Electrode Rotation Speed Research Articles

다양한 양극산화 공정조건에 따른 롤 금형 표면에 형성되는 나노포어 형상에 대한 연구

This study analyzes the effect of anodizing conditions on nanopore formation on a cylindrical aluminum roll. In general, a nanopore is formed at the center of a concave base-pattern. Occasionally, multiple nanopores are formed on a single base-pattern. However, to control the diameter and interpore distance precisely, single nanopores are required. In this study, the ratio of the number of single nanopores to the total number of nanopores was investigated by varying anodizing conditions such as electrode area, electrolyte concentration, and rotation speed of the roll mold. The areal ratio of the counter-electrode to the working electrode (aluminum), electrolyte concentration, and the roll-mold rotation speed were varied from 0.4% to 42%, 0.07 M to 0.3 M, and 5 rpm to 75 rpm, respectively. The experimental results showed that the single-nanopore ratio increased with increasing counter-electrode area and electrolyte concentration. However, the rotation speed had no significant effect on nanopore shape.

Optimization of process parameters in micro-EDM of Ti-6Al-4V based on full factorial design

The objective of this study was to investigate the effects of the micro-electro-discharge machining (micro-EDM) process parameters on the machining performance parameters, in order to understand the behavior of each process parameter as well as to find out their optimal values. This research was conducted through a series of experiments using full factorial design. Analysis of variance (ANOVA) and multivariate analysis of variance (MANOVA) were employed to analyze the findings and to determine the significance of each process parameters on the response variables. The process parameters included in this study were voltage, capacitance, electrode rotational speed, and the electrode coating. Voltage and capacitance were studied separately as well as in combination in terms of the discharge energy. The response variables were consisted of machining time, tool wear, crater size, and surface micro-hardness. The findings indicated that the increase in voltage had a decreasing effect on the machining time, while it increased the crater size. The increase in capacitance resulted in decreased machining time and the tool wear, while it had an increasing effect on the surface micro-hardness. It was found that the effects of titanium nitride (TN) coating and the electrode rotational speed were not statistically significant. There was slight improvement of machining time and accuracy for increasing electrode rotational speed due to improved flushing condition, but very high electrode rotational speed was found to be unsuitable for machining accuracy. The overcut of the micro-holes was found to increase gradually with the increase of voltage and capacitance due to increase in spark gap and discharge duration, respectively. The voltage and the capacitance were found to be the two major parameters influencing the micro-EDM performance. Assuming that the importance and the weight of all response variables had been identical, the optimal process parameters for improved micro-EDM of Ti-6Al-4V were found to be TN-coated electrode, 60 V, 4700 pF, and 3000 rpm.

Performance Evaluation of Electrode Materials in Electric Discharge Deep Hole Drilling of Inconel 718 Superalloy

In the present study, electric discharge deep hole drilling of Inconel 718 was experimented with three different commercial tube electrodes viz., copper, copper-tungsten and graphite. The pertinent process parameters selected for the study were peak current, pulse on-time, duty factor and electrode rotational speed. The machining performance was investigated by analysing Material Removal Rate (MRR), Electrode Wear Ratio (EWR) and Surface Roughness (SR). The experiments were planned according to Response Surface Method (RSM) and Central Composite Design (CCD). Through holes of diameter around 3.0mm and 25mm depth were drilled. Experimental data was fitted and regression analysis was done. The experimental results indicated that copper electrode outperformed copper-tungsten and graphite electrodes with regard to MRR and SR. Further, the EWR was high in copper electrode followed by copper-tungsten and graphite electrodes. Among the three electrode materials tested, copper is the best choice of electrode material with respect to high MRR and low SR.

Electrochemical self-assembly of nano-polyaniline film by forced convection and its capacitive performance

We report the discovery of a nanostructuring process of PANI electrochemical self-assembly through a forced convection method. The morphology and structure of PANI films can be controlled by varying the rotation speed of the disk electrode during electropolymerization.

Electrical Discharge Machining of Metal Matrix Composites with a High Speed Non-Round Electrode

An electrical discharge machining process with a high electrode rotation speed (EDM-HS) has been developed to solve the problems of the conventional EDM process in machining metal matrix composites (MMCs). The EDM-HS process employs a non-round tool electrode. The experiment results showed that the materials removal rate (MRR) of the workpiece can be improved significantly by employing a non-round tool electrode. The relationship between the pulse duration, machining current, duty cycle, the rotation speed of the tool electrode and the MRR has been studied respectively. And the machining mechanism of this EDM-HS process has been analyzed both theoretically and experimentally. The results showed that the non-round electrode can enlarge the machining gap and with a high electrode rotation speed, the machined debris can be discharge out of the machining area effectively and hence a stable machining condition can be obtained. As a result, a higher MRR can be achieved. Moreover, an orthogonal analysis has been utilized to study the relative importance of the machining parameters on MRR. It was found that to obtain the highest MRR, the electrode rotation speed was the most influential factor among the duty cycle, machining current, pulse duration and electrode rotation speed. This outcome supports that it is feasible to use this novel method to machining particulate reinforced MMCs, where a higher MRR can be achieved.

Synergism between Tartaric acid and Zinc ions under hydrodynamic conditions for corrosion inhibition of steel in cooling water solution-electrochemical impedance and morphological studies

A study of the St37 steel rotating disc electrode/cooling water interface was carried out using an environmentally friendly inhibitor mixture including Tartaric acid (TaA) and Zinc sulfate. Electrochemical Impedance Spectroscopy measurements were performed in the absence and presence of inhibitor in cooling water under static conditions and at different rotation speeds. TaA did not show good inhibition efficiency at quiescent conditions. However, its performance became significantly better in the presence of Zn2+ ions. The increase in electrode rotation speed also enhanced the inhibition efficiency of TaA and its mixture with Zn2+ ions. The synergism between TaA and Zn2+ ions and the solution hydrodynamics promoted the formation and adsorption of Tartrate-Zn2+ complexes on the metal surface, leading to a highly protective layer formed on metal surface as a barrier against diffusion of corrosive ions. Analysis by scanning electron microscopy and energy dispersive X-ray analysis was presented for both the corroded and protected metal surfaces. Based on results, a mechanism for corrosion inhibition and the synergism between two components was proposed.

Parameters optimization for sustainable machining of Ti6Al4V using a novel high-speed dry electrical discharge milling

Cleaner production and sustainability are of crucial importance in the field of machining processes where great amount of energy is being consumed. This paper outlines the application of gray relational theory in order to optimize the machining parameters for Ti6Al4V in high-speed dry electrical discharge milling (EDM) using a tubular graphite electrode. The objective of optimization is to achieve simultaneously the minimum power consumption and the maximum material removal rate (MRR). The maximum MRR 5634 mm3/min was obtained with a power consumption of 7.61 kW. MRR stayed in the similar level, and power consumption was reduced by 17.82 % compared with that of the parameters in our previous study. Current is the main effect factor on MRR and power consumption. The corresponding single pulsed experiments were conducted to deeply explore the reasons for the influence of air pressure and electrode rotation speed on the MRR and power consumption.

Controlled hydrodynamic conditions on the formation of iron oxide nanostructures synthesized by electrochemical anodization: Effect of the electrode rotation speed

Iron oxide nanostructures are of particular interest because they can be used as photocatalysts in water splitting due to their advantageous properties. Electrochemical anodization is one of the best techniques to synthesize nanostructures directly on the metal substrate (direct back contact). In the present study, a novel methodology consisting of the anodization of iron under hydrodynamic conditions is carried out in order to obtain mainly hematite (α-Fe2O3) nanostructures to be used as photocatalysts for photoelectrochemical water splitting applications. Different rotation speeds were studied with the aim of evaluating the obtained nanostructures and determining the most attractive operational conditions. The synthesized nanostructures were characterized by means of Raman spectroscopy, Field Emission Scanning Electron Microscopy, photoelectrochemical water splitting, stability against photocorrosion tests, Mott-Schottky analysis, Electrochemical Impedance Spectroscopy (EIS) and band gap measurements. The results showed that the highest photocurrent densities for photoelectrochemical water splitting were achieved for the nanostructure synthesized at 1000rpm which corresponds to a nanotubular structure reaching ∼0.130mAcm−2 at 0.54V (vs. Ag/AgCl). This is in agreement with the EIS measurements and Mott-Schottky analysis which showed the lowest resistances and the corresponding donor density values, respectively, for the nanostructure anodized at 1000rpm.

Effect of Hydrodynamic Conditions, Temperature and Immersion Times on the Corrosion Inhibition Efficiency of API 5L X52 Steel in 1M HCl Containing 1H-1,2,4 or 1H-1,2,3-triazoles

From electrochemical means, the concentration effect of 1H-1,2,4 and 1H-1,2,3 triazoles on the corrosion behavior of API 5L X52 steel samples immersed in 1M HCl was evaluated. The results obtained through electrochemical impedance spectroscopy demonstrated that at stagnant and room temperature conditions, the IE increased with inhibitor concentration, although it reached an IE > 90 %, at 200 ppm, in both cases. It was found that for [1H-1,2,4-triazole] \({\leq 200}\) ppm, the IE value reached, ca. 85 %, at 40 rpm; however, it diminished then to ca. 65 % upon changing the working electrode rotation speed to 1000 rpm. A similar situation was observed for the 1H-1,2,3-triazole under static conditions, where a value of ca. 96 % was reached at 200 ppm, although it was also observed decreasing inhibition efficiency with increasing rotation speed. Furthermore, when the temperature of the corrosive media was increased \({T \geq 40 ^{\circ}{\rm C}}\), at static conditions and 100 ppm inhibitor, the IE values diminished to ca. 83.8 % for 1H-1,2,4-triazole and 77 % for 1H-1,2,3-triazole. For stagnant conditions, 100 ppm of either 1H-1,2,3-triazole or 1H-1,2,4-triazole at \({25 ^{\circ}{\rm C}}\), an IE greater than 95 % was found even after 672 exposure hours to the corrosive media. The results showed that, in both cases, the triazoles inhibition mechanism involves blockage of the steel surface through a Langmuir-type physisorption process.

High-speed near dry electrical discharge machining

High-speed near dry electrical discharge machining (EDM) is a novel and promising machining method, which obtains higher material removal rate, lower surface roughness and thinner width of overcut compared with that of high-speed dry EDM. Moreover, debris deposition on the machined surface and electrodes are significantly reduced and an obviously thin heat affected zone is obtained using the near dry dielectric (mist). In this study, a low-flux pump is utilized to supply deionized water at a controlled rate to the high-speed air pipe, which affords a mist dielectric to the machining process. Compared with dry EDM, the high-speed near dry EDM improves the cooling capacity and increases the dielectric strength of the dielectric. Furthermore, electrode injection flushing assisted by side flushing of high-speed mist was used to reduce debris deposition and improve cooling capacity. Comparative milling experiments of Ti6Al4V were conducted under the dry and near dry conditions using the different flushing ways. The effects of current, pressure, droplet size, electrode rotation speed, and droplet density on the material removal rate, surface roughness, width of overcut in continuous machining and material removal weight, trace length, trace width in single pulse machining were studied. In addition, scanning electron microscope, X-ray diffractometer, energy dispersive spectrometer, and micro-hardness tester were also used to study the micro-characters of the machined materials.

High-efficient Dry Hybrid Machining of EDM and Arc Machining

EDM milling experiments on AISI 304 stainless steel (AISI 304 SS) using high-efficient hybrid machining with a high-speed air dielectric were conducted in this study. The novel and efficient hybrid machining is the arc machining and electrical discharge machining (EDM) working in parallel. AISI 304 SS can be quickly melted by significantly high machining energy and fast expelled by high-speed air flow and high-speed electrode rotation. The maximum material removal rate (MRR) of 5534 mm3/min was obtained, which was hundred times compared with that of conventional dry EDM. Comparative experiments on AISI 304 SS using high-efficient dry hybrid machining, dry arc machining, and dry EDM were conducted. The influences of air flow rate, peak current of arc machining, peak voltage of EDM, and electrode rotation speed on MRR, relative electrode wear rate and surface roughness were also studied. Moreover, the cross section and surface morphology were investigated. This study demonstrates that high-efficient dry hybrid machining is an efficient rough machining method in the processing fields that require removing vast materials.

Optimizing Machining Parameters of Compound Machining of Inconel718

The compound machining (CM) compounded with electrical discharge machining (EDM) and arc machining is a novel approach to process difficult-to-machine materials especially for the aerospace materials such as Inconel718. An exciting material removal rate (MRR) and a small diameter of overcut (DOC) can be received in this approach. A suitable selection of machining parameters plays a key role in CM of Inconel718. Therefore, a various machining parameters affecting MRR and DOC such as peak current, electrode rotation speed and peak voltage were analyzed. This paper highlights the combined influence of these parameters in CM. A 23 factorial with central composite design (CCD) and a total of 20 experiments were conducted in this study. The mathematical model of objective function between the machining parameters and the dependent variable was obtained by utilizing the response surface method (RSM). Finally, the optimized machining parameters can be acquired in CM of Inconel718.

Deep micro-hole drilling of Hardox 500 by electro-discharge machining

Abstract In this study, micro-size drillability of Hardox 500 was investigated by the electro-discharge machining (EDM) method. For this purpose, holes were drilled by using different machining parameters (discharge current, electrode rotational speed, dielectric spray pressure) and the effect of these parameters on machining performance and hole profile was specified. At the end of the tests, it was detected that discharge current and electrode rotational speed increased material removal rate (MRR), electrode wear rate (EWR) and hole dimensional error (DE) whereas dielectric spray pressure increased the MRR values and decreased the EWR and DE values.

Mathematical modeling and multi-criteria optimization of rotary electrical discharge machining process

In this paper, mathematical modeling of three performance characteristics namely material removal rate, surface roughness and electrode wear rate in rotary electrical discharge machining RENE80 nickel super alloy is done using regression approach. The parameters considered are peak current, pulse on time, pulse off time and electrode rotational speed. The regression approach is very much effective in mathematical modeling when the performance characteristic is influenced by many variables. The modeling of these characteristics is helpful in predicting the performance under a given set of combination of input process parameters. The adequacy of developed models is tested by correlation coefficient and Analysis of Variance. It is observed that the developed models are adequate in establishing the relationship between input parameters and performance characteristics. Further, multi-criteria optimization of process parameter levels is carried using grey based Taguchi method. The experiments are planned based on Taguchi's L9 orthogonal array. The proposed method employs single grey relational grade as a performance index to obtain optimum levels of parameters. It is found that peak current and electrode rotational speed are influential on these characteristics. Confirmation experiments are conducted to validate optimal parameters and it reveals the improvements in material removal rate, surface roughness and electrode wear rate as 13.84%, 12.91% and 19.42% respectively.

Analysis of dry electrical discharge machining in different dielectric mediums

Dry electrical discharge machining (EDM) is a modification of the oil EDM process in which the liquid dielectric is replaced by a gaseous dielectric. This study investigates the effects of different types of gas (air, nitrogen, and mixture of argon/air) on the machining characteristics of dry EDM of M35 workpiece material. A Taguchi L27 orthogonal array design was applied to investigate the effects of six control factors, including current, pulse on-time, duty factor, gas pressure, electrode rotational speed and specifically type of gas on machining responses, including material removal rate (MRR), surface roughness, and radial overcut. Also, the surface integrity was investigated in different dielectric mediums. Results show that the argon/air mixture can improve the MRR with respect to air and nitrogen. The best dimensional accuracy can be obtained by using nitrogen as the dielectric medium. Also, the machined surface with nitrogen has the fewest small drops and the microcracks in Aagon/air mixture is more than those air one. So, the argon/air mixture is the best dielectric with respect to nitrogen and air mediums for dry EDM of high-speed steel M35.

Characteristics of Nitrogen and Boron Co-Doped Graphene Nanosheets Synthesized By Simple Microwave-Hydrothermal Method

Graphene nanosheets have received much attention in electrochemical energy research areas because of its remarkable properties such as high specific surface area and electrical conductivity. The properties satisfy various requirements for electrochemical device’s electrode. In that application, the enhancement of the oxygen reduction reaction (ORR) activity has been considered as one of the important issues. For enhancing ORR activity, various precious metal catalysts have been investigated in spite of their high prices. In recent years, research efforts have been focused on developing various non-metal catalysts for overcoming the disadvantage of metal catalysts. Most of carbon-based non-metal catalysts were synthesized via expensive method such as chemical vapor deposition (CVD) method. The method is not suitable for mass production method. In this study, we synthesized nitrogen and boron co-doped graphene nanosheets (BNG) from graphene oxide (GO) by simple microwave-hydrothermal method. The synthesis time can be significantly reduced result from assistance of microwave heating. The synthesis process includes doping and reduction process. The samples were prepared under different reduction temperature conditions. For observing the morphology of samples, we carried out scanning electron microscopy (SEM). From Raman spectra analysis, we confirmed that intensity ratio (ID/IG) increased with reduction temperature. And we investigated chemical composition and bonding configuration of the BNG samples by X-ray photoelectron spectroscopy (XPS). The results of XPS analysis demonstrated that co-doping and reduction process are successfully achieved. Catalytic activities were characterized by three-electrode system. Linear sweep voltammetry (LSV) was measured in 0.1M KOH electrolyte purged oxygen gas over 1 h, with a 1500 rpm electrode rotation speed and a 10 mVs-1 scan rate. The LSV results revealed that co-doped samples show higher ORR activity compared to that of non-doped sample and the activity is enhanced with reduction temperature. Acknowledgement This research was supported by the MSIP(Ministry of Science, ICT and Future Planning), Korea, under the “IT Consilience Creative Program” (NIPA-2014-H0201-14-1002) supervised by the NIPA(National IT Industry Promotion Agency)

Individual and combined effects of fluid flow and inhibitor concentration on inhibition of St-37 steel corrosion using K3PO4 in neutral solution

Most of the common inhibitors that are used commercially to control the corrosion of steel in neutral solutions are not environmentally friendly. Therefore, use of inhibitors with low toxicities is preferred in industries. The phosphates are inorganic inhibitors with relatively low toxicity that are used in different applications. The solution hydrodynamics is also one of major factors that influence the corrosion behavior of metals and the performance of inhibitors in corrosive systems. Present work is a systematic investigation of the combined effects of inhibitor concentration and hydrodynamic conditions on the electrochemical corrosion behavior of St37 steel in 3.5% NaCl solution containing potassium phosphate. The obtained results showed that behavior of phosphate under hydrodynamic conditions is influenced significantly by its concentration. When the phosphate concentration was relatively high (5 mM), the inhibition efficiencies were not changed by variation of electrode rotation speed. It was attributed to the little influence of hydrodynamic conditions on stability of the protective layers formed on metal surface. It was also observed that at lower phosphate concentrations (less than 1 mM), the inhibitor performance decreased significantly applying hydrodynamic conditions due to the formation of frail and weak protective films on metal surface.

High-throughput electrical discharge milling of WC–8%Co

Experiments of high-throughput electrical discharge milling (HTED milling) of WC–8%Co at 600-A peak current and 4766 mm3/min material removal rate (MRR) using a 12-mm-external-diameter and 4-mm-internal-diameter tubular graphite electrode were conducted. The HTED milling process parameters, including peak current, electrode rotation speed, flushing pressure, and peak voltage, were studied to evaluate the effect on MRR, relative electrode wear rate, and diameter of overcut. The cross section, surface morphology, and microhardness of WC–8%Co for HTED milling were also investigated. Peak current has proven to be a critical factor for MRR. The MRR of HTED milling at peak current 600 A can be increased by ten times compared to that of HTED milling at peak current 100 A. Faster electrode rotation speed, larger flushing pressure, and higher peak voltage are essential to achieve low relative electrode wear rate (REWR) and high MRR. This study demonstrates that, using proper HTED milling process parameters and tubular graphite electrode, the HTED milling of WC–8%Co can be processed efficiently.

High-speed dry compound machining of Ti6Al4V

Milling experiments on Ti6Al4V using high-speed compound machining with high-speed air dielectric were conducted in this study. The new and efficient compound machining combines arc machining and electrical discharge machining (EDM) together, both of them are working in parallel. Ti6Al4V can be quickly melted by significantly high processing energy and rapidly expelled by high-speed air flow and high-speed electrode rotation. The maximum material removal rate (MRR) of 5862mm3/min was obtained, which was hundred times higher than that of conventional dry EDM. The influences of air flow rate, inner diameter of the tubular electrode, peak current of arc machining, peak voltage of EDM, and electrode rotation speed on MRR, relative electrode wear rate and surface roughness were studied. Moreover, the re-solidified layer, surface morphology and elementary composition were also investigated. This study demonstrates that high-speed dry compound machining of Ti6Al4V can be processed efficiently using the proper machining parameters.

Initial study of Nickel Electrolyte for EnFACE Process

Nickel electrolyte for a micro-pattern transfer process without photolithography, EnFACE, has been developed. Previous work on copper deposition indicated that a conductivity of ~2.7 Sm -1 is required. Electrochemical parameters of electrolyte i.e. current density and overpotential are also crucial to govern a successful pattern replication. Therefore, the investigation focused on the measurement of physicochemical properties and electrochemical behaviour of the electrolyte at different nickel concentrations and complexing agents of chloride and sulfamate. Nickel electrolytes containing sulfamate, chloride and combined sulfamate-chloride with concentrations between 0.14 M and 0.3 M were investigated. Physicochemical properties i.e. pH and conductivity were measured to ensure if they were in the desired value. The electrochemical behaviour of the electrolytes was measured by polarisation experiments in a standard three-electrode cell. The working electrode was a copper disc (surface area of 0.196 cm 2 ) and the counter electrode was platinum mesh. The potential was measured againts a saturated calomel reference electrode (SCE). The experiments were carried out at various scan rate and Rotating Disc Electrode (RDE) rotation speed to see the effect of scan rate and agitation. Based on the measured physicochemical properties, the electrolyte of 0.19 M nickel sulfamate was chosen for experimentation. Polarisation curve of agitated solution suggested that overall nickel electrodeposition reaction is controlled by a combination of kinetics and mass transfer. Reduction potential of nickel was in the range of -0.7 to -1.0 V. The corresponding current densities for nickel deposition were in the range of -0.1 to -1.5 mA cm- 2 .