Pressureless sintering of boron carbide ceramics with Al–Si additives

Abstract In this work, the pressureless sintering behavior of boron carbide (B 4 C) ceramics with 5–10 wt.% Al–Si binary additives was studied, while separate addition of individual elemental Al and Si was also investigated for comparison. Near fully-dense B 4 C ceramics can be prepared at 2150–2250 °C when 5–7 wt.% of Al–Si with molar ratio of 9:1 is added. In contrast to individual Al and Si, the use of the binary Al–Si additives in B 4 C ceramics results in a refined microstructure and increasing the Al–Si molar ratio from 1:1 to 9:1 promotes the densification of the B 4 C ceramics. Energy dispersion spectrum (EDS) analysis demonstrates the formation of SiC at the B 4 C grain boundaries.