香螺壳的结构和微观力学性能

The structure and micromechanical properties of mollusk shell

测量产自黄/渤海海域的香螺贝壳的硬度和弹性模量,研究了贝壳的结构与性能之间的关系.结果表明,香螺贝壳主要由方解石和文石两种矿物镶嵌在有机质中构成,方解石结构为不均匀的柱状晶,文石结构为多级超微的交错纹状结构,其中第三级结构为10—80 nm的纳米级纤维.文石的力学性能优于方解石的性能.贝壳类复合材料的压痕效应主要源于裂纹扩展,而微观裂纹扩展与晶体类型以及晶体结构的排列方式是密切相关的.方解石裂纹形状曲折、不规则且沿着方解石层的边界扩展,抗裂纹扩展能力较差;而文石压痕周围平直清晰,裂纹沿着其二级结构界面扩展,性能较好.

The hardness and elastic modulus of the conch shell of Hemifusus tuba living in Huang/Bo sea area were measured and the relationship between structure and mechanical properties has been investigated. The results indicated that the shell of the conch Hemifusus tuba is composed of calcite and aragonite which are enchased in organic phase. The outer layer of calcite consists of cylindrical grains, and the middle layer and inner layer of aragonite consist of crossed-lamellar ultrastructure. The third-order lamellar of aragonite has 10-80 nm fiber. The mechanical properties of aragonite are better than that of calcite. The effect of indentation of mollusk shell mainly origins form the crack propagation, Moreover the performance and microcrack propagation correlate with crystal structure and crystal arrangement, The cracks exist around microindentation of calcite layer. The cracks paths are meandering and irregular, and the cracks are propagated along with the boundary of calcite crystal. However the microindentation of aragonite layer is distinct and regular, and the cracks are propagated along with the second-order interface.