A new nanometre resolution method for probing densification ratio at nanoindentation sites in glass: Unravelling discrepancies in the literature

TL;DR

This paper introduces a novel chemical dissolution method with high spatial resolution to accurately measure the densification zone beneath nanoindentation sites in silica glass, resolving previous discrepancies in literature.

Contribution

It presents a new nanometre resolution technique combining chemical dissolution and indentation testing to analyze densification in glass, improving spatial accuracy and reliability.

Findings

Densification zone is homogeneous with a steep transition to non-densified regions.

Size of densification zone is approximately twice the maximum indentation depth.

Good agreement between chemical dissolution results and Raman spectroscopy data.

Abstract

The region of permanent densification beneath a Berkovich indentation imprint in silica glass is investigated using a novel chemical dissolution technique. The use of the similitude regime in sharp indentation testing allows one to record reliable data with a good spatial resolution that makes it possible to deal with low loads (typically below 10 mN) and, more importantly, crack-free imprints. The densified zone dissolves more quickly than the non densified regions. The analysis of the results, along the vertical axis, indicates that the densification zone is rather homogeneous with a steep transition to the non densified zone. The size of the densification zone, with respect to the initial free surface, is estimated to be around two times the maximum penetration depth of the instrumented indentation test. These findings are compared with those obtained by numerical simulations using different constitutive equations from the literature. A very good concordance between Raman spectroscopy and chemical probe results is found for imprints made with no or few cracking events during indentation testing.