Characterization of Aluminum Powders I. Parameters of Reactivity of Aluminum Powders

Abstract

For testing the determination of the reactivity of aluminum powders it is proposed to use the following parameters: temperature of the beginning of oxidation, maximal oxidation rate, degree of transformation (degree of oxidation) of aluminum, relative thermal effect. Parameters for an evaluation of the reactivity of powders were chosen following the analysis of results of a non‐isothermal oxidation of powders of different grain size under conditions of programmed heating (the oxidizer being air). According to the proposed method of testing, the sample of ultrafine powder UFAP‐4 produced by the electrical explosion of wires has the highest reactivity among the studied powders.

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

“…Two other exothermic peaks (973 K and 1303 K) were observed in the DTA traces after the Al melting endotherm (T = 933 K). This behaviour was contrasted with a conventional µAl (20 µm) powder [36]. The latter showed the exothermic reactions at T > 933 K and a deep endotherm corresponding to Al melting.…”

“…Intense Al oxidation before melting is one of the peculiar features of nAl, providing its enhanced reactivity with respect to µAl; due to the lower reactivity of µAl, its intensive oxidation starts above Al melting point (T = 933 K). For µAl powders ASD-4 and ASD-1, with BET particle diameters of 9 µm and 80 µm respectively, the oxidation onset temperatures were 1093 K and 1193 K [36]. Two relatively small exothermic peaks before the nAl intense oxidation appeared on the DTA/DSC curves due to adsorbed gas desorption and simultaneous surface oxidation ( Figure 2).…”

“…The formation of nano γ-Al 2 O 3 by slow non-isothermal oxidation (0.5-20.0 K/min) occurs at low temperatures (T = 673-773 K) for electroexplosive nAl [23]. Furthermore, the different definitions of the intense oxidation onset temperature and other parameters on the DTA/DSC/TGA curves can lead to confusing comparisons Copyright © 2017 Institute of Industrial Organic Chemistry, Poland between different datasets [23][24][25][26][27][28][29][30][31][32][33][34][35][36][37][38][39][40][41]. For certain nAl samples with a specific surface area 12 m 2 /g, the mass fraction of micron-sized particle clusters (1-3 µm) could be 68 wt.%, but the number of clusters was only 2% of the total number of particles [56].…”

Activated aluminum powders for space propulsion

“…ALEX™ refers to a nominally 100 nm aluminum produced by electrical explosion of wire (EEW). ASD-4 is a micrometric Russian product, comparable to H3 [31,32]. Both powders are naturally passivated by air and are commercially available.…”

Combustion Propagation of Pyrolants

“…Numerous experimental studies have been carried out on the burning rate characteristics of propellants and pyrolants [1][2][3][4][5][6][7][8][9][10][11][12][13][14]. The heats of reaction of energetic materials are evaluated by measurements obtained using combustion bombs, where the measured values are dependent not only on the chemical components but also on the method of burning in the bombs.…”