Powders


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The following article is from The Great Soviet Encyclopedia (1979). It might be outdated or ideologically biased.

Powders

 

solid (condensed), compressed explosive compounds that initiate self-propagating exothermic reactions in a narrow zone to form chiefly gaseous products. The combustion of powders occurs in parallel layers in a direction perpendicular to the combustion surface and is governed by the transfer of heat from layer to layer. In contrast to other explosives, the combustion of powders remains stable over a wide range of external pressures (0.1–1,000 meganewtons/m2); this is because the combustion products cannot penetrate within the substance. Combustion along parallel layers makes it possible to control the overall rate of gas formation with time by the size and shape of powder elements. As a rule, these are tubes of varying length or diameter with one or more channels. The combustion rate is governed by composition, initial temperature, and pressure.

There are two types of powders: plasticized systems and heterogeneous systems. Plasticized systems (smokeless powders) with a nitrocellulose base are divided into pyroxylin powders, cordites, and ballistites. Heterogeneous systems (mixed powders), which are composed of a fuel and an oxidizing agent, include black powder.

Powders are used in firearms to impart the necessary velocity to the shell. The powders used in rocket engines are called solid propellants. Mixed powders are basically highly filled thermosetting polymer systems, whose physical and mechanical properties depend far less on temperature than do the properties of ballistic powders. Modern mixed powders contain approximately 60–70 percent ammonium perchlorate (the oxidizing agent), 15–20 percent polymer binder (the fuel), 10–20 percent powdered aluminum, and other additives. When used as solid propellants, mixed powders offer many advantages over ballistic powders: higher specific thrust, less dependence of the combustion rate on pressure and temperature, a wider range of combustion rate control with the aid of various additives, and control over physical and mechanical properties. Owing to the high elastic capacity of mixed powders, charges may be firmly secured to the engine wall; this sharply increases the coefficient of admission of the solid propellant into the engine unit.

Black powder was the first powder in use. Although the time and place of its invention have not been clearly established, it probably originated in China and was later used by the Arabs. Black powder was first used in Europe and Russia in the 13th century; it remained the only explosive for mining operations until the mid-19th century and the only propellant until the end of the 19th century. Black powder lost its importance late in the 19th century owing to the invention of smokeless powders.

Pyroxylin powder was invented in France in 1884 by P. Vieille and was developed in Russia in 1890 by D. I. Mendeleev (pyro-collodian powder) and by a group of engineers in the Okhta Powder Plant (pyroxylin powder) in 1890–91. Cordite powder was invented in Great Britain in the late 19th century, and ballistic powder in Sweden in 1888 by A. Nobel. Ballistic powder charges for rockets were first developed in the USSR during the 1930’s and were successfully used by Soviet troops during the Great Patriotic War of 1941–45 in the Katiusha rocket mortars. New types of mixed powders as well as jet-engine charges made with them were invented during the second half of the 1940’s, first in the USA and then in other countries.

REFERENCES

Serebriakov, M. E. Vnutrenniaia ballistika, 2nd ed. Moscow, 1949.
Corner, J. Vnutrenniaia ballistika orudii. Moscow, 1953. (Translated from English.)
Paushkin, Ia. M. Khimiia reaktivnykh topliv. Moscow, 1962.
Sarner, S. Khimiia raketnykh topliv. Moscow, 1969. (Translated from English.)

G. K. KLIMENKO

The Great Soviet Encyclopedia, 3rd Edition (1970-1979). © 2010 The Gale Group, Inc. All rights reserved.
References in classic literature ?
Maston, "you will get to this, that as soon as your shot becomes sufficiently heavy you will not require any powder at all."
I only keep to statistical facts when I say that, during the war, and for the very largest guns, the weight of the powder was reduced, as the result of experience, to a tenth part of the weight of the shot."
There he crushed to a powder two soluble tablets, each containing a quarter of a grain of morphia.
And then my lamps fall on another party present, who, I says to myself, is failin' in a proper affection toward his comin' son-in- law, so I watches my chance and dumps that powder in old man Riddle's coffee--see?"
"It's too bad the Powder of Life was all used up," remarked the shaggy man; "it would be a handy thing to have around."
"A while ago the crooked Sorcerer who invented the Magic Powder fell down a precipice and was killed.
"What did old Mombi the Witch do with the Powder of Life your husband gave her?" asked the boy.
Well, I just stated that she used the Rollings Reliable in it, and that was why it turned out so well; and then, in the last paragraph, where PERCEVAL clasps AVERIL in his arms and says, `Sweetheart, the beautiful coming years will bring us the fulfilment of our home of dreams,' I added, `in which we will never use any baking powder except Rollings Reliable.'"
We were all hard at work, changing the powder and the berths, when the last man or two, and Long John along with them, came off in a shore-boat.
In South Kensington the streets were clear of dead and of black powder. It was near South Kensington that I first heard the howling.
The officer had followed the brilliant train in the air; he endeavored to precipitate himself upon the barrel and tear out the match before it reached the powder it contained.
However, I said no more to the boy, but bade him lie still, and I took our biggest gun, which was almost musket-bore, and loaded it with a good charge of powder, and with two slugs, and laid it down; then I loaded another gun with two bullets; and the third (for we had three pieces) I loaded with five smaller bullets.