文哈贝壳多级微结构特征及螺旋交叉微结构的韧性机制

Hierarchical Microstructural Characteristics and Toughness Mechanism of Corkscrew Cross Microstructure of Mactra Sulcataria Shell

使用扫描电镜(SEM)观察了文蛤贝壳的微结构。结果显示:文哈贝壳是一种由无机霰石和有机胶原质组成的多级生物陶瓷复合材料。贝壳由平行的霰石层组成,每一霰石层由长而薄的霰石片所组成,每一霰石片又是由直径在纳米尺度的霰石纤维组成;在不同霰石层中的霰石纤维具有不同的方向,它们构成一种螺旋交叉微结构。对螺旋交叉微结构和平行微结构进行了与材料断裂韧性有关的最大拔出力的比较分析,结果表明:螺旋交叉微结构的最大拔出力明显大于平行微结构的最大拔出力,螺旋交叉角越大,拔出力的差值也越大。

The microstructures of a Mactra Sulcataria shell were observed with a scanning electronic microscope （SEM）. It shows that the shell is a kind of hierarchical bioceramic composite consisting of aragonite and collagen matters. The shell consists of parallel aragonite layers which are composed of thin and long aragonite sheets. The aragonite sheets consist further of aragonite fibers whose diameter is in nanometer scale. The SEM observation also showed that the aragonite sheets in different aragonite layers are of different orientations, which compose a kind of corkscrew cross microstructure. A comparative analysis of the maximal pullout forces between the corkscrew cross and parallel microstructures was conducted. It shows that the maximal pullout force of the corkscrew cross microstructure is markedly larger than that of the parallel microstructure. The larger the crossed angle of the corkscrew microstructure is, the larger the difference of the maximal pullout forces is.