Batch coating

If we consider different particles, we can see from Eq. (11) that the variation in the total amount of material deposited on each particle is a function of the number of times the particle passes through the spray zone, TV and the amount of material that it receives in each pass, x. Since both x and N vary, we expect that Xlolal will vary between particles in the same batch. Mann (1974) has shown that for a batch coating process in which the operating time is greater than about 20 times the average circulation time,... 

The RIE samples produced using this technique were formed over areas of cm. These samples could easily be broken up to create dozens of samples ready for batch-coating with metal, thus providing an efficient means of substrate production. Their SERS enhancement factors were determined in the same manner as for the butterfly wing substrates, and were found to be of similar magnitude. 

Electrolyte composition Electrolyte concentration Ionic strength of the buffer pH of the buffer Capillary Age Batch Coating... 

A large batch coating system especially designed to coat astronomical telescope mirrors with A1 films is shown in Fig. 37. The mirror substrate to be coated is made of glass ceramics, its thickness is 60 cm and the weight is about 14 tons. 

Batch coating of steel hardware with aluminum to form aluminum-iron alloy coatings is also done by hot dipping or cementation. Pure aluminum coatings are applied on a batch basis by thermal spray, ion plating, and electroplating from nonaqueous solvents. 

The industry uses batch or continuous coaters (Figure 12.2). Batch coating for salty products is typically performed with inclined enrobing pans that turn on an axis inclined at 30°. The base product is placed in the pan, and the oil coating and seasonings introduced as the pan rotates. The coating is either poured or pumped. 

The liquid stationary phase can be applied to the solid support in a number of ways, but usually by a batch coating procedure. Previously washed and deactivated support is suspended in a solution of the liquid phase in a volatile solvent and the solvent removed by evaporation. The amount of stationary phase added to the solvent is expressed in weight per cent of a solid support, and this phase loading is selected to give the required characteristics of the column. 

The next day comes and the hung-over chemist wakens to see a dark red solution stirring away. In some cases where the chemist had made an enormous batch of this stuff, there may be seen a small mass of crystalline precipitate at the bottom of the flask. This is no big deal and will go away in the next step. If the chemist had made this in a flat-bottomed flask (which she really should have for convenience) then the ice tray is removed, the flask returned to the stir plate, a distillation setup attached, and the acetone is vacuum distilled from the flask. After all the acetone has come over the chemist can proceed in two different ways. One way is to just keep on distilling the solution until all of the formic acid has been removed. The chemist knows that just about all the formic has been removed when there is about 300mL of thick black liquid remaining in the reaction flask and hardly any clear formic acid is dripping over into the collection flask. If one were to swirl the reaction flask, the liquid will appear syrupy and kind of coat the sides of the flask. This is more evident when the flask cools. A quick sniff of the flask may indicate that some formic is still in there, but it should be too minimal to be of any concern. 

Higher alkyl acrylates and alkyl-functional esters are important in copolymer products, in conventional emulsion appHcations for coatings and adhesives, and as reactants in radiation-cured coatings and inks. In general, they are produced in direct or transesterification batch processes (17,101,102) because of their relatively low volume. 

Both cold- and warm-coating processes employ solutions of phenoHc resins. The principal process used for foundry resins is the hot-coating process. It is the fastest, least expensive, and safest process, and it requires no volatile removal. The sand is heated to 135—170°C in a muller, and soHd novolak resin in flake form is added, which melts quickly and coats the sand. A lubricant may be added at this point. After one minute of mulling, the batch is cooled by adding water, which evaporates rapidly. 

Hexa, which is not suppHed with the resin, is usuaUy added either with the water as a solution or just before or immediately after the water addition. By quenching the mix with water, the resin-coated sand is cooled to a point where there is no significant reaction with the curing agent. Any reaction between the resin and the hexa in the muller affects the bonding properties of the coated sand. As the batch cools and begins to break up, more lubricant may be added, which remains on the outside of the coated grains where it is most effective. 

The total cycle time for most production batches is 2.5—3.5 min, considerably shorter than the cold- or warm-coating processes. Although a few... 

A number of instmments are based on the extmsion principle, including sHt flow and normal capidary flow (Table 6). These instmments are useful when large numbers of quahty control or other melt viscosity test measurements are needed for batches of a single material or similar materials. When melt viscosities of a wide range of materials must be measured, rotational viscometers are preferable. Extmsion rheometers have been appHed to other materials with some success with adhesives and coatings (10,161). 

Another large appHcation is as an ingredient in the production of charcoal briquettes. The amount of sodium nitrate used in charcoal briquette manufacture depends on the type and amount of wood and coal used. Typically charcoal briquettes contain up to almost 3% sodium nitrate. Sodium nitrate is also used in the manufacture of enamels and porcelain as an oxidizing and fluxing agent. In porcelain—enamel frits used for metal coating, the amount of sodium nitrate in a batch varies with the various metal bases to be coated, typically from about 3.8 to 7.8 wt %. 

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