Abstract
The effects of starting particle size and Ba addition on the flexural strength of bulk SiOC ceramics were investigated in polymer-derived SiOC ceramics prepared by a conventional ceramic processing route. Crack-free, dense SiOC discs with 6–7 mm thickness and a 30 mm diameter were successfully fabricated from commercially-available polysiloxane without any fillers or 1 mol % barium isopropoxide-derived Ba as an additive. Agglomerates formed after pyrolysis of polysiloxane led to the formation of domain-like structures surrounded by pores after sintering. The flexural strength of bulk SiOC is strongly dependent on the domain size formed and Ba addition. Both minimization of the agglomerate size in the starting powders by milling after pyrolysis and judicious selection of additives which reinforce the SiOC structure are efficient ways to improve the flexural strength of bulk SiOC ceramics. The typical flexural strength of bulk Ba-doped SiOC ceramics fabricated from submicron-sized SiOC powders was 220 MPa.
