PhD (M/F) in mechanics of materials: Exploring the fracture and corrosion of glass-ceramics using molecular dynamics simulations

Job Description

Thesis Subject

Controlled crystallization of certain glasses leads to structured materials, designated glass-ceramics (GC), which consist of nano or microcrystals dispersed in a residual glass matrix. GC take advantage of beneficial ceramic and glass properties and have numerous applications to our daily lives, e.g., cookware, bone and dental implants, architecture, cell phone displays, etc. [2, 3]. In literature today, GC datasets concerning physical, mechanical, and fracture properties remain disjointed revealing only a handful of properties on a single GC sample. Furthermore, the susceptibility of glass-ceramics to stress corrosion cracking has been scarcely studied. This phenomenon is highly dependent on the relative humidity and temperature [4], and on material parameters (chemical composition [5] and microstructure [6], herein structure and length scale associated with crystal phases) and can severely restrict GC´s uses due to slow crack propagation leading to the failure of the GC under (apparently) harmless stresses.

Our long-term goal is to establish the link between the microstructure and the so-called stress corrosion cracking mechanism in glass-ceramics. In general, the stress corrosion cracking behaviour can be modelled by Wiederhorn's formalism [4,7]. In 2020, Grutzik et al. [8] extended Wiederhorn's formulation proposing a single equation to model the crack front velocity in a glass, where the velocity depends on the fracture toughness. The equation is constituting on a parameter set, which also includes the activation energies and characteristic length scales for both dry and wet environments and the temperature and relative humidity dependencies along with a few macroscopic parameters (Young's modulus, density, etc.). Most of these parameters are from trivial to determine experimentally for a single glass-ceramics microstructure and composition, therefore we want to build chemically-specific molecular models to facilitate these characterizations. We have already established a protocol to construct molecular models of glass-ceramics but now the resulting structures and mechanical properties need to be validated. The mechanical properties will be probed using all-atom molecular dynamics simulations (elastic properties) and the advanced simulation technique called CAPRICCIO (fracture toughness) [9]. We will perform these calculations for varying glass-ceramics microstructure which will help us understand the influence of crystal phase morphology on the structural and mechanical properties of the resulting glass-ceramics.

The PhD thesis will take place in the Département Mécanique et Verres of the Institut de Physique de Rennes. The department has an original and transdisciplinary position which lies at the crossroads of mechanics, physics and chemistry. Innovative experimentation (from synthesis to testing) coupled with computer simulation have made it possible to develop a recognized research activity on the mechanical behaviour of amorphous materials. The internship is part of a larger ANR-funded project involving stress corrosion cracking experts from CEA Saclay (Laure Chomat, Cindy Rountree, Daniel Bonamy) and glass-ceramics synthesis and characterization experts from Universidade Federal de São Carlos in Brazil (Edgar Zanotto, Vinicius Sciuti, Rodrigo Canto).

This PhD will be an opportunity to learn about and implement a number of numerical and experimental tools. Firstly, the LAMMPS code (https://www.lammps.org/) to simulate the molecular dynamics of materials. Secondly, to ensure the transfer of scales and link atomic structure and mechanical properties, strong multiscale coupling through a collaboration with S. Pfaller (FAU-Erlangen) [9] (https://www.capriccio.research.fau.eu/). The high-performance calculations required for this thesis will be prepared upstream at the Institute's computing centre, then deployed on national (GENCI) and European (ARCHER2, SuperMUC-NG) supercomputers. Validation of the predictions of the numerical simulations will make use of data from structural (XRD, AFM, NMR, DSC) and viscoelastic (Resonant Frequency Dynamical Analysis) and fracture (Single Edge Precracked Beam) mechanical characterization methods.

[1] Durán, A., Hu, L., & Richardson, K. A. Editorial special issue women in glass. Int. J. Appl. Glass Sci., 11(3):383–384, 2020.
[2] Zanotto, E. D. Bright future for glass-ceramics. Am. Ceram. Soc. Bull., 89(8):19–27, 2010.
[3] Zanotto, E. D. & Mauro, J. C. The glassy state of matter: Its definition and ultimate fate. J. Non-Cryst. Solids, 471:490–495, 2017.
[4] Wiederhorn, S. M. Influence of water vapor on crack propagation in soda-lime glass. J. Am. Ceram. Soc., 50(8):407, 1967.
[5] Rountree, C. L. Recent progress to understand stress corrosion cracking in sodium borosilicate glasses: Linking the chemical composition to structural, physical and fracture properties. J. Phys. D: Appl. Phys, 50:34, 2017.
[6] Feng, W. Stress Corrosion Cracking of Sodium Borosilicate Amorphous Phase Separated Glasses. Phd thesis, Université Paris-Saclay, 2022.
[7] Wiederhorn, S. M. & Bolz, L. H. Stress corrosion and static fatigue of glass. J. Am. Ceram. Soc., 53:543–548, 1970.
[8] Grutzik, S. J., Strong, K. T., & Rimsza, J. M. Kinetic model for prediction of subcritical crack growth, crack tip relaxation, and static fatigue threshold in silicate glass. J. Non-Cryst. Solids, 16:100134, 2022.
[9] Weber, F., Vassaux, M., Laubert, L., & Pfaller, S. The Capriccio method as a versatile tool for quantifying the fracture properties of glassy materials under complex loading conditions with chemical specificity. arXiv:2501.16537 (preprint), 2025.

Your Work Environment

Created in 2008, the Rennes Institute of Physics is a major research unit in experimental physics, theory and modelling, driving numerous interdisciplinary research partnerships at the interfaces with chemistry, engineering, biology and environmental sciences. The Mechanics and Glasses Department has a unique, transdisciplinary position at the crossroads of mechanics, physics and chemistry. Innovative experimentation and digital simulation methods have enabled the development of recognised research activity focusing on the mechanical behaviour of amorphous materials: glasses and elastomers.

Compensation and benefits

Compensation

2200 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

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