Crystallization and oxidation resistance properties of boron modified silicon oxycarbides derived from polymeric precursors by sol-gel method

摘要

Boron modified silicon oxycarbides (SiBOCs) were prepared from sol-gel derived pre-ceramic polymeric gels followed by pyrolysis at 950 ℃ under nitrogen. As-prepared SiBOC was found to be amorphous in nature and partially crystallized to SiO_2 at 1500 ℃. The effect of boron incorporation on the crystallization of SiBOC was studied and the result revealed that the tendency to crystallization decreased with increasing boron content. This is due to the formation of Si-O-B bridges at higher temperatures, which retards the crystallization of SiO_2, evidenced from FTIR studies. SiBOC also exhibited excellent oxidation resistance ability at high temperature.