Atomistic Fabrication Technology to Enhance Accuracy

Atomistic Fabrication engineering science to Enhance Accuracy richness of Atomistic Fabrication Technology to Enhance Machining Accuracy During Electrochemical Machining of MetalsRitesh Upadhyay, Arbind Kumar P.K. SrivastavaAbstractAtomistic fabrication technology fully utilizes forcible and chemical phenomena with atomistic and electronic understanding. In the case of mechanical machining many defects are introduced when pushing the motherfucker on the take shapepiece surface and then atoms on the workpiece surface are removed by the displacement and multiplication of such(prenominal) defects. Therefore many defects remain on the workpiece surface after mechanical machining. Machining accuracy is considerably affected by disturbances such as thermal deformation and external vibration because remotion depth is dependent on the cutting depth of the tool and is very difficult to establish precision products by mechanical machining. In the case of atomistic fabrication technology surface atoms are naturally removed by chemical reaction caused by reactive species and therefore no deformed layer on the workpiece surface. A very high-precision product can be easily manufactured with shelter physical and chemical phenomenon used for removal reaction. In this paper possibility of atomic level removal of work piece (Iron workpiece) have been explored. The current and potentiality requirements for removal of some thousand atoms allow for be reckon along with. the mechanism of removal of metals in relation with everywhere-potential and conductivity.IntroductionThe essence of nanotechnology is the ability to work at the molecular(a) level, atom by atom, to create large structures with fundamentally new molecular organization. Compared to the doings of isolated molecules of about 1 nm (10 -9 m) or of bulk materials, behavior of structural features in the range of about 10-9 to 10-7 m exhibit important changes. Nanotechnology is concerned with materials and sys tems whose structures and components exhibit novel and significantly improved physical and chemical offsetes due to their nanoscale size of it. The goal is to exploit these properties by gaining control of structures and turn of eventss at atomic, molecular, and supramolecular levels and to learn efficient manufacturing and use these devices 1-4. Maintaining the stability of interfaces and the integration of these nanostructures at micron-length and macroscopic scales are all keys to success.New behavior at the nanoscale is not necessarily predictable from that observed at large size scales.The most important changes in behavior are caused not by the order of magnitude size reduction, but by newly observed phenomena intrinsic to or becoming predominant at the nanoscale5-6. These phenomena include size confinement, predominance of interfacial phenomena and quantum mechanics. Once it becomes possible to control feature size, it will also become possible to enhance material properti es and device functions Being able to reduce the dimensions of structures down to the nanoscale leads to the unique properties of carbon nanotubes, quantum wires and dots Nanotechnology is the exploitation of the novel and improved physical, chemical, mechanical, and biological properties, phenomena, and processes of systems that are intermediate in size surrounded by isolated atoms/molecules and bulk materials, where phenomena length and time scales become comparable to those of the structure. It implies the ability to gene localize and utilize structures, components, and devices with a size range from about 0.1 nm (atomic and molecular scale) to about 100 nm by control at atomic, molecular and macromolecular levels. Novel properties occur compared to bulk behavior because of the small structure size and short time scale of various processes7-8.Electrochemical ReactionWhen the current passed through a NaCl electrolyte solution following reaction occureNaCl = Na+ + Cl body of water = H + + OHThe positive ions moves towards cathode and negative ions moves towards anode. Each Na+ ions gain an electron and is converted to Na . Hence Na+ ions are reduced at the cathode by means of electrons.Cathode ReactionNa+ + e = NaNa +H2O = NaOH + H+2H+ + 2e = H2It shows that only hydrogen gas evolve at cathode and there will be no depositionAnode ReactionFe = Fe2+ +2eFe2+ + 2Cl = FeCl2Fe2+ + 2OH = Fe (OH)2FeCl2+ 2OH = Fe(OH)2 + 2Cl2Cl Cl2 + 2e2FeCl2 + Cl2 = 2FeCl3H+ + Cl = HCl2Fe(OH)2 +H2O +O2 = 2Fe(OH)3Fe(OH)3 + 3HCl = FeCl3 + 3H2OFeCl3 + 3NaOH = Fe(OH)3 + 3NaClTheoretical AspectsBuilding block atoms play an important part in future atmostic fabrication technology. Material removal rate for removal of Fe work piece at atomic level have been calculate by using Faradays law.Where MRR = Metal Removal Rate , A = Atomic weight, I = Current, Z = valency,F = faradays constant . The results are shown in figure 1,Fig 1 Plot of Metal Removal Rate against Current Density, A=55.8 5,Z=2,F=96500It is clear from the figure that very low current is undeniable for atomic scale removal of iron atoms from the iron work piece. The requirement of voltage for removal of iron at atomic scale have been calculated using ohms Law and shown in figure 2Fig 2 Plot of Metal Removal Rate against Voltage, where specific conduction=0.0387ohm-1 cm-1others arguing are same as in figure 1.It is clear from the figure that voltage requirement is very low. The current and voltage data for removal of few thousand atoms shows that conductivity and over-voltage play important role in current carrying process.Effect of electrolyte conductivity on MRRElectrolytes are substances that become ions in solution and having content to conduct electricity. The electrolyte has three main functions in the ECM process. It carries the current between the tool and the workpiece, it removes the product of the reaction from the cutting region, and it removes the heat produced by the current lower in the operation. Electrolytes must have high conductivity, low toxicity and corrosivity, and chemical and electrochemical stability. The rate of material removal in ECM is governed by Faradays laws and is function of current density which depends upon the concentration of electrolyte with increment in concentration of electrolyte the MRR increases continuously up to a limiting value after which if further increase in concentration is made the MRR decreases due to decrease in ionic mobility.Effect of Over voltageThe over-voltage is the important parameter which restrict the material removal rate and is sensitive to toolfeed rate and equaliser machining gap. Material removal rate decreases due to increase in over voltage and decrease in current efficiency, which is directly related to the conductivity of the electrolyte solution.Over voltage was calculated asV = V where V = over voltage, V = utilise voltage, = density of work piece, F = Faraday constant, K = conductivity / specific conductance of electrolyte solution, A = atomic number of work piece metal, Ye = equilibrium gap and f = tool feed rate. The variation of over voltage with equilibrium gap is shown in Figure 3 which indicate that over-voltage decreases linearity with increase in equilibrium gap. When equilibrium gapapproaches to zero, over voltage approaches to applied voltage. Figure 4 shows variation of tool feed rate with overvoltage, which shows that over voltage decreases sharply with discernment rate and goes to negative side after a certain tool feed rate. Negative value of V, seems to be unreal because un-matching long range values of penetration rate for single fixed value of equilibrium gap.Fig 3. Plot of Over voltage against equilibrium machining gapFig 4. Plot of over voltage against penetration gapConclusionThe effort is made to focus on the importance of atomistic fabrication technology with the effect of key factors like over voltage and electrolyte concentration influencing the qual ity of machined surface and dimensional accuracy. The application of this technology during machining of metals and alloys proves that the electrochemical reactions can be used for nanometer accuracy, which allows high precision machining.The make up including power supply, electronic circuit, tool and electrolyte feed devices have been proposed to perform nano electrochemical machining in order to enhance the machining accuracy.ReferencesMukherjee S.K, Kumar S , and Srivastava P.K effect of electrolyte on the current- carrying process in electrochemical machining. J . Mechanical Engineering Science 221,1415 -1419 2007.Stotes J, Lostao A, Gomez C, Moreno , Baro A.M. Jumping mode AFM imaging of biomolecules in the repulsive electrical double layer basal microscopy 1-6 2007.McGeough, J.A. principles of electrochemical machining chapterIII (chapman,Hall.London) 1974.Ma, and R. Schuster, Locally enhanced cathodoluminescence of electrochemicallyfabricated gold nanostructures, Journal o f Electroanalytical Chemistry, vol. 662, pp. 1216, 2011.McGenough J A, Leu M, Rajurkar K P, et al. Electroforming process and application tomicro/macro manufacturing. CIRP AnnalsManufacturing Technology, 50(2) 499-514, 2001.Zhang Z Y, Zhu D, Wang M H. Theoretical and experimental research into electrochemicalmicromachining using nanosecond pulse Chinese Journal of Mechanical Engineering43(1) 208-213, 2007 in Chinese.Lee E S, Baek S Y,Cho C R. A case of the characteristics for electrochemical micromachining withultrashort voltage pulses The International Journal of Advanced Manufacturing Technology 31(7-8)762-769, 2005.Schuster R., Kirchner V, Allonue P, and Ertl G, Electrochemical micromachining, Science 289, 98101_2007.Datta M, Shenoy R. V, and Romankiw L. T, Recent advances in the study of electrochemicalmicromachining, ASME J. Eng. Ind. 118, 2936,1996.Datta M, Microfabrication by electrochemical metal removal, IBM J. Res. Dev. 42, 655669,1998.Rajurkar K.P, Kozak J, and Wei B, St udy of Pulse Electrochemical Machining Characteristics AnnalsInternational College for Production Research Vol. 42, 231-234, 1993.Hocheng, H., Kao, P. S. and Lin, S. C., Prediction of the Eroded visibleness during ElectrochemicalMachining of Hole, Proc. JSME/ASME Int. Conf. Materials and Processing, pp. 303_307 (2002).Keown, Mc. P. A., The Role of Precision Engineering in Manufacturing of the Future, Annals CIRP,Vol.36, pp. 495_501 (1987).Electrochemical Machining in Production Technology, HMT, Bangalore, Tata McGraw HillPublishing Company, New Delhi, India, p. 478 (1980).