Type of Explosive Chemicals

An explosive mixture of sulfur, charcoal, and saltpeter, called black powder, was known to the Chinese centuries ago, its use in propelling missile was demonstrated shortly after 1300. the discoveries of nitro-glycerine and nitrocellulose shortly before 1850 and the invention of dynamites and the mercury fulminate blasting cap soon after, were epochal events of the high explosives era. Smokeless powder was first made in 1867. The demand for more powerful and uniform propellants for the space program offered a recent, new challenge. In times of war, increased quantities are required; for example, roughly 3 x 103 kg was manufactured in the United States between January 1840 and V-J day. Industrial and commercial use is very substantial 1.6 x 109 kg/year in 1982. Although a great many compounds and mixtures are explosive, comparatively, few of them are suitable for explosive use because of the critical restrictions on ability, safety, and price. Most explosive compounds are too expensive and too sensitive for such use.

Types of explosives
An explosive is a material that, under the influence of thermal or mechanical shock, decomposes rapidly and spontaneously with the evolution of a great deal of heat and much gas. The hot gases cause extremely high pressure of the explosive is set off in confined space. Explosive differ widely in their sensitivity and power. Only those of a comparatively insensitive nature, capable of being controlled and having a high energy content are of importance industrially or militarily. These are three fundamental types of explosives; mechanical, atomic, and chemical. It is a convenient to place chemical explosives in two divisions in accordance with their behaviour.

1. Detonating, or high explosives: (a) primary, or initiating explosives (detonation); (b) booster and secondary explosives.
2. Deflagrating, or low, explosives.

There exist a very great difference between the detonating and deflagrating explosive types. High explosives detonate at very high rates, from 2 to 9 x 103 m/s and the reaction front is a shock phenomenon moving actively throughout the material. Low explosives, or propellants, burn in layers parallel to the surface at low rates, around 10-2 m/s, and the reaction front is a flame.

The major explosive according to military or commercial use have variation in their blasting characteristics obtained; by altering physical conditions such as density and granulation and combining ingredients, paraffin, aluminium, and waxes for example.