High temperature oxidation behavior of polymer-derived SiBNC–Al ceramics

Abstract

Modification with metallic elements improves the performance of polymer-derived SiBNC ceramics in high temperature aerobic environments. However, there is still need for a deep-set comprehension of the effects of metal modifiers on the phase composition, microstructural evolution of these ceramics. To elucidate, the changes in the internal crystal structures of three Aluminium modified SiBNC ceramics (SiBNC–Al) subsequent to oxidative treatment in flowing air (1200–1600°C) at different times are reported. The binding states and free carbon systems of the SiBNC–Al ceramics after high-temperature oxidation were examined by XPS and Raman spectroscopy. SiBNC–Al ceramics showed a sustained amorphous state after oxidative treatment at 1200°C. After oxidative exposure at 1400°C for 2 h, the mass retention of SiBNC–Al containing the least to the highest Al content (Al 5c, Al 3c, Al 1c, respectively), was 99.4 wt%, 96.3 wt%, and 98.6 wt%. Meanwhile, the interior of modified SiBNC–Al was comprised of β-Si3N4, β-SiC, mixed AlN(+SiC) and Mullite phases, after oxidation at 1500°C for 2 h. And the surface morphology of Al 3c at different oxidation temperatures for 8 h was analyzed by SEM, which proved that the thin oxide layer can effectively prevent further oxidation inside the ceramics.