SHOCK COMPRESSION INDUCED HOT SPOTS IN ENERGETIC MATERIAL DETECTED BY THERMAL IMAGING MICROSCOPY

1,1-diamino-2,2-dinitroethene (FOX-7) is a novel energetic material with high performance and low sensitivity. In order to deeply understand the reaction mechanism in the initiation “hot spots” of FOX-7 and reveal the growth mechanism of these initiation “hot spots” in the explosion process, the detailed mechanisms of bimolecular reaction of NO2 and FOX-7, as well as the subsequent reactions have been investigated by the quantum chemical calculations. The mechanism of NO2 and FOX-7 bimolecular reaction and the catalytic effect of NO2 were revealed by three key dissociation paths. It is demonstrated that the NO2 molecule plays an important role in promoting the decomposition of the FOX-7 molecule, and the main exothermic pathways were the reactions between oxidizing intermediates (NO, NO2), and reducing intermediates (CO, NH3).

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Hot Spots from Dislocation Pile-up Avalanches

MRS Proceedings ◽

10.1557/proc-0896-h06-03 ◽

2005 ◽

Vol 896 ◽

Author(s):

William Grisé

Keyword(s):

Hot Spots ◽

Hot Spot ◽

Energetic Material ◽

Shear Banding ◽

Dislocation Dynamics ◽

Circular Loop ◽

Dislocation Mechanics ◽

Pile Up ◽

Localized Heating ◽

Realistic Assessment

AbstractThe model of localized adiabatic heating associated with release of a dislocation pile-up avalanche is described and re-evaluated. The model supplies a fundamental explanation of shear banding behavior in metal and non-metal systems. Now, a dislocation dynamics description is provided for more realistic assessment of the hot spot heating, for both straight dislocation pile-ups and circular loop pile-ups. Such a localized heating effect was overestimated in the earlier work, in part, to show the dramatic enhancement of the work rate, and the corresponding temperature build-up, potentially occurring in the initial pile-up release, say, at achievement of the critical dislocation mechanics-based stress intensity for cleavage. Proposed applications are to potentially brittle metal, ionic, and energetic material systems.

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Molecular Composition, Structure, and Sensitivity of Explosives

MRS Proceedings ◽

10.1557/proc-296-25 ◽

1992 ◽

Vol 296 ◽

Cited By ~ 2

Author(s):

Carlyle B. Storm ◽

James R. Travis

Keyword(s):

Molecular Structure ◽

Hot Spots ◽

Energetic Materials ◽

Physical State ◽

Hot Spot ◽

Energetic Material ◽

Specific Situation ◽

Reaction Products ◽

Ambient Conditions ◽

Delayed Reaction

AbstractHigh explosives, blasting agents, propellants, and pyrotechnics are all metastable relative to reaction products and are termed energetic materials. They are thermodynamically unstable but the kinetics of decomposition at ambient conditions are sufficiently slow that they can be handled safely under controlled conditions. The ease with which an energetic material can be caused to undergo a violent reaction or detonation is called its sensitivity. Sensitivity tests for energetic materials are aimed at defining the response of the material to a specific situation, usually prompt shock initiation or a delayed reaction in an accident. The observed response is always due to a combination of the physical state and the molecular structure of the material. Modeling of any initiation process must consider both factors. The physical state of the material determines how and where the energy is deposited in the material. The molecular structure in the solid state determines the mechanism of decomposition of the material and the rate of energy release. Slower inherent reaction chemistry leads to longer reaction zones in detonation and inherently safer materials. Slower chemistry also requires hot spots involved in initiation to be hotter and to survive for longer periods of time. High thermal conductivity also leads to quenching of small hot spots and makes a material more difficult to initiate. Early endothermic decomposition chemistry also delays initiation by delaying heat release to support hot spot growth. The growth to violent reaction or detonation also depends on the nature of the early reaction products. If chemical intermediates are produced that drive further accelerating autocatalytic decomposition the initiation will grow rapidly to a violent reaction.

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Hot spots in energetic materials generated by infrared and ultrasound, detected by thermal imaging microscopy

Review of Scientific Instruments ◽

10.1063/1.4864197 ◽

2014 ◽

Vol 85 (2) ◽

pp. 023705 ◽

Cited By ~ 31

Author(s):

Ming-Wei Chen ◽

Sizhu You ◽

Kenneth S. Suslick ◽

Dana D. Dlott

Keyword(s):

Thermal Imaging ◽

Hot Spots ◽

Energetic Materials

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Study of the Localized Heating of Si Solar Cells by Thermal Imaging and Scanning Electron Microscopy

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.770.157 ◽

2013 ◽

Vol 770 ◽

pp. 157-160

Author(s):

Buntoon Wiengmoon

Keyword(s):

Electron Microscopy ◽

Scanning Electron Microscopy ◽

Solar Cells ◽

Energy Dispersive Spectroscopy ◽

Thermal Imaging ◽

Hot Spots ◽

Micro Cracks ◽

Impurity Contamination ◽

Localized Heating ◽

Scanning Electron

The aim of this study was to investigate the localized solar cells heating by thermal imaging, scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The electrical measurements and thermal infrared measurements were done on the commercial crystalline Si cells (10 cm x 10 cm). SEM was used for the observation of the localized heating. The I-V characteristics of all cells were quite similar with a small spread in the electrical parameters, while the IR images were different: some cells had quite uniform temperature profiles distribution and other ones showed the localized heating. The energy dispersive spectroscopy (EDS) analysis showed that some hot spots have high metal impurity contamination. The micro-structure investigation of hot spots revealed the micro-cracks presence. Our study found direct correlation between areas of high impurity contamination, micro cracks and hot-spot heating.

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Smartphone Thermal Imaging Can Enable the Safer Use of Propeller Flaps

Seminars in Plastic Surgery ◽

10.1055/s-0040-1714291 ◽

2020 ◽

Vol 34 (03) ◽

pp. 161-164

Author(s):

Geoffrey G. Hallock

Keyword(s):

Thermal Imaging ◽

Hot Spots ◽

Cell Phone ◽

Postoperative Monitoring ◽

Complementary Method ◽

Preferred Direction ◽

Propeller Flap ◽

Proper Interpretation ◽

Hub Effect

AbstractThe use of thermography for the identification of cutaneous “hot spots” that coincide with perforators is not a new concept, but the required professional cameras may be prohibitively expensive. Only relatively recently, incredibly cheap but adequate thermal imaging cameras have become available that work in concert with the ubiquitous cell phone. This can now serve as a rapid, accurate, and complementary method for finding a perforator sufficient to serve as the hub for a perforator pedicled propeller flap. In addition, the preferred direction of rotation about that hub, effect of flap insetting on perfusion, and then postoperative monitoring are possible by proper interpretation of corresponding thermograms. Every reconstructive surgeon should be able to obtain this device, and then easily learn what potential attributes for them are available when planning a propeller flap.

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Identification of the hot spots phenomenon in brakes by using a thermal imaging camera

10.21611/qirt.2016.115 ◽

2016 ◽

Author(s):

W. Sawczuk

Keyword(s):

Thermal Imaging ◽

Hot Spots ◽

Thermal Imaging Camera ◽

Imaging Camera

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Thermal Evaluation of High-Current Polyimide Rigid and Rigid-Flex Printed Wiring Board Trace Widths in a Vacuum

International Symposium on Microelectronics ◽

10.4071/isom-2013-thp64 ◽

2013 ◽

Vol 2013 (1) ◽

pp. 000964-000969

Author(s):

Bennion Cannon ◽

Frank Friedl ◽

Gary Gisler

Keyword(s):

Thermal Imaging ◽

Hot Spots ◽

Test Results ◽

High Current ◽

Printed Wiring Boards ◽

Printed Wiring Board ◽

Thermal Imaging Camera ◽

Industry Standards ◽

Imaging Camera ◽

Wiring Board

This paper details the thermal evaluation of high-current polyimide rigid and rigid-flex printed wiring boards in a vacuum. Although industry standards, such as IPC-2152 or MIL-STD-275, can be used to determine required trace width for PWB traces that carry current to between 20 or 30 amps for multiple copper plane thicknesses, they typically cannot be used to determine trace width for PWB traces that handle current greater than 15 amps. This paper presents results from testing and analysis of high-current rigid and rigid-flex PWBS that must carry current of up to 60 amps. Testing was performed in vacuum on a controlled-temperature platen, measuring board temperature at specific locations to determine performance of different trace widths using 2 and 4 ounce copper layers. A thermal imaging camera was used to identify PWB hot spots. Test results were compared to IPC-2152 standards, extrapolated to 60 amps current.

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Experiments Probing Fundamental Mechanisms of Energetic Material Initiation and Ignition

MRS Proceedings ◽

10.1557/opl.2012.254 ◽

2012 ◽

Vol 1405 ◽

Author(s):

Christopher M. Berg ◽

Kathryn E. Brown ◽

Rusty W. Conner ◽

Yuanxi Fu ◽

Hiroki Fujiwara ◽

...

Keyword(s):

Shock Waves ◽

Shock Front ◽

Time Scales ◽

Vibrational Spectroscopy ◽

Shock Compression ◽

Energetic Materials ◽

Emission Spectroscopy ◽

Energetic Material ◽

Thick Layers

ABSTRACTTwo fundamental processes associated with shock compression of energetic materials (EM) are initiation and ignition. Initiation occurs just behind a shock front and ignition occurs anywhere from a few nanoseconds to hundreds of nanoseconds later. Experiments are described that probe the fundamental mechanisms of these processes on relevant length and time scales: picosecond vibrational spectroscopy of nanometer thick layers of energetic materials (EM) with laser-driven shock waves, and nanosecond emission spectroscopy of micrometer thick layers of EM using laser-driven flyer plates.

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