Chromčíková, Mária

Karell, Radovan

Kraxner, Jozef

Liška, Marek

English

DSpace at VSB Technical University of Ostrava

llll\1LI� Sborník vědeckých prací Vysoké školy báňské - Technické univerzity Ostrava číslo I, rok 2008, ročník LI, řada hutnická článek č. 1400 PROPERTIES OF SELECTED ZIRCONIA CONT AlNING SILIC A TE GLASSES R. KARELL 1 , J. KR.AXNER2, M. CHROMČÍKOVÁ2, M. LIŠKA2 1 Faculty of lndustrial Technologies, Alexunder Dubček University o/ Trenčín, Ivana Krasku 491130, Púchov,SK-020 OJ, Slovak Republic, karell@Jnuni.sk :Vitrum Laugaricio -Joint Glass Centre ofthe Institute o/ lnorganic Chemislry, Slovak Academy o/ Sciences, Alexander Dubček University o/ Trenčín and RONA, a.s., Študentská 2, Trenčín, SK-91 I 50, Slovak Republic, chromcikovu@Jnuni.sk ABSTRACT: Viscosity, density, thermal expansion, glass transition temperature, refractive index, molar refraction, and chemical durability of compositional series of Na2O-K2O-ZnO-CaO-ZrO2-SiO2 glasses containing I and 3 mol. % ZrO2 were measured and interpreted according to the network­forming I modifying activities of particular oxides. The influence of ZrO2 / SiO2, ZnO / CaO, and K2O / Na2O substitution on measured physical and chemical properties was detected. The regression formulae describing the temperature and composition dependence of the above properties were proposed. KEY WORDS: density, zirconia-silicate glasses I. INTRODUCTIONThe tendency to produce crystal glass without toxic elements like BaO and PbO is observed in recent years. The most suitable elements to substitute harmful oxides belong to fourth group of periodical tahle (e.g. Zr02 and TiO2). Addition of ZrO2 has positive influence on hydrolytic durability, refractive index and density of glasses. On the other hand, it increases the glass transition temperature and viscosity thereby increases the melting temperature [I, 2]. ln silicate glasses with lower ZrO2 amount (1-4 wt. %) Farges and Calas [3] found Zr to be mainly 6coordinated. The abundance of6-coordinated Zr should increase with melt depolymerization as a result of the increasing network modifier content. The possible structural model of 6coordinated zirconium in silicate glasses based on the EXAFS study [4] consists in Zr06 octahedron with four bridging and two non-bridging oxygen atoms ·(schematically[ZrO2O4/2]4°). Thus, ZrO2 not only takes part in the formation of the silicate network, but in additionit heals the broken Si-O-Si bridges according to the reaction:4 =Si-O- + Zr02 ........ 2 =Si-O-Si= + [ZrO2Q412 ]<1- {I) The literature data conceming the composition - property relationships for more than three component zirconia containing silicate systems are relatively scarce [5, 6]. Therefore the effect of the equimolar Zr02 I SiO2, ZnO / CaO, and K2O / Na2O substitution in the Na2O-K2O-CaO-ZnO-Zr0i-SiO2 system is aimed in the present work. 2. EXPERIMENT AL PARTThe glass batches were prepared by mixing of powdered Na2CO3 (AFT, p.a.), K2CO3 (Fluka, p.a.), ZnO (Fluka, p.a.), ZrSiO4 (Aldrich, p.a.) and SiO2 (AFT, min. 96.5 %). Sodium sulphate (AFT, p.a.) and potassium stllphate (Lachema, p.a.) were used as fining agents. Glasses were _melted in Pt-JO¾Rhcrucible in superkanthal fumace at temperature of I 600°C for two-three hours in ambient atmosphere. 235 

Properties of selected zirconia containing silicate glasses

http://dspace.vsb.cz/bitstream/10084/67114/2/VSB%20HUF%202008-1_50_Karell.pdf

Properties of selected zirconia containing silicate glasses

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