Papers by Keyword: Electrolyte

Abstract: Electrochemical Honing (ECH) is a process of precision finishing of functional surfaces with the use of the electrical and mechanical energy. It is reported that the 90 percent of the material is removed by electrochemical machining (ECM) process and remaining 10 percent by mechanical scrubbing, which shows the electrical energy is the main constituent in the ECH process. Basically, electrical energy is combined with chemical to form an electrolysis dissolution to remove material from the workpiece surface. This work presents a study for the factors affecting the electrochemical honing of SS-316 turned surfaces, especially the processing time and electrolyte composition. The percentage improvement in surface roughness (Ra, Rt) and out-of-roundness (OOR) as a monitored output of ECH were determined. The results are finally furnished with the aim to generalize a useful guideline for the user to enable proper selection of conditions for obtaining good surface quality.

Abstract: A series of mesoporous carbon sample had been synthesized by using a modification of template silica, SBA-15. Sucrose was added into a large pore size of SBA-15 by using incipient wetness impregnation method. A proper carbonization and removal silica process had been done to produce large pore size of mesoporous carbon. Two electrode cells were prepared by coating mesoporous carbon into stainless steel mesh as a supercapacitor electrode. A few of electrolyte concentration also had been investigated by cyclic voltammetry using a various concentration of KOH in the range 1-12 M. It shows that 6M KOH gives a better performance of EDLC.

Abstract: Lithium ion batteries have become a popular power source for portable electronic equipments. It is found to be superior in gravimetric energy density as it provides about 1.5 times more energy compared to nickel hydride battery. In this study, Polyethylene Oxide based polymer electrolytes were used for investigation. PEO based solid polymer electrolyte films were prepared by solution casting technique with different concentration of salt and different %wt of zirconia nanofiller. The X-ray diffraction analysis was carried out for the identification of compounds available in the sample and to determine the relative concentrations by the intensities of pattern lines. Also the superposition of absorption bands of specific functional groups was confirmed with the infra-red spectrum of FTIR. The Complex Impedance Spectroscopy technique was further used to measure the cell admittance / impedance in a wide range of frequencies and analyzed in the complex admittance/ impedance plane. From the impedance test results it is observed that the conductivity of polymer electrolyte was improved from 7.39×10−4 Scm−1 to 5.24×10−3 Scm−1 after adding 3%wt of ZrO₂ nanofiller with pure polymer. Set up of nano Lab is rare, new and uncommon. It is also an emerging technology. Fabrication of powder needs extra machines which are not popular among common people. It will become popular in the coming future. When particle size is reduced, the quantity of powder is reduced, quality is increased.

Abstract: Electrochemical discharge machining (ECDM) is an ideal process for machining of nonconductive materials in micro-domain. The material removal takes place due to combined action of localised sparks and electrolysis in an electrolytic chamber. The electrolyte is most important process parameter for ECDM as it governs spark action as well as electrolysis. This article presents a comparison of three preferred electrolytes used in ECDM viz. NaCl, KOH and NaOH on drilling of glass workpiece material. The quality characteristics measured are material removal rate (MRR) and hole overcut. Results reveal that NaOH provides 9.7 and 3.8 times higher MRR than NaCl and KOH respectively. MRR and hole overcut are found significantly affected by spark characteristics.

Abstract: The aim of this paper is to investigate the effects of voltage flow (V) in the alkaline electrolyser system and the pH value (pH) of the electrolyte used in the electrolyser. The output measurement of both investigated factors in in the flow rate of the hydrogen gas produced by the system per minute (ml/min). The voltage flow was altered in the system by altering the voltage supply from the workbench power supply ranging from 11V to 14V. The pH value of the electrolyte solution in the electrolyser was altered by the addition of Potassium Hydroxide (KOH) in the distilled water. The pH value samples of the tested solution ranging from 13.0 to 14.0 pH value due to the limitation of the electrolyser used in this experiment. The results found that, the hydrogen gas produced per minute increases with voltage flow in the system. The flow rate of the hydrogen gas produced however only increases when the solution’s pH value reaches at 14 pH level and unreactive below the value.

Abstract: In the electronics industry, people has higher and higher demand for the performance of electronic products, but the requirement of volume is more and more small, it will promote the electronic products toward the direction of miniaturization. Porous ceramic capacitor is one of the most commonly used small electronic devices, but the capacitor thermal failure problem is always a difficult problem plagued capacitor design. This paper establishes the mathematical model of porous ceramic capacitors failure stress, and ABAUQS software is introduced to the failure simulation calculation process of porous ceramic capacitor, to establish the numerical simulation model of capacitor. Through the boundary conditions, the capacitor’s maximum failure stress are calculated, the failure force and the relationship between the thickness of dielectric layer and ceramic layer are obtained, which provide a new computer method for the design of porous ceramic capacitor and the study.

Abstract: The electrochemical behavior of vanadium solution containing V (III) and V (IV) ion each 50% was characterized by cyclic voltammetry and chronopotentiometry with different working electrodes, temperatures, H₂SO₄ concentrations and vanadium ion concentrations. Cyclic voltammetry analysis indicated that V(IV)/V(V) redox reaction at graphite electrode showed good electrochemical activity and reversibility while V(III)/V(II) redox reaction showed bad electrochemical activity and reversibility on Pt, glassy-carbon and graphite electrode. The cathodic peak current density of V(III)/V(II) couples increased first then remained almost unchanged as temperature raised and approached a maximum at 60°C. With H₂SO₄ concentration elevated, the electrolyte became viscous and diffusion step was the controlling step. The electrochemical activity of electrolyte increased with ascending vanadium concentration, so did the reversibility of V(IV)/V(V) couples. However, no matter what vanadium concentration was, the reversibility of V(III)/V(II) couples stayed poor. Stirring in solution benefited to the anodic peak current density of V(IV)/V(V) couples whereas it did not to the cathodic peak current density of V(III)/V(II) couples. The diffusion coefficients of V(III),V(IV) were calculated as 1.17×10^-5,0.919×10^-5 cm²·s^-1 , respectively. Chronopotentiometry test indicated that solution as anolyte showed good charging performance while solution as catholyte showed poor charging performance.

Abstract: An experimental investigation of an electrochemical dissolution of steel 110G13L (steel of Hadfield) in NaNO₃, Na₂SO₄, and NaCl aqueous solutions was carried out. It has been found that the electrochemical dissolution of steel 110G13L in NaNO₃, Na₂SO₄ aqueous solutions occurs in the active state when φ = 4.5 V. Based on the results of the polarization analysis and determination of the steel 110G13L dissolution depth in each of these solutions, the rational electrolyte composition was chosen for ECJM. The technologic experiment has shown that an increase in the electrolyte feeding pressure up to two МPа leads to a machining depth increase up to 600 μm.

Abstract: Specific features of electrochemical dissolving of 12X18H9T stainless steel, OT-4 titanium alloy and BK8 hard alloy in the sodium nitrate water solution exposed to 1.06 micrometer wavelength laser irradiation are considered. It is found that the main mechanism of activating the dissolving process is to increase the reactivity of the electrolyte by stepwise photoactivation.

Abstract: In this paper, a three-dimension model for the vanadium redox flow battery was established to simulate its mass transfer. The distribution of VO₂⁺and VO²⁺ in positive electrode area, the distribution of V²⁺ and V³⁺ in the negative electrode area, and the influences of flow velocity, temperature and the electrolyte concentration on the mass transfer are analyzed. The results show that the mass fraction of VO₂⁺ and V²⁺ decrease while those of VO²⁺and V³⁺increase along the channel direction; the species concentration under the ridge is lower than that under the flow channel. The flow velocity of electrolyte affects the mass distribution at the entrance of the cell, and hardly affects the electrochemical reaction rate; Increase of the temperature accelerates the electrochemical reaction rate; the electrolyte concentration affects both of the mass distribution and the number of ions. The study has great significance both on the optimization of vanadium redox flow battery and its application.