鲍鱼壳的跨尺度结构及性能表征

The multiscale structure and performance characteristics of abalone shell

目的:鲍鱼壳具有特殊的结构和优异的性能,通过对鲍鱼壳的跨尺度结构和性能进行深入研究,揭示鲍鱼壳从宏观到微观的结构特点和其结构与性能的关系.方法:采用数码光学显微镜和扫描电镜(SEM)对鲍鱼壳的结构进行表征,利用万能试验机测试鲍鱼壳整体的压缩强度,借助显微硬度仪表征鲍鱼壳表面和截面的硬度和断裂韧性.结果:鲍鱼壳宏观结构分为5部分,表面有生长线和螺肋;介观结构分为2层,厚度比例接近;微观结构包含角质层、棱柱层和珍珠层,珍珠层中存在棱柱层-珍珠层交替结构.整个鲍鱼壳的压缩破坏力为185 N,压缩强度约为52 MPa;鲍鱼壳不同部位的硬度显示有差异,背部的硬度最高为354 HV,其次为中顶部298 HV,头部、腹部和尾部相差不大,约为270 HV;鲍鱼壳背部的截面硬度高于表面,最高值达到了427 HV.结论:鲍鱼壳背部特殊的结构增加了其硬度,且断裂韧性高于氧化铝陶瓷(3.0 MPa·m^(1/2))材料.

Objective:Abalone shell has special structures and excellent performance.The aim of this study was to reveal the features of macroscopic and microscopic structures,as well as the relationship between the structure and performance of abalone shell.Methods:The structure of abalone shell was characterized by digital optical microscope and scanning electron microscope(SEM),and a universal test machine was used to determine the compressive strength,the hardness and fracture toughness on surface.The cross section of abalone shell was characterized by microhardness tester.Results:The macrostructure of abalone shell exhibited five parts,and the surface showed growth lines and spiral ribs.The mesoscopic structure was divided into two layers with approximate thickness.The microstructure showed stratum corneum,prism layer and nacre layer,existing as prismatic layer-pearl layer alternate structures.Compression power of the whole abalone shell was measured,which was about 185 N,and the compression strength was approximately 52 MPa.Hardness was found different among the parts of abalone shell:the highest hardness was found in the back,354 HV,followed by the middle top,298 HV,meanwhile the hardness in the locations of the head,abdomen and tail had little difference from each other,about 270 HV.However,the hardness of the cross section was higher than that of the surface,with amaximum of 427 HV.Conclusion:The special structure of abalone shell contributes to its hardness,and the fracture toughness is higher than alumina ceramic material.The present study on the cross-scale structure and performance characteristics of abalone shell might provide with a theoretical foundation for preparation of bionic structure composite materials.