Model nucleation and growth studies of nanoscale oxide coatings suitable for modification of microcellular and nano-structured carbon

In this paper, a detailed study of the nucleation and growth of plasma assisted oxide coatings on model graphitic substrates has been performed. The surface chemistry and morphology of these films (as they grow on graphite) have been monitored using X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM). It is shown that oxide coatings start as islands having average height of 3-5 nm. The density and lateral size of these islands grow to form complete layers. Therefore complete and smooth coverage can be obtained with a film thickness in the range of a few nanometers (3-5 nm). The coating chemical composition is identical to SiO2. Detailed XPS analysis during overlayer growth reveals the presence of strong -Si-C- bonds at the graphite-coating interface. This is an important finding that can help to predict the mechanical, thermal and other functional properties of the interface. The durability of this coating at high operating temperatures has been investigated, and it is found to withstand up to 1000 °C heat treatments in argon environment.