MARTIN Christophe
My research is focused on particulate media, with a particular interest for powders with engineering applications. Since 2001, I am the principal investigator in the development of a discrete element code, dp3D, dedicated to the processing of powders (compaction and sintering) and to the investigation of the fracture behaviour of brittle materials. The applications are mainly on materials for energy applications (thermal insulation, nuclear pellets, ceramic electrodes, thermoelectric materials, capacitors), but may also relate to other fields like the densification of snow or the mastication of cellular food. The numerical simulations are coupled and compared as much as possible with experiments such as x-ray tomography.
Examples of application of the dp3D code are available here:
PhD offer: Engineering ceramics offer some of the highest stiffness and strength of any material class. They are therefore the best choice for high-stress, high-temperature applications. However, they all suffer from one drawback: brittleness. In high-temperature applications in particular, they can be subjected to thermal shocks that can lead to their ruin. Complex ceramics with multi-phase microstructures are used for such applications, but the physical phenomena behind their good resistance to thermal shock are still poorly understood. The challenge, therefore, is to develop optimized microstructures for this type of application, through a better understanding of thermal shock behavior and the use of modeling. Improving the durability of refractory products is an important issue in the global context of reducing greenhouse gas emissions.
The general purpose of this thesis is to understand the link between the microstructure and thermomechanical properties of an industrial ceramic. The thesis will be based on the fused cast refractory ceramic Magmalox® 550 produced by Saint Gobain. Its microstructure is complex and multiphase, composed of alumina, zirconia, silica and porosities.
The aims of the thesis are to:
- Understand the role played by the different phases on the mechanisms of crack initiation and propagation under thermal shock.
- Develop a model to predict the damage and residual behavior resulting from a given thermomechanical loading.
- Suggest optimization avenues for microstructures (phase volume fraction, grain size, interface properties, etc.) with regard to thermal shock resistance.
The thesis includes a significant experimental component and some modeling. The first step will be to characterize the macroscopic properties of Magmalox® 550, in particular its residual strength properties after thermal shock. Microstructural analyses using electron microscopy (SEM) on a high temperature micro-mechanical device (in situ, between 20°C and 800°C) and microtomography (post-mortem) will be carried out to understand small-scale crack initiation and propagation processes. Based on these analyses, a discrete mesoscopic model will be developed, well suited to the multiphase microstructure of Magmalox® 550. It will be based on SIMaP's work in this field. These numerical simulations, combined with experimental observations, should enable optimization options to be explored with regard to thermal shock.
The thesis is part of the M² Brittle'S CODEX Chair, which includes another PhD (more focused on dynamics). The PhD student will interact with the various laboratories involved in the Chair (Saint-Gobain's CREE in Cavaillon, 3SR laboratory on the Grenoble campus).
The thesis is scheduled to start between October and December 2024.
Laboratory: SIMaP
Gross salary: 2200€/month
Industrial partner: Saint-Gobain (Chaire M² Brittle’S CODEX)
Needed skills: Materials science, mechanics of materials
Techniques: mechanical testing, microscopy, X-ray tomography, discrete simulations
Contacts:
Selected Publications:
- K. Radi, D. Jauffrès, S. Deville, & C. L. Martin, Elasticity and fracture of brick and mortar materials using discrete element simulations. Journal of the Mechanics and Physics of Solids 126, 101–116 (2019).
- A. Burr, P. Lhuissier, C. L. Martin & Philip, A. In situ X-ray tomography densification of firn : The role of mechanics and diffusion processes. Acta Materialia 167, 210–220 (2019).
- E. Guesnet, B. Bénane, D. Jauffrès C. L. Martin, G.P. Baeza, G. Foray et al. Why fumed and precipitated silica have different mechanical behavior : Contribution of discrete element simulations. Journal of Non-Crystalline Solids. 2019
- W. Gonçalves, J. Morthomas, P. Chantrenne, M. Perez, G. Foray, C.L. Martin, Elasticity and strength of silica aerogels: A molecular dynamics study on large volumes, Acta Mater. 145 165–174 (2018).
- D. Jauffrès, C.L. Martin, R.K. Bordia, Design of strain tolerant porous microstructures – A case for controlled imperfection, Acta Mater. 148 193–201 (2018).
- J. Villanova, R. Daudin, P. Lhuissier, D. Jauffrès, S. Lou, C.L. Martin, S. Labouré, R. Tucoulou, G. Martínez-Criado, L. Salvo, Fast in situ 3D nanoimaging: A new tool for dynamic characterization in materials science, Mater. Today. 20 354–359 (2017).
- A. Burr, W. Noël, P. Trecourt, M. Bourcier, F. Gillet-Chaulet, A. Philip, C.L. Martin, The anisotropic contact response of viscoplastic monocrystalline ice particles, Acta Mater. 132 576–585 (2017).
- D. Roussel, A. Lichtner, D. Jauffrès, J. Villanova, R.K. Bordia, and C.L. Martin, Strength of hierarchically porous ceramics : discrete simulations on X-ray nanotomography images, Scr. Mater., 113 250–253 (2016).
- R. Kumar, S. Rommel, D. Jauffrès, P. Lhuissier, and C.L. Martin, Effect of packing characteristics on the discrete element simulation of elasticity and buckling, Int. J. Mech. Sci., 110 14–21 (2016).
- A. Lichtner, D. Roussel, D. Jauffrès, C.L. Martin, and R.K. Bordia, Effect of Macro-Pore Anisotropy on the Mechanical Properties of Porous Ceramics, J. Am. Ceram. Soc., 1–9 (2015).
- L. Hedjazi, C.L. Martin, S. Guessasma, G. Della Valle, and R. Dendievel, Experimental investigation and discrete simulation of fragmentation in expanded breakfast cereals, Food Res. Int., 55 28–36 (2014).
- Z. Yan, O. Guillon, C.L. Martin, S. Wang, C.-S. Lee, and D. Bouvard, In-situ synchrotron x-ray transmission microscopy of the sintering of multilayers, Appl. Phys. Lett., 102 223107 (2013).
- Z. Yan, C.L. Martin, O. Guillon, and D. Bouvard, Effect of size and homogeneity of rigid inclusions on the sintering of composites, Scr. Mater., 69 327–330 (2013).
- D. Jauffrès, C.L. Martin, A. Lichtner, and R.K. Bordia, Simulation of the toughness of partially sintered ceramics with realistic microstructures, Acta Mater., 60 4685–4694 (2012).
- X. Liu, C.L. Martin, D. Bouvard, S. Di Iorio, J. Laurencin, and G. Delette, Strength of Highly Porous Ceramic Electrodes, J. Am. Ceram. Soc., 94 3500–3508 (2011).
- P. Pizette, C.L. Martin, G. Delette, P. Sornay, and F. Sans, Compaction of aggregated ceramic powders: From contact laws to fracture and yield surfaces, Powder Technol., 198 240–250 (2010).
- C.L. Martin and R.K. Bordia, The effect of a substrate on the sintering of constrained films, Acta Mater., 57 549–558 (2009).
- C.L. Martin and R.K. Bordia, Influence of adhesion and friction on the geometry of packings of spherical particles, Phys. Rev. E, 77 31307 (2008).
- C.L. Martin, G. Delette, and D. Bouvard, Compaction of ceramic aggregated powders, J. Am. Ceram. Soc., 89 3379–3387 (2006).
- C.L. Martin, L.C.R. Schneider, L. Olmos, and D. Bouvard, Discrete element modeling of metallic powder sintering, Scr. Mater., 55 425–428 (2006).
- L.C.R. Schneider, C.L. Martin, Y. Bultel, D. Bouvard, and E.Siebert, Discrete modelling of the electrochemical performance of SOFC electrodes, Electrochim. Acta, 52 314–324 (2006).
- C.L. Martin, Elasticity, fracture and yielding of cold compacted metal powders, J. Mech. Phys. Solids, 52 1691–1717 (2004).
- C.L. Martin, D. Bouvard, and S. Shima, Study of particle rearrangement during powder compaction by the Discrete Element Method, J. Mech. Phys. Solids, 51 667–693 (2003).