Vol. 42, Issue 2, pp. 399-406 (2012)

Abstract

The aim of the work described was to study the load dependence of micro- and nano-hardness for soda-lime silicate glass doped with some univalent cations. The Fourcault-type glass samples were chemically treated by dipping them in melted baths of KNO₃, AgNO₃ and CuCl. The nano- and micro-hardness were determined by using the Vickers diamond indenters for applied loads ranging between 0.1 and 500 mN (registered loading and unloading mode), and between 0.2 and 30 N (conventional application of the load), respectively. For the behavior of hardness and Young’s modulus (registered nano-indentation) the normal indentation size effect has been observed, but in the low load range of conventionally indented specimens the reverse indentation size effect has been found. The detected size effects were discussed in terms of some empirical models proposed in the literature for crystalline materials. It has been shown that: 1) the Meyer’s law is only suitable for describing the nano-indentation characteristics measured in a narrow range of indentation load; 2) the classical Meyer’s law and the energy balance model are insufficient for describing the reverse indentation size effect; 3) the difficulties in acquiring accurate and precise micro-hardness readings in the range of low loads can result in the inconformity of experimental data with the empirical models.