No abstract

Microelectromechanical system (MEMS) fuzes are an important development for detonator miniaturization, leading to devices often used as input for an explosive train. The output capability of a microdetonator is strongly influenced by detonation growth of the primary explosive. In this article, research made use of a manganin piezoresistance measuring method to investigate the detonation growth properties of charges of lead azide (Pb(N 3 ) 2 ) at micrometer diameters and density of 80% theoretical mean density (TMD). The samples developed for this research were cylindrical charges of lead azide contained in stainless steel capsules 0.9 mm in diameter and 3 mm in height. An electrical igniter was applied to ignite the charges. The fitting curve for detonation pressure versus height of the explosive charge was obtained, revealing that the critical height of the detonation growth in the microcharge was 1.8 mm, and the detonation growth was stable at the height of the charge at 2.4 mm. The maximum detonation pressure achieved was 6.0 GPa.

The initiation capability of a microdetonator 0.9 mm in diameter and 3 mm in height is studied. The critical height of the lead azide explosive is 1.8 mm. The optimal ratio of the heights of the primary and secondary explosives in a microdetonator is determined to be 0.7-2.3. At an identical ratio of the primary and secondary explosive heights, the output pressure changes from the highest to the lowest value in the sequence from CL-20 to HMX and then to RDX.

Reactive materials (RMs) are usually prepared from metal/non-metal mixed powders through hot processing. The main feature of the material is that it will react and release energy when impacted. However, the impact-induced chemical energy release during impact has a complicated mechanism and needs to be further explored. This work investigated the impact-induced chemical process by split Hopkinson pressure bar and low-pressure experimental system, different atmospheric pressure environment has been simulated. Moreover, High-speed photography was used to reveal the macroscopic ignition phenomena. Furthermore, X-ray diffraction (XRD) was used to study the material composition of raw and recovered specimens. The results of the experiments described here clearly show that metal reacts with oxygen and PTFE at atmospheric environment, which reaction produces are metal oxides and metal-fluoropolymers. However, the material only undergoes fluorination reaction at low pressure, which reaction produces only has metal-fluoropolymers. Meanwhile, the reactive ratio of the material increases with the pressure increase, furthermore, the maximum reaction ratio of the material in an atmospheric pressure environment is about 29.5 %, which reaction ratio is 4.7 times more than the pressure of 750 Pa.