Powder high explosive

Nonel fuse, invented by Nitro Nobel AB in Sweden, consists of a thick plastic tube of bore about 1 mm, the inside surface of which is dusted with a small amount of powdered high explosive. If a shock wave is formed at one end of the tube the explosive powder is raised to a dust and a stable detonation at velocity 2000 m s 1 proceeds indefinitely along the fuse. The plastic itself is unaffected and the only outside effect is a flash of light seen through the tube walls. This therefore is an extremely safe method of propagating a detonation from one place to another. 

Thermites, pyrophoric metal powders, high explosive incendiaries (HEI)... 

Add 15 parts (by weight) powdered high explosive to 80 parts gdlcd fuel (half fuel, half polystyrene, for instance). 

Various sulfides of the halogens are formed by direct combination of sulfur with fluorine, bromine, and chlorine. No evident reaction occurs with iodine instead, the elements remain as components of a mixture. Mixtures of sulfur and potassium chlorate, or sulfur and powdered zinc, are highly explosive. 

Minen-bombe, /. mine bomb, high-explosive bomb, -gas, n. mine gas. -granate,/ mine grenade, -korper, m. Mil.) shell body, -pul-ver, n. blasting powder, -werfer, m. trench mortar. 

There is also an as-yet small but growing class of formulations known as PBX Plastic Bonded Explosive. PBXs are similar to rubber-base, composite rocket proplnts in that they consist of 85% or so of powdered high-energy explosive incorporated into a plastic matrix (which can be a conventional plastic or a double-base) and cast into place. 

Finely divided aluminium powder or dust forms highly explosive dispersions in air [1], and all aspects of prevention of aluminium dust explosions are covered in 2 recent US National Fire Codes [2], The effects on ignition properties of impurities introduced by recycled metal used to prepare dust were studied [3], Pyrophoricity is eliminated by surface coating aluminium powder with polystyrene [4], Explosion hazards involved in arc and flame spraying of the powder are analysed and discussed [5], and the effect of surface oxide layers on flammability was studied [6], The causes of a severe explosion in 1983 in a plant producing fine aluminium powder are analysed, and improvements in safety practices discussed... 

A pyrotechnic mixture containing the powdered ingredients was found dangerously sensitive to frictional initiation and highly explosive. 

Mixtures with calcium hydride or strontium hydride may explode readily, and interaction of the molten chlorate is, of course, violent. A mixture of syrupy sodium phosphinate ( hypophosphite ) and the powdered chlorate on heating eventually explodes as powerfully as glyceryl nitrate. Calcium phosphinate mixed with the chlorate and quartz detonates (the latter producing friction to initiate the mixture). Dried mixtures of barium phosphinate and the chlorate are very sensitive and highly explosive under the lightest confinement (screwed up in paper). 

At 240° C mixtures of finely divided metals (aluminium, iron, tungsten) with the peroxide ignite under high friction, and molybdenum powder reacts explosively. 

The lower explosive limit and minimum explosive concentrations of flax, wool, cotton, jute, hemp and sisal fibres are of the same order of magnitude as those of highly explosive dusts [15], The explosibility of pyrites dusts with sulfur contents above 20% was evaluated experimentally. Dusts of 30% sulfur content gave explosion pressures of 3 bar at pressure rise rates of 16 bar/sec. Mixtures of 60% pyrites and 40% powdered limestone still showed significant pressure effects, and the proportion of limestone actually needed to suppress explosions was considerably above the values currently accepted by mining industries [16], Effects of mixtures of particle sizes in combustible dusts upon minimum ignition temperature (T ") and upon presence or absence of explosion were studied. Presence of 30% of fines in a coarse dust lowers Tf significantly [17], Experimental explosions of polyethylene,... 

Aluminum dust and fine powder are highly explosive and can spontaneously burst into flames in air. When treated with acids, aluminum chips and coarse powder release hydrogen. The heat from the chemical reaction can then cause the hydrogen to burn or explode. Pure aluminum foil or sheet metal can burn in air when exposed to a hot enough flame. Fumes from aluminum welding are toxic if inhaled. 

Simultaneously, the discovery of nitroglycerine in 1845 by Sobrero in Italy, and Nobel s work with dynamite, led to the development of a new generation of true high explosives that were far superior to black powder for many blasting and explosives applications. The development of modern smokeless powder -using nitrocellulose and nitroglycerine - led to the demise of black powder as the main propellant for guns of all types and sizes. 

Haid, Becker and Dittmar Stability Test (Designed for high explosives). 42g of powdered explosive, previously dried over phosphorous pentoxide, is introduced through a side tube into a glass vessel connected with a manometer which is in the form of a U-tube and contains mercury covered with a layer of paraffin oil. The glass vessel is also fitted with a side tap. The ensemble is heated at 75° for several hours and pressures are recorded in mm of Hg as a function of time. The steeper the pressure-time curve the less stable is the explosive... 

An explosive insensitive to mech and rifle bullet impact, but detonable by a blasting cap, is claimed in a US patent. It consists of Hydrogen Peroxide, water glycerol (Ref 3) Another patented high explosive composition contains powdered metal and Hydrogen Peroxide, eg 29.7% powd B 70.3% H202 (Ref 19)... 

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