Experimental Investigations of Catalytic Effect of Cu2+

observational Investigations of Catalytic final result of Cu2+Experimental Investigations of Catalytic Effect of Cu2+ During Anodic Di solving of Iron in NaCl ElectrolyteR.K Upadhyay1, Arbind Kumar2 and P.K Srivastava3AbstractTaguchis orthogonal coordinate L9 has been effectively used to study the effect of make parameters such as voltage, feed graze and electrolyte tightness on material remotion number in context of two different types of electrolyte namely sedimentary NaCl dissolvent and electrolyte termination containing Cu2+ ions. The results indicated that Cu2+ has a catalytic effect on the anodic profligacy of press out, which waitrict the oxidation of Fe2+ to Fe3+ and cast ups the adjournment straddle during machining. The experimental results were analyzed employ summary of departure (ANOVA) method to investigate the significance and percentage persona of individual process parameters on work characteristics.Key Words electrochemical Machining, Aqueous N aCl, Cu2+, Parameters, Oxidation, Material Removal score.IntroductionElectrochemical machining (ECM) has got an industrial immensity due to its capability of controlled atomic level surface removal1. It is an anodic profligacyprocess based on electrolysis, where the application of a more traditionalistic process is not convenient. ECM has been successfully employed in aerospace, gondola industries and now gaining much importance in the electronics and other high-tech industries for the forum of micro components2-3. Mask less and by dint of mask electrochemical micromachining techniques rush been successively used thin films and foils of materials those are difficult to machine by other methods4-5. Electrochemical machining is low voltage (5-25 volt) machining process which offers high metal removal identify and to a fault capable to machine hard semiconductive materials into complicated profiles without any thermal damages consequently suitable for throne production wor k with low labor requirements6-7. The dissolution rate is passing reliant on the selection of electrolytes and its period carrying capacity. On increasing the ducking of electrolyte solution dissolution rate also amplifications tho excess denseness allows the crystal system, which may damage the accessories of ECM and reduce the volume of electrolyte in accrue pipes. The conductivity of electrolyte depends not only if on the concentration but also on ionic interaction. Thus, the current carrying process done by the base electrolyte is small, but H+ and OH ions produced in electrolysis of water play eventful role8-9. The achievement of high dissolution rate in ECM is a strong research base which is possible by change in composition of electrolyte solution to promote catalytic effect during dissolution10.During electrochemical machining of saddlelift at low current density it has been observed that Fe+ cation organize very easily but it is highly unstable and immediately oxidises into Fe2+ state. addition in current density leads to simultaneous production of Fe2+ and Fe3+, at higher current density apparent valence of iron emergences above three11. Therefore, to stabilize Fe2+ in the sedimentary solution is a challenge during dissolution.EXPERIMENTAL SET-UP AND doctrine OF ECMFig 1 Experimental set-upECM is an anodic dissolution process works on the principle of Faradays law. While machining of iron in comportment of aqueous NaCl electrolyte solution the following(a) chemical reactions are observed12.Reactions at CathodeNa+ + e NaNa + H2O NaOH + H+2H+ + 2e H2It shows that only hydrogen gas will evolve at cathode.When pure iron is being machined electrochemically the following reactions would occur13-14.Fe Fe2++ 2e Fe2+ + 2Cl FeCl2Fe2+ + 2(OH) Fe(OH)2FeCl2 + 2(OH) Fe(OH)2 + 2Cl2Cl Cl2 + 2e 2FeCl2 + Cl2 2FeCl3H+ + Cl HCl2Fe(OH)2 + H2O +O2 2Fe(OH)3Fe(OH)3 + 3HCl FeCl3+ 3H2OFeCl3+ 3NaOH Fe(OH)3 + 3NaClIt shows that during elec trochemical machining of iron in NaCl electrolyte, iron is removed as Fe(OH)2 and precipitated as max mend sodium chloride is recovered back. Due to go on reaction, formation of Fe(OH)3 is also possible Which, confirms the existence of iron in +2 and +3 states during dissolution. goal of Fe2+ and Fe3+ ions in electrolyte solutionThe electrolyte solution containing Fe+2 and Fe+3 ions was collected. Fe+2 ions were determined directly by titrating a cognise volume of iron electrolyte solution with K2Cr2 O7 in blistering medium (HCl).Cr2O7 2- + 6Fe+2 + 14H+ = 2Cr+3 + 6Fe +3 + 7H2OInternal indicator N- phenyl anthranilic acid was used to scrawl the end point. Fe+3 ions were determined after all the Fe+3 ions are reduced into Fe+2 ions with SnCl2 in presence HCl in hot.Sn+2 + 2Fe +3 = Sn+4 + 2Fe+2The solution was then cooled and excess SnCl2 was removed by adding HgCl2 solution.2Hg+2 + Sn+2 +Cl = Sn+4 +Hg2Cl2 (white ppt)Titration of known volume of meter solution was done using e nsample solution of K2Cr2O7 in acidic medium. From the volume of K2Cr2O7 used, the total amount of Fe+2 and Fe+3 ions was determined. The amount of Fe+3 ion was determined by subtracting amount of Fe+2 which is determined earlier.Material removal rate during electrochemical machining is greatly influenced by dissolution valence. As the dissolution valence decreases MRR increases. In this subject an approach is made to enhance the electrochemical dissolution of iron through control of valency (transition) therefore, in this direction, use of electrolyte solution containing Cu2+ is suggested. The dissolution check of iron by Cu2+ ions can be is justified by considering the standard electron potential E for Cu2+, Fe/Fe2+and Fe/Fe3+ described as follows15.Cu2+ + 2e- Cu E = +0.34V Fe2+ + 2e- Fe E = -0.44V Fe3+ + e- Fe2+ E = +0.77VAs E for Cu2+ Cu is more positive than Fe2+ Fe, Cu2 +will oxidize Fe to Fe2+. However, as E for Cu2+ Cu is less positive than Fe3+ Fe2+, Cu2+ will not oxidize Fe2+ to Fe3+. Making electrolyte solution250 gramsof NaCl was mixed with400 gramsof CuSO4 in10 litersof water. The mixture is stirred well for 2 minutes then heated until it loses its green color. The crystals of sodium sulphate (Na2SO4) and bullshit chloride (CuCl2) were removed by filtering the solution and thi the solution thus obtained was saturated solution of Na2SO4 containing Cu2+ ions which participates in anodic dissolution process.MACHINING CONDITIONSFollowing machining parameters are selected on the keister of performance characteristics,Table1 Machining conditions for analysisSELECTION OF MACHINING PROCESS PARAMETERSTable 2 shows machining parameters and selected levels for experimental procedureTable 2 exercise parameter and their levelsMeasurement of MRRThe sign weight of the work voice was taken for calculation of MRR. Keeping the flow rate constant at 15 lit/min and the rest of the parameters are set according to table 1 for each run. work up piece was kept ho rizontal, and cylindrical electrode was used for machining. Gap between slam and workpiece was maintained carefully to avoid the choking. The electrode was fed continuously towards the work piece during machining and time was recorded. After machining, the cavity was formed on the work-piece. The final weight of the work-piece was taken and material removal rate was calculated as per the following formulaMRR= . (1)EXPERIMENTAL PROCEDUREThe design resulted in total of cardinal experiments, which are performed at 10V-18V supply voltage, 10-30 g/lit electrolyte concentration and 0.0001-0.0005 cm/ second gear feed rate as the values for the control variables. The responses mensurable are Material removal rate (MRR) Scheme of the experiments is as shown in Table 3.Table 3 Taguchi L9 OA for MRRRESULTS AND DISCUSSIONAnalysis of Variance (ANOVA) when machinating in presence of NaCl electrolyte solution Percentage contribution of each parameter on material removal rate during electrochemica l machining of iron in aqueous NaCl electrolyte solution is shown in table 4 and represented graphically in mental image 2.Table 4 ANOVA for MRR NaCl as electrolyte Fig 2. Contributions of the parameters when machining in presence of aqueous NaCl electrolyte solutionRegression EquationMRR= -0.01096 +0.002296Voltage +64.0 plyRate +0.000540 preoccupation. (2)The equation (2) shows that break rate is dominant factor affecting MRR. The graphs shown in rule 3 are plan from the regression equation (2).Fig 3. Main do Plot for SN ratios (NaCl electrolyte solution)Figure shows the main effect plot of the MRR portraiture the effect of various machining parameters on MRR. As seen from the plot obtained, the MRR increased with increase in both voltage and feed rate. This is due to the fact that with increase in voltage the current increases in the inter electrode gap thus increasing the MRR. open rate is another important parameter. Increase in feed rate results in decrease of the condu cting path between the workpiece and the peckerwood hence resulting in high current density thus enhancing the speedy anodic dissolution. An overall increase in the MRR was also observed with increase in the concentration as the larger number of ions associated with the machining process which increases the machining current and thus results in higher MRR.Effects of selected process variables (i.e. Voltage, guide rate and tightfistedness) on material removal rate (MRR) at different sets of conditions while machining in presence of aqueous NaCl solution are shown in figure 4(a), 4(b) and 4(c). Fig. 4(a) Effects of Voltage on material Fig. 4(b) Effects of Feed rate on materialremoval for different Concentration, removal for different Voltage,Feed rate= 0.0001 cm/sec. Concentration = 20 g/lit.Fig.4(c) Effects of Concentration on material removal for different Feed rates, Voltage= 14 VNaCl electrolyte tend to promote the oxidation of Fe2+ to Fe3+ during the dissolution process the l evel best MRR obtained during machining of iron in aqueous NaCl solution recorded was 0.0653 cm3/sec. Although the higher concentration of NaCl is favorable for better MRR but excess concentration allows the crystal formation which reduces the volume of electrolyte in flow pipes and also affects the dissolution rate.Analysis of variance when machining in presence of electrolyte solution containing Cu2+ ionsPercentage contribution of each parameter on material removal rate during electrochemical machining of iron in electrolyte solution containing Cu2+ ions is shown in table 5 and represented graphically in figure 5.Table 5 ANOVA for MRR electrolyte solution containing Cu2+ ionsFig 5. Contributions of the parameters when machining in presence of electrolyte solution containing Cu2+ ionsRegression EquationMRR = -0.0157 +0.002908Voltage +75.3FeedRate +0.000602Concentration. .. (3)The equation (3) shows that voltage is dominant factor affecting MRR. The graphs shown infigure 6 are plot ted from the regression equation (3).Fig 6. Main Effects Plot for SN ratios (electrolyte solution containing Cu2+ ions)The oxidation of Fe2+ in to Fe3+ is restricted due to the presence of Cu2+ in electrolyte solution which promotes the higher dissolution rate during machining. The influence of selected process variables i.e. Voltage, Feed rate and Concentration on material removal rate at different sets of conditions in presence of electrolyte solution containing Cu2+ ions are shown in figure 7(a), 7(b) and 7(c) respectively. Fig. 7(a) Effects of Voltage on material Fig. 7(b) Effects of Feed rate on materialremoval for different Concentration, removal for different Voltage,Feed rate= 0.0001 cm/sec. Concentration = 20 g/lit. Fig. 7(c) Effects of Concentration on material removal for different Feed rates, Voltage= 14 V.The maximum MRR obtained during machining of iron in presence of Cu2 electrolyte solution containing Cu2+ ions was 0.0774 cm3/sec, which is 18.5% more when compared wi th aqueous NaCl electrolyte.CONCLUSIONThe electrochemical characteristics of iron in aqueous NaCl solution and electrolyte solution containing Cu2+ ions has been analyzed experimentally to investigate the influence of process parameters on MRR. The Process parameters such as voltage, feed rate, Electrolyte concentration, were successfully controlled. The different cabals of these parameters were used for the experimentation in rescript to determine their influence on MRR. The experiment was performed by varying all parameters in combination as per L9 orthogonal array. The experimental observations support the conclusion that the presence of Cu2+ ions in electrolyte solution restrict the further oxidation of Fe2+ to Fe3+ and enhance the low valence dissolution of iron during machining. tendency of experiments and analysis of variance helped in identifying the significant parameters affecting MRR. The best combination of the parameters are Voltage= 18 V, Feed Rate=0.0005 cm/sec an d electrolyte Concentration = 20 g/lit when using a solution containing Cu2+ ions as electrolyte. The maximum MRR obtained was 18.5 % higher when compared with aqueous NaCl electrolyte for the same set of working conditions.AcknowledgementI express my sincere thanks to Department of use interpersonal chemistry BIT Extension Centre Deoghar for their cooperation to conduct the experiments in order to observe the catalytic behavior of Cu2+ ions.References1.Sekar T, Marappan R. Experimental investigations into the influencing parameters ofelectrochemical machining of AISI 202. journal of innovative Manufacturing Systems 20087(2)337-43.2.Bhattacharyya B, Munda J. Experimental investigation on the influence of Electrochemicalmachining parameters on machining rate and accuracy in micromachining domain. Int J Mach cocks Manuf 2003 43(13)1301-10.3. Kozak J, Rajurkar KP, Makkar Y, Selected problems of microelectrochemical machining daybook of Materials Processing Technology 2004 149 426 431 .4. Bhattacharya B, Doloi B and Sridhar PJ. Electrochemical Micromachining New possibilitiesfor Micro- Manufacturing. J. Material. Proc.Tech 2001113301-305.5. Bhattacharyya B, Malapati M, Munda J, Sarkar A. Influence of tool vibration onMachining performance in electrochemical micro-machining of copper International Journalof Machine Tool and Manufacture 2007 47 335342.6.Hocheng H, Sun YH, Lin SC, Kao PS. A material removal analysis of Electrochemicalmachining using flat-end cathode. Journal of Materials Processing Technology 2003 140264-268.7.Yong L, Di Zhu, Yongbin, Zeng, Shaofu Huang, Hongbing Yu. Experimental Investigationon Complex Structures Machining by Electrochemical Micromachining Technology, ChineseJournal of Aeronautics 2010 23578-584.8.Mukherjee SK, Kumar S, Srivastava PK. Effect of electrolyte on current- carrying processin ECM, I Mech E Part C J. Mechanical engine room Science 2007 2211415-1419.9. Byk MV, Tkalenko DA and Tkalenko MD. On participation of hydroxide ion s in the anodicdissolution of metals in aqueous electrolyte solution. Prot Met t 2004 40(3) 294-296.10.Ayyappan S and Sivakumar K. Investigation of electrochemical machining characteristics of20MnCr5 alloy mark using potassium dichromate mixed aqueous NaCl electrolyte andoptimization of process parameters.Proc I MechE part B Journal of EngineeringManufacture 2014.11.Srivastava PK, Kumar R, Barhai PK. brawn Profile and Thermodynamic Feasibility ofIron(I) during Electrochemical Machining of Iron.International Journal of MechanicalEngineering 2013 411146-1158.12.Mukherjee SK, Kumar S, Srivastava PK. Effect of over voltage on material removal rateduring Electrochemical Machining. Tamkand Journal of Science and Engineering 2005 823- 28.13. Neto JC.d.S, silva, EMd, Silva MBd. Intervening variables in electrochemical machiningJournal of Materials Processing Technology 2006 1799296.14.Mount AR, Muir RN. Dissolution characteristics of iron and stainless steels in chloride underelectrochemi cal machining conditions Journal of the Electrochemical Society 2007154 3E57 E61.15. Electrochemistry 3 Cell potentials and thermodynamics, chemwiki.ucdavis.edu Analytical Chemistry Electrochemistry (2014, accessed 15 May 2015).Stephen K. Lower. Redox equilibria in natural waters Chem1 environmental Chemistry, http//www.chem1.com/acad/webtext/pdf/c3redox.pdf(1998, accessed 15 May 2015).1