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Vickers hardness and fracture toughness of glasses with composition 22Na2O.8CaO.5MO2.65SiO2 (M = Si, Ti, Ge, Zr, Sn, Ce)


We intend to prepare and characterize glasses with composition (% mol) 22Na2O.8CaO.5MO2.65SiO2, with M being a tetravalent ion (Si, Ti, Ge, Zr, Sn, Ce). The behavior of the Vickers microhardness, Hv, the fracture toughness, KIC, and the Young modulus, E, will be studied as a function of the tetravalent ion in the glass structure. Samples of these glasses will be submitted to Ag+Na+ ion exchange in molten AgNO3-NaNO3 salt. The surface with Ag, due to the ion migration, will be submitted to Vickers hardness, fracture toughness, energy dispersive spectroscopy and infrared spectroscopy measurements. Hardness, toughness and infrared results will be analyzed in terms of structural changes produce by the presence of the tetravalent elements and by the migration of Ag+ ions. Energy dispersive spectroscopy measurements will provide results which will enable to define the tetravalent elements which hinder and enhance the Ag+ migration to the bulk. Measurements of the Ag+ and Na+ concentration profiles will make possible to calculate the self-diffusion coefficients of these ions by the Boltzmann-Matano technique. In order to develop the research here proposed, we are requesting an optical microscope with a Vickers indentation device, and an equipment to determine the ultrasonic velocities in the glass samples, which will enable to calculate their elastic moduli. (AU)

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(References retrieved automatically from Web of Science and SciELO through information on FAPESP grants and their corresponding numbers as mentioned in the publications by the authors)
BRAUNGER, M. L.; ESCANHOELA, C. A.; FIER, I.; WALMSLEY, L.; ZIEMATH, E. C.. Electrical conductivity of silicate glasses with tetravalent cations substituting Si. Journal of Non-Crystalline Solids, v. 358, n. 21, p. 2855-2861, . (08/07238-4, 08/07304-7, 05/04397-6)

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