Development of hydrogen-free fully amorphous silicon oxycarbide coating by thermal organometallic chemical vapor deposition technique

Abstract

In this study, a dense fully amorphous (hydrogen-free) silicon oxycarbide (SiOC) coating was successfully deposited by thermal organometallic chemical vapor deposition (thermal MOCVD) technique using mixtures of liquid hexamethyldisiloxane (HMDSO) and ethanol. The nature of chemical bonding, microstructure and mechanical properties of the prepared coating were studied using field emission scanning electron microscopy (FESEM), scanning transmission electron microscopy (STEM), 29Si magic-angle-spinning nuclear magnetic resonance (MAS NMR), X-ray photoelectron spectroscopy (XPS), Raman spectroscopy and nano indentation techniques. The results showed that the prepared silicon oxycarbide coating is fully amorphous and it is composed of SiO4 and SiO3C structural units. The hardness (11.0 GPa) and elastic modulus (96.0 GPa) of the prepared coating were comparable or even better than other SiOC ceramic materials prepared by traditional high temperature processing techniques.