Flat spray technique

Recently, the flat spray technique has been applied successfully on pilot scale for the homogeneous deposition ofAu colloid containing lead silicate glass coatings on 1 m size float glass panes (Fink-Straube, 1998/2002). The appropriate coating line (producer Venjakob) is shown in Figure 29-7. 

In conclusion, droplet size measurements in the range 10 to 100 m can be performed, also in hostile environments, from the visibility of individual scattered signal. Advantages of this method are simultaneous measurement of particle size, concentration and velocity no calibration is necessary good spatial resolution up to less than 1 mm-3 the visibility is independent on particle trajectory. Limitations are individual scattered signal can be obtained only with moderate particle concentration it is difficult to automatically process scattered signals to extract the visibility value and to check validation conditions it seems very difficult to extend the technique to cover the entire spray distribution the lower limit in the small particle end of the distribution curve depends upon experimental sensitivities and V(d) curve flatness... 

Electrophoresis has been used as a separation technique for decades, particularly by biochemists, in the open-bed format. In this mode, a layer of a gel is formed on a flat-bed support which is in contact with an electrolyte and two electrodes are situated at either end of the open slab. The sample is placed at one end of the separation medium, and when voltage is applied, the molecules migrate through the gel by electrophoresis. The components in the sample are separated based on their differences in electrophoretic mobility. The electrophoretic mobility is controlled by molecular parameters such as charge, size, and shape. After the electric field is turned off, the separation is evaluated by spraying the plate with a dye and the bands of the sample components become visible, similar to the detection format used in paper or thin-layer chromatography. 

The thick-film metallization process requires modest capital equipment and the process is relatively simple. Typical capital equipment for thick-film metallization includes a silk screening printer and a furnace for annealing and removal of the organic binder. This equipment is relatively modest in cost. In addition to silk screening on a flat substrate, thick-film techniques can be applied by dipping, spraying, or roller coating the non-flat surface [4], Thick-film techniques can also be applied in a continuous operation which can be cost effective. 

Researchers operating with the TLC technique have some general options, shown in Fig. 1. The pure (unencapsulated) TLC substance applied in very thin films onto a flat surface offers temperature field measurements with a spatial resolution of about 800 nm. But, unencapsulated TLCs require sophisticated application techniques, and the pure TLC substance is very sensitive to UV light and contaminatirMis, particularly oxygen from the air. More common are micro-encapsulated TLCs which are stable and easier to handle. They are available as complete foils, in binder mixtures for spray applications, and as tracers. With the latter it is possible to acquire the temperature distribution in liquid flows. 

This technique is widely used to apply an even coat of adhesive on large and flat surfaces (Fig. 20). There are several methods of spraying ... 

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