Nanotribology of nacre: Anisotropic dissipation in a multiscale hybrid material

Philippe Stempflé (1) , Xavier Bourrat (2) , Marthe Rousseau (3) , Evelyne Lopez (4) , Jamal Takadoum (1)

1 FEMTO-ST - Franche-Comté Électronique Mécanique, Thermique et Optique - Sciences et Technologies (UMR 6174)
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

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.

Mots clés: Mother of pearl; Biocrystal; Strength; Organic matrix

Domaines: Interfaces continentales, environnement; Milieux et Changements globaux

Philippe Stempflé, Xavier Bourrat, Marthe Rousseau, Evelyne Lopez, Jamal Takadoum. Nanotribology of nacre: Anisotropic dissipation in a multiscale hybrid material. Tribology International, 2013, 63, pp.250-264. ⟨10.1016/j.triboint.2012.09.010⟩. ⟨insu-00804509⟩