Fabrication and mechanical properties of SiO2–Al2O3–BNNPs and SiO2–Al2O3–BNNTs composites

Hexagonal BN nanoparticles (BNNPs) and boron nitride nanotubes (BNNTs) were determined to fabricate the composites of 75 wt% SiO2–10 wt% Al2O3–5 wt% BNNPs (S-A-BNNPs) and 75 wt% SiO2–10 wt% Al2O3–5 wt% BNNTs (S-A-BNNTs) via hot pressing. Comprehensive investigations on mechanical properties of the two composites were conducted, respectively. The two composites had high flexural strength and fracture toughness. The flexural strength of S-A-BNNPs and S-A-BNNTs composites are approximately 216.1% and 279.1% higher than that of the unreinforced SiO2, and the fracture toughness increases from 0.58 MPa m1/2 to 1.23 MPa m1/2, and to 1.39 MPa m1/2, respectively. Based upon detailed examination on microstructures, the strengthening and toughening mechanism was discussed.