Variations in glass composition in an operating furnace

1998 ◽  
Vol 55 (11-12) ◽  
pp. 340-343
Author(s):  
E. K. Polokhlivets ◽  
V. I. Kiyan ◽  
A. B. Atkarskaya

Author(s):  
M. A. McCoy

Transformation toughening by ZrO2 inclusions in various ceramic matrices has led to improved mechanical properties in these materials. Although the processing of these materials usually involves standard ceramic powder processing techniques, an alternate method of producing ZrO2 particles involves the devtrification of a ZrO2-containing glass. In this study the effects of glass composition (ZrO2 concentration) and heat treatment on the morphology of the crystallization products in a MgO•Al2•SiO2•ZrO2 glass was investigated.



2015 ◽  
Vol 48 (6) ◽  
pp. 145-150
Author(s):  
Bong-Ki Ryu ◽  
Il-Gu Kim ◽  
Young-Seok Kim ◽  
Jong-Hwan Kim ◽  
Jae-Yeop Jung ◽  
...  


2021 ◽  
Vol 83 (4) ◽  
Author(s):  
L. R. Monnereau ◽  
B. S. Ellis ◽  
D. Szymanowski ◽  
O. Bachmann ◽  
M. Guillong

AbstractDense, glassy pyroclasts found in products of explosive eruptions are commonly employed to investigate volcanic conduit processes through measurement of their volatile inventories. This approach rests upon the tacit assumption that the obsidian clasts are juvenile, that is, genetically related to the erupting magma. Pyroclastic deposits within the Yellowstone-Snake River Plain province almost without exception contain dense, glassy clasts, previously interpreted as hyaloclastite, while other lithologies, including crystallised rhyolite, are extremely rare. We investigate the origin of these dense, glassy clasts from a coupled geochemical and textural perspective combining literature data and case studies from Cougar Point Tuff XIII, Wolverine Creek Tuff, and Mesa Falls Tuff spanning 10 My of silicic volcanism. These results indicate that the trace elemental compositions of the dense glasses mostly overlap with the vesiculated component of each deposit, while being distinct from nearby units, thus indicating that dense glasses are juvenile. Textural complexity of the dense clasts varies across our examples. Cougar Point Tuff XIII contains a remarkable diversity of clast appearances with the same glass composition including obsidian-within-obsidian clasts. Mesa Falls Tuff contains clasts with the same glass compositions but with stark variations in phenocryst content (0 to 45%). Cumulatively, our results support a model where most dense, glassy clasts reflect conduit material that passed through multiple cycles of fracturing and sintering with concurrent mixing of glass and various crystal components. This is in contrast to previous interpretations of these clasts as entrained hyaloclastite and relaxes the requirement for water-magma interaction within the eruptive centres of the Yellowstone-Snake River Plain province.





1998 ◽  
Vol 240 (1-3) ◽  
pp. 66-78 ◽  
Author(s):  
H. Ebendorff-Heidepriem ◽  
D. Ehrt ◽  
M. Bettinelli ◽  
A. Speghini


1996 ◽  
Vol 465 ◽  
Author(s):  
M. Mika ◽  
M. J. Schweiger ◽  
J. D. Vienna ◽  
P. Hrma

ABSTRACTThe liquidus temperature (TL) often limits the loading of high-level waste in glass through the constraint that TL must be at least 100°C below the temperature at which the glass viscosity is 5 Pa-s. In this study, values of TL for spinel primary crystalline phase were measured as a function of glass composition. The test glasses were based on high-iron Hanford Site tank wastes. All studied glasses precipitated spinel (Ni,Fe,Mn)(Cr,Fe)2O4 as the primary crystalline phase. TL was increased by additions of Cr2O3, NiO, Al2O3, Fe2O3, MgO, and MnO; while Li2O, Na2O, B2O3, and SiO2 had a negative effect. Empirical mixture models were fitted to data.



2004 ◽  
Vol 68 (1) ◽  
pp. 83-100 ◽  
Author(s):  
E. Salvioli-Mariani ◽  
L. Toscani ◽  
D. Bersani

AbstractThe lamproite of Gaussberg is an ultrapotassic rock where leucite, olivine and clinopyroxene microphenocrysts occur in a glass-rich groundmass, containing microliths of leucite, clinopyroxene, apatite, phlogopite and rare K-richterite.Abundant silicate melt inclusions occur in olivine, leucite and, rarely, in clinopyroxene microphenocrysts. Raman investigations on melt inclusions showed the presence of pure CO2 in the shrinkage bubbles. On the other hand, the glass of the groundmass is CO2-poor and contains up to 0.70 wt.% of dissolved H2O, as estimated by infrared spectra. It is inferred that CO2 was released at every stage of evolution of the lamproite magma (CO2-rich shrinkage bubbles), whereas H2O was retained for longer in the liquid. At Gaussberg, CO2 seems to have a major role at relatively high pressure where it favoured the crystallization of H2O-poor microphenocrysts; the uprise of the magma to the surface decreased the solubility of CO2 and caused a relative increase in water activity. As a consequence, phlogopite and K-richterite appeared in the groundmass.The glass composition of both the groundmass and melt inclusions suggests different evolutions for the residual liquids of the investigated samples. Sample G886 shows the typical evolution of a lamproite magma, where the residual liquid evolves toward peralkaline and Na-rich composition and crystallizes K-richterite in the latest stage. Sample G895 derives from mixing/mingling of different batches of magma; effectively glasses from melt inclusions in leucite and clinopyroxene are more alkaline than those found in early crystallized olivine. Leucite and clinopyroxene crystallized early from a relatively more alkaline batch of lamproite magma and, successively, a less alkaline, olivinebearing magma batch assimilated them during its rise to the surface.



1999 ◽  
Vol 14 (9) ◽  
pp. 3759-3764 ◽  
Author(s):  
Shunsuke Ito ◽  
Tomokatsu Hayakawa ◽  
Toshihiro Kasuga ◽  
Masayuki Nogami

Persistent spectral hole burning was observed in Eu3+-doped BaO–PbO–P2O5 glasses, and the dependence of hole properties on the glass composition was investigated in relation to the local structure surrounding the Eu3+ ions. The hole was burned on the 7F0 → 5D0 transition of the Eu3+ ions, the depth of which decreased with increasing PbO content, whereas the hole width increased. The hole was burned at 6 K, filled on increase in temperature, and erased above 120 K. Judd–Ofelt parameters and fluorescence line-narrowing spectra indicated that the symmetry of the Eu3+ site increases and the covalency of the Eu–O bond decreases with increasing PbO content.



1997 ◽  
Vol 11 (3) ◽  
pp. 398
Keyword(s):  


2020 ◽  
Vol 25 ◽  
pp. 247-289
Author(s):  
Joanna Sawicka

The study presents 175 artefacts from the settlement center in Gniezno – beads and rings. The materials come from settlement levels from around the mid-10th to the 13th centuries. The latest chronological findings based on 14C dating have made it possible to refine the dating, especially of the early settlement levels of the stronghold, where the vast majority of glass artefacts come from. Threeba sic groups of beads have been distinguished based on the technique of their production – beads made of a drawing a tube, the technique of winding a glass strip, as well as casting and sintering. The results of 7 physico-chemical analyzes of the glass composition (performed with the X-Ray Fluorescence, XRF method) are presented. Physicochemical analyzes of the chemical composition of the tested beads made it possible to determine the technological group and the type of glass. An attempt was made to explain the origin of the starting material (glass) for jewelery. A comparative analysis made it possible to indicate in a general manner possible manufacturers and to outline the likely directions of the influx of these glass ornaments to Gniezno.



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