RT Journal Article
ID 1d00e0a20f753100
A1 Yeh, Chun-Liang
A1 Zhao, E.
A1 Ma, H. K.
T1 COMBUSTION SYNTHESIS OF SiO, IN PREMIXED FLAMES
JF International Journal of Energetic Materials and Chemical Propulsion
JO IJEMCP
YR 2002
FD 2002-01-01
VO 5
IS 1-6
SP 994
OP 1003
AB An experimental study of gas-phase combustion synthesis of silicon dioxide (SiO2) particles was investigated in premixed propane/air flames. Two different types of organosilicon compounds, hexamethyldisiloxane (HMDSO) and hexamethyldisilazane (HMDSA), were used as silicon precursors. The objective of this research was to study the effects of HMDSO and HMDSA concentrations and flame temperatures on the synthesis of SiO2 particles. The chemical composition of synthesized products was analyzed by an energy dispersive spectrometer (EDS), which was coupled with a scanning electron microscope (SEM). The change in flame structure with the introduction of HMDSO and HMDSA into the flame zone was observed in details and recorded by a high-resolution digital camera. As a small amount of HMDSO or HMDSA was added to premixed mixtures, a secondary flame, orange in color, appeared around the conical luminous zone of C3H8/air flames. At a flame condition of φ (equivalence ratio) = 0.57, when the mole fraction of HMDSO was higher than 0.67%, the appearance of a bright yellow flame brush was observed on the tip of the conical luminous zone. The flame brush phenomenon is believed to be caused by a particle-laden flame. With a higher equivalence ratio, the occurrence of flame brush phenomena was found at a lower HMDSO concentration. When HMDSA was used at flame conditions with high equivalence ratios (φ = 0.65 and 0.73), the flame brush like a flamelet was also observed. Moreover, the measured flame temperature was decreased with the increase of HMDSO and HMDSA mole fractions. The chemical composition of synthesized particles in this study was considered as SiOx, where x ranged from 1.75 to 2.5 when HMDSO was used and from 1.12 to 3.1 when HMDSA was entrained. This implies that the synthesized product is the combination of silicon monoxide (SiO), SiO2, and silicate (SiO32− or SiO44−). The variation of x values in SiOx suggests that HMDSO produce the synthesized particles with a composition closer to pure silicon dioxide (SiO2) than does the HMDSA.
PB Begell House
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