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Abstract  

New oxyfluoride glasses based on the system ZrO2-Pr2O3-ZrF4-BaF2 were obtained, and the glass forming ability of this system was evaluated. The effects of glass composition on both thermal stability and the crystalline phases formed upon heat treatment were determined by the DSC and XRD methods, respectively. The composition with higher thermal stability and better glass forming ability contained 2 mol% of oxides.

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Abstract  

New fluorindate glass compositions have been investigated in order to improve optical transmission as well as thermal properties. Chloride inclusion extends transmission of a fluoride matrix to longer wavelength in infrared region. In the present work thermal parameters of an IZnBS composition, based on InF3, ZnF2, BaF2 and SrF2, with various amounts of alkaline chlorides were investigated by differential scanning calorimetry. The chloride presence decreased all characteristic temperatures and increased both thermal stability and glass forming ability up to 10% of MCl content, where M=Li, Na, K and Rb. The presence of NaCl promoted glass phase separation. For samples containing same concentration of NaCl, this effect is accentuated for increasing the contents of SrF2.

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Abstract  

New glasses have been synthesized in the system ZrF46BaF26PrF3. Glasses were prepared by conventional fusion method and the vitreous domain was established. For vitreous samples the thermal stability parameters were determined, so that the best compositions could be selected according to a compromise between high glass forming ability and thermal stability vs. crystallization.

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Abstract  

Waste compromises environmental preservation as well human health in many countries. Recycling is an alternative that sometimes represents the only economical activity for a significant population in the big cities. Almost 3% of waste materials in Brazil are vitreous. Ceramic production adding waste glass is possible with advantages of costs reduction associated to decrease on firing temperatures and to the raw material itself. At present paper up to 80 mass% of waste glass was added to clay. The sintering temperature decreased linearly and the shrinkage increased with glass content, an effect more pronounced for high glass amount.

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Abstract  

Xerogels were prepared from zirconium, barium, aluminum, lanthanum and lithium acetates, corresponding to a Li containing ZBLA composition. The study of their thermal properties (DSC, TG/DTG, FT-IR) showed that they might be used as chemically stable precursors in the preparation of fluoride glasses. Hydrofluoric acid in solution was chosen as a mild fluorinating agent. This newly proposed technique of fluorinating allowed to obtain high quality ZBLALi glass which presents the advantage of higher thermal stability and homogeneity in comparison with the glass obtained using individual commercial fluorides.

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Journal of Thermal Analysis and Calorimetry
Authors: J. R. J. Delben, S. S. Rojas, K. Miazato, P. Melnikov, A. A. S. T. Delben, C. X. Cardoso, and A. Job
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Journal of Thermal Analysis and Calorimetry
Authors: P. Melnikov, F. J. dos Santos, S. B. Santagnelli, M. A. C. Secco, W. R. Guimarăes, A. Delben, and J. R. Delben
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Abstract  

Membranes of latex extracted of the seringueira tree (Hevea brasiliensis), genetically improved by selection and statistics methods, were prepared by air drying a 10 mL suspension of the ammonia in latex 10% (v/v). TG-DTG and DSC curves were used to characterize the membranes. Thermal stability and thermal decomposition of these compounds were analyzed. The results obtained show no differences among latex from different clones.

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