Glass science and technology 

About: Glass science and technology is an academic journal. The journal publishes majorly in the area(s): Float glass & Crystallization. It has an ISSN identifier of 0946-7475. Over the lifetime, 442 publications have been published receiving 3826 citations.

Three-dimensional radiative heat transfer in glass cooling processes

Abstract: For the numerical simulation of 3D radiative heat transfer in glasses and glass melts, practically applicable mathematical methods are needed for optimal handling of problems using workstation-class computers. Since the exact solution would require supercomputer capabilities, approximate solutions with a high degree of accuracy are given. An improved diffusion approximation is presented. In contrast to the classical Rosseland approximation this method makes use of the geometry and the nongrey character for the absorption of glass. The improved 3D diffusion approximation studied in this paper has the advantage to be both efficient and sufficiently accurate.

Quantification of H2O contents in silicate glasses using IR spectroscopy: a calibration based on hydrous glasses analyzed by Karl-Fischer titration

Abstract: Water-related IR absorption bands were investigated in hydrous soda-lime-silica glass (SLS) and float glass (FG). Glasses containing between 0.5 and 6 wt% H 2 O (corresponding to 0.7 and 8 mol/l) were synthesized in platinum capsules by re-melting glass powder to which water had been added. Synthesis were perfomed in an internally heated gas pressure vessel at temperatures of 1200 to 1250 °C and pressures 100 to 500 MPa. The total water content (C w a t e r ) of glasses was analyzed by pyrolysis and subsequent Karl-Fischer titration. Five bands at 3550, 2850, 2350, 1730 and 1635 cm - 1 in the IR spectrum of an SLS glass containing 4 wt% H 2 O were identified as vibration modes of water-related species by comparison with a D 2 O-bearing glass. With increasing C w a t e r , the absorbance band at 3550 cm - 1 (OH stretch of weakly H-bonded hydrous species) grows in intensity relative to the band at 2850 cm - 1 (OH stretch of strongly H-bonded hydrous species). As a consequence, the practical absorption coefficient for the band at 3550 cm - 1 (e 3 5 5 0 p r a c t , defined by assigning the total water to this band) is 20% lower at 0.1 wt% water than at 4 wt% water. The dependence of e 3 3 5 0 p r a c t on C w a t e r is most pronounced above 0.5 wt% but appears to be present also in water-poor glasses. In contrast, e 2 8 5 0 p r a c t does not noticeably depend on water content (FG: e 2 8 5 0 p r a c t = (40.2 ′ 2.4) l.mol - 1 .cm - 1 ; SLS: e 2 8 5 0 p r a c t = (50.8 ′ 2.0) l.mol - 1 .cm - 1 and, hence, it is preferred for water determination in float glass and soda-lime-silica glass. Scbolze's two-band method [1] using the peak height of both bands at 3550 and 2850 cm - 1 to quantify C w a t e r in glasses is a suitable first approach also for hydrous glasses, predicting the water content within 20% relative. However, for a more precise determination the dependence of the e-values on C w a t e r has to be considered. A preliminary evaluation of the H 2 O bending vibration band at 1635 cm - 1 shows that molecular H 2 O is a minor hydrous species in FG and SLS glasses with a maximum concentration of 2.0 wt% in FG glass containing 5.7 wt% Total water. On the basis of the new spectroscopic results and data from literature the assignment of the so-called ABC triplet (bands 2850, 2350 and 1750 cm - 1 ) is discussed.