Improvement of the mechanical and oxidation resistance of pyrolytic carbon coatings by co-deposition synthesis of pyrolytic carbon-silicon carbide nanocomposite

Abstract

In this work, pyrolytic carbon- silicon carbide (PyC-SiC) nanocomposites were prepared via pyrolysis of Trimethylsilyl chloride (TMSCl) as precursor using chemical vapor deposition method at high temperature (1100 ºC). The nanocomposite of PyC-SiC was synthesized by the deposition of SiC and PyC components from the stream of nitrogen as carrier gas by the co-deposition method. The effect of substrate type and TMSCl concentration on microstructure, composition, thermal properties, and mechanical behavior were investigated. The formation of PyC-SiC nanocomposites was followed by Raman spectroscopy, Fourier transform infrared spectroscopy and X-ray diffraction. Scanning electron microscopy was used to study of nanocomposite morphology. Additionally, the amount and distribution of Si element in the PyC-SiC nanocomposites was determined by energy dispersive X-ray mapping. The results showed that the nanocomposite containing higher SiC content was synthesized by TMSCl at 2.5 vol% on graphite. Furthermore, the results of thermogravimetric analysis and wear resistance (via tribometer) showed that the oxidation and wear resistance of nanocomposites increased with an increase in the amount of embedded silicon in the nanocomposites. Oxidation temperature and wear resistance of prepared nanocomposites in comparison with PyC increased to about 100 ºC and 300%, respectively. The tribology results showed that the friction coefficient of nanocomposites increases about 25–300% with increasing TMSCl concentration. Finally, the results of the nanoindentation test showed that increasing the amount of SiC embedded in nanocomposites improved the elastic modulus and hardness of nanocomposites about 180% and 100%, respectively.