Pressureless sintering of boron carbide ceramics with Al–Si additives

In this work, the pressureless sintering behavior of boron carbide (B4C) 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 B4C 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 B4C ceramics results in a refined microstructure and increasing the Al–Si molar ratio from 1:1 to 9:1 promotes the densification of the B4C ceramics. Energy dispersion spectrum (EDS) analysis demonstrates the formation of SiC at the B4C grain boundaries.

► Pressureless sintering of boron carbide ceramics using 5-10wt.% Al-Si additive was studied. ► Al-Si addition in B4C ceramics promotes the densification of B4C ceramics and results in a refined microstructure. ► The dissolving of Al in B4C grains in prior to Si does results in the concentrating of element Si at B4C grain boundaries.