The 4th International Conference on Matter and Radiation at Extremes (ICMRE 2019)

322 / 2019-02-25 20:06:09

Experimental study of aluminized RDX under laser ablation in air and argon

Laser Ablation, Emission Spectra, Aluminized Explosive, plasma, reaction.

Plenary track > High Pressure Physics and Materials Science

The destructive effect of explosion is not conducive to the further study of experimental phenomenas and reaction behaviors in energetic materials. Laser ablation is an alternative method for studying the chemical reactions and energy release in explosives, which has the advantages of high safety, high efficiency and low resource consumption.
In this work, we have investigation the reaction process of aluminized RDX through time-resolved observation of self-emitting imaging and emission spectra under nanosecond laser ablation in air and argon atmosphere. Since the recording devices can only conduct single recording, we have to perform a series of experiments with different time delays between the laser ablation and recording to realize time-resolved measurement. We also designed a sample plate with rectangular array of circular holes to load the explosive powder, which ensures each laser ablation can be acted on a fresh sample.
The results show that, the aluminized RDX in air has typical secondary reaction characteristics, and exhibits better combusting performance in duration and intensity: Before 6 μs, the plasma formed by laser ablation begins to cool and dissipates since no sustained energy, the decay of light intensity and spectral height are all related to the dissipation of plasma; After 6 μs, the oxidizing reaction of Al dominates the reaction, and leads a local extreme value near 12 μs, AlO molecules are the most important intermediate product in the reaction. The overall light intensity decreases monotonically with time in argon atmosphere. The change relation of light intensity can be approximated by two exponential decay functions (before 6 μs/after 6 μs), and this indicates that there is no secondary reaction phenomenon and increase in chemical reaction in argon. Its essence should be the dissipation process of two kinds of matter from the initial value to zero, the discrepancy of dissipation rate can be attributed to different dominant element in each period.
In general, the improvement of the reaction performance of aluminized explosives in the air is mainly manifested in two aspects: one is the oxidation reaction between RDX and aluminum particles, generally occurs in the early stage; the other is the oxidation reaction between oxygen and aluminum particles, it mainly occurs in the middle stage, and belongs to the typical exothermic reaction, it is the main reason for the reaction growth and the secondary reaction of aluminized explosives.