An experimental investigation of deformation and fracture of nacre-mother of pearl
An experimental investigation of deformation and fracture of nacre-mother of pearl
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DOI：
10.1007/s11340-007-9040-1
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发表时间：
2007-06-01
影响因子：
2.4
通讯作者：
Espinosa, H. D.
中科院分区：
文献类型：
--
作者：
Barthelat, F.;Espinosa, H. D.
珍珠层，也被称为珍珠母，是一种坚硬的生物复合材料，存在于许多贝壳的内层，如牡蛎或鲍鱼。它由多层排列的微观陶瓷片组成，紧密堆叠形成三维砖墙结构，其中砂浆是生物聚合物的薄层（20-30 nm）。虽然珍珠层主要由脆性陶瓷制成，但其结构设计得非常好，其韧性比制成它的陶瓷大几个数量级。珍珠层的微观结构如何控制其机械性能一直是过去二十年来众多研究的焦点，因为这种理解可能会通过仿生学激发新颖的复合材料设计。本文详细介绍了微型珍珠层单轴拉伸实验。在水合条件下观察到大的非弹性变形，这是通过片剂彼此滑动和由其微观波纹产生的渐进锁定来解释的。断裂实验也进行了，并首次建立了完整的抗裂曲线珍珠层。上升的电阻曲线是该材料的鲁棒性和损伤容限的指示。这些测量，然后讨论和相关的增韧外在机制在微观尺度上操作。此外，微观结构的具体特征及其相关的增韧机制进行了鉴定。这些特征和机制对外壳的坚固性至关重要，在数百万年的进化中得到了很好的调整。因此，他们预计将作为一个基础，建立指导方针的设计新型人造复合材料。
Nacre, also known as mother-of-pearl, is a hard biological composite found in the inside layer of many shells such as oyster or abalone. It is composed of microscopic ceramic tablets arranged in layers and tightly stacked to form a three-dimensional brick wall structure, where the mortar is a thin layer of biopolymers (20-30 nm). Although mostly made of a brittle ceramic, the structure of nacre is so well designed that its toughness is several order of magnitudes larger that the ceramic it is made of. How the microstructure of nacre controls its mechanical performance has been the focus of numerous studies over the past two decades, because such understanding may inspire novel composite designs though biomimetics. This paper presents in detail uniaxial tension experiment performed on miniature nacre specimens. Large inelastic deformations were observed in hydrated condition, which were explained by sliding of the tablets on one another and progressive locking generated by their microscopic waviness. Fracture experiments were also performed, and for the first time the full crack resistance curve was established for nacre. A rising resistance curve is an indication of the robustness and damage tolerance of that material. These measurements are then discussed and correlated with toughening extrinsic mechanisms operating at the microscale. Moreover, specific features of the microstructure and their relevance to associated toughening mechanisms were identified. These features and mechanisms, critical to the robustness of the shell, were finely tuned over millions of years of evolution. Hence, they are expected to serve as a basis to establish guidelines for the design of novel man-made composites.