Ammonium perchlorate general

Polymer-based rocket propellants are generally referred to as composite propellants, and often identified by the elastomer used, eg, urethane propellants or carboxy- (CTPB) or hydroxy- (HTPB) terrninated polybutadiene propellants. The cross-linked polymers act as a viscoelastic matrix to provide mechanical strength, and as a fuel to react with the oxidizers present. Ammonium perchlorate and ammonium nitrate are the most common oxidizers used nitramines such as HMX or RDX may be added to react with the fuels and increase the impulse produced. Many other substances may be added including metallic fuels, plasticizers, stabilizers, catalysts, ballistic modifiers, and bonding agents. Typical components are Hsted in Table 1. 

Catalysts which enhance the burning rate of composite propellants are generally believed to accelerate the decomposition of ammonium perchlorate, but the catalytic mechanism is still not very clear. The important observed aspects of this catalysis can be summarized as follows ... 

Samples of mixtures of ammonium perchlorate and the highly explosive liquid nitrate kept at 60° C ignited after 7 days. Many adverse criticisms of the general planning and execution of the experiments were made. 

When a composite propellant composed of ammonium perchlorate (AP) and a hydrocarbon polymer burns in a rocket motor, HCl, CO2, H2O, and N2 are the major combustion products and small amounts of radicals such as OH, H, and CH are also formed. These products are smokeless in nature and the formation of carbon particles is not seen. The exhaust plume emits weak visible light, but no afterburning occurs because AP composite propellants are stoichiometrically balanced mixtures and, in general, no diffusional flames are generated. 

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. 

Some technological information on the Aerojet General Corporation s composite propellants technology was published recently [20]. Ammonium perchlorate is ground to the particle sizes ranging from 1 to 200 fx and then mixed to form a blend of the various particle sizes which gives the best mechanical and ballistic properties. Ammonium perchlorate is mixed with liquid polybutadiene-acrylonitrile fuel, liquid plasticizer and aluminium powder (Fig. 118). The motor casing is coated internally... 

Fig. 118. Pre-mixing ammonium perchlorate with liquid polymer, plasticizer or aluminium (Aerojet General Corp. [20]).

C EN 42, 50-3 (Sept 28, 1964) [Description of cast composite proplnts manufd at Aerojet -General Plant, near Homestead, Florida, for use in large rocket motors, such as 120 156l, diam. Ammonium perchlorate, (previously ground to particles ranging from 1 to 2 microns and blended with ca 0.2% of tricalcium phosphate to improve their flow props), is used as an oxidizer. Aluminum powder is used as a fuel and liquid polybutadiene-acrylonitrite as the fuel-binder. To these ingredients are added a catalyst, such as iron oxide (to... 

A General Description of the Hydrazine Perchlorate Deflagration Process. Let us first describe the deflagration process for hydrazine perchlorate from the above results. It is a process characterized by the formation of a molten zone which is quite turbulent and foamy it is a very erratic process, particularly for the pure material, and it is subject to very potent catalysis by copper chromite and potassium dichromate and to moderate catalysis by magnesium oxide. The process is comparatively reproducible in the presence of small amounts of fuel, and the rate obtained apparently does not depend on the nature of the fuel but only on the ambient pressure. It can be expressed by r — 0.22P where f is in cm./sec. and P in atmospheres. This corresponds to a rate, at 1 atm., some 15 times greater than that calculated by extrapolation for ammonium perchlorate (16). However the process is unstable at pressures above about 7 atm. and steady deflagration cannot be attained above this pressure. 

The fine constructions of representative burning surfaces are shown in Fig.27. A creates oxygen bubbles caused by the dissociation of the oxidizer potassium chlorate, potassium perchlorate, potassium nitrate etc. On the contrary, B creates no bubbles this is where ammonium perchlorate is the oxidizer. Generally an organic fuel makes small craters... 

Generally firework compositions which contain potassium chlorate, perchlorate or ammonium perchlorate as oxidizer will detonate from a strong mechanical initiation, especially when the composition are in the powdered state.Potassium chlorate or other chlorate, red phosphorus, realgar, sulphur, antimony trisulfide etc. promote the inclination. On the contrary, potassium nitrate or other nitrates decrease it. Black powder is not likely to detonate. 

Pine charcoal burns in combination with ammonium perchlorate at F/O = 2 10 producing a yellow flame, but no sparks or fire dust. A mixture of pine charcoal, sulphur and potassium nitrate in the weight ratio 30 10 60 burns producing pretty. orange red fire dust. This characteristic is generally seen with other charcoals but pine charcoal produces the most pretty fire dust of all. On the other hand, the phenomenon shows that pine charcoal does not complete the reaction and produces less gas in black powder-type compositions. Therefore pine charcoal is used to produce fire dust and not to obtain force. 

The composition which contains sulphur and some oxidizer is generally sensitive to shock and friction. The highest degree of sensitivity is in combination with chlorate next with ammonium perchlorate with potassium perchlorate the third and with nitrates less sensitive than above. V/ith any oxidizer sulphur gives a higher ignition sensitivity than charcoal. 

When realgar, is mixed with an oxidizer, it becomes generally quite sensitive to shock and friction to cause an explosion. But the degree differs very much depending upon the kinds of mechanical action, i.e. shock or friction,and the kinds of oxidizer. In combination with potassium chlorate it is quite sensitive both to shock and friction. V/hen an amount of water is added to the mixture, it suddenly loses the sensitivity, but even up to 13% water content(a muddy state) it is not perfectly safe for handling. Alcohol cannot lower the sensitivity. In combination with potassium perchlorate it is sensitive to friction, but not so sensitive to shock with ammonium perchlorate, on the contrary, it is sensitive to shock, but not so sensitive to friction the difference between the two is quite clearly observed. With potassium nitrate it is generally not so sensitive to either kind of action, shock or friction, and the sensitivity to shock is almost the same as that of potassium perchlorate. 

---