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(80) Production(s) de GEORGE M.
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Wetting Phenomena at The Nanoscale Inside Sharp Cracks in Silica Glasses
Auteur(s): Ciccotti Matteo, George M., Grimaldi Antoine, Pallares Gaël, Charlaix E., Marliere Christian
(Affiches/Poster)
Statphys23 (Genova, Italy, FR), 2007-07-09 |
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Formation and evolution of a confined liquid condensate at the crack tip in glasses
Auteur(s): George M., Ciccotti Matteo, Wondraczek L., Dittmar A., Oelgardt C., Celarie Fabrice, Marliere Christian
Conférence invité: Proceedings of the Fifth conference on the fractography of glasses and ceramics (Rochester, New-York, United states of america, FR, 2007)
Actes de conférence: Wiley & Sons, vol. 199 p.25-34 (2007)
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Effect of stress gradient at the vicinity of a crack tip on ionic diffusion in silicate glasses : an AFM study 
Auteur(s): Celarie F., Ciccotto Matteo, George M., Marliere Christian
Conference: The Fifth Conference on the Fractography of Glasses and Ceramics (Rochester, US, 2006-06-09)
Actes de conférence: Fractography of glasses an ceramics V, vol. p.35 (2007)
Ref HAL: hal-00408605_v1
Exporter : BibTex | endNote
Résumé: The slow advance of a crack in sodo-silicate glasses was studied at nanometer scale by in-situ atomic force microscopy (AFM) in a well-controlled atmosphere (N2 and H2O). An enhanced diffusion of sodium ions in the stress-gradient field at the sub-micrometric vicinity of the crack tip was revealed through several effects: growth of nodules in height images, changes in the AFM tip–sample energy dissipation as detected in phase images. Ex-situ chemical micro-analyses completed the AFM measurements. The nodules patterns revealed a dewetting phenomenon evidenced by “breath figures”, i.e. analog to the fogging that occurs when a vapour condenses onto a 'cold' surface [D. Beysens et al., Phys. Rev. Let. 57, 1433 (1986)]. These experimental results were explained by a two-step process: i) a fast migration of sodium ions towards the fracture surfaces as proposed by Langford et al. [J. Mat. Res. 6, 1358 (1991)], ii) a slow backwards diffusion of the cations as evidenced in these AFM experiments (typical time: few minutes). Measurements of the diffusion coefficient of that relaxing process were done at room temperature. Our results strengthen the theoretical concept of a near-surface structural relaxation due to the stress-gradient at the vicinity of the crack tip. Raman and SIMS studies revealed that nodules – for samples studied after exposition to common air - are preferentially covered by an organic overlayer of a carboxylate salt with a long aliphatic chain. The catalytic role of sodium ions in that chemical process is suspected.
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FORMATION AND EVOLUTION OF A CONFINED LIQUID CONDENSATE AT THE CRACK TIP IN GLASSES
Auteur(s): George M., Ciccotti M., Ranieri V., Wondraczek L., Dittmar A., Oelgardt C., Celarie F., Marliere C.
Conference: 5th Conference on the Fractography of Glasses and Ceramics (Rochester (NY), FR, 2006-07-09)
Ref HAL: hal-00656886_v1
DOI: 10.1002/9781118144152.ch3
Exporter : BibTex | endNote
Résumé: Crack propagation in oxide glasses at low crack velocities is controlled by stress corrosion. Proper knowledge of the crack tip chemical environment is thus crucial to understand the slow fracture process of these materials. The formation of a liquid condensate in the confined area of the crack tip is theoretically expected and is classically mentioned to explain specific behavior during the crack propagation. Since this condensate is of the nanometer scale and cannot be traced post mortem, it is extremely difficult to observe. This paper reports the experimental evidences of the presence of a liquid condensate at the tip of a crack propagating by stress corrosion in silica glass. The observation has been performed in situ under carefully controlled atmosphere through phase imaging by atomic force microscopy (AFM). The evolution of the condensate has been followed as a function of the relative humidity. The impact of those evidences of the liquid condensate will be discussed and information on its size or evolution kinetic will be reported.
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The characterisation of rough particle contacts by atomic force microscopy
Auteur(s): George M., Goddard D.T.
(Article) Publié:
Journal Of Colloid And Interface Science, vol. 299 p.665-672 (2006)
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Formation and evolution of a confined liquid condensate at the crack tip in glasses
Auteur(s): George M., Ciccotti Matteo, Marliere Christian, Wondraczek L., Dittmar A., Oelgardt C., Celarie Fabrice
Conference: Fractography of glasses and ceramics (Rochester, US, 2006-07-09)
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Nanomechanics of slow crack propagation in oxide glasses
Auteur(s): Ciccotti Matteo, George M., Wondraczek L., Celarie Fabrice, Marliere Christian
Conference: European fracture conference (ECF 16) (Alexandropolis, Greece, FR, 2006-07-03)
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