Primary explosives tetrazene

Fig. 49. Diagram of the design and operation of a reactor for the manufacture of lead azide and other primary explosives (tetrazene, lead styphnate and lead picrate).

Interaction, without addition of acid, produces tetrazolylguanidine ( tetrazene ), a primary explosive of equal sensitivity to mercury(II) azide, but more readily initiated. 

Primary explosives differ from secondary explosives in that they undergo a rapid transition from burning to detonation and have the ability to transmit the detonation to less sensitive (but more powerful) secondary explosives. Primary explosives have high degrees of sensitivity to initiation through shock, friction, electric spark, or high temperature, and explode whether confined or unconfined. Some widely used primary explosives include lead azide, silver azide, tetrazene, lead styphnate, mercury fulminate, and diazodinitrophenol. Nuclear weapon applications normally limit the use of primary explosives to lead azide and lead styphnate. 

Tetrazene (C2H8N10O) is a pale yellow crystalline explosive generally used in ignition caps, where a small amount is added to the explosive composition to improve its sensitivity to percussion and friction. Tetrazene is not suitable for filling detonators because its compaction properties make the transition from burning to detonation very difficult. This primary explosive is stable in ambient temperatures. Its ignition temperature is lower and it is slightly more sensitive to impact than mercury fulminate. 

The reaction of aminoguanidine with sodium nitrite under neutral conditions yields tetra-zolylguanyltetrazene hydrate (85), a primary explosive commonly known as tetrazene. Tetrazene (85) is only formed in the absence of free mineral acid and so a common method for its preparation treats the bicarbonate salt of aminoguanidine (84) with one equivalent of acetic acid followed by addition of aqueous sodium nitrite. " Tetrazene (85) is decomposed by aqueous alkali to form triazonitrosoaminoguanidine (86) which is isolated as the cuprate salt (87) on addition of copper acetate to the reaction mixture. Acidification of the copper salt (87) with mineral acid leads to the formation of 5-azidotetrazole (88) (CHN7 = 88 % N).55 56... 

Despite the fact that LA, LS and tetrazene suffer from serious drawbacks, they are still being used in detonators and cap compositions for military and civil applications. Thus LA, LS and tetrazene are the most commonly used primary explosives at present and research is in progress in order to find out suitable substitutes free from such drawbacks. The aim of research in initiatory explosives has all along been to get less sensitive, more compatible, more stable and more efficient material so that safety in manufacture and handing is ensured. 

Impact Sensitivity of Wetted Primary Explosives as Determined by the Ball Drop Test , PATR 4311 (1972) [The authors report that no fires were observed in ten consecutive trials at a max drop ht of 42 inches, using a 1 (2 inch diam steel ball weighing 8.35g, which was dropped on liq-wetted Tetrazene specimens spread uniformly on a hardened steel block. The test liqs studied were Freon-TF 90%, Freon-10%, ethanol 95%, ethanol 50/w 50%, and w]... 

Primary Explosives Mercury fulminate Lead azide Silver azide Lead styphnate Mannitol hexanitrate (Nitromannite) Diazodinitrophenol Tetrazene... 

Typical primary explosives are lead azide and lead styphnate (see Fig. 1.17). The latter one is less powerful than LA but easier to initiate. Tetrazene (Fig. 2.2) is often added to the latter in order to enhance the response (sensitizer). (N.B. mercury fulminate used to be used as a sensitizer). Tetrazene is an effective primer which decomposes without leaving any residue behind. It has been introduced as an additive to erosion-free primers based on lead trinitroresorcinate. Unfortunately, tetrazene is hydrolytically not entirely stable and in long term studies decomposes at temperatures above 90 °C. Diazodinitrophenol (Fig. 2.2) is also a primary explosive and is primarily used in the USA. However, the compound quickly darkens in sun-... 

Tetrazene. Tetrazene, 14, is classified as a primary explosive that is a very hazardous material. An explosion can occur during the preparation that is based on sodium nitrite and amino guanidine sulfate (15). 

The practical use is limited to detonators which are initiated by another primary explosive and tetrazene is used as an intermediate booster or when mixed with another primary explosive to increase its sensitivity to flame or spark. The mixture tetrazene was used in explosive rivets (Vol III, p. 240), Pynamit A.G. patented [150] mixtures of tetrazene with lead azide for this purpose. 

Tetrazene is a relatively weak primary explosive. It should always be used with a sensitive booster charge such as PtTN. When used in the manufacture of detonators, tetrazene should be freely poured into a capsule. Tetrazene loses much of its effectiveness when pressed. 

Primary explosives such as mercury fulminate, lead azicte, lead styphnate, tetrazene, and diazodinitrophenol are characterised a very high sensitivity to... 

Apart from the already mentioned lead azide and mercury fulmiate, the classic examples of primary explosives include lead styphnate (LS), silver azide (SA), dinol (DDNP), and tetrazene (GNGT). Primary explosives (individual components) are often mixed and used in the form of compositions rather than as single component energetic materials. Mixtures may consist of either individual primary explosives (astryl-MF/SA [2]) or primary explosives plus some nonexplosive additive (LA/LS/ dextrine or ASA composition— LA/LS/Al). 

Despite the above-mentioned problems, most common primary explosives have been compared and the order of their impact sensitivity has been evaluated by various authors. The sensitivity of LA and SA is lower than that of MF and comparable to that of PETN. The sensitivity of DDNP is mentioned as lower than for MF [4, 18, 50]. 1-Amino-l-(tetrazol-5-yldiazenyl)guanidin (GNGT, tetrazene) is sometimes reported as slightly more sensitive than MF [41] but slightly less sensitive than MF by [33], SF, often mentioned as a very sensitive substance, has an impact sensitivity comparable to that of LA. Its high sensitivity to friction is sometimes misleadingly attributed to impact. TATP is often reported as extremely sensitive but, as indicated by the figures in Fig. 2.15, the results are relatively evenly spread from about 0.2 to over 3 J. Of the usual primary explosives, LS shows the lowest sensitivity to impact. 

Tetrazene is a heavy metal-free primary explosive that could be used in many applications. Its main drawbacks are its poor thermal stability, low initiating efficiency, and the tendency toward dead-pressing [27]. The use of GNGT is further limited by its low flame temperature which is a problem if it is used in priming mixtures. One possible solution to this problem (employed in NONTOX priming mixture) is the addition of pyrotechnic components that increase the flame temperature sufficiently to reliably ignite the gun powder [26]. 

Mercury(ll) fulminate - Used since the early 1800s in percussion caps for black powder shooting, this primary explosive is highly sensitive to friction and shock. Thus it is used to trigger secondary, but more powerful explosives. Although potassium chlorate is sometimes used in its place, the mercury(ll) fulminate is less corrosive, but may weaken with time. Today it is usually replaced with materials that are non-corrosive, less toxic and more stable over time lead azide, lead slyphnate and tetrazene derivatives. It also causes brass to become brittle a concern for reloaders. 

Typical primary mixtures contain some of the following lead styphnate, tetrazene, aluminum, antimony sulfide, calcium silicate, lead peroxide, boron, metals, barium nitrate, secondary explosive, binder, sensitizer, etc. (Fig. 1.3). Variations in the ingredients and their relative amounts result in compositions which possess sensitivity and ignition properties tailored to specific requirements. 

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