Glass - Back to the Future!



Presenting Author:
Carolin Hühn
<carolin.huehn@uni-jena.de>

article posted 11 April 2016


Carolin Hühn studied Materials Science at the Ilmenau University of Technology (Germany). After completing her B.Sc. degree in September 2012 she continued her study at the Friedrich Schiller University of Jena and finished her M.Sc. on the topic "Structure and Properties of Gold on SiO2 Surfaces” (DOI: 10.1039/C5CP04803F). In November 2014 she joined the group of Prof. M. Sierka at the Otto Schott Institute of Materials Research as a PhD student (http://www.sierkalab.com/).






Empirical estimation of subcritical crack growth energy barrier

Bruno P. Rodrigues, Carolin Hühn*, Marek Sierka, Lothar Wondraczek
Otto Schott Institute of Materials Research, Friedrich Schiller University, 07743 Jena, Germany


In this work we present an empirical equation to describe the temperature and stress-intensity dependency of crack propagation velocity in its subcritical growth range and show its robustness by comparing the results obtained from its application to crack growth data on silica glass and soda-lime-silicate glass (SLS) with fracture surface energy from crystalline and amorphous silica and energetic calculations from ab initio quantum chemical simulations. While closely related to the Wiederhorn equation, our proposed expression
(where v is the crack propagation speed, v0 is the pre-exponentinal constant, E* is the activation energy for bond breakage, R is the ideal gas constant, T is the a bsolute temperature, C is a constant related to the crack geometry and KI is the stress intensity factor at the crack tip) has the advantage of allowing for the experimental determination of the necessary parameters. Fracture surface energy literature data yield values of 360 kJ/mol for the fracture activation energy in silica glass and between 310 – 340 kJ/mol for the cleavage of the a plane in monocrystalline a-quartz. The simulated model consists on a dimeric hydridosilsesquioxane (DHS), where the single Si-O-Si linkage between the two “cages” was strained to acquire the energy necessary to dissociate the aforementioned bond, resulting in a value of 312 kJ/mol on the absence of H2O molecules and between 167 – 158 kJ/mol when up to 3 water molecules are added. Finally, our proposed equation was used to evaluate crack growth data on Region I and Region III of the subcritical crack growth range, producing values for the activation energy of 314 kJ/mol for SLS in Region III, 114 kJ/mol for SLS in Region I and 156 kJ/mol for silica in Region I. The agreement shown between the evaluated data is remarkable.