Grains dispersion

Native silver is rarely found in the form of nuggets, and it is probably for this reason that silver was recognized and came into widespread use at later times than did gold. Much native silver occurs as minute grains dispersed in small concentration in argentiferous (silver-rich) sands. Now, when silver is mixed with mercury, it forms amalgams (see below) the amalgamation... 

Eq. (2), together with assumptions about the grain shape (typically cylinders with constant height 8), the demagnetization field and the actual Eb/IcbT requirement, can be used to estimate the minimal thermally stable grain size Dp Before calculating Dp for a variety of media materials, we first consider the effect of physical grain dispersions on the Ej kRT requirement. 

Figure 13 A cluster of syngenetic pyrite framboids in a bituminous coal. Micrometer-sized bright grains dispersed in the cluster are crystals of clausthalite (PbSe). Scanning Electron photomicrograph, back-scattered electron image (scale bar = 10 p,m).

Brownian motion If you were to observe a liquid colloid under the magnification of a microscope, you would see that the dispersed particles make jerky, random movements. This erratic movement of colloid particles is called Brownian motion. It was first observed by and later named for the Scottish botanist Robert Brown, who noticed the random movements of pollen grains dispersed in water. Brownian motion results from collisions of particles of the dispersion medium with the dispersed particles. These collisions prevent the colloid particles from settling out of the mixture. 

Fig. 8. Ordered distribution of iron sulfide. The photomicrograph (a) shows individual pyrite grains dispersed throughout the matrix and clustered inside an organic ( ) envelope, 70 X. The graininess typical of pyrite framboids is evident at 320 x (b). X-Ray images of sulfur (c) and iron (d) portray the tendency of pyrite to conform to organic templates.

The incorporation of metals into thin organic polymer films gives rise to a new class of so-called hybrid films with interesting physical, chemical, medical, and electrical properties. E. Kay [90-92] introduced the principal methods of metal-incorporation into organic matrices research of composite plasma polymer films with metal grains dispersed in the organic polymer has since been pursued actively. 

Quasi-viscoplastic flows of cohesionless grains, dispersive pressure support mechanism, localized, small-scale events... 

Lapping is an abrasive machining process in which abrasive grains dispersed either in a paste or a fluid are applied to the moving surface of an opposing formed tool (the lap) so that the individual grains follow a disordered path (DIN 8589). 

Kang, C. H. and Yoon, D. N., Coarsening of cobalt grains dispersed in liquid copper matrix, MetalL Trans. A, 12A, 61-69, 1981. 

Figure F.5.1. AC susceptibility at different frequencies for a granular film consisting of iron grains dispersed in an alumina matrix (Fe-Al Oj). The out-of-phase component x" is reported for v = l Hz. (Reproduced with permission from Ref. 181.)...

In the past few years a variety of mathematical models have been proposed in order to quantitatively account for the interactions between kinetic and diffusional resistances in gas-solid reactions (1-7). Most of the proposed models are categorized as grain models which assume the reactant solid exists in the form of small grains dispersed uniformly throughout the volume of the solid particle. In the most general of these models three major resistances are taken... 

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