Planar cells processing methods

Once the structural support layers have been fabricated by extrusion or EPD for tubular cells or by tape casting or powder pressing for planar cells, the subsequent cell layers must be deposited to complete the cell. A wide variety of fabrication methods have been utilized for this purpose, with the choice of method or methods depending on the cell geometry (tubular or planar, and overall size) materials to be deposited and support layer material, both in terms of compatibility of the process with the layer to be deposited and with the previously deposited layers, and desired microstructure of the layer being deposited. In general, the methods can be classified into two very broad categories wet-ceramic techniques and direct-deposition techniques. 

It follows from Equation 6.12 that the current depends on the surface concentrations of O and R, i.e. on the potential of the working electrode, but the current is, for obvious reasons, also dependent on the transport of O and R to and from the electrode surface. It is intuitively understood that the transport of a substrate to the electrode surface, and of intermediates and products away from the electrode surface, has to be effective in order to achieve a high rate of conversion. In this sense, an electrochemical reaction is similar to any other chemical surface process. In a typical laboratory electrolysis cell, the necessary transport is accomplished by magnetic stirring. How exactly the fluid flow achieved by stirring and the diffusion in and out of the stationary layer close to the electrode surface may be described in mathematical terms is usually of no concern the mass transport just has to be effective. The situation is quite different when an electrochemical method is to be used for kinetics and mechanism studies. Kinetics and mechanism studies are, as a rule, based on the comparison of experimental results with theoretical predictions based on a given set of rate laws and, for this reason, it is of the utmost importance that the mass transport is well defined and calculable. Since the intention here is simply to introduce the different contributions to mass transport in electrochemistry, rather than to present a full mathematical account of the transport phenomena met in various electrochemical methods, we shall consider transport in only one dimension, the x-coordinate, normal to a planar electrode surface (see also Chapter 5). 

OPLC is an instrumentalized version of planar layer liquid chromatography, and it is suitable for on-line as well as off-line sample application, separation, and detection, and their variations (partial off-line methods). In the on-line mode, the solutes are measured in the drained eluent by connecting a flow-cell detector to the eluent outlet. In the off-line mode, all the principal steps of the chromatographic process, such as sample application, separation, and quantitative evaluation, are performed off-line (2b-28). 

Planar aligmnent ean be aehieved in many ways. A eonunonly employed method is to first coat the cell wall with some polymer such as polyviityl alcohol (PVA) and then mb it unidirectionally with a lens tissue. This process creates elongated stress/strain... 

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