Carbon steel electrodes

ENA was recently used for remote on-line corrosion monitoring of carbon steel electrodes in a test loop of a surge water tank at a gas storage field. An experimental design and system for remote ENA and collection of electrochemical impedance spectroscopy (EIS) data (Fig. 13) have been presented elsewhere. In the gas storage field, noise measurements were compared with electrode weight loss measurements. Noise resistance (R ) was defined as... 

Raeissi et al. [236, 237] showed that temperature, pH, and current density affected the morphology and texture, as well as the nucleation mechanism of the zinc deposits on carbon steel electrode. 

Figure 51 Fast Fourier transform of the potential noise from two nominally identical carbon steel electrodes exposed to 0.2 M HC1 + 0.5 M NaCl + 0.15 M NaN02. (Data courtesy of J. Yuan, M. Inman, T. Lunt, J. Hudson, University of Virginia.)...

The voltammetry measurements, the Tafel tests, were conducted between -1000 and 1000 mV potentials at a sweep rate of 100 mV/ s. Before each experiment, the working electrodes were polished with a series of wet sandp>ap)ers of different grit sizes (320,400, 600, 800,1000 and 1200). After polishing, the carbon-steel electrode are washed with ultrapure water and dried at room temperature and then the active p>art was immersed in porphyrin solution. 

The working electrode is the carbon-steel electrode, (paepjared as mentioned earlier) with 0,28 cm2 active surface, (coated or uncoated) platinum coimter electrode with 0.8 cm active surface and saturated calomel electrode, (SCE), as reference electrode all of which connected to the PGZ 402 Dynamic EIS Voltalab, from Radiometer Copenhagen. 

We continued the studies, cyclic voltammetry and Tafel method for carbon steel electrodes treated in different ways. 

Figure 9-30 shows the frequency response of the carbon steel electrode in neutral (pH 7), aerated, 0.5 mol dm NaC104 solution. The depressed semicircle usually describes the carbon steel frequency re-... 

AWS A5.1-91,1991. Specification for Carbon Steel Electrodes for Shielded Metal Arc Welding. American Welding Society, Miami, FL. 

The external heating boxes for the caustic soda evaporator with forced circulation must be anodically protected separately. Ring-shaped impressed current electrodes of carbon steel are mounted and insulated on supporting brackets (see Fig, 21-12). 

In general, the baser the metal, the lower (more negative) the electrical potential at the anode and the higher the potential rate of corrosion. Carbon steel and low-alloy steels (which are widely used in boiler plants) have a relatively low potential with respect to the standard hydrogen electrode and can therefore be expected to corrode readily unless active prevention measures are taken. Copper and brasses have a relatively higher potential. 

Figure 33.2 shows results obtained by studies of electrochemical noise for the corrosion behavior of carbon steel A516-70 in carbonate solutions with and without NaCl as an activator (Cheng et al., 2000). It can be seen that in ordinary carbonate solution the fluctuations of potential of a test electrode and the fluctuations of current flowing between a pair of identical electrodes are small. Added NaCl causes a drastic increase in intensity of the electrochemical noise. The PDS plots (Fig. 33.3) differ accordingly. 

Ketec cell Eltech Vertical metal (or carbon) foam electrodes in a tank Discontinuous cathode steel (chemically stripped for reuse carbon No ... 

Rotating Electrode Atomization (REP, PREP) -20 Standard deviation 1.3-1.5 Armco Fe, Cu, Al, Zn, Co-Cr, Ti, Zr, Ni alloys. Low carbon steels SlO2 1-10 -0.04 Spherical, very smooth, ultraclcan particles, Relatively high EE High cost, Low capacity and volume, D Relatively Coarse particles I... 

Electrochemical oxidation-reduction of eluting mixture components is the basis for amperometric electrochemical detectors. The three electrodes needed for the detection, the working (indicator) electrode, reference electrode, and auxiliary electrode, are either inserted into the flow stream or imbedded in the wall of the flow stream. See Figure 13.13. The indicator electrode is typically glassy carbon, platinum, or gold, the reference electrode a silver-silver chloride electrode, and the auxiliary a stainless steel electrode. Most often, the indicator electrode is polarized to cause oxidation of the mixture components... 

Figure 2, Electrode potential ts. Inmerslon time in 3 % NaCl solution and impedanoe diagrams for steel electrodes with, zino pigmented coating modified by substitution of 1 of zinc with conducting carbon blade.

The most efficient system devised by Monsanto uses electrodes fabricated from carbon steel plate, electro-coated on one face with cadmium. These are stacked in parallel so that the electrolyte can be pumped through the gap between successive plates. Overall tire system forms a series of electrochemical cells with a cadmium cathode and a carbon steel anode. Each plate of metal forms the cathode of one cell and the anode of the next in the stack. Electric current is passed across the stack. The electrolyte contains phosphate and borate salts as corrosion inhibitors, EDTA to chelate any cadmium and iron ions generated by corrosion together with hex-amethylenebis(ethyldibutylammonium) phosphate to provide the necessary telraal-kylammonium ions. This electrolyte circulates through the cell from a reservoir and there is provision for the introduction of acjylonitrile and water as feedstock. The overall cell reaction is ... 

A patented electrochemical unit that uses sacrificial iron electrodes to generate the ferrous ion is effective in removing hexavalent chromium as well as other heavy metals. In the electrochemical cell, a direct current is conducted through the cell containing a number of carbon steel plate electrodes. This generates the ferrous ion (Fe ) and hydroxyl ion (OH ). The ferrous ion reduces hexavalent chromium to the trivalent state as follows ... 

Due to the lack of S02 electrolysers, alkaline electrolysers are considered as the reference for economic assessment. Electrodes are assumed to be made of carbon steel with a platinum coating. Electrolysis unit requires an investment of EUR(08) 303.8 M with each electrolyser requiring about EUR(08) 2 920/m2. 

Tin—lead coatings (10—60 wt % tin) can be applied by hot-dipping or electrode position to steel and copper fabricated articles and sheet. A special product is teme plate used for roofing and flashings, automobile fuel tanks and fittings, air filters, mufflers, and general uses such as covers, lids, drawers, cabinets, consoles for instruments, and for radio and television equipment. Teme plate is low carbon steel, coated by a hot-dip process with an alloy of tin and lead, commonly about 7—25 wt % tin, remainder lead. Electroplating is another possibility. 

The present process is shown schematically in Fig. 15.6. The solution is an emulsion of acrylonitrile and 10-15 per cent disodium hydrogen-phosphate in water containing a quaternary ammonium salt, hexamethylene-bis(ethyldibutylammonium) phosphate, to conduct the current. The anode is carbon steel and the cathode is cadmium (a sheet fixed on to the anode) this cell is a good example of the use of bipolar electrodes (Section 15.3). EDTA and borax are added in small quantities... 

Figure 7 (a) Cathodic polarization data for a low carbon steel rotating disk electrode in 0.6 M NaCl with ambient aeration. Oxygen reduction limiting current densities are shown for the indicated rotation rates, (b) Plot of experimental limiting current density versus square root of the rotation rate, showing the experimental and predicted linear behavior. 

The five electrodes in solution will be AISI 1020 carbon steel, tin graphite, an aluminum alloy, and 303 stainless steel. The SCE has a potential of +0.241 VNHE whereas the Hg/Hg2S04 has a potential of +0.400 VSCE. 

Figure 7 (a) Cathodic polarization data for a low carbon steel rotating disk electrode... 

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