Sponge-like particle

Fig. 5 HREM micrograph of ruthenium sponge-like particles obtained in pure methanol...

The limitations of the adsorption method are those implied in the basic assumptions, namely the existence of a monomolecular layer as above determined, and the arrangement of closest packing assumed. However, results thus far obtained appear to warrant the assumptions made. There can be no question but that the method gives the correct order of surface measured. As in the solubility method previously described, the surface measured by the Emmett-Brunauer technique measures the surface at all indentations and infinitesimal cracks present. It possesses a marked advantage. over other methods since it can fee used with sponge-like particles possessing infinite labyrinth-like structures and is independent of chemical activity. 

Figure 46. SEM photomicrographs of copper powder particles obtained by electrodeposition from 0.15 M CUSO4 in 0.50 M H2SO4, at an overpotential of 1,000 mV (a) sponge-like particle, and (b, c) Part (A) and Part (B) details from Fig. 46a. (Reprinted from Ref. 80 with permission from Elsevier).

Figure 47. SEM photomicrographs of copper powder particles shown in Fig. 46 after treatment in an ultrasonic field (a, b) the basic elements of the sponge-like particles, and (c) the micro structure of the basic element. (Reprinted from Ref.80 with permission from Elsevier).

Compressed CO2 dissolves in melts of fats. Solubility measurements show at higher pressures, a minimum in the liquid-vapour isopleth, which is an indication of type III phase behaviour. Batch particle formation experiments show an influence of C02/melt-ratio, feed rate, temperature and pressure on the particle size and structure. This information is crucial for the development of applications and for optimization of the process. Three main shapes can be distinguished, spherical (solid or hollow), distorted and sponge-like particles. The particle sizes are in the range of 5-200pm... 

Figure 12 shows possible mechanisms of particle formation during PGSS operation. Under the influence of CO2 concentration, melt temperature, atomization pressure and feed rate, these mechanisms predict the formation of completely solid spherical particles, a hollow spherical particles, agglomerated distorted particles or sponge like particles. 

Condensation of metal vapors followed by deposition on cooler surfaces yields metal powders as does decomposition of metal hydrides. Vacuum treatment of metal hydrides gives powders of fine particle size. Reaction of a metal haHde and molten magnesium, known as the KroU process, is used for titanium and zirconium. This results in a sponge-like product. 

Thermosetting Reactive Polymers. Materials used as thermosetting polymers include reactive monomers such as urea—formaldehyde, phenoHcs, polyesters, epoxides, and vinyls, which form a polymerized material when mixed with a catalyst. The treated waste forms a sponge-like material which traps the soHd particles, but not the Hquid fraction the waste must usually be dried and placed in containers for disposal. Because the urea—formaldehyde catalysts are strongly acidic, urea-based materials are generally not suitable for metals that can leach in the untrapped Hquid fractions. Thermosetting processes have greater utiHty for radioactive materials and acid wastes. 

Similar schemes may also be derived for the sponge-like systems that are considered as negative to the system of particles or systems of growth by Radushkevich [123],... 

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