Browsing by Author "Halleux, Francis"

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    Detonation performance of urea hydrogen peroxide
    (Unknown, 2022-04-06) Halleux, Francis; Pons, Jean-François; Wilson, Ian; Van Riet, Romuald; Simoens, Bart; Lefebvre, Michel
    Carbamide Peroxide is commonly used in the cosmetic and pharmaceutical industries as a solid source of hydrogen peroxide. This adduct of Urea and Hydrogen Peroxide (UHP) has explosive properties, which have been only recently studied, highlighting its behaviour of non-ideal tertiary explosive and detonability at large scale. Our work focussed on investigating UHP detonability in the 100 g-scale. A maximum of experimental data, collected from combining laboratory and underwater measurement campaigns, is required to evaluate the detonation performance of non-ideal explosives. Our lab results confirmed self-sustained detonation under heavy confinement, with observed detonation velocities consistent with literature values from large-scale field experiments. We further fired UHP charges underwater and quantified brisance and explosive power respectively from underwater shock pressure and bubble period. By comparing experimental results and numerical simulations, we could assess the level of agreement between lab and underwater detonation performance parameters.
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    Detonation performance of Urea-Hydrogen Peroxide (UHP)
    (Wiley, 2023-02-23) Halleux, Francis; Pons, Jean-François; Wilson, Ian; Simoens, Bart; Van Riet, Romuald; Lefebvre, Michel
    Carbamide Peroxide, an adduct of Urea and Hydrogen Peroxide, is commonly used in the cosmetic and pharmaceutical industries as a solid source of hydrogen peroxide. However, it exhibits explosive properties and can be easily manufactured from readily available household chemicals, making it a potential emerging threat. We carried out a detailed performance assessment, combining experiments, thermochemical calculations and numerical simulations and highlighted a good level of agreement between experimental data from lab, field and underwater firings. A maximum detonation velocity of 3.65 km/s was recorded for unconfined 25 kg UHP charges at 0.85 g/cm 3 (200 mm charge diameter). We determined in these conditions an infinite diameter detonation velocity of 3.94 km/s. These results are also consistent with previous results obtained at small scale under heavy confinement. Airblast measurements highlighted an average 40% TNT equivalence for impulse and 55% for peak overpressure at short distance, which are in good agreement with the 57% (Power Index) calculated from Explo5, while 50% for bubble energy (explosive power) and 20% for shock pressure (brisance) were obtained from underwater experiments. The use of different experimental approaches has proven useful to characterise the performances parameters of a non-ideal explosive for risk assessment purposes.
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    Home Made Explosives (HME), how to understand the threats and model the risk?
    (Cranfield University, 2022-01-12T12:46:55Z) Halleux, Francis
    Within the scope of countering the threat of Improvised Explosive Devices, HME constitute a major public security concern, requiring specific risk assessments for first responders such as Explosive Ordnance Disposal (EOD) teams. An initial literature review helped identify current HME threats worldwide, i.e. the synthesis of peroxide explosives and/or the mixing of highly energetic pyrotechnics. Following a first study on Urea Hydrogen Peroxide as a potential emerging threat, Flash Powder (FP) is now investigated, considering the ease of manufacture combined with the availability of its precursors. FP can also be directly extracted from well-known fireworks, which are still widely available despite strong regulation efforts. These materials are much more than “just pyro’s”. Because of their explosive output, flash compositions have become attractive and largely misused by experimenters, ranging from backyard hobbyists to insurgents. Flash powder has been studied in the literature, but mainly in the context of regular applications. Research data are still lacking when it comes to performance as an explosive. After initial chemical, physical, and thermal characterization, sensitivity and performance assessments will be executed, including free-field and underwater firings and heat flux measurements.
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    Investigation into the detonation performances of Urea Hydrogen Peroxide (UHP)
    (Cranfield University, 2023-01-04T10:28:53Z) Halleux, Francis
    Within the scope of countering the threat of Improvised Explosive Devices, Home Made Explosives constitute a major public security concern, requiring specific risk assessments for first responders such as Explosive Ordnance Disposal (EOD) teams. Among potential emerging threats, Urea Hydrogen Peroxide (UHP) is investigated, considering the ease of manufacture combined with the availability of its precursors. Previous research from the same authors demonstrated UHP detonability at small-scale under heavy confinement and provided an initial characterisation (lab-scale) of detonation performance parameters. As a maximum of experimental data is particularly desirable to accurately evaluate the detonation parameters of non-ideal explosives, initial lab characterisation is here completed and complemented by field and underwater instrumented firings using scaled-up charges.
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    Small-scale characterisation of urea hydrogen peroxide explosive performance using heterodyne velocimetry
    (Royal Society of Chemistry, 2022-06-24) Halleux, Francis; Stennett, Christopher; Pons, Jean-François; Wilson, Ian; Lefebvre, Michel
    Urea Hydrogen Peroxide (UHP) is widely available in the cosmetic and pharmaceutical industries. UHP exhibits the behaviour of a tertiary explosive and previous research from the same authors has highlighted its detonability at small-scale under heavy confinement. In this work, UHP performance parameters are further investigated by heterodyne velocimetry. An average detonation pressure of 3.7 GPa for UHP at a mean density of 0.75 g/cm3 has been determined using the impedance window method, corresponding to a 20% TNT equivalence for brisance. This result is consistent with calculation from empirical correlations. An average 3200 m/s detonation velocity was recorded using contact probes, in excellent agreement with measurements from passive optical probes. This small-scale experimental campaign, which was complementary to and consistent with previous research, has proven useful to characterise the performances of non-ideal explosives for risk assessment purposes.
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    Small-scale detonation of industrial Urea-Hydrogen Peroxide (UHP)
    (Wiley, 2021-12-03) Halleux, Francis; Pons, Jean-François; Wilson, Ian; Van Riet, Romuald; Lefebvre, Michel
    The adduct of Urea and Hydrogen Peroxide (UHP), also called Carbamide Peroxide, is industrially produced as a solid source of hydrogen peroxide for bleaching, disinfection, and oxidation reactions. As a chemical combination of fuel and oxidiser, UHP has explosive potential but it is unclear whether it could sustain a detonation at small scale. In the configuration we tested, we succeeded in recording self-sustained detonation at relatively small scale under heavy confinement, measuring a maximum experimental velocity of detonation of 3860 m/s at an optimum 1.1 g/cm3 loading density. UHP can sustain a detonation, even at the 100 g scale, but this is strongly dependant on booster size, confinement material, loading density, charge length and diameter. According to our performance assessment, pure UHP exhibits the behaviour of a non-ideal tertiary explosive. Maximum calculated detonation pressures are below 10 GPa, the order of magnitude for commercial blasting explosives. Small-scale results are consistent with literature values from large-scale experiments, although literature on the matter is quite limited. The proposed experimental method can be used to quantify the detonability and performance of other industrial materials that may have energetic properties, or small samples of homemade explosive compositions, avoiding time-consuming, expensive and potentially hazardous large-scale experiments.
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    Urea-Hydrogen Peroxide (UHP): comparative study on the experimental detonation pressure of a non-ideal explosive
    (Wiley, 2023-08-28) Halleux, Francis; Pons, Jean-François; Wilson, Ian; Stennett, Christopher; Van Riet, Romuald; Lefebvre, Michel
    Carbamide Peroxide, an adduct of Urea and Hydrogen Peroxide (UHP) industrially used as a solid source of hydrogen peroxide, exhibits the behaviour of a tertiary explosive but a detailed performance characterisation is still lacking in the literature. In this work, we calculated a 20% experimental TNT equivalence for brisance, i.e. the shattering effect from the shock wave transmitted from the detonating high explosive into adjacent materials, by experimental indirect measurement of UHP detonation pressure. We determined a 3.5 GPa detonation pressure for 5 kg unconfined UHP charges (0.87 g/cm3, 120 mm charge diameter) by measuring the attenuated shock wave velocity (ASV) in adjacent inert materials using passive optical probes. Particle velocity measurements at the interface of a PMMA impedance window carried out with Photonic Doppler Velocimetry on scaled-down charges of 90 g UHP under heavy confinement (0.85 g/cm3, 30 mm charge diameter, 4 mm thick steel) are consistent with ASV results in the PMMA acceptors but further investigations are required to determine the detonation pressure, using a small-scale experimental set-up. The ASV method has proven reliable to assess the brisance of a non-ideal explosive for risk assessment purposes.