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Mapping of elastic modulus and hardness in Trochus niloticus seashell nacre by nanoindentation

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dc.contributor.advisor Christine Ortíz. en_US
dc.contributor.author Villarreal, Julián Enrique en_US
dc.contributor.other Massachusetts Institute of Technology. Dept. of Materials Science and Engineering. en_US
dc.date.accessioned 2008-09-03T14:46:12Z
dc.date.available 2008-09-03T14:46:12Z
dc.date.copyright 2006 en_US
dc.date.issued 2007 en_US
dc.identifier.uri http://hdl.handle.net/1721.1/42164
dc.description Thesis (S.B.)--Massachusetts Institute of Technology, Dept. of Materials Science and Engineering, June 2007. en_US
dc.description Includes bibliographical references ( p. 22). en_US
dc.description.abstract Positionally-sensitive nanoindentation was carried out in the freshly-cleaved nacre found in the shell of the gastropod mollusk Trochus niloticus. Nacre is a hierarchical biocomposite composed of mineral tablets of 95 weight % calcium carbonate (CaCO3) in the aragonite mineral form and a biomacromolecular organic matrix. Nanoindentation was carried out in a pattern of square grids of 256 indents at maximum loads of 1 mN and 500 gN. The average elastic modulus and hardness for the 1 mN indents were found to be 97.8 GPa + 6.41 GPa and 5.41 GPa ± 0.49 GPa, respectively, and for the 500 gN indents average elastic modulus of 94.8 GPa ± 7.28 GPa and hardness of 4.89 GPa ± 0.53 GPa. Maps of the 2-D spatial distribution of elastic modulus and hardness for the indent areas were generated. Tapping mode Atomic Force Microscopy was performed on the indented nacre after a treatment of surface etching, which revealed the tablet boundaries in order to correlate qualitatively the topographical features with the properties distribution. The properties distribution maps revealed a non-uniform distribution of nanomechanical properties as well as highly-localized regions in which the values of the properties differed from the average values. Future studies may point to a direct correlation between structural heterogeneity and the properties distribution. en_US
dc.description.statementofresponsibility by Julián Enrique Villarreal. en_US
dc.format.extent : en_US
dc.language.iso eng en_US
dc.publisher Massachusetts Institute of Technology en_US
dc.rights M.I.T. theses are protected by copyright. They may be viewed from this source for any purpose, but reproduction or distribution in any format is prohibited without written permission. See provided URL for inquiries about permission. en_US
dc.rights.uri http://dspace.mit.edu/handle/1721.1/7582 en_US
dc.subject Materials Science and Engineering. en_US
dc.title Mapping of elastic modulus and hardness in Trochus niloticus seashell nacre by nanoindentation en_US
dc.type Thesis en_US
dc.description.degree S.B. en_US
dc.contributor.department Massachusetts Institute of Technology. Dept. of Materials Science and Engineering. en_US
dc.identifier.oclc 228658260 en_US


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