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MEMS Devices and Thin Film-Based Sensor Applications
Published in Suman Lata Tripathi, Parvej Ahmad Alvi, Umashankar Subramaniam, Electrical and Electronic Devices, Circuits and Materials, 2021
Ashish Tiwary, Shasanka Sekhar Rout
Figure 15.11 illustrates the typical electrodeposition process in which a current source in the form of a battery or any low-voltage dc source is used to provide a necessary electric current. The counter electrode and the wafer are immersed in the electrolyte solution connected to the two ends of the DC voltage source [15]. The wafer to be coated with metallic layer is connected to the negative terminal of the power source through an electrical connector and becomes a negative electrode (cathode). The counter electrode behaves as a positive electrode (anode), which is connected to the positive terminal of the power source, thus completing the entire electric circuit arrangements. When the direct current is supplied to the electrolyte, a chemical reaction occurred at the electrode terminals placed at some distance. The anode terminal releases metal ions and the ions are transferred to the wafer (cathode) end. The chemical substance carries the ions from one electrode to another depending upon their polarities. The transportation of charged particles will continue as long as supply exists. Faraday’s law of electrolysis states that the amount of electricity used is directly proportional to the material deposited on the electrode. Thus, the wafer will have a very thin metallic deposition until the process ends.
F
Published in Carl W. Hall, Laws and Models, 2018
This basic understanding led to the development of electric motors and dynamos. The principle of electromagnetism, the existence of a magnetic field surrounding a currentcarrying conductor, was discovered by Oersted in 1820. J. Henry independently made the same discovery in 1831. The concept developed by Faraday was first expressed in mathematical terms by F. Neumann in 1845. Keywords: electricity, lines of force, magnetic field FARADAY, Michael, 1791-1867, English physicist NEUMANN, Franz Ernst, 1798-1895, German physicist OERSTED, Christian, 1777-1851, Danish scientist Sources: Bynum, W. F. 1986; Daintith, J. 1981; Parker, S. P. 1989; Peierls, R. E. 1956; Thewlis, J. 1961-1964. See also HENRY; MAXWELL; OERSTED FARADAY LAWS OF ELECTROLYSIS (1834) First Law The quantity of an electrolyte decomposed by the passage of electric current is directly proportional to the quantity of electricity that passes through it. To deposit or to dissolve one gram equivalent of any material at an electrode requires the passage of 96,500 coulombs of electricity. Second Law If the same quantity of electricity passes through different electrolytes, the weights of different ions deposited will be proportional to the chemical equivalents of the ions. Keywords: chemical, electricity, electrolysis, electrolyte FARADAY, Michael, 1791-1867, English physicist Sources: Brown, S. B. and Brown, L. B. 1972; Daintith, J. 1981; Hodgman, C. D. 1952; Lederman 1993; Thewlis, J. 1961-1964. See also ELECTROLYSIS FARADAY-NEUMANN--SEE NEUMANN FARR LAW OF EPIDEMICS A property of all zymotic diseases (such as smallpox) in which the epidemic curve first ascends rapidly, then less rapidly to a maximum, and then descends more rapidly than the ascent, or a subsidence, until the disease attains a minimum density and remains stationary.
Surface Engineering of Metals
Published in Zainul Huda, Metallurgy for Physicists and Engineers, 2020
In modern surface engineering practice, electrolytic solutions usually contain additives to brighten or enhance the uniformity of the plating metal. The amount of plating material deposited strongly depends on the plating time and current levels to deposit a coating of a given thickness. The electroplating process is governed by Faraday’s laws of electrolysis.
The wear behavior of Al/(Al2O3 + SiC + C) hybrid composites fabricated stir casting assisted squeeze
Published in Particulate Science and Technology, 2018
C. S. Kalra, Vinod Kumar, Alakesh Manna
However, the presence of abrasive reinforcements in MMC makes it difficult to machine because of its heterogeneity and abrasive nature of reinforcement as discussed by various researchers as Seeman et al. (2010), Rajmohan and Palanikumar (2012), Premnath (2015b) and Yadav and Yadava (2016). The machining of HMMCs is one of the important barriers which resist its wide spread applications. Keeping in view, the present study analyses the effect of electrochemical machining (ECM) on machining response characteristics of hybrid Al/(Al2O3 + SiC + C) MMC as it has potential for machining of difficult to machine materials. In ECM, the electrical energy is used to produce a chemical reaction and this process works based on the principle of Faraday’s laws of electrolysis. In this process, there is no formation of heat-affected zone (HAZ). However, this process should be applicable only for an electrically conductive material. Bhattacharyya and Munda (2003) studied on ECMM and explained that the machining precision might increase by reducing the electrolyte concentration and pulse on time. Li et al. (2003) claimed that the micron-level gap during ECMM can be controlled by insulated electrode with applied pulse voltage. Wang et al. (2016) claimed that the double insulating layers consist of TiO2 ceramic coating and organic film can improve the service life of electrode. Goel and Pandey (2016) concluded that the ultrasonic assistance in ECMM increased material removal rate and reduced holetaper. Venkatesh, Arun, and Venkatesan (2014) claimed that the 0.38 mm diameter micro-hole can be machined on composite specimen by Micro-ECM.
Towards improved electroplating of metal-particle composite coatings
Published in Transactions of the IMF, 2020
The consecutive stages during electrodeposition of included particles into a metal matrix composite coating are shown in Figure 3. The deposit composition is controlled by the relative rates of particle incorporation and metal matrix growth. Any contemporary mechanism describing the process of composite electrodeposition must consider the following aspects: (1). The rate of particle transport to the cathode is governed by both electrophoresis (migration of charged particles in an electric field), allowing for the fact that different particles do not acquire the same surface charge in different electrolytes, and convective-diffusion mass transport (movement driven by concentration and velocity gradients).(2). The electrodeposition rate of metal is governed by Faraday’s laws of electrolysis, allowing for a known current efficiency due to side reactions. The current may be controlled by charge transfer, mass transfer or both, i.e. be under mixed control.(3). The charged particle, when dispersed in solution, changes to a neutral adsorbed particle on the cathode surface.(4). The rate of electrophoretic deposition of charged particles on the cathode can be described by the Hamaker equation (see section 4), which involves the potential gradient and an efficiency factor.(5). The particles must stick to the cathode surface, initially by adsorption, rather than glancing off it due to lack of incorporation into the growing metal matrix coupled with excess momentum, high shear and possible collision from other moving particles.(6). Any contemporary model must be able to predict the particle loading in the deposit, for a given bath composition (both solution chemistry and particle type), known operating conditions, fixed electrode geometry and bath agitation.