SiO2 thin films obtained from silica sols by thermal spraying

Abstract

The mechanism of the synthesis of silicon dioxide thin films on the surface of a stainless steel band substrate, by thermal spraying of a silica sol as a precursor was the subject of this work. The structural design of the hydro thermally obtained particles was defined as an organized structure of basic motives-silica tetrahedrons, over silica chains and finally sol particles, which were used as a well-defined precursor for the preparation of corresponding thin films. IR spectroscopy and TGA analysis were employed to define the structure of the silica tetrahedrons and the size of the silica chains in the sol particles. The thickness of the film and the dependence of the film morphology and structure on its surface and of its cross section were investigated. The mechanism of film formation and the differences on its appearance depending of the SiO2 sol concentration was also investigated. The sizes of the particles were 50 - 250 nm, while the agglomerate sizes were mostly 250 nm in diameter and 1 - 2 mu m in the length. The thicknesses of the films were 6.5 - 33 mu m.