Propellants powdered metals

The key to the successful application of high performance, pourable nitrocellulose plastisols lies in a reasonably priced, high quality source of fine-particle, at least partially colloided, spheroidal nitrocellulose. Here we are speaking of particles much finer than the well-known ball powder, produced by the Olin Mathieson Chemical Co. for small arms for over 30 years (7). Actually, particles on the order of 5-50/x diameter appear to be required to assure a reasonable continuum of uniformly plasticized nitrocellulose binder in a propellant containing 45% or more of combined crystalline oxidizer and powdered metal fuel. Such a continuum of binder is necessary to assure acceptable mechanical properties and reproducible burning characteristics of the finished propellant. Preincorporation of a certain content of the water-insoluble solids within the nitrocellulose microspheres is an effective means of helping to assure this continuum of binder and alleviates the requirements for extremely small ball size. The use of a total of 45% or more of crystalline oxidizer and (generally) metal fuel is essential if the propellant is to be competitive with other modern propellants now in service. 

Some of the unusual properties of a solid propellant results from its basic composition. The two general categories of double-base and composite rubber binder propellants have many subcategories, but no exhaustive compilation will be attempted here. Most modem propellants consist of a deformable binder phase and a crystalline salt filler, such as ammonium perchlorate and usually a powdered metallic fuel such as aluminum. Table I gives some typical compositions for both composite rubber-based and composite double-base systems. 

The nylon-coated bullets from Smith Wesson and the Geco TMJ bul-let/new primer composition, although effective in markedly reducing the lead levels, did not totally eliminate the problem. In 1983, Dynamit Nobel introduced 9 mmP caliber ammunition with a TMJ bullet and a primer free of lead, antimony, barium. The new primer type was called Sintox. A typical Sintox primer composition contains 15% diazodinitrophenol (DDNP) and 3% tetracene as the explosive ingredients, 50% zinc peroxide as the oxidizer, 5% of 40-pm size titanium metal powder, and 27% nitrocellulose as propellant powder.202 As expected, other munitions manufacturers eventually introduced similar ammunition, some with primers that were lead free but containing antimony and barium and others free of lead, antimony, and barium. The objective was to produce ammunition which performed satisfactorily in every way and did not produce any toxic product on discharge. 

Gelled Propellants. As with powdered metallic fuels in solid composite propellants, early interest in gelled liquid propellants focused on gelation as a means of incorporating high-energy solids into liquid propellants... 

In general, the modern commercial silencer is a metal tube, 1 Inch to 3 Inches In diameter and about a foot long. The tube Is mounted on the muzzle end of the barret and Is aligned with the axis of the bore, I.e. the bullet travels down- the exact center of the tube. The front of the tube Is covered with an endplate, the center of which has a hole that Is slightly larger than the diameter of the bullet to be fired. The Interior of the silencer tube contains a series of baffles and chambers which catch and delay the rapidly escaping gases produced by the propellant powder as it bums. 

In all these instances, a cartridge may either be consumed in its entirety or for ballistic reasons a metal base used, leading to a partially combustible case. The advantages of a combustible case are obvious. Enormous amounts of strategic metal would be released for other purposes and there is no question of collection and reuse of such metal. Special benefits are derived for the gunner within a tank The hot used metal cases are an encumbrance in the close quarters, and residual toxic gases from burned propellant powder remain in the conventional metal cases. 

Lubricants--Internal, Mold, Surface Paper Components, Coatings Propellants--Missiles, Rockets Powdered Metal Products Plastic Film... 

A Small but important daSS of fOi mUlatiOnS comprises the Composite Solid Rocket Propellants. Composites typically contain a major amount of an oxidizer such as AP or HMX, a metal powder such as Al, a binder which is one or another type of rubber (or double-base), and up to a dozen trace ingredients such as catalysts, stabilizers, etc. There are literally hundreds of formulations, all to a degree similar and the choice comes down to specific missions, economics, and special requirements Loading of End Items. The blends and formulations described above may be loaded into their hardware in the plant where they are made, or they may be shipped to another plant for Load/... 

Polymers which give mouldable propellants are mixed with the oxidiser in a similar manner, but the product is usually worked mechanically between rolls and evacuated to remove air bubbles. The powder is then moulded by pressure into the metal casing. Alternatively, such plastics can give a propellant which can be extruded into charges which are afterwards cut and machined to suitable shape. The Rocket Propulsion Establishment at Westcott has used ammonium perchlorate and polyisobutene to produce a propellant of putty-like consistency. 

Main uses. Caesium metal is used in the production of vacuum tubes as a scavenger to reduce residual gaseous impurities after the tubes have been sealed. Cs may be generated in situ by heating a pellet of caesium chromate mixed with a metal powder (Zr, Ca, Ba). Cs metal is used as the propellant in ion thrusters (employed in satellites for orientation control) it is ionized in a vacuum chamber, the Cs+ are then accelerated through a nozzle (high specific impulse because of high atomic mass). 

Combustion of powdered aluminum with steam is a potentially attractive propulsion system for torpedoes, because of the very high-energy density (energy per unit volume) that can be achieved. Since the oxidizer can be taken from the environment, on-board storage is required only for the aluminum propellant. A study of potential torpedo propellant/oxidizer combinations including Al, Zr, Mg, and Li metals, hydrocarbon fuels, and typical solid rocket propellants, and... 

Though the oxidation potentials of potassium nitrate (KN KNO3) and sodium nitrate (SN NaN03) are high, both metal nitrates generate combustion products of high Mg, Thus, the specific impulse becomes low when KN or SN is used in a rocket propellant KN and SN are used as major ingredients of explosives and in pyrotechnics. KN is a weU-known material as a major component of black powder. 

Fig. 6.25 Increased burning rates of a double-base propellant resulting from the addition of metallic copper and/or lead powders.

Aluminum (Al) is a silver-colored light and soft metal used as a major component of aluminum alloys, which are used to construct aircraft and vehicles, similar to Mg alloys. However, Al is known as a readily combustible metal. Thus, Al particles are used as major fuel components of pyrolants. Al particles are mixed with ammonium perchlorate particles and polymeric materials to form solid propellants and underwater explosives. The reaction between aluminum powder and iron oxide is known as a high-temperature gasless reaction and is represented by ... 

Hydrocarbon polymers (HCP) are used not only as fuel components but also as binders of crystalline oxidizers and metal powders in the formulation of pyrolants, similar to composite propellants and plastic-bonded explosives. There are many types of HCP, the physicochemical properties of which are dependent on their molecular structures. The viscosity, molecular mass, and functionality of the poly-... 

Primer A term for the device used to ignite smokeless powder in small arms ammunition. An impact-sensitive composition is used. When struck by a metal firing pin, a primer emits a burst of flame capable of igniting the propellant charge. Several typical primer mixtures are given in Table 6.2. 

Another substantial increase in delivered energy was obtained by incorporating substantial amounts of solid oxidizer e.g., ammonium perchlorate) and metallic fuel e.g., aluminum) in the casting powder. The resulting family of composite-modified double-base (CMDB) propellants has found widespread use in ballistic missiles and space motors. 

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