Lead azide drop test

According to various authors, the ignition temperature of lead azide ranges from 327 to 360°C. When a test sample is dropped onto a metal plate instant explosion ensues if the temperature of the plate is 380°C or higher. The ignition temperature of lead azide is the highest ignition temperature of an explosive ever to have been observed. 

The rate of detonation of a thin film of lead azide (0.1-0.5 mm thick) is 2100 m/sec (Bowden and Williams [101]). Lead azide is less sensitive to impact than mercury fulminate, but drop test figures quoted by various authors differ widely. Some of them report a negligible difference between the two, while others state it is considerable (e.g. that azide requires 2-3 times the height of drop necessary to explode fulminate). On the other hand, when mixed with pulverized sand lead azide is more... 

Amm acetate soln and add sufficient Na bichromate soln to ppt all lead as chromate. Test for the completion of destruction by transferring a portion of slurry to a filter paper and treating the filtrate with a few drops of Na bichromate soln. Confirm the absence of LA by washing.with distd w,the residue on filter,free of so azide salts, drying it,and subjecting a 20 mg portion to the impact test, using 2 kg wt. The material should not detonate... 

Hexamethylenetriperoxidediamine is almost insoluble in water and in the common organic solvents at room temperature. It detonates when struck a sharp blow, but, when ignited, bums with a flash like nitrocellulose. Taylor and Rinkenbach 63 found its true density (20°/20°) to be 1.57, its apparent density after being placed in a tube and tapped 0.66, and its density after being compressed in a detonator capsule under a pressure of 2500 pounds per square inch only 0.91. They found that it required a 3-cm. drop of a 2-kilogram weight to make it explode, but that fulminate required a drop of only 0.25 cm. In the sand test it pulverized 21/ to 3 times as much sand as mercury fulminate, and slightly more sand than lead azide. It is not dead-pressed by a pressure of 11,000 pounds per square inch. It is considerably... 

The specifications for Special Purpose lead azide given in U. S. military specification MIL-L-14758 are the same as those for RD1333 lead azide except that the detonator test and other minor requirements are dropped. 

The iron from the capsule experiments was brittle and fell apart when rubbed. In this investigation iron azide (ferric or ferrous azide) and hydrazine could not be detected, contrary to the work of Franklin [51] and Curtius and Risson [52]. Polyethylene becomes brittle, opaque, and porous when exposed to hydrazoic acid, and hydrazoic acid diffused through 0.008 in polyethylene bags within 90 days. Blay and Dunstan [53] reported little azide interaction with polyethylene, but noted a marked drop in azide value when Service lead azide was in contact with various rubbers, plastics, and other synthetic packaging materials. A reduction in azide content as high as 70% was shown (Figure 4). This was attributed to the slow release of carbon dioxide from the test material, followed by further hydrolysis of the lead azide. 

The ball-drop test (Figure 5) is the simplest and has been used for many years to determine the impact sensitivity of lead azide, particularly in industrial laboratories, such as those of the duPont de Nemours Company in the U.S.A. and the Nobel Explosives Company in Scotland. A /2-in.-diam steel ball weighing 8.35 g is dropped from heights varying by 1-in. increments onto azide powder spread in a 0.03-in layer on a hardened and polished steel block. After each explosion, the lead deposited on the block is cleaned off and the ball and block are replaced whenever their surfaces become noticeably affected. 

In the ball-drop test the RD1333 lead azide and the Costain process silver azide had practically the same impact sensitivities, but the other two silver azides, although still less sensitive, showed a wider disparity (Figure 13). 

Figure 19. Impact tests of lead azide and lead azide with different liquids [56] Picatinny Arsenal apparatus 1-kg weight dropped at indicated heights 20 samples per data point.

The question of the effects of iron impurities on the explosive properties, of lead azide was addressed by Hutchinson, who subjected pure and Fe" -doped lead azide (0.016 mole % iron) to thermal decomposition and explosive tests [67], Both samples pressed to the same density had identical detonation velocities, 4650 m/sec at a 3.5 g/ml. The iron-doped material was slightly more sensitive to impact (ball-drop test) and to heat (time to explosion tests) than was the pure material. However, the differences in results were close to the scatter in the data. 

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