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The influence of basicity on oxygen activity and antimony oxide fining efficiency in alkali alkaline earth aluminosilicate glasses
Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. (glas)
Växjö University, Faculty of Mathematics/Science/Technology, School of Technology and Design. (glas)
(Glafo)
2009 (English)In: European Journal of Glass Science and Technology. Part A: Glass Technology, ISSN 1753-3546, Vol. 50, no 5, p. 241-246Article in journal (Refereed) Published
Abstract [en]

The number of bubbles was monitored in antimony oxide fined R2O-MxOy-SiO2 and R2O-CaO-Al2O3-SiO2 glasses (R = Na, K; M = Ca, Mg, Ba, Sr, Zn, B, Al, Ti, x = 1 or 2, y = 1, 2 or 3) in order to evaluate the fining efficiency. Electrochemical measurements of oxygen activity were used to, in situ, monitor the fining characteristics and conditions in some of the investigated glass melts. The results showed that an increase of the calculated optical basicity was related to an increased number of bubbles in the glass samples. The oxygen activity in the melt during fining decreased with increased optical basicity.

Place, publisher, year, edition, pages
Sheffield: Society of Glass Technology , 2009. Vol. 50, no 5, p. 241-246
National Category
Materials Engineering
Research subject
Technology (byts ev till Engineering), Glass Technology
Identifiers
URN: urn:nbn:se:vxu:diva-6605OAI: oai:DiVA.org:vxu-6605DiVA, id: diva2:285804
Available from: 2010-01-13 Created: 2010-01-13 Last updated: 2017-12-12Bibliographically approved
In thesis
1. Redox reactions and structure - properties relations in mixed alkali/alkaline earth glasses: - The role of antimony oxides during the fining process- A structural study of copper(I) and copper(II)
Open this publication in new window or tab >>Redox reactions and structure - properties relations in mixed alkali/alkaline earth glasses: - The role of antimony oxides during the fining process- A structural study of copper(I) and copper(II)
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

It is important to optimize glass compositions for their specific purpose but also for the efficiency of the production process, the manufacturing of glass. This will be beneficial economically and environmentally. Today many processes and glass compositions are already optimized, but due to more strict legislation on toxic elements and substances there must be changes in many glass compositions. One of these elements is antimony; the oxide is used as fining agent to obtain a bubble free glass within a reasonable process time. One aim with this thesis is to obtain a deeper understanding of the fining mechanism in 20R2O-10MO-70SiO2 (R=Na and/or K, M = Ca and/or Ba, Mg, Sr) glasses in order to minimise the amount of Sb2O3. Another intention is to study the structure of 20R2O-10CaO-70SiO2 (R = Na, K) with Cu2+ as probe ion and thus get a deeper knowledge of the surrounding glass matrix.  The optical basicity scale is used to determine the acid/base character of the different glass compositions.

 

Fining efficiency results showed a remarkable increase of the number of remaining bubbles when the glass contains either approximately equal amounts of Na and K or Ca and Ba, Mg or Sr. The much higher number of bubbles in the potassium containing glasses compared to the sodium containing is explained by the increase in viscosity, the increase in optical basicity and thus lower oxygen activity. The differences in the fining efficiency when altering alkaline earth ions cannot be explained by the optical basicity values, it seems to be a more complicated situation.

 

This thesis also reports maximum in Vickers hardness and packing density as well as minimum in glass transition temperature for the mixed alkali glasses. The mixed alkaline earth glasses do not exhibit any clear nonlinear behaviour. Raman spectroscopy measurements showed a variation in the network connectivity which has a clear relation to the optical basicity of the different glass compositions. The combination of UV-Vis-NIR and X-ray absorption spectroscopy measurements showed that the coordination sphere for Cu(II) is a tetragonal distorted octahedron with two elongated Cu-O bonds along the z axis. There were no trends in the degree of tetragonal distortion, thus it was about the same for all the investigated glass compositions. Cu(I) is found to be coordinated by two oxygen ligands in mainly linear coordination sphere, evidenced from X-ray absorption spectroscopy.

Place, publisher, year, edition, pages
Växjö: Linnaeus University Press, 2015. p. 73
Series
Linnaeus University Dissertations ; 231
Keywords
Fining, oxygen activity, redox reactions, mixed alkali effect, mixed alkali silicate glasses, copper, antimony
National Category
Civil Engineering
Research subject
Technology (byts ev till Engineering), Glass Technology
Identifiers
urn:nbn:se:lnu:diva-46782 (URN)978-91-87925-82-5 (ISBN)
Public defence
2015-11-06, Södrasalen, Universitetsplatsen 1, Växjö, 13:00 (English)
Opponent
Supervisors
Available from: 2015-10-20 Created: 2015-10-19 Last updated: 2016-01-27Bibliographically approved

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Grund Bäck, LinaJonson, Bo

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