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 m(1/2) to 1.23 MPa m(1/2), and to 1.39 MPa m(1/2), respectively. Based upon detailed examination on microstructures, the strengthening and toughening mechanism was discussed. Crown Copyright (C) 2011 Published by Elsevier B.V. All rights reserved.