Vertically oriented structure and its fracture behavior of the Indonesia white-pearl oyster

• Published in: Journal of the mechanical behavior of biomedical materials Vol. 66; pp. 211 - 223
• Main Authors: Chen, Guowei, Luo, Hongyun, Luo, Shunfei, Lin, Zhenying, Ma, Yue
• Format: Journal Article
• Language: English
• Published: Netherlands Elsevier Ltd 01.02.2017
• Subjects: Acoustic emission; Aragonite tablet; Bivalvia shell; Calcite prism; Fracture process; Oriental growth; Bivalvia shell; Calcite prism; Aragonite tablet; Acoustic emission; Fracture process; Oriental growth
• ISSN: 1751-6161; 1878-0180
• DOI: 10.1016/j.jmbbm.2016.11.002

Structural calcites, aragonites, and the bonding organic network decide the growth, structure and mechanical properties of the mollusk bivalvia shell. Here, it was found out that the calcite prisms together with the coated organics construct another kind of ‘brick and mortar’ structure similar to the aragonite tablets. The calcite layer can be divided into three sublayers and direct evidences show that the calcite prisms are produced by two methods: nucleation and growing in the first sublayer; or fusing from the aragonites, which is quite different from some previous reports. The crystallographic orientation, micro hardness and crack propagations were tested and observed by XRD, micro harness tester, SEM and TEM. Submicron twin crystals were observed in the immature aragonite tablets. The fracture processes and the micro deformation of the aragonite tablets are detected by acoustic emission (AE) in the tensile tests, which gave the interpretation of the dynamical fracture processes: plastic deformation and fracture of the organics, and friction of the minerals at the first two stages; wear and fracture of the minerals at the third stage. Calcites and aragonites are combined and working together, like two layers of vertical ‘brick and mortar's, ensuring the stable mechanical properties of the whole shell. •The calcite layer can be divided into three sublayers produced by two methods.•Submicron twin crystals were observed in the immature aragonite tablets.•The deformation and fracture of nacre tablets were detected by acoustic emission.•Calcites and aragonites constitute two layers of vertical ‘brick and mortar’s.