Prismatic grains

Miicklich F, Ohser J, Hartmann S, Hoffmann MJ, Petzow G (1994) 3D-Characterisation of Sintered Microstructures with Prismatic Grains-A Precondition for Microstructural Modelling of Si3N4 Ceramics. In Hoffmann MJ, Petzow G (eds) Tailoring of Mechanical Properties of Si3N4 Ceramics. NATO ASI Ser E 276. Kluwer Academic Publishers, Dordrecht, p 73... 

Figure 10.2 Commonly observed micro structures of ceramics produced by liquid-phase sintering, (a) Rounded grains in a moderate amount of liquid (> 5 vol%) (b) grains with flat contact surfaces in a low volume fraction of liquid (<2-5 vol%) (c) prismatic grains dictated by anisotropic interfacial energy with a moderate to high liquid volume (>10 vol%) (d) elongated grains with flat or curved sides resulting from anisotropic interfacial energy with a low liquid content (<2-5 vol%).

The hydrostatic balance principal has been used in Bode s Densimeter for density detns of large grain expls or proplnts, such as of prismatic BkPdr. Here the prism is weighed first in air and then suspended in mercury at known temp... 

Rodman s work is important, nevertheless, because the prismatic form powder grains of which he later built up his charges, owing to difficulties in the manuf of the cake cartridges, was adopted by all the leading nations in the world, and because his reasoning was later successfully applied to brown prismatic and to propint powder which is still being used in the form of perforated cylinders... 

I feel like a white granular mass of amorphous crystals—my formula appears to be isomeric with Spasmotoxin. My aurochloride precipitates into beautiful prismatic needles. My Platinochloride develops octahedron crystals,—with a fine blue florescence. My physiological action is not indifferent. One millionth of a grain injected under the skin of a frog produces instantaneous death accompanied by an orange blossom odor. 

Rodman, U. S. Army, discovered the principle of the progressive combustion of gunpowder and proposed perforated grains in prismatic form. 

Pyro manufacture on large scale in Russia. Maxim and Schupphaus developed perforated black powder grain and the subsequent perforated prismatic cocoa powder. 

The grain refinement is achieved by an increase in the nucleation rate. The first four deposit types are seen with two-dimensional nucleation, but UD type requires three-dimensional or secondary nucleation. The nucleation intensity increases with increasing inhibition and deposition current density. The FI type of crystals is usually seen at low inhibition. With increasing current density, the deposit form changes from whiskers to prismatic crystals, dendrites, and finally powder deposits. The BR type is seen at moderate inhibition level and the deposit follows the structure of the base material. 

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