Manufacturing and Structural Evaluation of Polymer Derived SiOC/TiC and SiOC/TiC/mullite Nanocomposites

Silicon oxycarbide (SiOC) materials derived from silicone attracted great attention for their superior high-temperature behavior. In the present study, Si (Ti)OC and Si (Ti,Al)OC nanocomposites, in which alkoxide precursors were used with the main silicone precursor, have been compared with SiOC material. Although in SiOC, C was bonded with Si in a carbon-rich SiOC phase, X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) showed that TiC was the preferred state for C atoms upon adding Ti into the system. This claim was also substantiated by Raman spectroscopy, where adding Ti into the system lowered the intensity of the D band, indicating the high affinity of C to form crystalline TiC. In the Si(Ti,Al)OC nanocomposites synthesized by adding AlCl3 into the Si(Ti)OC system, mullite nanocrystals formed a superlattice structure with TiC. UV-vis spectra of the nanocomposites showed Si (Ti,Al)OC with mullite-TiC superlattice had a larger bandgap compared with Si(Ti)OC with only TiC nanocrystals.