Cathodes cathode design

The discovery of the x-ray effect spurred the development of a new generation of hot-cathode gauges designed to minimise this effect. One of the earhest, and commercially the most successful, the Bayard-Alpert gauge shown in Eigure 14b, was developed in 1950 (13). A fine wire, the ion collector, is... 

Sometimes there is no practical, economical way to reduce deposition, protect surfaces cathodically, change design and operation, or treat existing systems chemically. A material change is required. The most economical solution usually is to coat existing structures with water-impermeable, sacrificial, or corrosion-resistant materials. 

Table 10.13 Current density used in ship hull cathodic protection design...

The latter part of this chapter has dealt with the design considerations for a sacrificial anode cathodic protection system. It has outlined the important parameters and how each contributes to the overall design. This is only an introduction and guide to the basic principles cathodic protection design using sacrificial anodes and should be viewed as such. In practice the design of these systems can be complex and can require experienced personnel. 

Det norske Veritas Recommended Practice, Cathodic Protection Design, RP B401, March (1986). This document has been superseded by RP B401 (1993)... 

Evans, T. E., Mechanisms of Cathodic Protection in Seawater . In Cathodic Protection Theory and Practice, 2nd International Conference, Stratford-upon-Avon, June (1989) Choate, D. L., Kochanezyk, R. W. and Lunden, K. C., Developments in Cathodic Protection Design and Maintenance for Marine Struaures and Pipelines , NACE Conference on Engineering Solutions for Corrosion in Oil and Gas Applications, Milan, Italy, November (1989) not included in Proceedings... 

Howell, P. P., Potential Measurements in Cathodic Protection Design , Corrosion, 8, 300 (1952)... 

Kazimir, E.S. (1999) Monopolar Cathode Design Improvements and Other Diaphragm Cell Component Advances. ELTECH Systems Corporation, Chlorine/Chlorate Seminar. 

Any one of the three components in SOFC, the cathode, anode, or electrolyte, can provide the structural support for the cells. Traditionally, the electrolyte has been used as the support however, this approach requires the use of thick electrolytes, which in turn requires high operating temperatures. Electrode-supported cells allow the use of thin electrolytes. The Siemens—Westinghouse Corporation has developed a cathode-supported design,although this has required electrochemical vapor deposition of the YSZ electrolyte. Most other groups have focused on anode-supported cells. In all cases, it is important to maintain chemical compatibility of those parts that come in contact and to match the thermal expansion coefficients of the various components. A large amount of research has been devoted to these important issues, and we refer the interested reader to other reviews. 

This cathode design, with the stirring described, is regarded as preferable to the combination used by Lukens 3 and much simpler in construction. It provides better dispersion of the organic material, a feature which is particularly necessary if these reductions are carried out in aqueous solution (Note 6). 

Planar SOFCs are composed of flat, ultra-thin ceramic plates, which allow them to operate at 800°C or even less, and enable less exotic construction materials. P-SOFCs can be either electrode- or electrolyte- supported. Electrolyte-supported cells use YSZ membranes of about 100 pm thickness, the ohmic contribution of which is still high for operation below 900°C. In electrode-supported cells, the supporting component can either be the anode or the cathode. In these designs, the electrolyte is typically between 5-30 pm, while the electrode thickness can be between 250 pm - 2 mm. In the cathode-supported design, the YSZ electrolyte and the LSM coefficients of thermal expansion are well matched, placing no restrictions on electrolyte thickness. In anode-supported cells, the thermal expansion coefficient of Ni-YSZ cermets is greater than that of the YSZ... 

Place 500 milliliters (17 fluid oz.) of this Epsom salt solution into the clay pot. This will be called the "cathode" liquid, designating... 

On the other hand, the medical condition where the heart beats too fast is known as tachycardia. If untreated, tliis condition may lead to ventricular fibrillation, that is, a condition in which the heart stops beating and shakes uncontrollably and is usually fatal. In 1980, a special device was developed and implanted in patients. It could sense the condition and provide a shock that would stop the fibrillation and restore the normal sinus rhythm via an electrode sutured onto the heart. The device was first powered by a lithium/vanadium pentoxide system later it was replaced by a system using a cathode material of silver vanadium oxide (SVO or Ag2V40ii). This is the actual system used in modem ICDs (implantable cardioverter/defibrillator). Another material used is the lithium/manganese dioxide system. Also, a new system using a sandwich cathode design with an inner cathode material of carbon monofluoride and an external cathode layer of silver vanadium oxide is in wide use. 

The cathode is the electrode in a voltaic cell at which reduction occurs. By convention, the cathode is designated the positive electrode. Because electrons flow along the wire... 

Dispenser cathodes were designed to have a current-loading density many times that of the conventional triple-oxide cathodes. This enabled the CRT to run at much higher beam currents with brightness and resolution much better than prior CRT s because the electron beam could be focused to a smaller spot. 

The static cylindrical geometry offers a convenient cathode design for small scale operations and has primarily been used for precious metal extraction. Mass transport may be enhanced by the use of tangential manifolds emd the use of a reasonable flow rate. 

A good example of the regenerative cell is the n-GaAs/alkaline solution of Se - + Se2 /metal cathode cell designed over 15 years ago yet retaining its importance In the dark equilibrium is set in the cell... 

Figure 8.12 (a) Schematic of the 4.0 kW ceramic end window X-ray tube, called the Super Sharp Tube , (b) Close up of the window end of the Super Sharp Tube , showing the circular cathode design of this tube. [Courtesy of PANalytical, Inc., The Netherlands (www.panalytical.com).]... 

The step change in pore structure can be fabricated in discrete steps. It also allows the use of dissimilar materials for the porous structure, as used in early Westinghouse SOFC cathode designs and discussed by Thorogood et al. for oxygen transport membranes [12]. 

With steady development in the modeling methods and computational techniques, this approach is expected to rule the future of cathodic protection design. Development of models has lead to a widespread increase in the theoretical understanding of the system. In the future it is expected to play wide role in developing new designs without wasting money on field experimental projects. 

L. E. Carlson, J.H. Prrzgerald III, F.R.D. Webster, Cathodic protection design for 1,900 miles (3,050 km) of high-pressure natural gas pipeline. Mater. Performance 40 (2001) 28—32. 

R.M. Degerstedt, K.J. KenneUey, M.E. Orazem,J.M. Estehan, Computer modeling aids. Traditional cathodic protection. Design methods for coated pipelines, Mater. Performance 35 (1996) 16—20. 

Det norske Veritas Industri Norge AS. Recommended practice, RP B401, Cathodic protecting design, 1993. 

In cathodic protection design, it is essential to be able to estimate the anode output and its lifetime. From these estimates, anode spacing over the structure to be protected can be calculated (i.e., the number of anodes required to protect the structure). 

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