Percussion mixtures sensitive

Chlorites are strong oxidizing snbstances. They, however, are less stable than the chlorates. They are sensitive to heat or impact. Most metal chlorites explode npon heating at 100-HOT (212-230°F). Sodinm chlorite does or explode on percussion. Mixtures of chlorites with finely divided metals or organic compounds may burst into flame on friction. Ammonium chlorite explodes when subjected to heat or shock, as does silver chlorite, AgC102 [7783-91-7]. 

Tetryl (C7H5N508) is a pale yellow crystalline solid. It is moderately sensitive to initiation by friction and percussion and is used in the form of pressed pellets as primers for explosive compositions that are less sensitive to initiation. It is slightly more sensitive than picric acid and considerably more sensitive than TNT. In the early 1900s, tetryl was used as base charges for blasting caps but now has been replaced by PETN and RDX. During World War II, tetryl was used as a component of explosive mixtures. 

Priming Composition. A physical mixture of materials that is very sensitive to impact or percussion and, when so exploded, undergoes very rapid autocombustion. The products of such an explosion are hot gases and incandescent solid particles. Priming compositions are used for the ignition of primary explosives, BkPdr, igniter charges and propellants in small arms ammunition (Ref 40a, p 112) (See also in Section 3, Part D and Section 4,... 

Uses Can be used in detonators when initiated by another primary expl and functioning as an intermediate booster or when mixed with another primary exp to increase the sensitivity of the latter to flame or heat. Its mixture with LA was patented by Dynamit AG (Ref 8) for use in explosive rivets. Tetracene can also be used in primer caps where as little as 2% in the compn results in improved uniformity of percussion sensitivity... 

The invention of percussion compositions for igniting powders is usually attributed to Forsyth [5]. In 1805 he employed pellets composed of a mixture of potassium chlorate and combustible materials, coated with wax to render them safer to handle, but even so they were still dangerous since the mixture was sensitive to friction. The first ignition caps were invented in the early nineteenth century. In these caps the ignitable composition was enclosed in a casing of brass or copper. This invention cannot be traced with any certainty to any individual. The literature on the subject names several chemists including Bellot and Egg in 1815 [5]. 

For many years the standard mixture in France for all caps which were to be fired by the blow of a hammer was made from 2 parts of mercury fulminate, 1 of antimony sulfide, and 1 of saltpeter. This was mixed and loaded dry, and was considered to be safer to handle than similar mixtures containing potassium chlorate. Where a more sensitive primer was needed, the standard French composition for all concussion and percussion primers of fuzes was made from 5 parts of mercury fulminate and 9 parts each of antimony sulfide and potassium chlorate. 

The primer cup contains a mixture of chemicals which sensitize each other to percussion and rapid burning, and consequently the primer burns rapidly producing a flame and a shower of hot particles that penetrates and ignites the propellant. 

Pyrophoric alloy primer mixtures never achieved widespread use, presumably because of their lack of sensitivity to percussion.50... 

Mercury nitride forms a chocolate colored powder, which is slowly decomposed by water. The dry nitride tarnishes in air, and is slowly decomposed in acidic media. The nitride is very explosive, and must be handled with extreme care. It detonates violently yielding a white flame with a bluish purple border, and also when heated. The salt can be detonated by rubbing it with a rounded glass stir rod—very friction sensitive. Mercury nitride also easily detonates by shock, or percussion. Handle with care never store dry keep submerged in a water free solvent such as kerosene in amber glass bottles in a cool place. It is advisable to desensitize mercury nitride with gum Arabic, paraffin wax, or starch immediately after preparation, and these mixtures should be carefully blended using a wood spoon or plastic spatula—metal and glass should be avoided. ... 

In stab and percussion detonators (Figure 1), motion of the firing pin initiates a deflagration in a sensitive primary mixture, such as NOL-130 (a mixture of 40% lead styphnate, 20% lead azide, 15% antimony sulfide. 20% barium nitrate, and 5% tetrazene) [2], The upper illustration shows a typical stab detonator. Its function is to ignite rapidly and produce enough output to detonate a lead over a small gap ( 0.127 cm). Such a detonator is mounted "out-of-line" in the train, while the lead is "in-line" with a booster charge. Lead azide is initiated rapidly by the primer and detonates with sufficient impulse to detonate the output charge (RDX). 

Basically identical drop-test methods have been devised for determining the sensitivity of stab or percussion primers. Stevenson discussed the method used at Frankford Arsenal with special modifications for an investigation of variations in a tracer igniter mixture and their relation to impact sensitivity. 

Primer (a common version is the percussion primer) A term for the device used to ignite smokeless powder in small arms ammunition or other propellant applications. An impact-sensitive composition is typically used. When struck by a metal firing pin, a primer emits a burst of flame and hot particulates capable of rapidly igniting the propellant charge. Several typical primer mixtures are given in Table 7.2. 

Priming compositions or priming mixtures are sensitive explosive mixtures that are designed to produce a flame in a particular application. They are most often mixtures containing a primary explosive as one of the components in such a form and amount that ensures the inability to initiate detonation of the mixture. The role of the primary explosive is to sensitize the mixture to external stimuli, not to make it detonatable. Priming mixtures are used in percussion caps for ignition of gun powder, on electric fuseheads, delay elements, etc. 

Impact sensitivity of GNGT is reported to be (a) about the same as MF [19] (b) shghtly more sensitive than MF [14, 15, 17, 18] or (c) slightly less sensitive than MF [1, 20]. Values of impact sensitivity reported by various authors are summarized in Fig. 2.15. Sensitivity to friction is about the same as that of MF according to our own measurement (see Fig. 2.19) [21]. The sensitivity to electrostatic discharge was found to be 2.7 ml and, as can be seen from Fig. 2.21, is comparable to that of DDNP. GNGT is often mixed with hard inert particles to increase its sensitivity especially when used in percussion and stab priming mixtures. 

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