Powders characteristics function

Thermoplastic polyesters achieved some commercial success during the mid-1980s however, these were eventually replaced by nylon coating powders in functional coatings and thermosetting polyester powders in decorative appHcations because of lack of any unique characteristics or price advantages (see Polyesters, thermoplastic). 

The unconfined yield strength of the powder,, is a powder characteristic which decides whether it can resist flow under gravity from a certain dipleg configuration, and is a function of the consolidating stress (c ) present during its preparation as shown in Fig. 25. 

Eslamian and Ashgriz [11,12] systematically investigated the effect of pressure on powder morphology and other powder characteristics. Particle shape and morphology depends on the precursor properties and precipitation mechanism, as well as on the droplet evaporation rate. Droplet evaporation rate is a function of the reactor pressure and temperature. Evaporation rate controls the solute distribution profile within the droplet, and determines whether the particles are solid or hollow. Eslamian and Ashgriz [11] have shown that, when the ambient pressure is reduced to 60 Toir, the decrease of the evaporation rate due to the non-cmitinuum effects is about 60% of that of the continuum-based evaporatiOTi rate. 

Figure 6.27. Schematic setup of a fluidized-bed reactor used either to cover a suspended sample with a fine-grained coating or to coat the fluidized particles to change their surface characteristics. Powder is fluidized in a precursor gas mixture at the reaction temperature. In addition to being the substrate for deposition the powder sometimes functions as a slowly evaporating precursor for deposition on the suspended substrate.

Table 6.2 summarizes the low pressure intercept of observed shock-velocity versus particle-velocity relations for a number of powder samples as a function of initial relative density. The characteristic response of an unusually low wavespeed is universally observed, and is in agreement with considerations of Herrmann s P-a model [69H02] for compression of porous solids. Fits to data of porous iron are shown in Fig. 6.4. The first order features of wave-speed are controlled by density, not material. This material-independent, density-dependent behavior is an extremely important feature of highly porous materials. 

The microstructure, properties, and performance of Ni-YSZ anodes depend sensitively on the microscopic characteristics of the raw materials (e.g., particles size and morphology of NiO and YSZ powders). The particle sizes of the starting YSZ powders vary usually from 0.2 to 0.3 pm, whereas those for the NiO powders are 1 pm. The Ni to YSZ volume ratio usually varies from 35 65 to 55 45. For example, the reported Ni to YSZ volume ratios include 34 66 [20, 21], 40 60 [24], 43 57 [22], and 55 45 [23], For a bilayer anode, the functional anode layer in contact with the electrolyte contains 45 to 50 vol% Ni, whereas the anode support layer has 35 to 40 vol% Ni [25, 26], A pore former is usually added to tailor the shrinkage (for the cofiring) and to achieve sufficient porosity (>30 vol%) in the anode or the anode support layer. 

Many sweet-tasting foods and beverages, however, do not require the functionality of sucrose and sweet carbohydrates. These products are the typical fields of application of intense sweeteners. As bulk sweeteners are used for taste reasons rather than functionality these products offer possibilities to reduce calories without sacrificing any important product characteristic. Intense sweeteners are used as the sole sweetening agents in beverages, table-top sweeteners like powder or tablets, desserts and dairy products besides a variety of further areas of lesser importance. 

A third problem with simulation of high resolution diffraction data is that there is no unique instrament function. In the analysis of powder diffraction data, the instalment function can be defined, giving a characteristic shape to all diffraction peaks. Deconvolution of these peaks is therefore possible and fitting techniques such as that of Rietveld can be used to fit overlapping diffraction peaks. No such procedure is possible in high resolution diffraction as the shape of the rocking curve profile depends dramatically on specimen thickness and perfection. Unless you know the answer first, you cannot know the peak shape. 

Single base" smokeless powder, developed mainly in the United States, uses only nitrocellulose. "Double base" smokeless powder, developed in Europe, is a blend of nitrocellulose and nitroglycerine. "Cordite," a British development, consists of 65% NC, 30% NG, and 5% mineral jelly. The mineral jelly (a hydrocarbon material) functions as a coolant and produces substantial amounts of CO 2, CO, and H 2O gas to improve the propellant characteristics. "Triple base" smokeless powder, containing nitroguanidine as a third component with nitroglycerine and nitrocellulose is also manufactured. 

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