Applications In Nuclear Industry Research Articles

Microstructural stability and mechanical property of AlCrFeMoTi high-entropy amorphous alloy thin films under He+ ions irradiation

High-entropy amorphous materials have recently proved exceptional radiation resistance, showing potential as a candidate materials for nuclear industry applications. This study synthesized nearly equi-atomic AlCrFeMoTi high-entropy amorphous thin films with a thickness of about 499 nm using magnetron sputtering. The prepared films were subjected to low dose, 0.5 MeV He+ ion irradiation, with varying irradiation damage ranging from 0.01 to 0.1 displacement per atom (dpa). Increasing the irradiation dose led to a decrease in the radius of the inner diffraction halo (r) and an increase in the crystal-like order, indicating an irradiation-induced structural relaxation process within the amorphous matrix. This relaxation results in more efficient atomic packing, yielding a denser amorphous structure and enhanced hardness of AlCrFeMoTi high-entropy amorphous thin films. This study demonstrates that AlCrFeMoTi high-entropy amorphous thin films exhibit remarkable radiation resistance, with stable microstructure and mechanical properties under He+ irradiation, making them promising candidates for applications in the nuclear industry.

High-temperature resistant, low dielectric SiO2@Quartz fiber composites for high fidelity communication cables

High-fidelity communication in extreme environments has attracted significant attention due to its potential applications in aerospace, polar, deep-sea exploration, fire rescue, and nuclear industries. Yet, challenges persist in constructing dielectric layers with both low dielectric constant and high-temperature stability in communication cables. Herein, low-dielectric inorganic composites utilizing pure silicon oxide (SiO2) are employed as a substitute for conventional organic materials or their composites. By incorporating the in-situ growth of SiO2 microspheres (m-SiO2) on the quartz fiber structure, the composites exhibit a reduced dielectric constant while improving mechanical performance. The flexural stress of the m-SiO2@quartz fiber composites is twice as high as that of the composites prepared by the ex-situ synthesis method. Furthermore, the m-SiO2@quartz fiber composites display high-temperature resistance up to 800 °C with a mass loss less than 1 %. With 30 wt% of quartz fibers, 20 nm of m-SiO2, and 6 wt% of the foaming agent, the composites exhibit a dielectric constant of 1.95. Based on the low-dielectric m-SiO2@quartz fiber composites, the cable demonstrates a voltage standing wave ratio (VSWR) of 1.46, an attenuation of 1.22 dB, and a characteristic impedance of 48 Ω.

Revealing microstructure and the associated corrosion mechanism of Al/amorphous Al2O3/Al tri-layer coating deposited on depleted uranium by magnetron sputtering

As important energy materials, uranium and its alloys have been widely used in the fields of material sciences and nuclear industrial applications. Applying metal and/or ceramic surface protective coatings can effectively retard easy corrosion of uranium with extremely high chemical activity. In principle, ideal surface protective coatings should possess (1) lowered density of elongated diffusion pathways (i.e. grain boundaries and growth defects) and (2) improved interfacial bonding to substrate by preventing corrosion medium from reacting with uranium. In this work, we have demonstrated that by magnetron-sputtering amorphous Al2O3 (a-Al2O3) interlayers within Al coatings on depleted uranium (DU), the corrosion resistance is significantly improved as indicated by corrosion potential datum DU substrate (−645 mV), DU with mono-layer Al coating (−610 mV) and DU with Al/a-Al2O3/Al tri-layer coating (−550 mV). Diffusion pathways are elongated with misalignment of columnar grain boundaries in Al coatings around a-Al2O3 interlayers. Meanwhile, density of diffusion pathways is lowered since a-Al2O3 does not contain conventional crystal defects, and can suppress accumulation and facilitate outgassing of Ar bubbles as major growth defects. The effect of coating/substrate interfacial bonding on corrosion behavior is investigated by introduction of intermixing layers between Al- and UO2-rich interfacial regions. A strategy to improve anti-corrosion stability of Al/a-Al2O3/Al tri-layer coating by optimizing degree of intermixing is proposed. The present findings may shed lights on compositional and microstructural design of anti-corrosion coatings on uranium and its alloys.

A Novel Application of High Thermal Conductivity Material on Superconducting RF Cavities: The Inner-wall Thermal Conducting Film (ITCF)

Superconducting Radiofrequency (SRF) technology has developed rapidly for the requirements of high-energy accelerators in fundamental physics research and nuclear industry applications. Thus, the SRF community endeavored to improve the performance from every aspect for niobium and thin-film cavities and made significant breakthroughs in the past decades. However, the positive feedback effect from the RF loss seriously limits the cavity’s maximum acceleration gradient and causes the high field’s unstable operation. Mitigating this effect requires increasing the cavity thermal conductivity to reduce the temperature at the heating point. Conventional technology conducts the RF-loss heat from the surface to the liquid helium outside the cavity while the inner cavity remains vacuum. This paper introduces a new strategy which coats an inner-wall thermal-conducting film (ITCF) in the cavity for the first time globally. The COMSOL simulation results show that ITCF absorbs heat from the RF surface and transmits the heat to the distance on the inner wall, generating a different heat transfer route, thereby reducing the heating-point temperature more efficiently.

Cold metal transfer welding of 316L/430 dissimilar stainless-steel welds

Purpose This paper aims to examine dissimilar joints for various applications in chemical, petrochemical, oil, gas, shipbuilding, defense, rail and nuclear industry. Design/methodology/approach This study examined the effects of cold metal transfer welding on stainless steel welds for 316L austenitic and 430 ferritic dissimilar welds with ER316L, ER309L and without (autogenous) fillers. The microstructural observation was done with an optical microscope. The mechanical test was done to reveal the strength, hardness and toughness of the joint. The electrochemical polarization tests were done to reveal intergranular and pitting corrosion in the dissimilar joints. Findings This microstructural study shows the presence of austenitic and ferritic phases with vermicular ferrite for ER309L filler weld, and for ER316L filler weld specimen shows predominately martensitic phase in the weld region, whereas the autogenous weld shows lathy ferrite mixed with martensitic phase. Mechanical test results indicated that filler welded specimen (ER316L and ER309L) has relatively higher strength and hardness than the autogenous weld, whereas ER316L filler weld exhibited the highest impact toughness than ER309L filler weld and lowest in autogenous weld. The electrochemical corrosion results displayed the highest degree of sensitization (DOS) in without filler welded specimen (45.62%) and lower in case of filler welded specimen ER309L (4.95%) and least in case of ER316L filler welded specimen (3.51%). The high DOS in non-filler welded specimen is correlated with the chromium carbide formation. The non-filler welded specimen shows the highest pitting corrosion attack as compared to the ER316L filler weld specimen and relatively better in ER309L filler welded specimen. The highest pitting corrosion resistance is related with the high chromium content in ER309L composition. Originality/value This experimental study is original and conducted with 316L and 430 stainless steel with ER316L, ER309 and without fillers, which will help the oil, shipbuilding and chemical industries.

CFD and machine learning based hybrid model for passive dilution of helium in a top ventilated compartment

Abstract For hydrogen management in the containment of Nuclear Power Plants (NPPs), besides the Passive autocatalytic Recombiners (PAR), the passive dilution of lighter gas plays an important role. This could be an attractive option to optimize the containment design and to estimate the extent of dilution. Passive dilution has many other applications in nuclear industry. The experimental studies of air entrainment in the upward rising helium plume and the resulting dilution of helium gas by the Canadians in terms of Volume Flow Magnification Factor (VFMF) have been utilized for Computational Fluid Dynamics (CFD) validation. The CFD based Fire Dynamics Simulator (FDS) predicted values of VFMF found to be in good agreement with the test data. After FDS code validation, parametric study has been carried out to generate a data base of VFMF for range of hydrogen injection, side opening area and opening height. In present study various Machine Learning (ML) models are evaluated based on two-parameter relationship i.e. non dimensional hydrogen injection and VFMF using the CFD code generated database. The trained ML models were used for the predictions of the mass flow rate of gas entrainment (through opening) in the rising buoyant plume in terms of VFMF. The ML predictions were in good agreement with the predictions against test data. Multivariate Adaptive Regression Splines (MARS) based ML model found to performed best and discussed in the paper. The paper highlights details of methodology of numerical simulation, results of the CFD studies and machine learning based predictions.

Effect of nickel interlayer on laser welding of copper/titanium dissimilar metal joint

Cu/Ti dissimilar metal welding components have significant potential applications in aerospace, nuclear industries, and other fields. To achieve a robust connection between titanium (TA2) and copper (T2), this study conducted laser-welding experiments using nickel as an intermediate layer. The influence of a nickel intermediate layer on the joint formation, microstructure, mechanical properties, melting, and element diffusion behavior were investigated. The results revealed that without the addition of a nickel intermediate layer, when the laser beam was biased toward the titanium side during welding, a 17 μm thick layer of intermetallic compounds formed in the copper-side weld region. In this area, a notable concentration of fragile Ti–Cu intermetallic compounds forms, rendering it the weakest point in the joint. As a consequence, the ultimate tensile strength of the joint measures at 131 MPa, which is roughly 55 % of the tensile strength of the copper base material. The introduction of a nickel intermediate layer led to a change in the microstructure of the fusion zone, with Cu–Ti intermetallic compounds dispersed within, preventing the formation of brittle Ti–Cu phases at the copper interface. The addition of the nickel interlayer increased the tensile strength of the TA2-T2 joint to 224 MPa, which is approximately 94 % that of the copper parent material, and the joint exhibited ductile fracture behavior in the copper parent material's heat-affected zone.

Bismuth Determination by Controlled-Potential Coulometry: Developing a Highly Accurate Procedure based on GET 176

In this work, we develop a procedure for reproducing the units of bismuth mass fraction in metallic bismuth and those of bismuth (III) mass concentration in bismuth nitrate solutions by controlled-potential coulometry based on the GET 176-2019 State primary standard of mass (molar, atomic) fraction units and mass (molar) concentration of components in liquid and solid substances and materials based on coulometry. The results obtained can be used when manufacturing certified reference materials (CRMs) for the composition of high-purity bismuth and CRMs for the composition of solutions of bismuth (III) ions directly traceable to GET 176-2019. These CRMs may find application in pharmacological, metallurgical, and nuclear industries.

Effect of rolling on crack behavior of FeCrAl alloys in ultra-long life

PurposeThe purpose of this paper is to determine (1) the relationship between microstructure and fatigue cracking behavior and (2) effect of rolling on the process of crack initiation and propagation in FeCrAl alloys.Design/methodology/approachThe qualitative and quantitative fracture studies were performed using scanning electron microscopy and the non-contact optical measurement system (IFMG5).FindingsThe results show that the formation of facets, rough facets and parallel stripes in the crack initiation and early crack propagation zones are closely related to the sensitivity of crack behavior to the microstructure of the material. Besides, the rolling process has a significant influence on the small crack initiation and propagation behavior. Quantitative analysis demonstrates that the size of the stress intensity factor and plastic zone size in the rough zone is associated with the rolling process.Originality/valueThe findings of this study have the potential to enhance the understanding of the microstructural crack formation mechanisms in FeCrAl alloys and shed light on the impact of rolling on the long-term and ultra-long fatigue behavior of these alloys. This new knowledge is vital for improving manufacturing processes and ensuring the safety and reliability of FeCrAl alloys used in nuclear industry applications.

Microstructure and mechanical properties of a nanoscale-precipitate-strengthened reduced-activation refractory complex concentrated alloy

Reduced-activation refractory complex concentrated alloys (RARCCAs) are promising for nuclear industrial applications due to their high strength, corrosion resistance, and irradiation resistance. However, the poor phase stability of the matrix and formation of a brittle second phase result in a poor strength-ductility balance. A novel Ti0.5Hf0.25Ta0.25 RARCCA with a single bcc (body-centered cubic) phase possessing excellent strength and ductility synergy is successfully developed in this study by deliberately combining the “d-electron” method and the empirical parameters calculation. The yield and tensile strengths are 903 and 929 MPa, respectively, with an excellent ductility of approximately 22%. A new type of ω precipitate with a small size (∼1.7 nm) is introduced, contributing to a strength increment of approximately 150 MPa through shearing mechanism without sacrificing ductility. Dislocation slip dominates the deformation during tension at room temperature.

Molten salt synthesis and antioxidation property of SiC‐coated mesocarbon microbeads

AbstractMesocarbon microbead (MCMB) is a prospective candidate as the raw material for nuclear graphite. However, the poor resistance to high‐temperature oxidation limits its application. Herein, a dense SiC coating was prepared by molten salt synthesis on the surface of MCMB to improve its antioxidation performance. The effect of molten salt synthesis reaction time on the phase composition, microstructure, and antioxidation performance of the SiC‐coated MCMB particles was investigated. A theoretical model was established to explain the SiC coating growth rule well, in conformity with the carbon vacancy diffusion mechanism in SiC coating. The SiC coating synthesized for 7 h with the thickness of .385 µm remarkably promoted the high‐temperature antioxidation property of MCMB. The kinetics analysis indicated that the SiC coating obstructed the oxygen diffusion effectively during the oxidation process. The as‐fabricated SiC‐coated MCMBs with good oxidation resistance show great promise for application in nuclear industry and other antioxidative fields.

Influence of Higher Stabilization Temperatures on the Microstructure and Mechanical Properties of Austenitic Stainless Steel 08Ch18N10T

Precipitation strengthening in titanium-stabilized austenitic stainless steels can improve the hot yield strength, as requested, e.g., for nuclear industry applications. The resulting properties depend mainly on the parameters of the heat treatment and previous forming. The influence of the heat treatment parameters on the development of the microstructure and mechanical properties was determined for steel 08Ch18N10T (GOST). Solution annealing and stabilization with different temperatures and holds were performed on the steel, which was, in delivered condition, stabilized at 720 °C. Heat-treated samples were subjected to static tensile testing at room temperature and at 350 °C, microstructural analysis using light, scanning electron and transmission electron microscopy focused on precipitates, and HV10 hardness testing. The strengthening mechanism and its dependence on the stabilization parameters are described. The results of the experiment show the influence of the state of the input material on the final effect of heat treatment—repeated heat treatment achieved lower-strength characteristics than the initial state, while almost all modes showed above-limit values for the mechanical properties. Stabilization temperatures of 720 to 800 °C were found to be optimal in terms of the achieved hot yield strength. At higher temperatures, slightly lower strengths were achieved, but at significantly shorter dwell times.

Application of shaped tube as preform to eliminate the forming defects of ribbed tube in multi-pass drawing

Thin-walled ribbed tube with small-diameter is a newly designed structure, which is used in nuclear fuel cladding. Due to the high precision requirements of nuclear industry applications, the integral forming and precision forming of ribbed tube are the focus of research. However, the forming defects — rib grooves often fail to achieve the precision forming of ribbed tube. Therefore, the two-pass drawing process is designed to realize the integral forming of ribbed tube and the forming mechanism of ribbed tube is analyzed. Further, the effect of round tube as billet on the forming accuracy of ribbed tube is studied. The results show that the rib groove defects are caused by local large deformation and excessive metal flow, which can not be completely eliminated only by changing the billet size of round tube. Based on this, three kinds of shaped tubes as preforms instead of round billet are proposed for eliminating the rib groove defects to realize the precision forming of ribbed tube. The effects of different preform schemes on the forming accuracy, drawing force and stress distribution of ribbed tube are compared and discussed. By selecting the optimal preform scheme and applying it to multi-pass drawing, the completely defect-free ribbed tube is obtained. At the same time, after adopting the appropriate billet size, the rib filling fullness of the tube is further improved and closer to the target size. Moreover, the microstructure of ribbed tube after multi-pass drawing are observed. The martensite and deformation twins appeared due to work hardening and the grain size refinement degree of different positions are different due to different deformation degree.

Comparing the Shielding Features of Graphene and Impregnated Activated Carbon with Selected Traditional Shielding Materials For Gamma-Rays

Graphene and carbon-based materials are widely used in daily life applications. The richness of optical and electronic properties has made them rapidly rising materials on the horizon of material science and condensed matter physics. Having the sheets of atoms stacked in disorganized manner makes activated carbon different from other forms of graphitic structures. The research about the shielding properties of reduced graphene oxide (RGO) and activated carbon for gamma-rays are very rare and active domain of study. Since the use of radioactive sources in different fields (nuclear industry, shielding materials, radiation biophysics and space research application, etc.) has been increasing expeditiously, the photon interactions with matter have gained importance in the world of material science technology. In this work, we review the basics of the impregnated activated carbon (AC) and RGO, as well as the relationship between the structures and the gamma shielding properties in terms of both quality and efficiency. XCom software and EGSnrc simulation code were used to obtain the theoretical values of various shielding parameters which are significantly important to be able to understand the shielding properties of AC and RGO for gamma-rays. We report the mass attenuation coefficients (μm), the half value layer (HVL), the tenth value layer (TVL), and the mean free path (MFP) values and compare them with other commonly used shielding materials like lead, borosilicate, concrete, and vermiculite. The calculated data showed that AC is very appropriate and consistent to be one of the candidates for shielding materials of gamma-rays even though the graphene is seen as inconsistent for such purpose.

Atomistic simulations of defect clustering evolution in heavily irradiated Ti35 alloy

Ti35 alloy (Ti-6wt.%Ta) has greatly promising applications in nuclear industries due to its excellent overall performance. Nevertheless, atomistic mechanisms of its defect clustering evolution due to long-term exposure to irradiation remain scarcely understood by far. Here we investigate the heavy irradiation damage in Ti35 alloy with a dose of up to 4.0 canonical displacement per atom (cDPA) using atomistic simulations of Frenkel pair accumulation. Results show that defect clustering becomes remarkable before 0.04 cDPA and thereafter tends to be relatively stable, and the fraction is not directly dependent on the irradiation dose. Interstitials exhibit a stronger ability than vacancies to form clusters and especially the Nint>5 clusters may cause the formation of 1/3<1‾210> dislocation loops. Compared to the matrix, Nint≤5 interstitial-type defects show a depletion of Ta atoms, while Nint>5 clusters are Ta-rich. This study provides an important insight into the understanding of the irradiation damage behaviors for Ti35 alloy.

Corrosion Behavior of High Entropy Alloys and Their Application in the Nuclear Industry—An Overview

With multiple principal components, high entropy alloys (HEAs) have aroused great interest due to their unique microstructures and outstanding properties. Recently, the corrosion behavior of HEAs has become a scientific hotspot in the area of material science and engineering, and HEAs can exhibit good protection against corrosive environments. A comprehensive understanding of the corrosion mechanism of HEAs is important for further design of HEAs with better performance. This paper reviews the corrosion properties and mechanisms of HEAs (mainly Cantor alloy and its variants) in various environments. More crucially, this paper is focused on the influences of composition and microstructure on the evolution of the corrosion process, especially passive film stability and localized corrosion resistance. The corrosion behavior of HEAs as structural materials in nuclear industry applications is emphasized. Finally, based on this review, the possible perspectives for scientific research and engineering applications of HEAs are proposed.

Augmented reality-assisted gesture-based teleoperated system for robot motion planning

Purpose The study proposed a human–robot interaction (HRI) framework to enable operators to communicate remotely with robots in a simple and intuitive way. The study focused on the situation when operators with no programming skills have to accomplish teleoperated tasks dealing with randomly localized different-sized objects in an unstructured environment. The purpose of this study is to reduce stress on operators, increase accuracy and reduce the time of task accomplishment. The special application of the proposed system is in the radioactive isotope production factories. The following approach combined the reactivity of the operator’s direct control with the powerful tools of vision-based object classification and localization. Design/methodology/approach Perceptive real-time gesture control predicated on a Kinect sensor is formulated by information fusion between human intuitiveness and an augmented reality-based vision algorithm. Objects are localized using a developed feature-based vision algorithm, where the homography is estimated and Perspective-n-Point problem is solved. The 3D object position and orientation are stored in the robot end-effector memory for the last mission adjusting and waiting for a gesture control signal to autonomously pick/place an object. Object classification process is done using a one-shot Siamese neural network (NN) to train a proposed deep NN; other well-known models are also used in a comparison. The system was contextualized in one of the nuclear industry applications: radioactive isotope production and its validation were performed through a user study where 10 participants of different backgrounds are involved. Findings The system was contextualized in one of the nuclear industry applications: radioactive isotope production and its validation were performed through a user study where 10 participants of different backgrounds are involved. The results revealed the effectiveness of the proposed teleoperation system and demonstrate its potential for use by robotics non-experienced users to effectively accomplish remote robot tasks. Social implications The proposed system reduces risk and increases level of safety when applied in hazardous environment such as the nuclear one. Originality/value The contribution and uniqueness of the presented study are represented in the development of a well-integrated HRI system that can tackle the four aforementioned circumstances in an effective and user-friendly way. High operator–robot reactivity is kept by using the direct control method, while a lot of cognitive stress is removed using elective/flapped autonomous mode to manipulate randomly localized different configuration objects. This necessitates building an effective deep learning algorithm (in comparison to well-known methods) to recognize objects in different conditions: illumination levels, shadows and different postures.

Metal-organic framework nanoparticles as a free radical scavenger improving the stability of epoxy under high dose gamma irradiation

Understanding the degradation mechanism of epoxy resin under irradiation and enhancing the radiation resistance of epoxy resin are of great significance for its application in aerospace and nuclear industries. In this study, we investigated the radiation resistance of epoxy reinforced by UIO-66-OH metal-organic framework. Outstanding radiation resistance was achieved by using UIO-66-OH nanoparticles as radical scavengers to retard epoxy degradation. The introduction of UIO-66-OH reduces the content of free radicals generated after irradiation by 88.17%. UIO-66-OH also improves the mechanical and thermal properties of epoxy before and after irradiation. The scavenging radicals mechanism of hydrogen atom transfer of UIO-66-OH is more dominant than that of graphene oxide and carbon nanotubes. The radiation resistance of UIO-66-OH nanoparticles is related to hydroxyl functionalization and porous structure. This work provides a new idea and method for improving the stability of epoxy resin under gamma ray radiation.

An Optimization of Manufacturing Process of SS304L Using Direct Energy Deposition Method

The direct energy deposition (DED) method is an emerging manufacturing technique that has been recently highlighted due to its capabilities to coat materials with complex geometry for high temperature and highly corrosive environmental applications, such as steam turbine blade. Amongst metallic materials, SS304L has been reported to have superior corrosion resistance in such environments. Therefore, 3D printing of complex-shaped parts using SS304 maybe a promising strategy to introduce 3D printing techniques for nuclear industry application. To obtain robust and stable products that can withstand extreme environments, optimization of the SS304 manufacturing process conditions is required. This study investigated the effects of process parameters including laser power, scan speed, coaxial gas flow, and feeder rate using the DED method with a 4 way nozzle. It was found that laser power has an effect on grain growth behaviors. If the other variables are fixed and the scan speed is above a certain value, then the scan speed does not affect surface oxidation. The feeder rate is related to height. As the feeder rate increases, the height increases. Coaxial gas works to prevent oxidation and damage to the optic components and is not a critical factor in determining the size of the deposited material. These results can be utilized in future studies to accelerate the process design time of other 3D printed materials and future applications using SS304L

Multi-objective optimization of µ-EDM parameters for µ-hole drilling on Hastelloy C 276 super alloy using Response Surface Methodology and multi-objective genetic algorithm

Hastelloy C 276 is one of the nickel-based super alloys which has an excellent resistance against corrosion at high temperature. It has a major application in nuclear and aerospace industry. Micro-electrical discharge machining (µ-EDM) is a highly accurate and precise non-conventional micro-machining process to fabricate this alloy. Thus, in this research paper an effort has been made to examine the impact of input process parameters like capacitance, gap voltage and pulse on time (t on ) on the response variables i.e., material removal rate (MRR), tool wear rate (TWR) and diametral overcut (DOC) during µ-EDM of Hastelloy C 276. Response Surface Methodology (RSM) is a collection of statistical and mathematical tools which determine the relationship between input and output characteristics. Box-Behnken design (BBD) is a special type of RSM based design that reduces the no of experiments without affecting the variation between the input and response parameters. RSM based BBD is used in the current study to develop the mathematical models for each response variable. RSM based desirability function (RSM-DF) which convert multiple responses into a scale free desirability, is used as an optimization tool in the present study. The current work used the multi-objective genetic algorithm (MOGA), a non-conventional searching based multi-response optimization algorithm, to optimize the machining parameters for maximum MRR along with minimum TWR and DOC. The lowest machining time is achieved by experiment no 10 and the least entry µ-hole diameter is drilled by experiment no 15. ANOVA analysis accomplished that capacitance has the highest significant contribution towards MRR, TWR and DOC. 3D response surface plot discloses that MRR, TWR and DOC is increased with capacitance until 5600 pF, 5600 pF and 8900 pF and then there is little reduction took place for all the three responses. The optimization result from RSM-DF is capacitance of 1001.560 pF, gap voltage of 137.6670 volt and t on of 41.532 µs for maximum MRR along with minimum TWR and DOC. MOGA approach reveals that maximum MRR of 0.005153 mm 3 /min along with minimum TWR of 0.002423 mm 3 /min and minimum DOC of 0.028691 mm is found at a capacitance of 1001.610 pF, gap voltage of 137.6671 volt and t on of 48.025 µs. Conformation experiments are conducted and the absolute percentage errors between the experimental and optimized values are found to be less than 5% for both approaches. Field emission scanning electron microscopy (FESEM) analysis reveals that MOGA settings drilled µ-hole with less DOC, more circularity and less surface cracks compared to the initial and RSM-DF parametric settings. A deposition of C and Cu took place in the side wall of the micro-hole from the dielectric fluid and tool material respectively.