Improvement of densification and mechanical properties of Al2O3–B4C ceramics

Al 2 O 3 –B 4 C ceramics had poor densification, due to the formation of Al 18 B 4 O 33 phase by reaction between Al 2 O 3 and B 2 O 3 on the surface of B 4 C. In the present work, Y 2 O 3 or Ti additive together with ZrO 2 from milling media were introduced into Al 2 O 3 –B 4 C ceramics. Results showed that Y 2 O 3 reacted with B 2 O 3 to produce YBO 3 phase, and removed Al 18 B 4 O 33 phase, resulting in the improved densification and the coarse microstructure. However, Ti and ZrO 2 reacted with B 2 O 3 to produce hard TiB 2 and ZrB 2 phases, removed the most of Al 18 B 4 O 33 phase, refined microstructure by pinning effect of hard particles, and improved densification and mechanical properties .