Explosion characteristics of micron- and nano-size magnesium powders
TL;DR: In this article, the explosion characteristics of micron-and nano-size magnesium powders were determined using CSIR-CBRI 20-L Sphere, Hartmann apparatus and Godbert-Greenwald furnace to study influence of particle size reduction to nano-range on these.
Abstract: Explosion characteristics of micron- and nano-size magnesium powders were determined using CSIR-CBRI 20-L Sphere, Hartmann apparatus and Godbert-Greenwald furnace to study influence of particle size reduction to nano-range on these. The explosion parameters investigated are: maximum explosion pressure (Pmax), maximum rate of pressure-rise (dP/dt)max, dust explosibility index (KSt), minimum explosible concentration (MEC), minimum ignition energy (MIE), minimum ignition temperature (MIT), limiting oxygen concentration (LOC) and effect of reduced oxygen level on explosion severity. Magnesium particle sizes are: 125, 74, 38, 22, 10 and 1 μm; and 400, 200, 150, 100, 50 and 30 nm. Experimental results indicate significant increase in explosion severity (Pmax: 7–14 bar, KSt: 98–510 bar·m/s) as particle size decreases from 125 to 1 μm, it is maximum for 400 nm (Pmax: 14.6 bar, KSt: 528 bar·m/s) and decreases with further decrease of particle size to nano-range 200–30 nm (Pmax: 12.4–9.4 bar, KSt: 460–262 bar·m/s) as it is affected by agglomeration of nano-particles. MEC decreases from 160 to 30 g/m3 on decreasing particle size from 125 to 1 μm, its value is 30 g/m3 for 400 and 200 nm and 20 g/m3 for further decrease in nano-range (150–30 nm). MIE reduces from 120 to 2 mJ on decreasing the particle size from 125 to 1 μm, its value is 1 mJ for 400, 200, 150 nm size and <1 mJ for 50 and 30 nm. Minimum ignition temperature is 600 °C for 125 μm magnesium, it varies between 570 and 450 °C for sizes 38–1 μm and 400–350 °C for size range 400–30 nm. Magnesium powders in nano-range (30–200 nm) explode less violently than micron-range powder. However, likelihood of explosion increases significantly for nano-range magnesium. LOC is 5% for magnesium size range 125–38 μm, 4% for 22–1 μm, 3% for 400 nm, 4% for 200, 150 and 100 nm, and 5% for 50 and 30 nm. Reduction in oxygen levels to 9% results in decrease in Pmax and KSt by a factor of 2–3 and 4–5, respectively, for micron as well as nano-sizes. The experimental data presented will be useful for industries producing or handling similar size range micron- and nano-magnesium in order to evaluate explosibility of their magnesium powders and propose/design adequate safety measures.
Citations
More filters
TL;DR: A comprehensive review of the advances made over the past few decades in the areas of synthesis, properties, and applications of metal-based energetic nanomaterials is provided in this paper.
268 citations
TL;DR: In this article, the authors aim to reduce the ambiguity between ignitability and flammability of Mg materials and bridge the gap in understanding by clearly demarcating the tests and standards available for the two.
94 citations
TL;DR: The necessary conditions for a dust explosion to occur are well-expressed by the explosion pentagon: fuel, oxidant, ignition source, mixing of the fuel and oxidant and confinement of the resulting mixture.
90 citations
TL;DR: In this paper, the flame propagation behaviors and microstructures in micro and nano-titanium dust explosions were observed and compared and results showed that flame propagation mechanisms in 50-nm and 35-μm titanium dust clouds were quite different.
68 citations
TL;DR: In this paper, a modified experimental setup for the test apparatus 20L-sphere (also known as 20-L Siwek Chamber), that enables the test samples to be kept under inert atmospheric conditions nearly until ignition, is described.
Abstract: This paper describes experiences and results of experiments with several metallic dusts within the nanometer range. The nano dusts (aluminium, iron, zinc, titanium and copper) were tested in a modified experimental setup for the test apparatus 20 L-sphere (also known as 20-L Siwek Chamber), that enables the test samples to be kept under inert atmospheric conditions nearly until ignition. This setup was already introduced in earlier papers by the authors. It was designed to allow the determination of safety characteristics of nano powders under most critical circumstances (e.g. minimisation of the influence of oxidation before the test itself). Furthermore the influence of passivation on explosion behaviour is investigated and additional tests with deposited dust were carried out to describe the burning behaviour of all dusts. For a better characterisation all samples were tested with a simultaneous thermal analysis (STA). To minimise the influence of oxidation all samples were handled at inert conditions until shortly before ignition or start of the test respectively.
44 citations
References
More filters
Book•
01 Jun 1991
TL;DR: In this article, a comprehensive account of the existing practical and theoretical knowledge of the origin, development, prevention and mitigation of dust explosions in the process industries is presented, along with an up-to-date evaluation of prevalent activities, testing methods, design measures and safe operating techniques.
Abstract: This work is a comprehensive account of the existing practical and theoretical knowledge of the origin, development, prevention and mitigation of dust explosions in the process industries. It offers an up-to-date evaluation of prevalent activities, testing methods, design measures and safe operating techniques in a detailed and comprehensive critique of all the significant phases relating to the hazard and control of a dust explosion. This should be a useful reference work for design, production, maintenance and safety engineers in the process industries, safety consultants and students.
586 citations
TL;DR: It is found that as the particle size decreases, minimum ignition temperature (MIT) and minimum ignition energy (MIE) decrease, indicating higher potential inflammation and explosion risks for the use of nanopowders.
177 citations
TL;DR: In this paper, the thermal behavior of two different Al nanopowders and a micron-sized Al powder was studied using DSC, simultaneous TG-DTA, and accelerating rate calorimetry (ARC).
Abstract: The thermal behaviour of two different Al nanopowders and a micron-sized Al powder was studied using DSC, simultaneous TG-DTA, and accelerating rate calorimetry (ARC). The results show that the reactivity of Al powder increases as the particle size decreases. The thermal stability of the smaller Al nanopowder (Als) in water and in a humid atmosphere was determined using ARC and TG-DTA, respectively. Atomic Absorption Spectrometry (AAS), X-Ray Photoelectron Spectrometry (XPS) and Auger Electron Spectrometry (AES) were used to characterize the surface chemistry of Alex. The outgassing behaviour for mixtures of RDX and the various Al powders was investigated using TG-DTA-FTIR-MS. Evolution of NO2 and N2O from a chemical interaction between Al nanopowders and RDX was observed. The effect of Als and Alex on the thermal stability of TNT, RDX, Comp B, and AP was determined using ARC. Addition of Als significantly lowered the onset temperature for TNT and RDX decomposition. Electrostatic discharge (ESD) sensitivities of Al nanopowders and their mixtures with TNT, Comp B, RDX and AP were determined. The results show that the AP/Als mixture is very sensitive to ESD. Standard dust explosibility tests demonstrated that Alex is highly explosible.
121 citations
TL;DR: In this article, the authors conducted a study of the explosibility of various metals and other elemental dusts, with a focus on the experimental explosion temperatures, using a unique multi-wavelength infrared pyrometer to measure the temperatures.
Abstract: The Pittsburgh Research Laboratory of the National Institute for Occupational Safety and Health (NIOSH) conducted a study of the explosibility of various metals and other elemental dusts, with a focus on the experimental explosion temperatures. The data are useful for understanding the basics of dust cloud combustion, as well as for evaluating explosion hazards in the minerals and metals processing industries. The dusts studied included boron, carbon, magnesium, aluminum, silicon, sulfur, titanium, chromium, iron, nickel, copper, zinc, niobium, molybdenum, tin, hafnium, tantalum, tungsten, and lead. The dusts were chosen to cover a wide range of physical properties—from the more volatile materials such as magnesium, aluminum, sulfur, and zinc to the highly “refractory” elements such as carbon, niobium, molybdenum, tantalum, and tungsten. These flammability studies were conducted in a 20-L chamber, using strong pyrotechnic ignitors. A unique multiwavelength infrared pyrometer was used to measure the temperatures. For the elemental dusts studied, all ignited and burned as air-dispersed dust clouds except for nickel, copper, molybdenum, and lead. The measured maximum explosion temperatures ranged from ∼1550 K for tin and tungsten powders to ∼2800 K for aluminum, magnesium, and titanium powders. The measured temperatures are compared to the calculated, adiabatic flame temperatures.
102 citations
TL;DR: In this paper, the minimum ignition energy (MIE) for each of the above mentioned powders was measured using a modified version of the 1.2-L Hartmann apparatus. And the results showed that the low MIE indicates that these powders are extremely combustible.
Abstract: Most manufacturing units that process nanoparticles face a threat from fires and explosions. This study examines Ti powders with diameters of 3 μm, 8 μm, 20 μm, 45 μm, 35 nm, 75 nm, and 100 nm, and Fe powders with diameters of 150 μm, 15 nm, 35 nm, and 65 nm. The goal of our study was to measure the minimum ignition energy (MIE) for each of the above mentioned powders using a modified version of the 1.2-L Hartmann apparatus. According to the data obtained from the experimental results, the MIEs for all the nanopowders were less than 1 mJ; the low MIEs of these powders indicate that they are extremely combustible. Therefore, it is imperative for manufacturing units of these powders to take precautionary measures against untoward incidents involving, electrostatic sparks, collisions, etc.
88 citations