Electrolysis Products Research Articles

Upcycling Spent Selective-Catalytic-Reduction Catalyst to Produce Titanium Carbide Through Molten-Salt Electrolysis

The molten-salt electrolytic method was employed to recycle spent SCR catalyst to prepare TiC compound. A systematic investigation has been carried out through thermodynamic calculation and experimental analysis. The effects of graphite content, cell voltage, electrolyzing temperature, and electrolyzing time on electrolytic products were explored. The results show that a suitable amount of graphite content, high cell voltage, and a high electrolyzing temperature are beneficial to promote the formation of TiC compounds. It has also been found that the electroreduction of spent SCR catalyst/graphite can completely transform it into TiC compound in a relatively short time. The final electrolytic product is confirmed to be a solid solution of (Ti, W, Si, V)C. Meanwhile, the electrolytic process and reaction mechanism were investigated through the analysis of intermediates and the thermodynamic calculation. The electrolytic product has a potential application as reinforcement in metal matrix, which is a high additional-value utilization for spent SCR catalysts.

Carbon Nanotube Production from Li2CO3 Via High Temperature Electrolysis

Electrochemical CO2 reduction (ECR) can provide an environmentally and economically viable route for converting CO2 into value-added products. A recently developed CO2 utilisation process involves its conversion into carbon nanotubes (CNTs) via high temperature electrolysis.1,2 CNTs are tubular structures consisting of graphitic carbon. Their mechanical strength, electrical conductivity, and thermal conductivity accelerated their application in a variety of systems, including nanoelectronics, catalysts and lithium-ion batteries. However, the high cost of CNTs (about $114,000 per tonne) currently limits their use.3 Production of CNTs via high temperature electrolysis of CO2 in molten carbonate salts has the potential to significantly reduce their production cost (on the order of $660 per tonne) whilst simultaneously processing CO2 emissions.4 The method involves several key steps: (i) selective exothermic absorption of CO2 from flue gas or from the air by an alkali metal oxide in molten electrolyte (e.g., Li2O in molten Li2CO3 electrolyte), forming an alkali metal carbonate; (ii) electrolysis of metal carbonate, producing CNTs and oxygen gas, while regenerating the metal oxide; (iii) heat released by CO2 absorption maintains the high temperature required for electrolysis.In our research, carbon nanostructures were electrochemically grown in molten Li2CO3 electrolyte at 800 °C. Carbonate ions were reduced electrochemically to a mix of carbon products, including CNTs, carbon nanofibers and carbon nanoparticles. Electrolysis was carried out at different current densities: 100, 200, 300 mA/cm2, normalised using the starting cathode surface area and using various combinations of iron and nickel as anodes/ cathodes. The resulting cell potential differences were in the range 1.65 – 2.50 V, substantially higher than the thermoneutral potential of 1.42 V at this operating temperature. The carbon products were characterised with Raman spectroscopy, scanning electron microscopy and transmission electron microscopy along with energy dispersive X-ray spectroscopy. High yield of CNTs was observed from the electrolysis products on the cathode at 200 mA/cm2 with a nickel anode and an iron cathode. The SEM and TEM images of the synthesized carbon products are shown in the below figure. We have systematically investigated and were able to relate different reaction parameters to the properties of the synthesised carbonaceous products. Experiments are now being carried out to study the micro-kinetics and reaction mechanism(s) of the CNT nucleation and growth process. A new reactor has been designed and fabricated to introduce CO2 gas into the electrolyte to regenerate the consumed Li2CO3. Our goal is to optimise the reaction process for prototype development. We shall present our experimental setup, procedure and key findings.

Sensitive and eco-friendly voltammetric detection of galantamine using a screen-printed sensor with a functional boron-doped diamond electrode

The presented study focused on developing and optimizing a modern electroanalytical platform for the direct quantitative determination of galantamine. This work used different voltammetric methods to use a screen-printed sensor with a working boron-doped diamond electrode (SP/BDDE). Beneficial analytical performance for detecting galantamine was achieved in a Britton-Robinson buffer with pH 3.0. The oxidation peaks at 0.92 V and 1.20 V were followed for electrochemical quantification of galantamine. High-resolution mass spectrometry was used for the first time to analyze the products of preparative electrolysis, and a mechanism for the electrochemical oxidation of galantamine was proposed, which describes the demethylation of galantamine and the further oxidation of the hydroxyl group to a ketone group in the galantamine molecule.Coupled with the optimized parameters of differential pulse voltammetry and square-wave voltammetry on the SP/BDDE detected galantamine in two linear ranges (the first range was from 1.22 μM to 10 μM; the second range was from 10 μM to 200 μM), providing the limit of detection and limit of quantification on a micromolar level (0.50 μM and 1.48 μM, respectively). Amperometry and chronoamperometry were employed to develop a rapid detection method for galantamine. In this approach, galantamine can be detected at a level of 1.08 μM (amperometry at the second peak). The selectivity of the optimized amperometric methods was found to be excellent in the presence of ten times higher concentrations of certain interferences. The practical applicability of the SP/BDDE for detecting galantamine was demonstrated through the analysis of pharmaceutical products and human urine samples. The proposed procedure fully complies with the latest requirements of green analytical chemistry.

Preparation of Titanium Metal by Deoxygenation Under KCl-NaCl-YCl3 System Using Soluble Anode

Titanium metal is primarily produced via the Kroll process, which is characterized by a semi-continuous production flow and a lengthy process cycle, resulting in high production costs. Researchers have explored alternative methods for titanium production, including molten salt electrolysis, such as the Fray–Farthing–Chen (FFC), Ono Suzuki (OS), and University of Science and Technology Beijing (USTB) processes, aiming to achieve more economical production. Among these, the USTB process, a representative of soluble anode electrolysis, has shown significant promise. However, controlling oxygen concentration in titanium produced by soluble anode electrolysis remains a challenge. This study proposes a novel approach to enhance deoxidation efficiency in soluble anode electrolysis for titanium production by introducing yttrium chloride (YCl3) into the molten salt electrolyte. Thermodynamic analysis and experimental validation demonstrate that the theoretical deoxidation limit for titanium can reach below 100 ppm under Y/YOCl/YCl3 equilibrium. We report the successful synthesis of titanium powder with an oxygen concentration of 6000 ppm from titanium-carbon-oxygen solid solution. Under optimized conditions, the purity of the titanium powder reached 99.42%, demonstrating a new approach for producing high-purity titanium. This method, based on soluble anode electrolysis, offers a potential alternative to the conventional Kroll process. The research elucidates the fabrication process and analytical methods for titanium-carbon-oxygen solid solution, and employs a combination of analytical techniques, including XRD, SEM-EDS, and ONH Analyzer, for characterization of the electrolytic product, encompassing phase analysis, microstructure, and oxygen concentration testing.

Literature Review−Effect of Additives and Post-Treatments on Corrosion Resistance and Mechanical Properties of Plasma Electrolytic Oxidation Products in Magnesium and Titanium

<p class="Abstract">Plasma Electrolytic Oxidation (PEO) is a method of converting metal surfaces into an oxide layer with the help of plasma to improve the surface mechanical properties and corrosion resistance of metals. A PEO layer of about 10-50 μm is obtained quickly from 1 second-10 minutes at a voltage range of 150-500 V with AC or DC mode. Characteristics of the outer layer of PEO have pores and cracks, while the inner layer is relatively denser. Cracks and pores reduce the corrosion resistance and mechanical properties of the coating. In this study, a literature search was carried out on the effect of adding additives and post-treatment on the characteristics of PEO coatings grown on magnesium (Mg) and titanium (Ti) metals for biomedical applications. Mg and Ti metals have opposite chemical properties; Mg is a reactive metal, while Ti is an inert metal. Comparing the behavior of the PEO process and the coating produced by the two different metals is absorbing and necessary to understand the fundamentals of the PEO process. The results of a literature search show that the addition of additives increases the growth rate of the coating so that the coating is thicker and more wear resistant. The hardness of the coating also increases due to the additive particles trapped in the oxide layer filling the micro pores so that the surface becomes denser and more homogeneous. Therefore, corrosion resistance also increases, as indicated by a decrease in corrosion current as measured by the polarization test and an increase in the impedance modulus as measured by the electrochemical impedance test (EIS). The post-alkali treatment allows for increased surface bioactivity, as indicated by the rise in the Ca/P ratio after immersion in a physiological solution.</p>

Photovoltaic to electrolysis off-grid green hydrogen production with DC–DC conversion

Green hydrogen (H2), being the product of water electrolysis powered by renewable energy sources, is expected to be an energetic vector of major importance toward a more sustainable energy mix. In this context, photovoltaic (PV) -based H2 production is a key element, where power electronics technologies are critical to enable its development. In off-grid applications, designing DC–DC power electronics converters with high efficiency and high power density is really important since it can impact significantly the global performance of the H2 production system. In this work, a two-stage DC–DC power conversion system composed by an unregulated DCX converter and a regulated partial power converter is considered to increase the H2 production system efficiency. The DCX converter works in open-loop at resonant frequency with a high DC–DC conversion ratio. A partial power converter (PPC), which regulates only a fraction of the total power between its input and output terminals, represents a improvement in PV-to-H2 direct conversion, particularly since the PV panels do not require regulation from zero to nominal voltage, and in this work, is introduced for regulation of the DCX-based system, by optimizing the PV produced power through a maximum power point tracking (MPPT) algorithm along with the current control of the electrolyzer. A comparison with state-of-the-art converters show an important improvement of the proposed DCX with PPC regulated system. Compared to the solution with classical interleaved-buck pre-regulator, significant improvements in terms of efficiency for the whole range of operation are obtained, up to 2.5% higher with the proposed system. Experimental evaluation of the proposed PPC and DCX two stage converter for PV-powered electrolysis system is provided, validating its feasibility and interest for off-grid green hydrogen production application.

Bimetal anchoring porous MXene nanosheets for driving tandem catalytic high‐efficiency electrochemical nitrate reduction

AbstractElectrochemical nitrate reduction reaction (NO3RR) is considered a promising strategy for ammonia synthesis and nitrate removal, in which catalyst development is crucial. Herein, a series of bimetal (Co and Cu) anchoring porous MXene nanosheets (CoxCuy@PM) catalysts were prepared by combining etching and reduction strategy. On the one hand, Cu and Co bimetals provided tandem catalytic active sites for NO3RR. On the other hand, the in‐plane PM exhibited good electrical conductivity and multiple transport pathways. Consequently, the optimized Co7Cu3@PM catalyst achieved a high ammonia yield of 7.43 mg h−1 mg cat.−1 and an excellent Faraday efficiency (FE) of 95.9%. The mechanism of NO3RR was investigated by analyzing electrolysis products and in situ Fourier transform infrared spectroscopy. Furthermore, the Co7Cu3@PM based ZnNO3− battery exhibited the superior power density of 5.59 mW cm−2 and an NH3 FE of 92.3%. This work presents an effective strategy to design MXene‐based high‐performance NO3RR electrocatalysts.

Research on wire electrochemical micromachining with a unidirectional traveling wire and horizontal electrolyte flushing

Wire electrochemical micromachining (WECMM) technology is well-suited for the processing of small parts, offering advantages such as high machining accuracy and the absence of a recast layer on the machined surface. However, the narrow width of the slit in WECMM makes the removal of electrolytic products a challenging process, which in turn results in a reduction in processing efficiency. To address this challenge, this paper proposes WECMM with a unidirectional traveling wire and horizontal electrolyte flushing. This approach aims to enhance the mass transfer efficiency of WECMM through the use of a unidirectional traveling wire, thereby optimizing the processing efficiency of WECMM. The experiment was conducted on 510 µm thick 9Cr18Mo stainless steel using 15 µm tungsten wire as the cathode. The experimental results demonstrate that the maximum feed rate (MFR) of a unidirectional traveling wire WECMM can reach 3.6 µm/s, thereby achieving comprehensive improvement in processing performance. Ultimately, two kinds of intricate microstructures based on four-layer workpieces were fabricated, resulting in a surface roughness Ra of only 0.052 µm.

Towards electrochemical machining of powder superalloy René 88DT with high surface integrity in different solvent-based electrolytes

Electrochemical machining (ECM) presents numerous applications in the production of aero-engine components. The effects of current density on surface quality during ECM of René 88DT in NaCl-ethylene glycol and NaNO3-aqueous solutions was investigated here. The results indicated that the René 88DT surface has lower sensitivity to current density and more homogeneous electrochemical dissolution in NaCl-glycol solution than in NaNO3-aqueous solution, which results in the suppression of stray corrosion and consistently high surface quality regardless of current density. These strengths are attributed that C2H5O2- and Cl- ions replace OH– ions and combine with alloy ions to form solubles and complexes, which prevent the formation of obstructive passive film, oxide layer, and insoluble electrolytic products. The electrochemical dissolution model in two solutions was established. Furthermore, the high tensile strength and precision machinability of René 88DT in NaCl-glycol solution were also demonstrated.

Study on micro electrochemical milling with programmable dynamic eccentric rotating electrode

Micro electrochemical machining (ECM) has the advantages of non-contact machining, no tool loss and no residual stress, and has great development potential in the field of microstructure manufacturing. However, the micron-scale machining gap is difficult to renew and discharge the electrolyte and electrolytic products in time. In this paper, a novel micro ECM with programmable dynamic eccentric rotating electrode (DER-ECM) is proposed, which can effectively improve the discharge of electrolytic products in the machining area. According to the process characteristics, a disc flexure hinge structure with one-stage amplification was designed, which was driven by a piezo-ceramic actuator, and the programmable eccentricity ranging from 0 to 20 μm. The multi-physics model of flow field and electric field of DER-ECM, micro ECM with eccentric rotating electrode (ER-ECM) and micro ECM with rotating electrode (R-ECM) were established. The theoretical simulation results showed that the flow rate generated by DER-ECM at the bottom of the electrode is 97 times that of ER-ECM. The current density generated by DER-ECM showed periodic pulsation, and the pulsation period was determined by the driving frequency of the piezo-ceramic actuator. The experimental results showed that DER-ECM could effectively eliminate the surface spike of the workpiece in the bottom machining area and effectively improve the machining accuracy. The micro-groove widths obtained under DER-ECM, ER-ECM and R-ECM were 418 μm, 446 μm and 468 μm, respectively. In addition, the influence of three types of dynamic eccentric rotation electrode trajectories on DER-ECM was studied. The experimental results showed that the sawtooth dynamic eccentric rotation electrode had better machining accuracy. Theoretical simulation and experimental results showed that DER-ECM could improve the flow field and achieve higher machining efficiency and machining localization.

Efficient evolution mechanism of electrolytic gas products from laser-assisted electrolyte jet machining

Efficient evolution of electrolytic gas products is one of the mechanisms for increased material removal rate in laser-assisted electrolyte jet machining. However, the evolution mechanism of electrolytic gas products with multiple energy fields in laser-assisted electrolyte jet machining is not clear. In order to quantitatively characterize the laser-assisted facilitation of the evolution of electrolytic gas products, a gas quantification and detection device was designed and built in this paper. Compared to traditional electrolyte jet machining, laser-assisted electrolyte jet machining of 2024-T3 aluminum alloy increased the gas production by 52 % in 180 s. For the anode, the surface modification induced by laser texturing reduces the oxygen evolution potential and surface free energy and promotes gas nucleation and detachment. In addition, laser-induced conductive plasma can enhance transient currents for electrolyte jet machining and cause machining vibrations. The cathodic gas discharge phenomenon was characterized in conjunction with interelectrode gap visualization experiments and cathodic nozzle damage. Experimental results show that cathodic gas discharge depends on strong electric field and high laser pulse fluence. In summary, laser temperature rise, anode surface modification, laser-induced plasma, plasma recoil and cathode gas discharge can all contribute to the evolution of electrolytic gas products.

Study of Chemical Reactions in Molten Salts By Electrochemical Transient Techniques

Processes of electrodeposition and electrochemical synthesis in many cases are accompanied by chemical reactions. In the present work, the following chemical reactions: comproportionation, disproportionation, displacement, cluster formation, heteronuclear complex formation, polymerization, competitive complex formation, and acidic-basic have been studied by electrochemical transient techniques. The effect of chemical reactions on the composition of electrolysis products is discussed and methods of suppressing the reactions complicating the electrolysis processes are suggested. The results of the synthesis of functional materials using chemical reactions are presented.

Exploring the graphitization transformation mechanism of deposited carbon in molten salt electrolysis: A novel insight from molecular structure models

Molten salt electrolysis graphitization is a novel method for the electrochemical graphitization, offering significant technological advantages. Researchers have shown keen interest in preparing graphite materials through molten salt strategies. However, there is still a lack of comprehensive research methodologies at the molecular scale for the removal of heteroatoms and rearrangement of carbon atoms in different amorphous carbon conversion systems. To address the above issue, the deposited carbon (DC, a coking byproduct) was converted into graphitized material (electrolysis products, EP) through the electrochemical method in this study. By processing Transmission Electron Microscope images with Python programming, aromatic skeleton structure information was quantitatively extracted. The evolution of the structure of DC was studied using Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Based on information about elemental content, aromatic skeletal structure, and heteroatom functional groups, average chemical structure models were constructed for DC and EP, and relevant chemical bond parameters were statistically analyzed. Then, the influence of the electric field on the structural transformation of amorphous carbon in molten salts was investigated. The research results show that the electric field significantly affects the graphitization transformation process of amorphous carbon in molten salts, enhancing the interaction between calcium ions and DC molecules, increasing the diffusion coefficient of particles in the system, and promoting the formation of more sp2-hybridized carbon atoms, thus forming a more compact aromatic ring network. This study provides a new research method and molecular/atomic-level insights for a deeper understanding of the mechanism of graphitization transformation of amorphous carbon.

Surface quality enhancement in ultrasonic vibration-assisted electrochemical machining

The aviation industry's evolution has introduced electrochemical machining (ECM) as a promising non-traditional technology for aero-engine blades. However, the surface quality of challenging-to-cut materials is compromised due to insoluble electrolytic products on the machined surface. To enhance ECM's surface quality, ultrasonic-assisted ECM (UA-ECM) was introduced for effective electrolytic product removal. This study conducted numerical simulations involving coupled flow field and cavitation models. It also performed observation experiments and a series of UA-ECM trials with varying inlet pressures (0.1 MPa, 0.2 MPa, 0.3 MPa, 0.4 MPa, and 0.5 MPa), vibration amplitudes (21 µm, 17 µm, 13 µm, 8 µm, 4 µm, and 0 µm), and current densities (31.9 A/cm2, 42.1 A/cm2, 61.1 A/cm2, 76 A/cm2, and 100.9 A/cm2). These aimed to elucidate the mechanism of tool ultrasonic vibration's influence on surface quality and corroborate the simulation findings. Notably, under conditions of low inlet pressure (0.1 MPa), high vibration amplitude (21 µm), and high current density (100.9 A/cm2), complete removal of electrolytic products, inhibition of pitting defects, and attainment of a mirror surface with a surface roughness of Ra = 0.14 µm were achieved, with no change in hardness. This clearly demonstrates that the surface quality of ECM on complex surfaces can be significantly enhanced by ultrasonic assistance.

Sr(Ti0·3Fe0.7)O3−δ-based perovskite with in-situ exsolved Fe–Ru nanoparticles: A highly stable fuel electrode material for solid oxide electrochemical cells with efficient electrocatalytic CO2 reduction ability and preferential selectivity

The development of solid-oxide cells requires fuel electrodes capable of promoting highly catalytic activities for CO2 electrochemical reduction (CO2R). This study develops a fuel electrode material, Sr(Ti0·3Fe0·63Ru0.07)O3-δ (STFR) perovskite, enhance with in-situ exsolved Fe–Ru nanoparticles (STFR–FeRu), demonstrating excellent electrochemical catalytic activity for CO2R, considerable stability, and high selectivity for CO2 electrolysis. Notably, the study discovered for the first time that STFR–FeRu exhibits significantly enhanced catalytic activity in a CO2-containing atmosphere compares to that in hydrogen-based fuels. At 800 °C and 1.3 V, La0·8Sr0.2Ga0.8Mg0·2O3-δ electrolyte-supported cells with STFR–FeRu fuel electrode, for direct CO2 electrolysis, realizes a current density of 1.77 A cm−2. This current density is 50 % higher than that of H2O electrolysis under the same conditions. Additionally, the cell achieves a current density of 1.54 A cm−2 for CO2–H2O co-electrolysis, with a high CO2 electrolysis selectivity (CO concentration exceeding 60 % in the electrolysis products).

Cobalt removal process from PDC with ultrasonication in neutral electrolyte

Cobalt removal is considered a common method to improve the performance of polycrystalline diamond compact (PDC). To effectively reduce the pollution during the process of cobalt removal, a neutral electrolyte was used in this work to remove cobalt from PDC by electrolysis with ultrasonication. The electrode process and mass transfer model of cobalt removal in a NaCl–KCl solution were established by performing electrochemical impedance spectroscopy (EIS) measurements. Different electrode potentials and electrolytic durations were set to investigate the limits of cobalt removal in the neutral electrolyte. Cobalt removal was assessed by conducting potentiodynamic polarisation, scanning electron microscopy (SEM), and energy dispersive spectroscopy (EDS) measurements. The ImageJ2x image analysis software was used to study the collected spectra. The experimental results indicated that cobalt was successfully removed in the neutral electrolyte and that ultrasonication enhanced its removal. The optimal electrode potential for cobalt removal in the NaCl–KCl solution was less than 500 mV or more than 2000 mV. As the electrolysis time increased, the porosity of the PDC surface first increased to 9.4 % and then decreased to 7.2 %, and the depth of cobalt removal was up to 224 μm. Over time, the rate of cobalt removal decreased, suggesting that the efficacy of ultrasonication in promoting the cobalt removal process gradually weakened as electrolysis products continued to accumulate.

Electric Field-Responsive Gold Nanoantennas for the Induction of a Locoregional Tumor pH Change Using Electrolytic Ablation Therapy.

Electrolytic ablation (EA) is a burgeoning treatment for solid tumors, in which electrical energy catalyzes a chemical reaction to generate reactive species that can eradicate cancer cells. However, the application of this technique has been constrained owing to the limited spatial effectiveness and complexity of the electrode designs. Therefore, the incorporation of nanotechnology into EA is anticipated to be a significant improvement. Herein, we present a therapeutic approach based on difructose dianhydride IV-conjugated polyethylenimine-polyethylene glycol-modified gold nanorods as electric nanoantennas and nanoelectrocatalysts for EA. We demonstrate that square-wave direct current (DC) fields trigger a reaction between water molecules and chloride ions on the gold nanorod surface, generating electrolytic products including hydrogen, oxygen, and chlorine gases near the electrodes, changing the pH, and inducing cell death. These electric nanoantennas showed significant efficacy in treating colorectal cancer both in vitro and in vivo after DC treatment. These findings clearly indicate that gold nanoantennas enhance the effectiveness of EA by creating a localized electric field and catalyzing electrolytic reactions for the induction of locoregional pH changes within the tumor. By overcoming the limitations of traditional EA and offering an enhanced level of tumor specificity and control, this nanotechnology-integrated approach advances further innovations in cancer therapies.

Techno-economic assessment of the Synthetic Natural Gas production using different electrolysis technologies and product applications

Power to Methane (PtM) systems are considered an attractive alternative for power generation, renewable sources’ potential harnessing, and atmospheric carbon dioxide (CO2) utilization. This study analyzes the potential use of Synthetic Natural Gas (SNG) for electrical power generation or its direct injection into the currently available Natural Gas Transportation infrastructure. A simulation approach using Aspen Plus v14 software was employed to assess various PtM configurations. Six different systems were analyzed for methanation processes, utilizing three types of electrolysis systems: Alkaline (AE), Proton Exchange Membrane (PEME), and Solid Oxide (SOE). Two primary methane applications were considered: integrated into a combined cycle for power generation and a standalone gas treatment stage for grid injection. As a result, the PEME-based system showed the highest generated-to-fed power ratio, larger than SOE (1.45% higher) and AE (20.66% higher). In addition, PEME technology reports the largest generation of SNG per power supply, exceeding 3.4% and 16.4% of those of SOE and AE, respectively. However, the SOE technology showed a larger efficiency than PEME technology by 8.2% and a PtM efficiency larger than PEME by 12.4%. Fixed capital investment for the PtM systems is around 8.6 and 13.9 million USD$, and their total earnings are between −8.2 and 20.9 thousand USD$ a year, depending on the electrolysis technology, methane application, and carbon credits scenario. According to these results, the PEME-based system is the most suitable option regarding technical and economic criteria.

In-Sn alloy extraction through novel process for recycling of spent ITO targets

The feasibility of utilizing spent indium tin oxide (s-ITO) as an inert anode for the recovery of s-ITO targets through the electro-deoxidation was investigated, which concurrently achieved the avoidance of molten salt pollution caused by graphite anodes and maximized the utilization of resources by using the same material as the anode and cathode. Various techniques including anodic polarization and Tafel polarization were employed to evaluate the corrosion resistance and electrochemical stability of s-ITO. XRD and XPS are used to analyze the phase and valence state of the anodic materials and products, respectively. The practicability of replacing graphite anodes with s-ITO anodes was discussed in detail under identical electrolytic conditions. When using s-ITO as the anode, the carbon content and oxygen content in the electrolytic product are 31 ppm and 57 ppm, respectively, which are lower than those of graphite as the anode. Moreover, based on the results of above investigations, a cathode and anode collaborative electrolytic device was devised to maximize the utilization of resources and recovery of high-value products. The findings indicate that s-ITO has good corrosion resistance when used as an inert anode.

Simulation and experimental studies on surface quality of vibration-assisted ECM

ABSTRACT Electrochemical machining (ECM) offers a superior technology for manufacturing hard-cutting metals such as modified Inconel 718 (IN718). However, in many cases, poor surface quality arises because of the specific dissolution characteristics of the material, hindering further application of the process. Vibration-assisted ECM (VA-ECM) has been proposed in the hope of solving the problem by oscillating the cathode. A multiphysics model was developed for pulsed ECM (PECM) and VA-ECM. Systematic experiments were performed to clarify the mechanism of cathode oscillation on surface quality and verify the computational results. With 20 Hz vibration frequency and 25% duty cycle, the surface roughness reaches 0.39 µm, show that higher oscillation frequency and lower duty cycle are effective in improving surface quality. Finally, dissolution models of modified IN718 under PECM and VA-ECM are proposed. By oscillating the cathode, electrolyte fluctuation is enhanced, electrolytic products are removed effectively, the surface quality is improved significantly.