ceramic-Based Composites

Accordingly, many engineering designers have improved the wear friction performance of such materials. Also, the use of polymers as reinforcements in their endeavors has been done to improve intrinsic performance. Intrinsic properties played an important role in intrinsic polymer orientations, improving the cohesion of some reinforcement while at the same time worsening those Effects Woven glass, carbon and amethyst polymeric composites Inter-laminar shear strength and abrasion composites samples. Wear properties are calculated using machine and testing machine in computer aided universal testing. Fracture of composites showed surface modifications for Group bonding. The mechanical properties of basalt are better than glass reinforced composites the result of the study confirms the applicability of basalt as a reinforcing agent in polymer composites. Hybrid Mechanical Processes Ultrasonic assisted laser/water jet machining processes are used to solve machining problems related to insulating ceramics such as ultrasonic assisted discharge machining, discharge milling, electro-chemical discharge machining and powder hybrid discharge machining and discharge diamond grinding. Processes can create complex patterns in spark discharges. An attempt has been made here to compare the convex stability with the above cast iron and polymer impregnated mechanical properties.

An experimental investigation on electrochemical discharge peripheral surface grinding process

An experimental investigation on electrochemical discharge peripheral surface grinding process

Discharge performance of Mg-Y binary alloys as anodes for Mg-air batteries

In this work, the electrochemical properties and discharge performance of Mg-xY (x = 0, 0.5, 1, 2, 3, and 5 wt.%) binary alloys have been systematically investigated as anodes for Mg-air batteries, using electrochemical techniques and Mg-air battery tests. The results reveal that the Mg24Y5 and Y-rich phases in Mg-Y alloys play the micro-cathode and micro-anode roles, respectively. By adding a small amount of Y (0.5 and 1 wt.%), the electrochemical activity of the anode can be effectively enhanced, and hydrogen evolution during discharge can be inhibited. Among the investigated anodes, the Mg-1Y anode possesses the highest discharge voltage at all current densities. The Mg-0.5Y anode exhibits excellent comprehensive discharge performance, with the highest anodic efficiency, specific capacity, and energy density of 63%, 1376 mAh·g− 1, 1899 mWh·g− 1 at 10 mA·cm−2, respectively. The discharge voltage and anodic efficiency decrease as the Y content increase further, attributed to the excessive second phases accelerating the self-corrosion and causing the "chunk effect".

Study of Gas Film Characteristics in Electrochemical Discharge Machining and Their Effects on Discharge Energy Distribution.

Glass is a hard and brittle insulating material that is widely used in optics, biomedicine, and microelectromechanical systems. The electrochemical discharge process, which involves an effective microfabrication technology for insulating hard and brittle materials, can be used to perform effective microstructural processing on glass. The gas film is the most important medium in this process, and its quality is an important factor in the formation of good surface microstructures. This study focuses on the gas film properties and their influence on the discharge energy distribution. In this study, a complete factorial design of experiments (DOE) was used, with three factors and three levels of voltage, duty cycle, and frequency as the influencing factors and gas film thickness as the response for the experimental study, to obtain the best combination of process parameters that would result in the best gas film quality. In addition, experiments and simulations of microhole processing on two types of glass, quartz glass and K9 optical glass, were conducted for the first time to characterize the discharge energy distribution of the gas film based on the radial overcut, depth-to-diameter ratio, and roundness error, and to analyze the gas film characteristics and their effects on the discharge energy distribution. The experimental results demonstrated the optimal combination of process parameters, at a voltage of 50 V, a frequency of 20 kHz and a duty cycle of 80%, that achieved a better gas film quality and a more uniform discharge energy distribution. A thin and stable gas film with a thickness of 189 μm was obtained with the optimal combination of parameters, which was 149 μm less than the extreme combination of parameters (60 V, 25 kHz, 60%). These studies resulted in an 81 μm reduction in radial overcut, a roundness error reduced by 14, and a 49% increase in the depth-shallow ratio for a microhole machined on quartz glass.

Electrochemical discharge machining of a high-precision micro-holes array in a glass wafer using a damping and confinement technique

Due to the unstable gas film, it is still a big challenge to achieve high repeatability and quality in electrochemical discharge machining (ECDM) of micro-hole arrays in glass. Based on our previous research on ECDM in micro channels, the present work uses a non-Newtonian fluid electrolyte (non-NTF electrolyte) in ECDM to further achieve a high uniform precision and quality micro-holes array in glass through the damping and confinement effect. The results revealed that an average entrance diameter of 343.8 ± 3.47 μm (mean ± standard deviation) and average heat-affected zone (HAZ) width of 18.01 ± 1.52 μm were successfully fabricated in a 300-μm-thick glass wafer. As compared to the conventional KOH electrolyte, the entrance overcut and the HAZ width of micro-holes were reduced by 43.84 %, and 64.81 %, respectively, while the repeatability improved by 67.92 %. The non-NTF electrolyte concentration and the tool rotation speed were also found to play a significant role in the damping and confinement effect, significantly affecting the geometrical properties of the micro-holes. Furthermore, the micro-holes array was filled with copper to form through glass vias (TGVs), and a standard deviation of the Kelvin resistance of TGVs was only 5.35 mΩ, further demonstrating an excellent repeatability and localization of ECDM micro-holes using a non-NTF electrolyte. The results illustrate that employing a non-NTF electrolyte is a simple way to increase the stability of the gas film and to improve the repeatability and localization of ECDM micro-holes.

Gas bubbles entrapment mechanism in the electrochemical discharge machining involving multi-tip array electrodes

This article addresses the gas bubble entrapment issue for the first time when a multi-tip tool array (MTA) is used in electrochemical discharge machining (ECDM). During the simultaneous creation of microholes by the MTA tools, the electrolyte vapor evaporates and condensates on the tool shank. The electrolyte droplet gradually grows in size and then drops, thus, interrupting the electrochemical discharge. The material removal process becomes intermittent, leading to the formation of poor-quality microholes and subsequent breakage of the glass substrate. The ECDM behavior was characterized by analyzing the gas film formation time and the variation in the mean discharge current. The experimental analysis shows that the gas bubble entrapment phenomenon occurs when the average entrapped gas bubble size and electrolyte condensate sizes are larger than the MTA tool electrodes' effective base size and tip length. Increasing the electrode lengths and pitch size reduced the bubble entrapment frequency by >60 %. Increasing the pitch size from 1 mm to 1.5 mm also reduced the bubble entrapment frequency and improved the uniform electrochemical discharges, which is essential to get good quality microholes.

Multi‐Objective Optimization During Magnetic Field Assisted ECDM of Alumina‐Zirconium Dioxide Ceramic Composite using Battle Royale Optimization

Alumina‐Zirconium dioxide (Al2O3‐ZrO2) Ceramic Composite Material (CCM) is specifically known for its enhanced mechanical and corrosion resistance properties and is widely used as raw material for mechanical parts like, pump components, die inserts, bearings, etc. As a result, industrialists are searching for an efficient method for machining this Al2O3‐ZrO2 material. In this regard, a hybrid unconventional machining process called Electrochemical Discharge Machining (ECDM) is adapted to analyze the machinability of Al2O3‐ZrO2 CCM. Besides, to ensure the efficiency of the ECDM process, a magnetic field is also given to the tool electrode during this study to improve the Material Removal Rate (MRR) of the ECDM machine. The experiment is designed using Response Surface Methodology (RSM) by changing the magnitudes of input controls, namely Electrolytic Concentration (EC), Inter‐electrode Gap (IEG) and Applied Voltage (AV). Moreover, a novel hybrid machine learning optimization strategy called Deep Belief Network based Battle Royal Optimization (DBN‐BRO) algorithm is developed to predict and optimize the ECDM process. Finally, the optimum results are perceived from 55 V AV, 22.727% EC and 40.909 mm IEG input levels. The proposed method shows less than 0.6207 Root Mean Square Error (RMSE) and tools nearly 80 iterations for optimizing the results.

Nickel-rich layered cathode LiNi0.8Co0.1Mn0.1O2 mediated by a selective lattice doping towards high-performance lithium ion battery

Rapid capacity loss and voltage fading pose a significant barrier to the commercialization of nickel-rich materials with layered structures due to particle cracking and structure degradation. Double element selective lattice modification strategy that can balance multiple performance requirements is gaining attention. Here, we proposed a selective lattice doping strategy to enhance the lattice stability of LiNi0.8Co0.1Mn0.1O2 via a double element co-doping of Mg and W. Impressively, the Mg/W co-doping improved electrochemical reaction kinetics and discharge capacity, and largely suppressed structure degradation simultaneously. In situ X-ray diffraction (XRD) results demonstrated that W/Mg co-doping can tune H2−H3 phase transition, relieving the lattice stress and mechanical degradation. These improvements can be attributed to a synergistic effect of W and Mg, in which high valence state W6+ induced the formation of Ni2+ and strong W−O bonds increased layer structure stability, meanwhile Mg2+ as a pillar inhibited Li+/Ni2+ mixing and maintained structural stability. This work provides selective lattice dual-doping strategic guidelines for the use of high energy efficiency and robust stability high-nickel low-cobalt cathodes in lithium-ion batteries.

Optimization of process parameters in ECDM machining using Taguchi based grey relation analysis

Electrochemical discharge machining (ECDM) is a hybrid machining process capable of micromachining conductive and nonconductive materials. The recent development and application of nonconductive materials, such as glass, composites, and ceramics in MEMS and microfluidic devices, have emphasized studying the ECDM process for micro holes and channel formation. The current study uses Taguchi's L27 orthogonal array to design the experiments, evaluate responses by the signal-to-noise ratio, analyze the variance of process parameters (ANOVA), and predict optimal settings for a multi-objective response using grey relation analysis (GRA). The experiments were conducted using two tools, a bare copper tool and Nickel coated copper tool, over a glass substrate. The machining process's output characteristics (radial overcut, heat-affected zone, and hole circularity) were studied by varying input parameters such as applied voltage, tool feed rate, and machining time. The experimental results revealed that Nickel coated Cu tool reduces the average hole overcut and heat-affected zone width and increases the overall circularity of the hole as compared to the bare Cu tool. Based on grey relational grade analysis, the optimal parameters were identified: the applied voltage of 36 V, tool feed rate of 110 µm/min, and one-minute machining time with Nickel coated copper tool. In contrast, a bare copper tool electrode provides optimal process parameters as an applied voltage of 36 V, 110 µm/min tool feed, and a machining time of two minutes for drilling holes in borosilicate glass.

Experimental investigation on the stability of electro chemical discharge machining (ECDM)

Experimental investigation on the stability of electro chemical discharge machining (ECDM)

On electrochemical discharge milling of glass with horizontal tool and vertically upward feeding technique

On electrochemical discharge milling of glass with horizontal tool and vertically upward feeding technique

Elucidating the dependence of electrochemical behavior and discharge performance on the grain structure of lean Mg-0.3Bi-0.3Ag-0.3In anodes in primary Mg-air battery

Elucidating the dependence of electrochemical behavior and discharge performance on the grain structure of lean Mg-0.3Bi-0.3Ag-0.3In anodes in primary Mg-air battery

Micro ECDM scanning process with feedback control of flexible contact force

Quartz glass has been widely used in frontier fields of MEMS (micro electro-mechanical systems) and sensors due to its excellent chemical and mechanical properties. Although ECDM (electrochemical discharge machining) is a non-traditional material removal process suitable for machining electrically non-conductive materials of high temperature resistance and hard brittleness, the adopted feeding strategy of tool electrode directly affects the machining results, especially in a micro ECDM scanning process. The existing feed methods still cannot maintain a suitable machining gap with a minimum given contact force during the micro ECDM scanning process, causing inconsistent gap state and the damage to machining stability and geometric accuracy of micro structures. In this research, a novel spindle combining a flexure hinge and a high-resolution micro-force sensor is designed, achieving the function of real-time servo control of a given micro contact force. Using the micro tool electrodes (<Φ200 μm) fabricated by the combined process of reverse-copying micro EDM and TF-WEDG (tangential feed-wire electrode discharge grinding), the circular structures are successfully machined on quartz glass with the optimized parameters of open-circuit voltage, scanning speed, and number of scanning. To guarantee the consistent depth along a scanning layer, a feed strategy of quantified depth with servo control of flexible micro force (SCFMF-QDFS) is proposed, and micro 3D structures of S-shape and square are machined with controllable accuracy of ±2 μm and ±4 μm in depth and width.

Ultrasonic assisted electrochemical discharge milling of complex glass microstructure with high-quality

IntroductionWith the rapid development of MEMS, the demand for non-conductive hard and brittle material microstructure is increasing. Electrochemical Discharge Machining (ECDM) is one of the most effective methods to machine non-conductive materials like glass and ceramics. However, in the milling process, the problem of discharge pits of different sizes and large thermal cracks caused by excessive discharge energy and heterogeneous energy distribution leads to low machining accuracy, poor stability and surface quality. ObjectivesIn order to solve the above dilemmas and improve the machining quality and stability, a newly developed micro Ultrasonic Assisted Electrochemical Discharge Milling (UAECDM) method is proposed in this paper. MethodsFirstly, a mathematical model is established to reveal the material erosion mechanism in the machining process. Secondly, the influence of ultrasonic vibration on gas film formation and discharge energy is analyzed by theory and simulation. Finally, the effects of ultrasonic amplitude and machining parameters on the quality of microchannels are experimentally studied and optimized by single factor optimization. The machining technology of UAECDM is creatively proposed. ResultsThe experimental results show that adding ultrasonic assistance and using the optimized machining parameters can refine the film thickness, optimize the energy distribution and stabilize the current signal. With assistance of ultrasonic vibration and optimized parameters, a smooth micro channel with width of 118.9 μm was fabricated, and its surface roughness was 0.23 μm, which was 80.99 % declined from 1.21 μm of ECDM. The successful fabrication of microchannel array, two-dimensional and three-dimensional complex glass micro-structures with surface roughness of about 0.2 μm also proves the excellent machining ability of UAECDM. ConclusionIt is proved that UAECDM can effectively improve machining accuracy, stability and surface quality. UAECDM is a desirable method to fabricate micro-channel on glass and will have a very broad industrial application prospect in the future.

Structure and electrochemical properties of CuO-ZnO nanocomposite produced by the one-step novel discharge process

The current study focuses on an alternative strategy for producing nanoparticles (NPs) using one-step electrochemical discharge process (ECDP) in different electrolyte mediums. Current and plasma discharge effects on morphology and mass output rate were examined in detail. FE-SEM and TEM results show dimensional control materials such as rod, flower and rice shapes are produced. The XRD, EDS, UV-vis and Raman characterization techniques confirm the formation of CuO-ZnO NPs with different morphology. The use of two semiconductors (n-type ZnO and p-type CuO) in combination have two different band energies may boost electrochemical performance. From the electrochemical study, the flower-shaped structure has high specific capacity (313 F/g at 2 A/g current density), with 84.1% retention capacitance after 5000 cycles. This study allows us to study the discharge-based composite formation, which could be used in supercapacitors.

Optimization of the Electrochemical Discharge of Spent Li-Ion Batteries from Electric Vehicles for Direct Recycling

Numerous studies have been conducted on spent lithium-ion batteries (LIBs) recycled from electric vehicles. Research on pre-processing techniques to safely disassemble spent LIB packs has mainly focused on water-based discharge methods, such as salt-water discharge. However, salt-water discharge corrodes the electrodes and case, causing internal contamination. Therefore, we propose an electrical discharge process that is suitable for the direct recycling and safe disassembly of spent Li-ion batteries. Spent LIBs from electric vehicles (EV) that were scrapped after EV operation were recovered and electrochemically discharged to voltages of 0, 1, 2, and 2.5 V. These discharged spent LIBs were analyzed through X-ray diffraction, scanning electron microscopy, and electrochemical impedance spectroscopy. The spent LIB with a state-of-health (SoH) of 66.8% exhibited significantly increased swelling and bulging when over-discharged. Notably, the discharging of the spent battery to 0 V increased the thickness of the cell by 115%, which could result in a fire and/or explosion. After being discharged to 0 V, the voltage was able to recover to 2.689 V. The appropriate voltage for the discharge process was estimated to be 2.5 V. The proposed electrical discharge process will be suitable for the direct recycling of spent LIBs in the form of pouch cells.