Low-Power Laser Ignition of Aluminum/Metal Oxide Nanothermites

Abstract : In this study, three different types of nanothermites, i.e., Al/CuO, MoO3, and Al/Bi2O3, were produced using the widely spread wet (i.e., isopropanol based) method. In addition to the above method, the three nanothermites were also produced using a Resodyn LabRAM mixer. A paraffin-coated spherical Al nanopowder (100 nm) was used as the fuel source, while the oxidizers were nanometric powders of CuO (40 nm), MoO3 (100 nm), and Bi2O3 (200 nm). The effect of nanothermite composition on the sensitivity for the tests of electrostatic discharge (ESD), impact, and friction was investigated. Scanning electron microscopy (SEM) was used to analyze the morphology and homogeneity of the nanothermites. Next, the nanothermites were thermally analyzed in terms of energy release, ignition temperature, and flame temperature using a thermogravimetric analysis differential and scanning calorimetry (TGA/DSC) technique. A low-power diode laser was used to evaluate the ability of different laser wavelengths (661, 532, and 445 nm) to produce the ignition energy needed for a specific thermite reaction. Low ignition delays (less than 15 ms) were obtained at approximately 300 mW laser power output for both Al/MoO3 and Al/Bi2O3 thermites. Finally, a forward-looking infrared camera was used to estimate the ignition and burning temperatures of the Al/MoO3 nanothermite.