Effects of Surface Defect Distribution of $SiO_x(x{\le}2)$ Plates on Chemical Quenching

$SiO_x(x{\le}2)$ 플레이트의 표면 결함 분포가 화학 소염에 미치는 영향

Effects of surface defect distribution on flame instability during flame-surface interaction are experimentally investigated. To examine the chemical quenching phenomenon, we prepared thermally grown silicon oxide plates with well-defined defect density. Ion implantation was used to control the number of defects, i.e. oxygen vacancies. In an attempt to preferentially remove the oxygen atoms from silicon dioxide surface, argon ions with low energy level from 3keV to 5keV were irradiated at the incident angle of $60^{\circ}C$. Compositional and structural modification of $SiO_2$ induced by low-energy $Ar^+$ ion irradiation has been characterized by Atomic Force Microscopy (AFM) and X-ray Photoelectron Spectroscopy (XPS). The analysis shows that as the ion energy increases, the number of structural defect also increases and non-stoichiometric condition of $SiO_x(x{\le}2)$ plates is enhanced. From the quenching distance measurements, we found out that when the surface temperature is under $300^{\circ}C$, the quenching distance decreases on account of reduced heat loss; as the surface temperature increases over $300^{\circ}C$, however, quenching distance increases despite reduced heat loss effect. Such aberrant behavior is caused by heterogeneous chemical reaction between active radicals and surface defect sites. The higher defect density, the larger quenching distance. This results means that chemical quenching is governed by radical adsorption and can be parameterized by the oxygen vacancy density on the surface.