Nanoaluminium: is there any Relationship between Powder Particles’ Size, Non-Isothermal Oxidation Data and Ballistics?

Abstract

This article focuses on data analyses and comparisons for aluminium nanopowders (or nanoaluminium, nAl) reactions under slow (0.5-20.0 K/min, using DTA/DSC/TGA) and fast (>10000 K/min, combustion in solid propellant formulations) non-isothermal oxidation. Particle sizes were defined through the BET method. Active Al content was related with the averaged reactivity parameters, taken from published DTA/DSC/TGA data. The specific oxidation onset temperature for nAl was poorly correlated with the BET particle size under the conditions investigated. Furthermore, the BET particle size exhibited no correlation with the observed ballistic response (burning rate) at 3.0 MPa. A logarithmic correlation y = 17.484 ln(x) -5813, with R² = 0.73, was found between nAl particle size and its aluminium content. A calibration equation for the oxidation onset temperature as a function of nAl particle size was determined as y = −0.0071x 2 + 3.3173x + 479.32, with R² = 0.75. Specific features of the nAl (metallic aluminum content in nAl and the oxidation onset temperature) can be predicted based on the measured powder parameters (such as BET particle size).

Influence of texture and microstructure on the reactivity of aluminum powders

“…Finally, on the plateau around 650°C, an endothermic peak corresponding to the melting of the Al core is observed. All those general features are consistent with the ones reported for spherical nanoparticles [20,35,47,48]. The enthalpies and onset temperatures corresponding to the oxidation events are listed in Table 1.…”

“…It is worth noting that, whatever the grinding ball diameter, all the powders have dimensions within the same order of magnitude around 1µm. It seems that slightly larger widths are observed for B15 powders, which would be consistent with a milling with larger balls diameters [48]. Nitrogen adsorption isotherms are presented in Fig.…”

Burning Characteristics of the HMX/CL‐20/AP/Polyvinyltetrazole Binder/Al Solid Propellants Loaded with Nanometals

“…The combustion properties of n-Me loaded propellants were studied in the Vielle bomb. No significant correlation between the reactivity parameters of n-Me oxidation process and the burning rate was found in [29]. The partial replacement of m-Al on n-Me resulted in the increased burning rate by 30 % for n-Al, n-Ni, n-Mo and n-B and by maximum 390 % and 260 % for n-Cu and n-Zn samples, respectively.…”