What is modern gunpowder made of



Gunpowder is a propellant for firearms and solid fuel rockets, which, in contrast to the previously used black powder, consists of the so-called low-smoke cellulose nitrate powders. Instead of the term “gunpowder”, which historically came from gunpowder, the term is usually used today Propellant powder used. Together with the initial explosives, explosives, black powder, detonators and pyrotechnic charges, these belong to the class of explosives.

   

development

The low-smoke gunpowder was developed at the end of the 19th century, when black powder, which until then was mainly used as a propellant, no longer met the requirements of modern artillery weapons.

The problem arose as follows: Black powder was unsuitable for use in large-caliber guns because it was too offensive: The propellant charge had already burned down before the projectile had reached the end of the barrel, causing a steep rise in pressure. Attempts to reduce the burning rate first by using a coarser grain size of the black powder and then by increasing the density of the raw powder mass have shown only limited success. Further disadvantages were the heavy smoke development and the heavy soiling of the pipes by salts, which are formed when black powder is burned. When burned, one kilogram of black powder yields around 560 grams of a salt mixture, mainly potassium sulfite and potassium carbonate. The salt pollution caused problems in particular with rifles (in which the aggressiveness of the black powder did not interfere) and was a hindrance to the transition to smaller calibers.

After unsuccessful experiments on the basis of potassium picrate and a mixture of potassium chlorate, blood liquor salt and sugar, experiments with nitrated cellulose began. This developed hardly any smoke and left no residue, but was too offensive even with rifles.

A remedy for the unwanted aggressiveness was found by gelatinizing with various solvents and phlegmatizing. Due to the gelatinization process used, the variation of the additives and the size and shape of the powder particles, the burning behavior could now be largely influenced, but the smoke development increased due to the additives used and the powder no longer burned completely without leaving any residue. However, this was accepted due to the other advantages.

composition

According to the composition, gunpowders are divided into three classes:

  • Single base gunpowder (cellulose nitrate powder): Mixtures of 80% gun cotton and 20% collodion wool, which are gelatinized with alcohol-ether (ether) mixtures and phlegmatized after molding and drying with plasticizers such as centralites, camphor, dibutyl phthalate and the like.
  • Two-base gunpowder: Mixtures of glycerol trinitrate and cellulose nitrate that are gelatinized with acetone / alcohol, then formed into cords and then the solvent is removed. A typical example is British cordite, which owes its name to the shape of the cord.
  • Triple base gunpowder: Mixtures of diethylene glycol dinitrate or triethylene glycol dinitrate and cellulose nitrate to which nitroguanidine is added as a third component; these powders have a low energy content with a large gas volume. Due to the lower combustion temperature, they protect the pipes and are particularly used for field artillery (continuous fire) and anti-aircraft guns (high cadence).

Other manufacturing processes

As POL powder (Powders without [organic] solvents) are two- or three-base propellant powders for artillery or rocket propellants. Gelatinization and homogenization are carried out with water using roller, extrusion or screw press processes, with diethylene glycol dinitrate or glycerol trinitrate acting as “solvents and swelling agents” for cellulose nitrate. Then the water is evaporated down to about 1% and then the powder is shaped by machine.

For the so-called tropical powder, triethylene glycol dinitrate was used instead of diethylene glycol dinitrate because of its lower volatility. Glycerin trinitrate was only available to a limited extent as a raw material during both world wars due to the shortage of fats and oils.

The finished powders are graphitized in order to avoid static charging when pouring and thus avoid sparks.

Additives

To reduce smoke development and increase storage stability, 0.5% to 2% diphenylamine can be added.

An addition of 1% sodium oxalate or 2% potassium sulfate prevents the flue gases from igniting and thus the muzzle flash.

Dinitrotoluene can be used as a substitute for glycerol trinitrate or diethylene glycol dinitrate, but it is significantly more toxic. Ethylene glycol dinitrate can also be used for the same purpose, but due to its much lower boiling point, evaporation and recondensation slowly separate. Because of this, this powder cannot be stored for a long time.

Up to 50% ammonium nitrate can be added as a substitute for cellulose nitrate, but the gunpowder is then sensitive to moisture. Pellets made from coal dust and ammonium nitrate were used as propellants for artillery in Germany during World War I and World War II.

shape

According to the shape, a distinction is made between tube powder, plate powder, strip powder, ring powder, noodle powder and other shapes. The shape and size of the powder particles is largely determined by the size and shape of the propellant charge and the desired combustion profile. Tubular powder is mostly used in large-caliber cannons, plate powder in high-angle guns, and mostly fine-grained powder in handguns. Propellant charges for rockets are produced in the form of cylindrical pellets, which are additionally provided with bores and grooves to increase the burn-off surface.

In order to prevent an artillery propellant charge from detonating instead of deflagrating, it is not ignited directly by the initial charge, but via an intermediate charge of black powder. This also ensures that the entire charge is ignited evenly.

Categories: Pyrotechnic Kit | Powder | Mixture of substances