Origin of cristobalite formation during sintering of a binary mixture of borosilicate glass and high silica glass

1994 ◽  
Vol 9 (4) ◽  
pp. 999-1005 ◽  
Author(s):  
Tapan K. Gupta ◽  
Jau-Ho Jean
Keyword(s):  
Binary Mixture ◽  
Borosilicate Glass ◽  
Silica Glass ◽  
High Silica ◽  
Dissolution And Precipitation

It was shown previously1 that cristobalite precipitates out of a mixture of borosilicate glass (BSG) and high silica glass (HSG) when sintered at temperatures ranging from 800 to 1200 °C. In this paper, both direct and indirect evidences are presented to conclude that the formation of cristobalite originates in HSG. It is proposed that the cristobalite is formed as a result of dissolution of HSG in BSG and precipitation at heterogeneously nucleated sites. The process of dissolution and precipitation continues until the whole HSG particle is consumed.

Devitrification inhibitor in binary borosilicate glass composite

1993 ◽  
Vol 8 (2) ◽  
pp. 356-363 ◽  
Author(s):  
Jau-Ho Jean ◽  
Tapan K. Gupta
Keyword(s):  
Binary Mixture ◽  
Reaction Layer ◽  
Borosilicate Glass ◽  
Crystalline Phase ◽  
Silica Glass ◽  
Glass Composite ◽  
Alkali Ions ◽  
Strong Affinity ◽  
Alumina Particles ◽  
High Silica

When an appropriate mixture of a low-softening borosilicate glass (BSG) and a high-softening high silica glass (HSG) is sintered at temperatures ranging from 800 to 1000 °C, a crystalline phase, identified as cristobalite by XRD, is known to precipitate out of the initial amorphous binary mixture of glasses as the sintering continues. The precipitation of cristobalite is found to originate in HSG, and is controlled by the transport of alkali ions (e.g., K+, Na+, and Li+) from BSG to HSG.1 In this paper, we report that when a small amount of alumina is present as a dopant in the above binary mixture of BSG and HSG, the cristobalite formation is completely prevented at the sintering temperatures investigated. The above result is attributed to a strong affinity between Al+3 from alumina and alkali ions from BSG, which diverts the diffusion of alkali ions from HSG to alumina, thus forming a K+ and Al+3-rich reaction layer adjacent to the alumina particles far too rapidly compared to that of cristobalite formation.

Devitrification inhibitors in borosilicate glass and binary borosilicate glass composite

1995 ◽  
Vol 10 (5) ◽  
pp. 1312-1320 ◽  
Author(s):  
Jau-Ho Jean ◽  
Tapan K. Gupta
Keyword(s):  
Borosilicate Glass ◽  
Silica Glass ◽  
Elevated Temperatures ◽  
Glass Composite ◽  
Binary Glass ◽  
High Silica ◽  
Glass Mixture

Cristobalite is known to precipitate out of borosilicate glass (Corning 7740) and a binary glass mixture of borosilicate glass and high silica glass when these glasses are heated to elevated temperatures. To prevent cristobalite from forming in these glass systems, a devitrification inhibitor needs to be found. Among oxides selected for testing, both Al2O3 and Ga2O3 are found to prevent cristobalite from forming in these glass systems.

An Experimental Comparison of Alternative Solid Forms for Savannah River High-Level Wastes

1981 ◽  
Vol 6 ◽  
Author(s):  
John A. Stone
Keyword(s):  
Borosilicate Glass ◽  
Silica Glass ◽  
Deionized Water ◽  
Experimental Comparison ◽  
Savannah River ◽  
Waste Forms ◽  
High Silica ◽  
High Level ◽  
Selection Of ◽  
High Aluminum

ABSTRACTSamples of borosilicate glass, high-silica glass, tailored ceramic, and SYNROC, incorporating simulated Savannah River high-level defense waste sludges, were leached by the MCC-1 procedure for times up to 28 days. Cesium, uranium, and cerium leach rates are reported for waste forms containing a composite sludge, at 40°C in deionized water, and at 90°C in deionized water, silicate water, and brine. The ordering of the waste forms from best to worst differs for each element leached, and none of the forms show a clear advantage for all the key radwaste elements. Some cesium leach rates for forms containing high-aluminum or high-iron sludges also are presented. So far, only small effects of sludge type have been observed, with one exception. This study is one of several inputs for selection of an alternative waste form for Savannah River waste.

Effect of gallium oxide in preventing cristobalite formation in binary borosilicate glass composite

1993 ◽  
Vol 8 (9) ◽  
pp. 2393-2399 ◽  
Author(s):  
Jau-Ho Jean ◽  
Tapan K. Gupta
Keyword(s):  
Binary Mixture ◽  
Reaction Layer ◽  
Borosilicate Glass ◽  
Crystalline Phase ◽  
Gallium Oxide ◽  
Oxide Particle ◽  
Glass Composite ◽  
Alkali Ions ◽  
High Silica ◽  
Oxide Particles

When an appropriate mixture of low-softening borosilicate (BSG) and high-softening high silica (HSG) glasses is sintered at temperatures ranging from 800 to 1000 °C, a crystalline phase, identified as cristobalite by XRD, is known to precipitate out of the initial amorphous binary mixture of glasses as the sintering continues. The precipitation of cristobalite is found to originate in HSG and is controlled by the transport of alkali ions (e.g., K, Na, and Li) from BSG to HSG.1 In this paper we report that when a small amount of gallium oxide is present as a dopant in the above binary mixture of BSG and HSG, the cristobalite formation is completely prevented at the sintering temperatures investigated. The above result is attributed to a strong affinity between Ga+3 from gallium oxide particle and alkali ions from BSG, which diverts the diffusion of alkali ions from HSG to gallium oxide, thus forming a K+ and Ga+3-rich reaction layer adjacent to gallium oxide particles far too rapidly compared with that of cristobalite formation.

An electron spin resonance study of ultraviolet photolyzed methanol adsorbed on porous high-silica glass

1969 ◽  
Vol 47 (8) ◽  
pp. 1375-1379 ◽  
Author(s):  
Michie Shimizu ◽  
H. D. Gesser ◽  
M. Fujimoto
Keyword(s):  
Free Radicals ◽  
Electron Spin Resonance ◽  
Electron Spin ◽  
Silica Glass ◽  
Electron Spin Resonance Study ◽  
Surface Contaminants ◽  
Spin Resonance ◽  
High Silica ◽  
Glass Surfaces ◽  
Spin Resonance Study

The electron spin resonance (e.s.r.) spectra of •CH3, •CHO, H and/or D, and possibly •CH2OH or •CH2OD were found by the ultraviolet (u.v.) photolysis of methanol —OH or —OD on porous high-silica glass at 77 °K. These e.s.r. spectra resemble the results of the u.v. photolysis of X-irradiated methanol indicating that some perturbation and/or sensitization occurred in the molecules by the glass surface. The absence of e.s.r. spectra from the same systems on the acid-leached glass, on the totally fluorinated glass, or on the totally —OH covered glass suggests that (i) the co-existence of surface contaminants, such as Al and Zr and not B, and some of surface —OH could be responsible for producing these free radicals, and (ii) the methanols adsorbed on these glass surfaces are stabilized against u.v. photolysis.

scholarly journals Improvement of Oxidation Resistivity of Carbon Material by High Silica Glass Impregnation

TANSO ◽  
1994 ◽  
Vol 1994 (163) ◽  
pp. 133-137 ◽  
Author(s):  
Shigeru Ikeda ◽  
Hiroshi Shioyama ◽  
Osamu Nakamura ◽  
Shoji Hori ◽  
Kiyohisa Eguchi ◽  
...  
Keyword(s):  
Carbon Material ◽  
Silica Glass ◽  
High Silica

Preparation and photoluminescence of high silica glass containing Eu:SnO2 nanocrystals

2020 ◽  
Vol 46 (16) ◽  
pp. 24955-24960
Author(s):  
Shupei Zheng ◽  
Zaijin Fang ◽  
Shuai Han ◽  
Yi Long ◽  
Jianfeng Li ◽  
...  
Keyword(s):  
Silica Glass ◽  
High Silica
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