Dry powder processing

The dry powder process has several additional advantages over the wet process. For example, much less waste of enamel occurs because the dry over-spray is airborne and recycled in a closed system. No-pidde ground coats have broadened the apphcation of both wet-process and dry-process systems. These enamels are appHed over cleaned-only metal. Thus the problems of disposing of pickling acid wastes containing iron sulfates and nickel wastes are eliminated (see Metal surface treatments) (7). 

Table 2 Coarser PCC 70% < 2 microns), slurry solids 75%, dispersant 0.80% as polymer solids/dry powder). Process A was not tested with this PCC ...

Zinc electrodes for secondary silver-zinc batteries are made by one of three general methods the dry-powder process, the slurry-pasted process, or the electroformed process The active material used in any of the processes for the manufacture of electrodes is a finely divided zinc oxide powder, USP grade 12. 

SVI formulations are relatively simple, composed of the active ingredient, a solvent system (preferably aqueous), a minimal number of excipients present for reasons described later in this chapter, and the appropriate container and closure packaging system. If the active ingredient is unstable in solution or suspension, the product can be a dry powder, processed either by lyophilization or by sterile crystallization. 

When fresh or as a freeze-dried powder processed soon after harvesting, a af bears an exceptional nutrient profile, being particularly dense in... 

Plaque. The sintered structure before impregnation is generally referred to as plaque. It usually has a porosity of 80 to 85% and ranges in thickness from 0.40 to 1.0 mm. Two generic sintering processes are used (1) the slurry coating process and (2) the dry-powder process. Both processes employ special low-density battery grades of carbonyl nickel powder. 

The dry-powder processes generally employ wire screen precut to the so-called master plaque dimension. The screens are placed in molds with loose powder on each side. They are then typically sintered in a belt furnace in a reducing atmosphere at 800 to lOOO C. 

The effects of electrolyte concentration on capacity were determined experimentally. Air Force positive electrodes and the Air Force 50-Ah NFH2 cells from the INTELSAT VI program were used for this investigation. The Air Force positive electrodes were impregnated with active material by the alcoholic electrochemical impregnation process. The plaque was manufactured using the dry-powder process. 

The influence of sedimentation process on the value of reduced thickness of various dry powder developers is carried out in our experiments. Fig 1 illustrates the pictures of real developer s layers before (a, c) and after (b, d) penetrant application. The pictures were... 

If lighter colors than these are desired it is necessary to decolorize all the melanin in the hair in a preliminary step, and then add color back to the desired depth in a second treatment. This is known as a double-process treatment. The decolorization step consists of treating the hair with an alkaline mixture of persulfate salts and peroxide. The persulfate is added to the peroxide as a dry powder immediately before applying to the hair. Although the persulfate salts alone do not have any bleaching effect, the persulfate—peroxide mixture can remove all the melanin in the hair. Dark brown or darker hair can be lightened to a light blonde shade in about an hour. 

Iron Browns. Iron browns are often prepared by blending red, yellow, and black synthetic iron oxides to the desired shade. The most effective mixing can be achieved by blending iron oxide pastes, rather than dry powders. After mixing, the paste has to be dried at temperatures around 100°C, as higher temperatures might result in the decomposition of the temperature-sensitive iron yellows and blacks. Iron browns can also be prepared directiy by heating hydrated ferric oxides in the presence of phosphoric acid, or alkaU phosphates, under atmospheric or increased pressure. The products of precipitation processes, ie, the yellows, blacks, and browns, can also be calcined to reds and browns. 

Forming additives or processing aids (2,33—37) are commonly used to render ceramic powders more processible. Binders and plasticizers (qv) are typically added to improve or aid dry powder and plastic forming, whereas deflocculants, surfactants (qv), and antifoams are commonly used in slurry processing. 

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