Search

Abstract Graphene oxide (GO) is one of the most important ceramic-toughening candidates due to its outstanding physical and chemical properties. In this paper, nacre-like alumina ceramics reinforced with GO have been prepared by freeze casting followed by hot pressing. The experimental results showed that a laminated structure with homogeneous distribution of GO was obtained in the composites. Microstructural analysis, relative densities, flexural strength and fracture toughness of the samples were investigated to reveal the effect of GO. Higher flexural strength and fracture toughness (~380 MPa and ~7.5 MPa m1/2, respectively) were achieved and the multiple length-scale toughening mechanisms of composites contributed to the improved mechanical properties. The results show that it is a promising method to enhance the mechanical properties of nacre-like alumina by the addition of GO. [ABSTRACT FROM AUTHOR]

In this paper, BNNSs/Al 2 O 3 composite powder was prepared by in-situ reaction using borate nitridation method and BNNSs/Al 2 O 3 composite ceramics were prepared by hot-pressing sintering. This method achieves uniform mixing of BNNSs and Al 2 O 3 ceramic matrix and reduces the introduction of impurities in the processing process. The BNNSs/Al 2 O 3 composite ceramics have excellent bending strength (549.4 MPa), fracture toughness (5.18 MPa m1/2) and hardness (21.3 GPa). The high hardness of composite ceramics is attributed to high grain boundary strength and density. The reinforcing mechanisms of ceramics include BNNSs pull-out, BNNSs bridging, crack deflection as well as the transgranular fracture and intergranular fracture of Al 2 O 3 matrix. [ABSTRACT FROM AUTHOR]

Synergic effect of graphene oxide (GO) and silicon nitride whisker (Si 3 N 4 w) on the mechanical properties of nacre-like alumina was investigated in this study. A comprehensive analysis on the composites, including microstructure, relative densities, flexural strength and fracture toughness, was carried out. The experimental results showed that, GO promoted the fracture toughness of the composites, but reduced the flexural strength slightly; while adding a certain amount of Si 3 N 4 w improved both flexural strength and fracture toughness. With the incorporation of GO and Si 3 N 4 w, the highest flexural strength reached 520 MPa and the fracture toughness reached 9.59 MPa m1/2. Microstructure observation revealed that the enhanced mechanical properties were ascribed to the synergistic toughening mechanisms induced by the nacre-like structure of alumina, GO pull-out, Si 3 N 4 w pinning and pull-out. [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]