Hollow grains

The low strength of the transition zone is attributed to higher porosity and to the orientation of large CH crystals with weak intercrystalline bonds. Hadley (1972) has shown that hollow grains composed of Portland cement hydration products, which increased porosity, appeared more often in the interface than in bulk cement paste. These are known as Hadley grains, where the pores and voids may appear in the form of clusters, which create critical flaws. 

Hollow grains. Sudden heating of the grain. Weevils found a few feet below the surface of stored grain. 

Elder has a hard white wood that is resilient yet easy to hollow out. Carpenters have long employed it, enjoying its close grains and the fact that it polishes easily. The wood has a pleasant musky smell. The wood has also been used for fishing rod parts, fishing floats, needles for net weaving, shoemaker s pegs, combs, bows, skewers and small toys. 

The detection of other molecules, such as ammonia, requires the use of a porous catalytic metal. To obtain a gas response from the NH3 molecule, it is believed that active sites of triple points are required where the molecules are in contact with the metal, insulator, and ambient [30, 31]. It has been shown that gas species such as hydrogen atoms or protons also diffuse out onto the exposed oxide surface in between the metal grains [Figure 2.1(b)] [32, 33]. Furthermore, Lofdahl et al. have performed experiments that provide clear evidence that hydrogen atoms or protons also diffuse under the metal from the triple point [34]. The hollow structure of the metal surface facing the insulator has been revealed by Abom et al. [35]. 

A new form of coaled abrasive has been developed that consists of tiny aggregates of abrasive material in the form of hollow spheres As these spheres break down in use, fresh cutting grains are exposed this maintains cut-rate and keeps power low. 

As the skin would not soften, the resulting grain would be hollow... 

Particle shape Hollow agglomerates Inhomogeneities Non-uniform grain... 

Fig. 2. Schematic of the synthesis of nanostructured metals and alloys in varying grain sizes supported on hollow, highly oriented protein templates (Behrens, Dinjus, and Unger, 1999 Behrens et al., 2000).

The hybrids consist of solid and liquid substances in the same system. The most widely used hybrid concept has a hollow solid fuel grain, much like a solid propellant grain, but with no solid oxidizer present. The fuel grain may contain other. energetic solid substances. The oxidizer is generally a storable liquid propellant such as nitrogen tetroxide or chlorine trifluoride. 

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