Hazard Characterization of Aluminum Nanopowder Compositions

Abstract

The thermal behaviour in air of two Al nanopowders, Alss and Alsstef, a Teflon coated version of Alss, was determined using DSC, TG-DTA and accelerating rate calorimetry (ARC). Compared to two larger Al nanopowders, for which hazards results have been reported, Alss and Alsstef are less reactive in air, possibly due to the nature of the passivating and coating layers. The stability of Alss and Alsstef in a wet environment was also investigated using ARC. Alss is very reactive with water, which could lead to a problem of aging in a humid atmosphere. The ∫coating∫ of Alsstef significantly reduces the reactivity of Alss with water. Outgassing behaviour of mixtures of ADN, GAP and various Al powders was investigated using TG-DTA-FTIR-MS. No chemical interactions were observed between ADN/Al, GAP/ Al and ADN/GAP. The effect of the addition of Al nanopowders on the thermal decomposition of ADN and GAP was studied using ARC. Al nanopowders had a minor effect on the thermal stability of ADN, while the addition of Alss and Alsstef lowered the onset temperature of GAP. The electrostatic discharge (ESD), impact and friction sensitivities of Al nanopowders and their mixtures with ADN and GAP were also determined. Al nanopowders appear to sensitize ADN to ESD, impact and friction.

Thermal characteristics of aluminum nanoparticles and oilcloths

“…Also, the greater the deviation of pH value from 7, the lower T onset and T p and the larger n. The order of T onset followed pH 13 < pH 1 < pH 11 < pH 3 < pH 9 < pH 5 < pH 7, indicating that the exothermic reaction of ANP could be accelerated by acidic or basic ingredients. The range of T onset obtained by the present DSC scanning Table 1 Thermal properties and reaction order of aluminum nanoparticles was consistent with the study of ANP in aqueous solution by an adiabatic reaction calorimeter [9,10]. For oxidation of desiccated ANP in air, T onset was located in 400-500 • C [9].…”

“…For oxidation of desiccated ANP in air, T onset was located in 400-500 • C [9]. It has also been observed that the enthalpy of damped ANP was much higher than that of desiccated ANP [10]. In the present study, the largest and smallest H occurred at pH 13 and 1, respectively.…”

“…Moreover, ANP could be still reactive over 47 days in surroundings with relative humidity of 90% [9,10]. Hence, self-heating in a system containing damped ANP might occur, leading to industrial accidents.…”

Effect of the passivating coating type, particle size, and storage time on oxidation and nitridation of aluminum powders

“…and fine powders (PAP-1, PAP-2, etc.) is assumed to be a low temperature of the onset of oxidation and ignition [3]. Eisenreich et al [2] gave data on oxidation of aluminum powders with different particle sizes (0.01-25 µm) under conditions of linear heating in air.…”

“…The mechanism of oxidation of promising energetic materials (nanoand micro-sized aluminum powders) in various gaseous model media is discussed in [1][2][3][4]. A specific feature of thermochemical properties of aluminum nanopowders (ALEX and its analogs) distinguishing them from commercial spherical powders (ASD-4, ASD-6, etc.)…”