Critical Role of Organometallic Chemical Vapor Deposition Temperature in Tuning Composition, Structural Units, Microstructure, and Corrosion Performance of SiOC Coatings

In this study, the impact of organometallic chemical vapor deposition (MOCVD) deposition temperature on the growth mechanism of SiOC coatings was studied in detail. For this purpose, four different SiOC coatings were prepared at deposition temperatures of 1050, 1100, 1150, and 1200 °C. The surface morphology and surface roughness of the prepared coatings were examined by field-emission scanning electron microscope (FESEM) and atomic force microscope (AFM), respectively. X-ray photoelectron spectroscopy (XPS) was employed to analyze the composition and structural units in the prepared coatings. The phase structure of SiOC coatings was analyzed by grazing incident diffraction of x-rays (GIXRD) and high resolution transmission electron microscope (HRTEM). Results revealed that, the starting temperature of homogeneous reaction in the cavity is 1100 °C, while the degree of heterogeneous reaction in the cavity reaches its maximum value at 1200 °C. With the increase in deposition temperature, more surface protrusions, a greater degree of homogeneous reaction and the evolution of graphite and 3C-SiC crystalline phases are resulted, which lead to the reduction of deposition rate of SiOC coatings. Furthermore, for SiOC coatings, flat surface morphology and less content of Si-O-Si bonds improve the HF acid etching resistance of SiOC coatings.