Surface modification of fine powders by atmospheric pressure plasma in a circulating fluidized bed reactor

Abstract

Surface modification of fine alumina powders (60 mum) by plasma-enhanced chemical vapor deposition (PECVD) at atmospheric pressure was carried out in a circulating fluidized bed reactor (18 mm i.d. by 1 m height). A stable glow discharge under atmospheric pressure can be attained successfully at a source frequency of 13.56 MHz with ring-shaped electrodes. The deposited thin film on alumina powder from TEOS/O-2 plasma was characterized by FTIR-ATR, XPS, and SEM-EDS. The organic silicon films, SiOxCyHz, are deposited by TEOS plasmas at atmospheric pressure. The FTIR spectra of deposited films exhibit the three characteristic bands of SiO2 near 1072, 800, and 450 cm(-1). These CH and Si-C bonds disappear with increasing input power. Input power and oxygen content in the reaction gas control carbon and oxygen contents in the deposited film. The film deposition on the particle surface is evenly distributed, and the layer thickness is approximately 2-4 mum.