Chapter 22 - Mechanical Probe for Micro-/Nano-characterization

Abstract

This chapter discusses the elastic, plastic, elastoplastic, and the viscoelastic surface deformations for the pyramidal indenters. The chapter reviews the applications of the contact mechanics to the carbon-related materials. A pyramidal indenter, as an efficient mechanical probe for micro-/nano-characterization, has been applied to the engineering materials with time-dependent/-independent mechanical responses. The elastoplastic parameters of carbons and the viscoelastic functions of pitches are, respectively, related to their microstructural parameters. The Meyer hardness (HM) is the indenter's geometry-dependent elastoplastic parameter—increasing with H and E. HM is defined as a mean pressure against the elastoplastic penetration, and is recognized as the elastoplastic energy consumed to create a unit volume of the pyramidal impression. Some of the results from the theoretical considerationsmadeare: it is possible to quantitatively separate the plastic (true hardness H) and the elastic (Young's modulus E) measurements in the elastoplastic regime, the energy-based considerations are efficient to understand the microscopic processes associated with the complicated elastoplastic penetration of indentation, and the conventional rule of the “time-temperature superposition” is also applicable to the pyramidal indentation.