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Well-dispersed boron nitride nanosheets (BNNSs) reinforced fused silica composites were successfully fabricated by surface modification assisted flocculation method. Surface modification can enhance the performance of flocculation process. BNNSs were homogeneously mixed with fused silica through the electrostatic interaction between hydroxylated BNNSs with negative charge and amino-modified fused silica with positive charge. The BNNSs can act as excellent nanofillers for enhancing the mechanical properties of fused silica composites. Approximately 74% and 48% increases in flexure strength and fracture toughness can be achieved for the 1.5 wt% BNNSs/fused silica composite, respectively. The toughening mechanisms were analyzed by microstructural characterization, especially for pull-out mechanism. [ABSTRACT FROM AUTHOR]

In order to overcome intrinsic brittleness and poor mechanical properties of fused silica (FS), boron nitride nanosheets (BNNSs) as a novel reinforcement were employed for fabrication of BNNSs/fused silica composites. BNNSs with micron lateral size were homogeneously dispersed with FS powder using a surfactant-free flocculation method and then consolidated by hot pressing. The flexural strength and fracture toughness of the composite with the addition of only 0.5 wt.% BNNSs increased by 53% and 32%, respectively, compared with those of pure FS. However, for higher BNNSs contents the improvement in mechanical properties was limited. Microstructural analyzes have shown that the toughening mechanisms are combinations of the pull-out, crack bridging, and crack deflection mechanisms. [ABSTRACT FROM AUTHOR]

Abstract Boron nitride nanosheets (BNNSs) have attracted increasing attention in the field of two-dimensional materials. In the paper, the BNNSs/alumina composites were fabricated by a flocculation method and hot pressing. It is found that the BNNSs were dispersed uniformly in the alumina matrix by the flocculation technique via pH adjustment. The experimental results showed that with the increasing BNNSs content, the density of the composites decreased. Compared with the monolithic alumina, bending strength of the composite with 1.0 wt% BNNSs was increased by 58.6%; while the fracture toughness was increased slightly. The addition of BNNSs changed the fracture pattern, refined the grains of composites and inhibited abnormal grain growth, which contributed to the improvement of mechanical properties of the composites. [ABSTRACT FROM AUTHOR]