Black powder, compressed

Black powder, compressed or Gunpowder, compressed or Black powder, in pellets or Gunpowder, in pellets 0028... 

SYNS BLACK POWDER, compressed (DOT) BLACK POWDER, granular or as a meal (UN 0027) (DOT) BLACK... 

Shock Synthesis. When graphite is strongly compressed and heated by the shock produced by an explosive charge, some (up to 10%) diamond may form (26,27). These crystaUite diamonds are small (on the order of 1 llm) and appear as a black powder. The peak pressures and temperatures, which are maintained for a few microseconds, are estimated to be about 30 GPa (300 kbar) and 1000 K. It is beheved that the diamonds found in certain meteorites were produced by similar shock compression processes that occurred upon impact (5). 

The plastic flow of sulfur is thought to be responsible for the increase in the burning time that is experienced with black powders of various pellet sizes as the pellets (or grains) are compressed to higher bulk densities. 

When black powder is used to propel rockets it is classed as a composite propellant (where the fuel and oxidiser are intimately mixed) and forms part of a rocket motor in which the powder is compressed to form a monolithic single grain inside a combustion chamber as shown in Figure 3.1. As well as gunpowder, the composite propellant mix will contain a binder which is used to improve the cohesion of the ingredients. Binders form a distinct phase and tend to reduce the sensitiveness of the propellant to shock and impact. When based on organic materials, as is normally the case, they will serve as part of the fuel component also. 

In 1808 Sir Humphry Davy tried in vain to decompose zirconia with the electric current, but Berzelius (36) finally obtained the metal in 1824 by heating a dry mixture of potassium and potassium zirconium fluoride in a very small closed iron tube placed inside a platinum crucible. After the quiet reaction had taken place, he cooled the tube and placed it in distilled water, whereupon, to use his own words, There fell from the tube a black powder as fast as the salt dissolved, and at the same time there was evolved a small quantity of hydrogen.. . . The zirconium obtained in this manner is easily deposited. It can be washed with water without oxidizing. Washed and dried, it forms a black powder resembling charcoal, which cannot be compressed nor polished like a metal (15). 

To the definition given under item (a), may be added that propellant igniters consist of a charge of quick-burning BkPdr (See BLACK POWDER in Ref 44, p B171), which can be either in the form of a compressed disc attached to a "simple"primer or in the form of small grains contained in a perforated tube. In a 3rd method, loose BkPdr is contained in a Small cloth bag which is placed, during... 

W. A. Proell, 64, 12454 (1966) Claims a mixt of Black Powders 30-50 smokeless powder 50-70%, compressed into a coherent cake to be used for igniting propellants USP 3234059... 

Hard, compressed grains of black powder are not porous—the sulfur appears to have colloidal properties and to fill completely... 

Silver-white metal. Occurs also as black powder and as spongy masses that can be compressed to a compact mass mp, 1555°C bp, 3167°C. ... 

A further design of exploding rifle bullet, without a firing pin, contained a primer with 40 mg mercury fulminate in the nose of the bullet which on impact ignited compressed black powder and this in turn detonated a metal cup containing an explosive mixture of potassium chlorate (56%) and antimony sulfide (44%). PETN explosive has also been used in exploding rifle bullets. 

Pyrodex P grade powder, for instance, is roughly equivalent to FFFG black powder. It will detonate with a pleasant, resounding thump when fired electrically. Yet even when used in large quantities and tightly compressed in an... 

You simply go down to your local chemist s supply store and buy some copper oxide, some barium carbonate, and some yttrium oxide, all readily available in white powders. You go home and you do a little calculation so you ll get the ratios right, so that the yttrium, barium, and copper are in a ratio of 1-2-3. If you ve had any chemistry at all, that s very easy to do. Then you simply stir the mixture thoroughly in a pan and stick it in your microwave oven and you bake it at 950° F for about four hours—and when you pull it out, you ve got this black powder. You compress it into a little plate, and you put it back in the oven to sinter it and make it one solid piece. And if you know a little more about what you re doing, you blow some oxygen on it and... 

FIG. 18 Powder compressibility C2 for (A) instant low-fat milk, (B) nonfat milk, and (C) instant coffee, at three aw values and different size ranges (gray aw = 0.15 black aw = 0.44 white aw = 0.56) (adapted from Yan and Barbosa-Canovas, 2000). 

Stiver-white metal, face-centered cubic structure occurs also as black powder and as spongy masses which can be compressed to a compact mass, mp 1555 bp 3167. dj 12.02. Hardness on Mohs scale 4.8, Brindl hardness 61.0. Spec heat 0.0584 cal/g at 0 C, Electrical resistivity at 0 -10.0 microohms-cm. Appreciably volatile at high temps. At a red heat is converted into the monoxide. Forms dihalides with fluorine or chlorine at a red heat. Reacts with nitric acid, sulfuric acid, a mixture of hydrochloric and chloric acids. Reacts slightly with coned HCI more readily in the presence of air or free chlorine. Forms a sulfide when heated with sulfur, a phosphide when heated with phosphorus. Absorbs a considerable amount of hydrogen. 

Syn. Tantalum.—It occurs very sparingly, in the minerals tantalite and yttro-tantalite, as columbic acid. The metal is obtained by the action of potassium on the double fluoride of columbium and potassium, as a black powder, which, when compressed, exhibits metallic lustre and when heated bums in air, yielding columbic acid. 

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