Meyer R., Koehler J., Homburg A. Explosives. Wiley-VCH, 2002 / Explosives 5th ed by Koehler, Meyer, and Homburg (2002)

Grist	156
no scratching parts admitted
silicic acid:	none

Grist*)

Particle size of pyrotechnic material (W Granulation)

Guanidine Nitrate

Guanidinnitrat; nitrate de guanidine

colorless crystals

empirical formula: CH6N4O3 molecular weight: 122.1

energy of formation: – 726.1 kcal/kg = – 3038 kJ/kg enthalpy of formation: – 757.7 kcal/kg = – 3170.1 kJ/kg oxygen balance: – 26.2 %

nitrogen content: 45.89 %

volume of explosion gases: 1083 l/kg heat of explosion

(H2O liq.): 587 kcal/kg = 2455 kJ/kg (H2O gas): 447 kcal/kg = 1871 kJ/kg specific energy: 72.6 mt/kg = 712 kJ/kg melting point: 215 °C = 419°F

heat of fusion: 48 kcal/kg = 203 kJ/kg lead block test: 240 cm3/10 g

deflagration point: decomposition at 270 °C = 518°F impact sensitivity: up to 5 kp m = 50 N m no reaction friction sensitivity:

up to 36 kp = 353 N pistil load no reaction critical diameter of steel sleeve test: 2.5 mm

Guanidine nitrate is soluble in alcohol and water. It is the precursor compound in the synthesis of W Nitroguanidine. It is prepared by fusing dicyanodiamide with ammonium nitrate.

Guanidine nitrate is employed in formulating fusible mixtures containing ammonium nitrate and other nitrates; such mixtures were extensively used during the war as substitutes for explosives, for which the raw materials were in short supply. However, a highbrisance explosive such as Hexogen or another explosive must usually be added

* Text quoted from glossary.

157	Guanidine Picrate

to the mixtures. It was also proposed that guanidine nitrate be incorporated in W Double Base Propellants.

Guanidine Perchlorate

Guanidinperchlorat; perchlorate de guanidine

empirical formula: CH6N3O4Cl molecular weight: 159.5

energy of formation: – 440.1 kcal/kg = –1841.4 kJ/kg enthalpy of formation: – 466.1 kcal/kg = –1950.0 kJ/kg oxygen balance: – 5.0 %

nitrogen content: 26.35 % melting point: 240 °C = 464°F lead block test: 400 cm3/10 g

This compound is prepared from guanidine hydrochloride and sodium perchlorate.

Guanidine Picrate

Guanidinpikrat; picrate de guanidine

yellow crystals

empirical formula: C7H8N6O7 molecular weight: 288.1 oxygen balance: – 61.1 % nitrogen content: 29.16 % melting point:

decomposition at 318.5 – 319.5 °C = 605 – 606°F deflagration point: 325 °C = 617°F

Guanidine picrate is sparingly soluble in water and alcohol. It is prepared by mixing solutions of guanidine nitrate and ammonium picrate.

Guar Gum	158

Guar Gum

Guarmehl; farine de guar

Guar gum is the ground endosperm of the Indian pant Cyanopsis tetragonoloba. It is a polysaccharide with a mannose main chain and galactose side chains. The product gels with water in the cold. It is added to commercial powder explosives so as to protect them from influx of water in wet boreholes. Guar gum gelled with water produces a barrier layer, which prevents any further penetration of water (W Water Resistance; W Slurries).

Gunpowder

propellant; Schiesspulver; poudre

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).

The main component of nitrocellulose powders is nitrocellulose, a mixture of guncotton (13.0 –13.4 % nitrogen) and soluble guncotton (11 –13 % nitrogen content). To manufacture the powder, the nitrocellulose mixture is gelatinized with the aid of solvents – mostly alcohol and ether. Additives – stabilizers in particular – can be incorporated at this stage. The plastic solvent-wet mass thus obtained is now shaped in extrusion presses to give strips or tubes and is cut to the desired length by a cutting machine. The residual solvents in the powder are removed by soaking the powder in water and drying. The dried powder is then polished in drums and is graphitized. A surface treatment is performed at the same time, using alcoholic solutions of Centralite, dibutyl phthalate, camphor, dinitrotoluene, or other phlegmatization agents.

To make nitroglycerine powder, nitrocellulose is suspended in water, the suspension is vigorously stirred, and nitroglycerine is slowly introduced into the suspension, when practically all of it is absorbed by the nitrocellulose. The bulk of the water (residual water content 25 – 35 %) is then centrifuged off or squeezed out, and the powder paste is ground. It is then mixed by mechanical kneading with ni- troglycerine-insoluble additives and is gelatinized on hot rollers, as a result of which the water evaporates, leaving behind a residual water content of about 1 %.

159	Gunpowder

This product, which is thermoplastic, can now be geometrically shaped as desired, in accordance with the type of the powder, using finishing rollers, cutting and punching machines, or hydraulic extrusion presses.

This solventless processing avoids variations in the characteristics of the products due to the presence of residual solvents. No prolonged drying operations are needed for ballistic stability of the gunpowder.

If the use of solvents is required in the production process of double and triple base propellants, the nitroglycerine can be introduced in the mixtures in the form of a “master mix”, a gelatinized mixture consisting of 85 % nitroglycerine and 15 % alcohol-wet nitrocellulose of the same type as the prescribed powder component.

Depending on their intended use, nitroglycerine powders have a nitroglycerine content between 25 and 50 %.

In the USA and in the United Kingdom, a large amount of nitroglycerine and nitroguanidine powders are still produced with the aid of solvents. Acetone is added to nitroglycerine in order to facilitate the kneading and pressing operations, but must be subsequently removed by drying.

A number of liquid nitrate esters other than nitrocellulose have been recently used, including diglycol dinitrate, metriol trinitrate, and butanetriol trinitrate, of which diglycol dinitrate has been the most extensively employed. Powders prepared with it or with triglycol dinitrate are lower in calories. This fact is relevant to the service life of the gunbarrels in which these powders are utilized. Such powders are known as “cold propellants”.

Further research for gunbarrel-saving propellants led to the development of nitroguanidine powders, in which W Nitroguanidine (picrite) is the third energy-containing component, beside nitroglycerine (or diglycol dinitrate or triglycol dinitrate) and nitrocellulose. Powders containing more than 40 % nitroguanidine can be made only with the aid of solvents.

Another special processing method is used for the manufacture of W Ball Powder. Floating spheres of concentrated nitrocellulose solutions are cautiously suspended in warm water; the solvent evaporates gradually and the floating spheres solidify. Finally, an intensive surface treatment is needed to reach the desired ballistic behavior. The ballistic properties of a powder are affected not only by its chemical composition, but also by its shape. Thus, in conventional weapons, it ought to bring about progressive burning, or at least ensure that the surface area of the grain remains constant during combustion.

Hangfire	160

The following geometric forms of powder grains are manufactured:

perforated long tubes	perforated tubes, cut short
multi perforated tubes	flakes
strips	ball powder
cubes	rods, cut short
rings

Finer-grained powders are used for portable firearms; tubular powder is mostly employed for guns; powders in the form of flakes and short tubes are employed for mortars, howitzers, and other high-angle firearms.

Finer-grained powders can be improved in their ballistic behavior by W Surface Treatment. Phlegmatizers are infiltrated in the outer layer of the powder grains; the burning rate in the weapon chamber begins slowly and turns progressive.

Hangfire*)

Spätzündung; explosion tardive

The detonation of an explosive charge at some non-determined time after its normally designed firing time. This can be a dangerous phenomenon.

Hansen Test

In this stability test, which was proposed by Hansen in 1925, 8 samples of the material to be tested are heated up to 110 °C (230°F). Every hour one of the, samples is taken out of the oven, extracted with CO2-free water, and the pH of the filtrate determined. Since the decomposition of propellants based on nitrates is usually accompanied by the liberation of CO2, which interferes with the potentiometric determination, the results obtained are unsatisfactory, and the test is now hardly ever used.

HBX, HBX-1 etc.

These are pourable mixtures of TNT, RDC and aluminum (W Torpex) containing phlegmatizing additives.

* Text quoted from glossary.

, Fifth Edition Rudolf Meyer, Josef Köhler, Axel Homburg

The following geometric forms of powder grains are manufactured:

perforated long tubes	perforated tubes, cut short
multi perforated tubes	flakes
strips	ball powder
cubes	rods, cut short
rings

Finer-grained powders are used for portable firearms; tubular powder is mostly employed for guns; powders in the form of flakes and short tubes are employed for mortars, howitzers, and other high-angle firearms.

Finer-grained powders can be improved in their ballistic behavior by W Surface Treatment. Phlegmatizers are infiltrated in the outer layer of the powder grains; the burning rate in the weapon chamber begins slowly and turns progressive.

Hangfire*)

Spätzündung; explosion tardive

The detonation of an explosive charge at some non-determined time after its normally designed firing time. This can be a dangerous phenomenon.

Hansen Test

In this stability test, which was proposed by Hansen in 1925, 8 samples of the material to be tested are heated up to 110 °C (230°F). Every hour one of the, samples is taken out of the oven, extracted with CO2-free water, and the pH of the filtrate determined. Since the decomposition of propellants based on nitrates is usually accompanied by the liberation of CO2, which interferes with the potentiometric determination, the results obtained are unsatisfactory, and the test is now hardly ever used.

HBX, HBX-1 etc.

These are pourable mixtures of TNT, RDC and aluminum (W Torpex) containing phlegmatizing additives.

* Text quoted from glossary.

161	Heat of Explosion

Heat of Combustion

Verbrennungswärme; chaleur de combustion

Unlike the heat of explosion, the heat of combustion represents the caloric equivalent of the total combustion energy of the given substance. It is determined in a calorimetric bomb under excess oxygen pressure. The heat of combustion is usually employed to find the heat of formation.

The heat of combustion depends only on the composition of the material and not on any other factor, such as loading density or other factors.

Heat of Explosion

Explosionswärme; chaleur d’explosion

The heat of explosion of an explosive material, an explosive mixture, gunpowder or propellant is the heat liberated during its explosive decomposition. Its magnitude depends on the thermo-dynamic state of the decomposition products; the data used in practical calculations usually have water (which is a product of the explosion) in the form of vapor as the reference compound.

The heat of explosion may be both theoretically calculated and experimentally determined. The calculated value is the difference between the energies of formation of the explosive components (or of the explosive itself if chemically homogeneous) and the energies of formation of the explosion products (for more details W Thermodynamic Calculation of Decomposition Reactions). The advantage of the calculation method is that the results are reproducible if based on the same energies of formation and if the calculations are all conducted by the same method; this is often done with the aid of a computer.

The values of heats of explosion can also be more simply calculated from the “partial heats of explosion” of the components of the propellant (see below).

The calculated values do not exactly agree with those obtained by experiment; if the explosion takes place in a bomb, the true compositions of the explosion products are different and, moreover, vary with the loading density. In accurate calculations these factors must be taken into account. In difficult cases (strongly oxygen-deficient compounds and side reactions, such as the formation of CH4, NH3, HCN, or HCl), the only way is to analyze the explosion products. For standard values of heats of formation at constant volume or constant pressure W Energy of Formation.

The experimental determination takes place in a calorimetric bomb. The bomb volume is usually 20 cm3, but can also be 300 cm3. The

Partial Heat of Explosion	162

sample quantity is usually so chosen as to obtain a loading density of 0.1 g/cm3. If a powder refuses to explode – as is often the case if the heat of explosion is smaller than 800 cal/g – a “hot” powder with a known heat of explosion is added, and the heat of explosion of the sample powder is calculated from that of the mixture and that of the hot powder.

The heat of detonation under “CJ conditions” (W Detonation) can differ from the explosion value, because the chemical reaction can be influenced by the conditions in the wave front (e.g., by the loading density of the explosive)*).

Moreover, the detonation energy is related to H2O in the gaseous state. The calorimetric values as well as the calculated values given for the individual explosives in this book are based on H2O in the liquid state as a reaction product.

Partial Heat of Explosion

partielle Explosionswärme; chaleur partielle d’explosion

A. Schmidt proposed a simplified way of estimating the probable heat of explosion of a propellant. In this method, a “partial heat of explosion” is assigned to each component of the powder. Materials with high negative oxygen balances (e.g., stabilizers and gelatinizers) are assigned negative values for the partial heat of explosion. The explosion heat of the propellant is calculated by the addition of the partial values weighted in proportion to the respective percentage of the individual components.

A number of such values have been tabulated. The value for trinitroglycerine is higher than its heat of explosion, since the excess oxygen reacts with the carbon of the other components.

*D. L. Ornellas, The Heat and Products of Detonation in a Calorimeter of CNO, HNO, CHNF, CHNO, CHNOF, and CHNOSi Explosives, Combustion and Flame 23, 37– 46 (1974).

163	Partial Heat of Explosion
Table 17. Values for the partial heat of explosion
Component		Partial
		Heat of
	Explosion
	kcal/kg	kJ/kg
Akardite I	– 2283	– 9559
Akardite II	– 2300	– 9630
Akardite III	– 2378	– 9957
ammonium nitrate	+1450	+6071
barium nitrate	+1139	+4769
barium sulfate	+ 132	+ 553
butanetriol trinitrate (BTN)	+1400	+5862
camphor	– 2673	–11192
Candelilla wax	– 3000	–12561
carbon black	– 3330	–13942
Centralite I	– 2381	– 9969
Centralite II	– 2299	– 9626
Centralite III	– 2367	– 9911
cupric salicylate	–1300	– 5443
basic cupric salicylate	– 900	– 3768
diamyl phthalate (DAP)	– 2187	– 9157
dibutyl phthalate (DBP)	– 2071	– 8671
dibutyl tartrate (DBT)	–1523	– 6377
dibutyl sebacate (DBS)	– 2395	–10028
diethyleneglycol dinitrate	+1030	+4313
(DGN, DEGN)
dioxyenitramine dinitrate	+1340	+5610
(DINA)
diethyl phthalate (DEP)	–1760	– 7369
diethyl sebacate (DES)	– 2260	– 9463
diisobutyl adipate (DIBA)	– 2068	– 8658
dimethyl phthalate (DMP)	–1932	– 8089
dinitrotoluene (DNT)	– 148	– 620
dioctyl phthalate (DOP)	– 2372	– 9931
diphenylamine (DPA)	– 2684	–11238
diphenyl phthalate (DPP)	– 2072	– 8675
diphenylurea	– 2227	– 9324
diphenylurethane	– 2739	–11468
ethyleneglycol dinitrate	+1757	+7357

Partial Heat of Explosion		164
Component		Partial
		Heat of
	Explosion
	kcal/kg	kJ/kg
ethylphenylurethane	–1639	– 6862
glycol	– 889	– 3722
graphite	– 3370	–14110
lead acetyl salicylate	– 857	– 3588
lead ethylhexoate	–1200	– 5024
lead salicylate	– 752	– 3149
lead stearate	– 2000	– 8374
lead sulfate	+150	+ 628
methyl methacrylate (MMA)	–1671	– 6996
Metriol trinitrate (MTN)	+1189	– 4978
mineral jelly	– 3302	–13825
nitrocellulose, 13.3 % N	+1053	+4409
nitrocellulose, 13.0 % N	+1022	+4279
nitrocellulose, 12.5 % N	+ 942	+3944
nitrocellulose, 12.0 % N	+ 871	+3647
nitrocellulose, 11.5 % N	+ 802	+3358
nitroglycerine (NG)	+1785	+7474
nitroguanidine (picrite)	+721	+3019
PETN	+1465	+6134
pentaerythrol trinitrate	+1233	+5163
polyethylene glycol (PEG)	–1593	– 6670
poly methacrylate (PMA)	–1404	– 5879
polyvinyl nitrate (PVN)	+ 910	+3810
potassium nitrate	+1434	+6004
potassium perchlorate	+1667	+6980
potassium sulfate	+300	+1256
TNT	+491	+2056
triacetin (TA)	–1284	– 5376
triethyleneglycol dinitrate (TEGN)	+750	+3140

The values refer to water in the liquid state as a reaction product.