title: Surface toughness of silicon nitride bioceramics: I, Raman spectroscopy-assisted micromechanics.
abstract: Indentation micro-fracture is revisited as a tool for evaluating the surface toughness of silicon nitride (Si3N4) bioceramics for artificial joint applications. Despite being unique and practical from an experimental perspective, a quantitative assessment of surface fracture toughness using this method is challenging. An improved method has been developed, consisting of coupling indentation with confocal (spatially resolved) Raman piezo-spectroscopy. Empowered by the Raman microprobe, the indentation micro-fracture method was found to be capable of providing reliable surface toughness measurements in silicon nitride biomaterials. In designing the microstructures of bioceramic bearing couples for improved tribological performance, surface toughness must be considered as a fundamentally different and distinct parameter from bulk toughness. The coupling of indention crack opening displacements (COD) with local stress field assessments by spectroscopy paves the way to reliably compare the structural properties of bioceramics and to quantitatively monitor their evolution during environmental exposure.
authors.affiliation: Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8126 Kyoto, Japan. Electronic address: pezzotti@kit.ac.jp.
authors.forename: Giuseppe
authors.initials: G
authors.lastname: Pezzotti
authors.affiliation: Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8126 Kyoto, Japan.
authors.forename: Yuto
authors.initials: Y
authors.lastname: Enomoto
authors.affiliation: Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8126 Kyoto, Japan.
authors.forename: Wenliang
authors.initials: W
authors.lastname: Zhu
authors.affiliation: Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8126 Kyoto, Japan.
authors.forename: Marco
authors.initials: M
authors.lastname: Boffelli
authors.affiliation: Ceramic Physics Laboratory, Kyoto Institute of Technology, Sakyo-ku, Matsugasaki, 606-8126 Kyoto, Japan.
authors.forename: Elia
authors.initials: E
authors.lastname: Marin
authors.affiliation: AMEDICA Corporation, 1885 West 2100 South Salt Lake City, UT 84119, USA.
authors.forename: Bryan J
authors.initials: BJ
authors.lastname: McEntire
mesh_terms: D002516:Ceramics / Q000737:chemistry*; D055595:Mechanical Phenomena; D010087:Oxides / Q000737:chemistry; D017655:Silicon Compounds / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D013499:Surface Properties
chemical_list: D010087:Oxides; D017655:Silicon Compounds; C032734:silicon nitride
keywords: Bioceramics; Confocal Raman piezo-spectroscopy; Crack bridging; Indentation crack opening displacement; Si(3)N(4); Surface toughness