Explosion Characteristics of Aluminum Nanopowders

Abstract

In 2005, an investigation conducted on three nanoscale attrition millers in Taiwan revealed that all three had undergone metal nanopowder explosions in the past. This research was aimed at determining the relationships between the particle diameter of an aluminum nanopowder and its maximum explosion pressure (P max ), maximum rate of pressure rise ((dP/dt) max ), minimum explosion concentration (MEC), and minimum ignition energy (MIE) by 20 liter apparatus and 1.2-L Hartmann apparatus. The results revealed that 35-nm aluminum powder has a P max of 7.3 bar and deflagaration index (K St ) of 349 bar·m/s, in 100-nm aluminum powder, P max of 12.5 bar and K St of 296 bar·m/s and 40-μm aluminum powder, P max of 5.9 bar and K St of 77 bar·m/s. The value of (dP/dt) max for the 35-nm aluminum powder is 4.5 times that for the 40-μm aluminum powder. The 35-nm, 100-nm, and 40-μm powders have MEC values of 40, 50, and 35 g/m 3 , respectively. The 35-nm and 100-nm powders both have MIEs less than 1 mJ, while the 40-μm powder has an MIE of 59.7 mJ.

Ignition of aluminum powders by electro-static discharge

“…Depending on the sensitivity of an optical sensor used, the MIE can vary widely even for the same powder ignited by the same ESD apparatus. Indeed, a brief review of the available literature data for MIE for Al powders shows a broad range of the reported values varied from 1 to 600 mJ [15][16][17][18][19]. This range includes the value of 25 mJ identified using the current setup [20] and following the testing methodology of the MIL-1751A Standard [10].…”

Ignition and explosion risks of nanopowders

“…One of them is obviously the particle size, which takes nanopowders now under higher scrutiny for OH&S issues; others are the particle concentration, the degree of agglomeration, and the degree of turbulence [1][2][3][4]. So far, literature studies concerning the evaluation of explosion and flammability hazards of powders were essentially carried out on micro-sized powders [5], albeit there are the recent extensive studies performed by the EU NANOSAFE2 project [6] during the 2005-2009 period and more recently by Wu in Taiwan [7,8] in 2009-2010. This work proposes to review measured explosion safety parameters of few nanoparticles and nanofibers (carbon blacks, aluminium and multiwalled carbon nanotubes) performed in course of the EU NANOSAFE2 project.…”

Ignition and explosion of nanopowders: something new under the dust

“…But the knowledge about the hazards related to these new materials is currently limited: if some studies are dedicated to the determination of their potential toxicity, only very few ones concern nanopowders fires and explosions [1]. In fact, since 2002 [2], one could quote the recent extensive studies performed by the EU NANOSAFE2 project [3] during the 2005-2009 period and more recently by Wu in Taiwan in 2009-2010 [4,5]. Obviously, dust explosion should not be neglected when the dusts are combustible [6].…”