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

2014 ◽  
Vol 85 (2) ◽  
pp. 023705 ◽  
Author(s):  
Ming-Wei Chen ◽  
Sizhu You ◽  
Kenneth S. Suslick ◽  
Dana D. Dlott
Keyword(s):  
Thermal Imaging ◽  
Hot Spots ◽  
Energetic Materials

scholarly journals Thermal imaging of hot spots in nanostructured microstripes

2010 ◽  
Vol 214 ◽  
pp. 012098
Author(s):  
E Saïdi ◽  
J Lesueur ◽  
L Aigouy ◽  
J Labéguerie-Egéa ◽  
M Mortier
Keyword(s):  
Thermal Imaging ◽  
Hot Spots

Hot Spot Histories in Energetic Materials

1992 ◽  
Vol 296 ◽  
Author(s):  
A. M. Mellor ◽  
D. A. Wiegand ◽  
K. B. Isom
Keyword(s):  
Hot Spots ◽  
Energetic Materials ◽  
Ignition Temperature ◽  
Hot Spot ◽  
Original Form ◽  
Independent Variables ◽  
Shock Impact ◽  
Similarities And Differences ◽  
Hot Spot Formation ◽  
Spot Formation

AbstractInterest in the mechanisms by which hot spots either grow to sustained reaction or are quenched results from the observation that the energy required to ignite a propellant or explosive can be significantly less than that needed to bulk heat a test specimen uniformly to its ignition temperature. This result is independent of the original form of non-thermal energy and has been used to interpret data for shock, impact, friction and electrostatic discharge (ESD) stimuli. We present new flowcharts which include 1) events resulting in hot spot formation and 2) subsequent pathways which lead to sustained reaction or quenching. The mechanism appears capable of categorizing and demonstrating the similarities and differences between hot spot growth or quenching, for impact and ESD stimuli. Sample confinement and temperature and stimulus duration are the independent variables whose roles are particularly clarified in the mechanism.

Molecular Composition, Structure, and Sensitivity of Explosives

1992 ◽  
Vol 296 ◽  
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.

Effects of Nanoscale Voids on the Sensitivity of Model Energetic Materials

1995 ◽  
Vol 418 ◽  
Author(s):  
C. T Whitea ◽  
J. J. C. Barretta ◽  
J. W. Mintmirea ◽  
M. L. Elert ◽  
D. H. Robertson
Keyword(s):  
Shock Wave ◽  
Molecular Dynamics ◽  
Hot Spots ◽  
Energetic Materials ◽  
Theoretical Study ◽  
Atomic Scale ◽  
Nanometer Scale ◽  
Higher Temperature ◽  
Detonation Transition ◽  
Dynamics Simulations

AbstractBecause of its importance in designing safer, more reliable explosives the shock to detonation transition in condensed phase energetic materials has long been a subject of experimental and theoretical study. This transition is thought to involve local hot-spots which represent regions in the material which couple efficiently to the shock wave leading to a locally higher temperature and ultimately initiation. However, how at the atomic scale energy is transferred from the shock front into these local “hot spots” remains a key question to be answered in studies of the predetonation process. In this paper we report results of molecular dynamics simulations that suggest that even nanometer scale defects can play an important role in the shock to detonation transition.

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

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.

An Effect of Hydrostatic Compression on Defects in Energetic Materials: AB Initio Modeling Maija

1998 ◽  
Vol 538 ◽  
Author(s):  
M. Kuklja ◽  
A. Barry Kunz
Keyword(s):  
Band Gap ◽  
Edge Dislocation ◽  
Hot Spots ◽  
Energetic Materials ◽  
Electronic Excitation ◽  
First Principle ◽  
Molecular Dissociation ◽  
External Hydrostatic Pressure ◽  
Pressure Changes ◽  
Favorable Conditions

AbstractFirst-principle theoretical investigation of the basic defects such as a molecular vacancy, a vacancy dimer, an edge dislocation, and a micro-crack in organic explosive molecular crystals is presented. As an example we considered solid RDX (C3H6N6O6) which is well studied unstable solid. It was established that external hydrostatic pressure changes optical properties of defect-free RDX as well as of the crystal with defects narrowing the band gap. The lattice defects (especially dislocations) are identified with the so-called “hot spots.” The nature of local electronic states introduced in the band gap by the edge dislocation and formed mainly by molecular orbitals of N-NO2 group is analyzed. Favorable conditions for molecular dissociation due to electronic excitation are shown.

scholarly journals Smartphone Thermal Imaging Can Enable the Safer Use of Propeller Flaps

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.

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

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.

Sign in / Sign up

Export Citation Format

Share Document