Controlling ceramic composition using precursor chemistry: A study on borosiloxane derived SiBOC ceramics

This paper reports the solventless synthesis and characterization of borosiloxane oligomers from boric acid and mixtures of vinyltriethoxysilane and phenyltriethoxysilane, using different monomer feed ratios. The oligomers were characterized by gel permeation chromatography and infrared spectral analysis. Microstructure of the oligomers was studied using ¹ H-, ¹³ C- and ²⁹ Si-NMR spectra. Ceramic conversion of the borosiloxane oligomers were carried out at 900°C. The ceramics obtained at 900°C were further heat treated at 1500 and 1650°C. The ceramic powders were characterized by FT-IR and XRD. The effect of monomer feed ratio on the oligomer structure and on its ceramic conversion process is discussed.