Phosphorus-Based Nanothermites: A New Generation of Pyrotechnics Illustrated by the Example of n-CuO/Red P Mixtures

The use of aluminium nanoparticles (e.g. Al SOP) with various metallic oxides to prepare superthermites was reported in numerous recent papers. These compositions have exceptional energetic performances, but their fabrication cannot be scaled up due to the difficulty in producing or supplying aluminium nanopowders. The use of red phosphorus as an alternative reducing agent in nanothermite compositions was found to be very promising. Surprisingly, although this substance is a component of many explosive compositions, it was never tested with metallic oxide nanoparticles. In a preliminarily study, the reactivity of different metallic oxides with red phosphorus was screened. These tests led to classify the oxides according to their combustion potential, by ascending order: NiO < Fe-2 O-3 << CuO << PbO2. The CuO/P mixture possesses an impressive reactivity, and its combustion residues are less hazardous than those formed with PbO2 insofar as lead derivatives are generally more toxic than their copper counterparts. CuO-based P-nano-thermites were prepared by physically mixing copper(II) oxide nanoparticles with micrometre-sized red phosphorus particles. The phosphorus content was varied from 16 to 50 wt.-% in order to investigate the effect of the mass ratio on the reactivity of CuO/P materials. The impact sensitivity of CuO/P nanothermites is moderate (27-39 J), but their friction (<5-8 J) and electrostatic discharge sensitivities (<0.12-0.21 mJ) are extremely high. The combustion of P-nanothermites (P-NT) gives droplets of molten copper with a typical fractal structure after cooling down.