Emissionspectroscopy of Boron Ignition and Combustion in the range of 0.2 m̈m to 5.5 m̈m

Abstract

Boron particle combustion is retarded by initial presence of an oxide coating. In current boron ignition models, oxygen is assumed to desolve in the oxide and diffuse to the B/B2O3 interface for reaction. One method to observe the reaction of boron with its surrounding atmosphere is the time resolved emission spectroscopy we applied in the range of 0.2 m̈m to 5.5 m̈m for different burning processes. In one experiment boron powder was burned in oxygen atmosphere initiated by an efficient pyrotechnic device. The energy transfer by the hot gases led to a glowing phase of the boron particles which then changed to a high temperature combustion and ended in a further glowing phase. The two glowing phases emitted continuous emission spectra, while the burning phase emitted the bands of BO and BO2. Another experimental setup was used to feed boron particles in a hot oxidizing atmosphere provided by a propane/air flame which flew into a combustion chamber. Herein the reaction of boron was recorded with high speed cinematography and time resolved emission spectroscopy. The flame contained a small amount of background radiation and we could identify emitted bands of BO, BO2, HBO2, CO and CO2.

Spectroscopic Characterization of B/KNO3 Diode-Laser Induced Combustion

“…The spectra were taken with oxygen, nitrogen, or helium rinsing the system (at 2 bar) The emission spectra at different times from laser activation can be seen in Figure for the case of nitrogen flushing of the system. The assignment of the peaks in the 400–600 nm range to BO 2 emission is based on the similarity of the spectra to previous work − and appears to be well founded. In contrast, the assignment of the peaks in the 300–400 nm range to BO is more ambiguous and is further discussed in the next section.…”