The main raw material coal fly ash was obtained from…….. The composition of fly ash is shown in table. Sodium hydroxide was purchased from HPLC Pvt. Ltd. Mumbai, India. Molybdic acid and calcium chloride was purchased from CDH Pvt. Ltd. New Delhi, India. Zinc chloride was purchased from MERCK Ltd. Mumbai, India. The solvent used in coating preparation i.e. Xylene was purchased from Avantor performance material India Ltd. The acrylic resin and epoxy resin with its hardener were obtained from Atul Polymers, India. The other chemicals used in this work were of AR & LR grade. 3.2. Techniques 3.2.1 Electrochemical Impedance Spectroscopy (EIS) Electrochemical impedance spectroscopy (EIS) technique is a useful method for the investigation of corrosion mechanism and the fundamental parameters of electrochemical reactions. EIS technique is very popular technique the reasons behind its popularity may be explained as follows: 1. The technique makes use of only very small perturbation signals without disturbing the properties of the electrode that is to be measured. 2. It can obtain charge transfer resistance as well as double layer capacitance data in the same measurement. 3. The measurements can be made in solution with low conductivity whereas, under similar such conditions. DC techniques are subjected to significant errors due to large ohmic drops. 4. The equipment is relatively inexpensive and it is very easy to obtain large quantities of data rapidly. 3.2.1.1. The basic principles of Electrochemical Impedance Spectroscopy (EIS). For any electric circuit, which consists of various passive elements (i.e. resistors, capacitors and inductors) the behaviour of the whole circuit to an applied ac voltage, is dependent upon both the behav... ... middle of paper ... ...i-circles [30]. Therefore, in such cases, the interpretation of the impedance data is usually difficult and care must be taken when doing so. 2) Finally, the measurements obtained using Electrochemical Impedance Spectroscopy (EIS) are sequential; e.g. each frequency point is considered in turn, which means that to obtain frequency spectra from, say 10 KHz to 10 mHz, it takes some time depending on how powerful the impedance machine is. This can be a long time for rapidly corroding systems whose rate of reaction is changing quickly. Also, at low frequencies, the system may be subject to noise ‘pick-up’ which can lead to frequency scatter on the impedance plot. Despite these drawbacks, Electrochemical Impedance Spectroscopy (EIS) has proven to be a valuable technique and can provide important information about the nature of corrosion processes in many systems [31].
Cyclic voltammetry makes possible the elucidation of the kinetics of electrochemical reactions taking place at the electrode surface [31, 32]. In a typical voltammogram, there can be several peaks. From the sweep-rate dependence of the possible to investigate the role of adsorption, diffusion and coupled homogeneous chemical reaction mechanism. [33]
Oscilloscope is acquainted as one of the most helpful instrument for testing circuits. It is able to show the signals at different points in the circuit. One way to inves...
C = Q/V = κε0A/d, this equation is derived using the capacitance of two charged parallel plates and through κ = ε/ε0. In this equation C is the capacitance of the capacitor, κ is the dielectric constant of the insulating material, ε0 is the permittivity of free space, A is the area of the charged plate, and d is the dielectric thickness. This equation was rearranged to C = κε0A(1/d) as a linear line of y = mx + b, in which C = y, 1/d = x, and κε0A = slope(m).
There can be percentage errors and uncertainties or heat loss in surrounding while executing the experiment.
Their performance can be modelled, predicted and analyzed using equivalent circuits, and this experiment examines one of these circuits. MEASUREMENTS ------------ Short-circuit test: Primary voltage (Vsc) = 26V Primary current (I1) =
Answer: The advantages of using several gap to measure the transfer or contact resistance using the TLM (transmission line method) are as follows:
Where NA is the equivalent number of A transferred per cell during the interval of time t, Q the current quantity supplied to the system during the same time and F is the Faraday constant (96 485 A s mol−1).
In this paper, I will talk about how AC circuits can be described by considering voltage and current using complex numbers. An AC circuit requires two separate numbers to be able to completely describe it. This is because it takes into account the amplitude and the phase of the current. The fact that complex numbers can be easily added, subtracted, multiplied or divided with each other makes them ideal for this operation where both amplitude and phase have to work together.
The purpose of this experiment is to determine the stoichiometry of a complex ion using Job’s method. In doing so, experience is gained in using the techniques and instrumentation involved in absorbance spectrophotometry.
It is highly beneficial to be able to calculate the concentration of a saturated solution. Indeed, knowledge of the concentration is required to calculate solute solubility and if precipitates will form when the solution is mixed with other reagents. This has many applications in industrial processes. For these reasons, this experiments aims to determine the concentration of a saturated barium hydroxide (Ba(OH)2) solution by conductometric titration and gravimetric analysis. Conductometric titration involve examining the change in Ba(OH)2 (aq) conductivity as sulphuric acid is added. Conductivity initially has a high reading due to the presence of ions in solution and then reaches a minimum at the reaction endpoint, due to complete neutralisation
You take voltage measurements by counting the number of divisions a waveform spans on the oscilloscope's vertical scale. Adjusting the signal to cover most of the screen vertically, then taking the measurement along the centre vertical graticule line having the smaller divisions makes for the best voltage measurements. The more screen area you use, the more accurately you can read from the screen.
Electroplating Experiment Aim To find the amount copper gains or loses on the electrodes using different amounts of current each time during electrolysis. How the changing of current affects the electroplating of copper. Introduction Electroplating is generally carried out in order to improve the appearance or corrosion resistance of the surface of a metal by electrodepositing a thin layer of metal ion on it. The metal substrate to be coated is made by the cathode in an electrolytic cell. The cell used in electroplating contains an electrolyte which is usually an aqueous solution containing a reasonably high concentration of an ion of the metal which is to be electroplated on the surface.
There are 10 types of corrosion, General Attack Corrosion, Localized Corrosion, Galvanic Corrosion, Environmental Cracking, Flow-Assisted Corrosion (FAC), Intergranular corrosion, De-Alloying, Fretting corrosion, High-Temperature Corrosion. General attack corrosion attacks the entire surface of the metal and is caused by chemical or electrochemical reactions (Bell, 2017). Localized corrosion attacks only portions of a metal structure (Bell, 2017). Localized corrosion can be classified as 3 types: pitting, crevice corrosion, and filiform corrosion. Pitting is creating smalls hole in the metal (Bell, 2017). Crevice corrosion occurs in stagnant locations (Bell, 2017). Filiform corrosion happens when water gets under a coating (Bell, 2017). Galvanic corrosion is when two different
There are formulas to calculate electrical conductivity and resistivity. Conductivity (s) is defined as the inverse of resistivity (a high conductivity means a low resistance), I=V/R or current equals voltage over resistance. Electrical resistance is calculated by the formula, R=V/I or resistance equals voltage over current.
Spectroscopy can help identify elements and compounds and elucidate the atomic and molecular structure by measuring the radiant energy absorbed or emitted by a substance at characteristic wavelengths of the electromagnetic spectrum on excitation by an external energy source. UV-Vis Spectroscopy is a technique useful for identification of organic and inorganic species and can be used for identification (qualitiative ana...