Author(s)

T. Motoda, M. Shima, T. Jibiki, S. Sasaki & K. Miyake

Abstract

Recently nano-indentation with a triangular pyramid indenter has been widely used as a method of measuring Young’s modulus of materials as well as the hardness. However, this method becomes difficult to measure Young’s modulus of thin films less than 1 µm in thickness accurately since an indenter penetration depth less than several tens nm is required avoiding the effect of the substrate. In this study we attempt to measure Young’s modulus of coating film by the elastic indentation of a spherical indenter into a coated flat. Young’s modulus of film can be accurately measured without being affected by the substrate material if the relation between the elastic normal approach and Young’s modulus of the coating film can be obtained for a given thickness of the film and given properties of substrate material. In order to attain the purpose an analytical method, which takes the elastic deformation of the substrate into consideration, is developed to calculate such the contact deformation, and the possibility of applying the calculation to measurement of Young’s modulus of films is examined. Keywords: coating film, spherical indenter, Young’s modulus, Hertzian contact, elastic indentation, new analytical method, nano-indentation. 1 Introduction Young’s modulus of films coated on the surface of materials is an essential physical parameter in analyses of the exfoliation of films or in analysis of the elastohydrodynamic lubrication of coated machine parts. Recently, nano-

Keywords

coating film, spherical indenter, Young’s modulus, Hertzian contact, elastic indentation, new analytical method, nano-indentation.