Nitroguanidine triple-base

Triple-based propellants are mixtures of nitroguanidine, nitrocellulose, and nitroglycerine. The mixture reduces the muzzle flash observed with double-based propellants, reduces the burn temperature, which protects the gun barrel, and increases the gas volume. Triple-based propellants are used in tank guns, large caliber guns, and some naval weapons. 

Nitroguanidine (NQ) is a nitramine compound containing one N-NOj group in its molecular structure. In contrast to cyclic nitramines such as HMX and RDX, its density is low and its heat of explosion is also comparatively low. However, the Mg of its combustion products is low because of the high mass fraction of hydrogen contained within the molecule. Incorporating NQ particles into a double-base propellant forms a composite propellant termed a triple-base propellant, as used in guns. 

Triple-base propellants are made by the addition of crystalUne nitroguanidine (NQ) to double-base propellants, similar to the way in which nitramine is added to CMDB propellants as described in the preceding section. Since NQ has a relatively high mole fraction of hydrogen within its molecular structure, the molecular mass of the combustion products becomes low even though the flame temperature is reduced. Table 4.13 shows the chemical composition, adiabatic flame temperature, and thermodynamic energy,/ as defined in Eq. (1.84), of a triple-base propellant at 10 MPa (NC 12.6% N). 

Single base" smokeless powder, developed mainly in the United States, uses only nitrocellulose. "Double base" smokeless powder, developed in Europe, is a blend of nitrocellulose and nitroglycerine. "Cordite," a British development, consists of 65% NC, 30% NG, and 5% mineral jelly. The mineral jelly (a hydrocarbon material) functions as a coolant and produces substantial amounts of CO 2, CO, and H 2O gas to improve the propellant characteristics. "Triple base" smokeless powder, containing nitroguanidine as a third component with nitroglycerine and nitrocellulose is also manufactured. 

Nitroguanidine Guanidine, Sulfuric acid, Water Secondary high explosive, Found in triple-base smokeless powders... 

Triple base A smokeless powder that contains nitrocellulose, nitroglycerin, and nitroguanidine. 

Uses. NC isused in single-base, smokeless propellants(NC non-expl ingredients) double -base, smokeless proplnts(NC NG) triple -base, smokeless proplnts(NC, NG nitroguanidine) and in dynamites. Commercially NC is used in pharmaceuticals, lacquers, and photographic products(Ref 80)(For more detailed info on NC s, see various types of NC listed in Table and discussed separately, next page)... 

Gun propellants usually are single base (NC), double base (NC and NG), or triple base (NC, NG, and nitroguanidine (NQ)). Some of the newer, lower vulnerability gun propellants contain binders and crystalline explosives and thus are similar to PBX. 

Propellants that contain nitrocellulose as the only oxidizer are referred to as single base and propellants that contain both nitrocellulose and nitroglycerine (or some other explosive plasticizer) as double base. Triple-based propellants are produced when substantial quantities of an organic, energy-producing, crystalline compound such as nitroguanidine are incorporated in double-based propellants. Triple-based propellants are unlikely to be encountered in small arms ammunition. 

Triple-base propellants have also been produced, having double-base composition plus nitroguanidine, added as a combustion coolant or as a ballistic modifier. 

The propellant which has exclusively been used for a long time in conventional military weapons is the smokeless (or, more accurately, low-smoke) powder. According to its composition, it can be classified as single-base powders (e.g., nitrocellulose powder), doublebase powders (e.g., nitroglycerine powder) and triple-base powders (e.g., nitrocellulose + nitroglycerine (or diglycol dinitrate) + nitroguanidine powders). 

Nitroguanidine (NQ) was first prepared by Jousselin in 1887 (Fig. 1.3). However, during WWI and WWII it only found limited use, for example in formulations with AN in grenades for mortars. In more recent days NQ has been used as a component in triple-base propellants together with NC and NG. One advantage of the triple-base propellants is that unlike double-base propellants the muzzle flash is reduced. The introduction of about 50 % of NQ to a propellant composition also results in a reduction of the combustion temperature and consequently reduced erosion and increased lifetime of the gun. NQ can be prepared from dicyandiamide and ammonium nitrate via guanidinium nitrate which is dehydrated with sulfuric acid under the formation of NQ ... 

Nitroguanidine, 17, is another aliphatic nitramine that is used as a major constituent in triple-base propellants. It exists in two crystalline forms, the a- and 3-forms. The a -form of nitroguanidine, 17, can be prepared by reacting guanidine nitrate in concentrated sulfuric acid followed by the addition of an excess of water from which guanidine nitrate, 19, is crystallized (Eqs. 12.11 and 12.12) [4]. 

Triple-base propellants are made by the addition of crystalline nitroguanidine (NQ) within double-base propellants. Since NQ contains a relatively high mole fraction of hydrogen atoms within the molecular structure, the molecular mass of the combustion products becomes low even though the flame temperature becomes low. 

Triple-base propellants of NC, NG, and nitroguanidine (556-88-7). These marry the higher power of double-bases with the cooling affect of nitroguanidine to minimize barrel wear. 

Triple base propellant consists of cellulose nitrate, glycerol trinitrate or diglycol dinitrate, nitroguanidine and a stabilizer. 

Triple-base propellant containing nitroguani-dine, with components (mass %) pyrocellulose 28%, nitroglycerine 22.5%, nitroguanidine 47.7%, stabilizer, etc. 

Figure 11.40 DTA curve of triple-base propellant containing nitroguanidine in static air. The inset is the TG curve obtained with LCT apparatus...

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