Thermal ignition of pyrotechnics with lasers

Conference · Thu Jan 01 04:00:00 EST 1987

OSTI ID:6641502

Chow, C T.S.; Mohler, J H

We are studying the transient phenomena of thermal ignition using laser energy. Present-day infrared scanning and recording techniques enable us to determine the heat content based on the thermal profiles, during ignition, with spatial and temporal resolution. Thus, we can actually observe the laser heating and onset of self-sustained combustion in the sample pellet, and we can use the data obtained with existing theory to characterize pyrotechnic materials and to develop more-precise kinetic models of the ignition process. The results demonstrate the viability of our methods for studying the pyrotechnic ignition process. The whole ignition process consists of two stages. In the first stage, a laser acts as an external heat source that heats the surface of a pellet, an inert body. When the temperature reaches a certain level, a second-stage chemical reaction occurs. The two stages are separated by the inflection point of the temperature-vs-time trace. We present a formula derived from the thermal-explosion theory that allows one to determine the kinetic constants, with the surface-heat flux and the inflection temperature as the only parameters. In addition, we also report the ignition delay time as a function of the heat flux and describe the experimental apparatus used. We investigated three reactions: Fe/sub 3/O/sub 4//Al, Fe/sub 2/O/sub 3//Al, and Ti/2B. For our test samples, we used several kinds of powders, including spherical and flaked aluminum powders and medium and fine iron-oxide powders, with various compact densities. 7 refs., 7 figs., 2 tabs.

• Research Organization: Lawrence Livermore National Lab., CA (USA); Monsanto Research Corp., Miamisburg, OH (USA). Mound
• DOE Contract Number: W-7405-ENG-48; AC04-76DP00053
• OSTI ID: 6641502
• Report Number(s): UCRL-94740; CONF-870668-1; ON: DE87006245
• Country of Publication: United States
• Language: English

Related Subjects

45 MILITARY TECHNOLOGY, WEAPONRY, AND NATIONAL DEFENSE
450100* -- Military Technology
Weaponry
& National Defense-- Chemical Explosions & Explosives
ALUMINIUM
BORON
CHALCOGENIDES
CHEMICAL REACTIONS
ELEMENTS
HEAT SOURCES
HEATING
IGNITION
IRON COMPOUNDS
IRON OXIDES
LASER-RADIATION HEATING
LASERS
METALS
OXIDES
OXYGEN COMPOUNDS
PELLETS
PLASMA HEATING
POWDERS
PYROTECHNIC DEVICES
SEMIMETALS
TITANIUM
TRANSITION ELEMENT COMPOUNDS
TRANSITION ELEMENTS
USES