Microstructure and mechanical properties of alumina ceramics reinforced by boron nitride nanotubes

Boron nitride nanotubes (BNNTs)/alumina composites were fabricated by hot pressing. The mechanical properties of the composites are greatly dependent upon the content of BNNTs. In comparison with monolithic alumina, the incorporation of BNNTs results in the improvement of bending strength and fracture toughness owing to the effective inhibition of grain growth. A routine toughening mechanism, especially the bridging of BNNTs at grain boundaries and the sufficient physical bonding between BNNTs and alumina matrix, is dominantly responsible for the increase in mechanical properties.

► BNNTs are used as reinforcing phase to improve mechanical properties of Al2O3.
► The bending strength and fracture toughness are increased obviously.
► The improvement is ascribe to BNNTs bridging and sufficient physical bonding.