Nanotribology of nacre: Anisotropic dissipation in a multiscale hybrid materialReport as inadecuate

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1 FEMTO-ST - Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies 2 ISTO - Institut des Sciences de la Terre d-Orléans - UMR7327 3 PPIA - Physiopathologie, Pharmacologie et Ingénierie articulaires 4 BOME - Biologie des organismes marins et écosystèmes

Abstract : Sheet nacre so-called mother-of-pearl is a hybrid biocomposite with a multiscale structure including nanograins of calcium carbonate 97 wt%-40 nm in size and two organic matrices: i the -intracrystalline- mainly composed by silk-fibroin-like proteins, and ii the -interlaminar- one mainly composed of β-chitin and proteins. Micro-nanotribological behaviour was investigated on sheet nacre displaying various configurations so-called face-on and edge-on, by varying the orientation of the matrices vs. the sliding direction. Different levels of frictional dissipated energy were observed as a function of both: i the type of matrix which is involved in the dissipation mechanism intracrystalline or interlaminar, and ii the orientation of the matrices themselves vs. the sliding direction. These various dissipative ways can involve either, multiscale wear processes entailing the both matrices, or irreversible deformation only, without any wear process. They have been identified and explained by considering the double composite structure of sheet nacre.

Keywords : Mother of pearl Biocrystal Strength Organic matrix

Author: Philippe Stempflé - Xavier Bourrat - Marthe Rousseau - Evelyne Lopez - Jamal Takadoum -



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