Plating uniformity

For large Wa, the current distribution is uniform. For example, when electroplating (qv) an object, usually a uniform deposit is desirable. Equation 35 suggests that a larger piece, ie, low Wa, would be more difficult to plate uniformly than a smaller one. 

FIG. 22-59 Schematic of two ways to pass solution across an ED membrane. Tortuous flow (left) uses a special spacer to force the solution through a narrow, winding path, raising its velocity, mass transfer, and pressure drop. Sheet feed (right) passes the solution across the plate uniformly, with lower pressure drop and mass transfer. Coutiesy Elsevier.)... 

In order to confirm the plating uniformity a copper panel electrode was prepared by etching depressions on the copper surface. These depressions are... 

Abu Mulaweh. H.L, Armaly, B.F., and Chen, T.S., Measurements of Laminar Mixed Convection Adjacent to a Vertical Plate-Uniform Wall Heat Flux Case , J. Heat Transfer. Vol. 114, Nov. 92, pp. 1057-1059,1992. 

A horizontal plate, uniform in temperature at400 K, has the shape of an equilateral triangle 45 cm on each side and is exposed to atmospheric air at 300 K. Calculate the heat lost by the plate. 

Rolls and sheets of thin layers on polyester films can be purchased ready to use, or glass plates can be coated in the laboratory. For small scale experiments, a microscope slide can be coated by simply dipping it into a slurry of stationary phase (e.g., 30% silica gel in chloroform). To coat large plates uniformly on one side, a spreader—either commercial or constructed by putting two collars of adhesive tape or rubber tubing around a glass rod—is used (Fig. 2-35). The spreader is drawn or rolled along in one motion to produce a uniform layer of stationary phase about 0.3 mm thick. The coated plate is in most cases air dried and then oven dried before use. 

A schematic ofthe process is shown in Fig. 12.7. A mixture of graphite and nodular iron is placed inside a 25 cm diameter cavity in a lead block. A flat metal plate, uniformly coated with TNT on the back side, is placed in front of the cavity. The TNT is detonated and the plate impacts the cavity at a peak velocity of 5 km/s. A peak pressure estimated at 300 kbar and a temperature of approximately 1000 K are maintained for a few microseconds. The formation of diamond is assisted by the presence of an iron solvent-catalyst. The diamond crystals are then separated by selective acid digestion and sedimentation. 

We will eompare in our investigations a thin circular plate uniformly loaded and fixed at its edges with a similarly loaded plate containing a central hole. This central hole is assumed to be closed by a simply supported plug. These two plates are shown in their radial cross-sections in Fig. 4a, b, respectively. 

Spray plate uniformly with 10 ml of buffer (0.1 M disodium EDTA-0.1% ammonium chloride) and immediately develop with buffer-satd. chloroform for 16 cm (about 45 min). Air dry... 

The key to analyzing the flow in the mold is recognizing that layers of fluid are stretched radially as the mold is closed. We assume that the stretching is uniform that is, if we mark a fluid layer of constant thickness, the layer will move toward the stationary plate uniformly and stretch radially such that it will still be of constant (smaller) thickness. This assumption is equivalent to the kinematic assumption that Uj is a function only of z we add the assumption of no circumferential flow and take... 

Ideal shape. Easy to plate uniformly, especially where edges are rounded... 

Bipolar plates uniformly distribute air and fuel supplied to FCs. They remove heat from the active area and carry current from cell to cell. Since they should not be too heavy, they are usually made from aluminum or other light metals. However, they are heavily corroded because of harsh conditions to FCs operation. Problems related to materials used for constraction of PEMFCs were reviewed by Hermaim et al. [112]. One of the solutions proposed in order to solve problems related to bipolar plates was coating them with various polymer-carbon-based composites. However, electric conductivity of such coatings may not be sufficient. Another approach proposed... 

Metal foam plate Uniform compression on DM surface, ease of manufacture Higher pressme drop... 

Fig. 13 (a) Bomb shaped end plate, uniform pressure distribution (from Evertz, 2002), (b) End plate based on Dbow-concept, head plate, schematic view (from Evertz, 2002), (c) End plate for axisymmetric fuel cell stack based on Dbow-concept, footplate, schematic view (from Evertz, 2002). 

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