The Formation of Nano—Size SiO2 Thin Film on an Aluminum Plate with Hexamethyldisilazane（HMDSA）and Hexamethyldisiloxane（HMDSO）

This study is using HMDSA(C6H19NSi2)or HMDSO(C6H18OSi2) vapor into C3H8/air premixed flames to form SiO2 thin film on the surface of an aluminum palte.With the addition of HMDSO or HMDS to premixed flames,an orange secondary flame or a flame brush appeared and was contributed to the formation of SiO2 particles.Based upon the EDS,XPS and FTIR analysis ,it is believed that the synthesized products consist of mainly SiO2 and a small amount of SiO,The pure SiO2 crystal structure,was proved by XRD analysis,which may form form the SiO2 amorphous structure after high temperature(1300℃) thermal treatment.The nano-size SIO2 particles,which ranged form 2.5-25nm,are proved by analysis of the BET and TEM.A 2-D CFD-RC code with 12 reduced chemical reaction mechanism.based upon the SIMPLER procedure,was successfully employed to predict the flame temperature and both of the SiO2 and SiO concentration profiles.Compared with the experimental results,the calculated temperature profiles in the post-flame region are in good agreement with the measured data and observation phenomena.