ABSTRACT
In recent years there has been considerable interest in the mechanical characterization of thin-film systems and small volumes of materials using depth-sensing indentation tests which utilize either spherical or pyramidal indenters [1,2]. Usually, to obtain values for hardness and elastic modulus of the specimen material from the experimental values of indenter load and depth of penetration is the principal goal of such testing. The forces involved are usually in the millinewton (10~3 N) range and are measured with a resolution of a few nanonewtons (10~9 N), and the depths of penetration are in the order of nanometers, hence the term "nano-indentation" (10~9 m). As the experimental values of indenter load and depth of penetration give an indirect measure of the area of contact, from which the mean contact pressure, and thus hardness, can be estimated, the relationship between the contact area and the load is considerably important. Thus the appropriate use of the corresponding theoretical model will play a key role in the experimental investigation.
