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 AlCl۳ 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.

Keywords:

SiOC nanocomposite , mullite , TiC , polymer-derived ceramics