Characterization and identification of local defects in glass

Abstract

Summary:The most relevant defects in glasses are categorized and investigated by appropriate microanalytical techniques. Since these defects very often present a real challenge because of complex chemical and mineralogical properties, a multimethod approach is necessary to supplement or confirm the findings from scanning techniques. The combination of electron probe microanalysis/energydispersive x-ray (EPMA/EDX) and laser ablation inductively coupled plasma mass spectroscopy (LA-ICP-MS) allows the determination of element trace concentrations in a knot, a glassy defect, thus finally enabling the identification of a special source of the defect from otherwise nondistinguishable refractories. The type of crystals can be determined exactly by the use of EPMA and x-ray dispersion (XRD), stones (a crystalline agglomerate) are analyzed by EPMA/EDX pointing to a possible source for this defect; results on metallic inclusions, "filled bubbles," and surface defects are reported and defect sources are discussed. Since close cooperation with the production departments and knowledge of production techniques and conditions are necessary for the diagnosis to take appropriate countermeasures, an approach is presented which systematically accumulates all information into a data base. The structure of such "expert systems" is described, which leads to correlation of appearance, analytical data, and source of the defects for even more accurate diagnosis and faster reaction.

Tunable Raman Gain in Transparent Nanostructured Glass-Ceramic Based on Ba2NaNb5O15 †

“…Because this study aimed to clarify the correlations between structural transformations of the glassy matrix and NLO properties, all the results were collected on glass specimens that were free of defects. Nevertheless, to focus on the different role of the distinct possible phases present in the glass (bulk, crystalline microdomains, and nanodomains) in modulating its NLO properties, we also selected and examined glass specimens with crystalline inclusions (microdomains) [ 59 ]. Optical microscopy was used to identify the presence and spatial distribution of microdomains and to assist with the elemental analysis of the subsequent SEM-EDS investigation of both the bulk and microdomain phases.…”

Phase diagram study and thermodynamic modeling of the Na2O–Al2O3–ZrO2 system

“…In particular, soda‐lime glass contains up to 14 wt.% Na 2 O (+K 2 O) 1 . Alkali oxides such as Na 2 O and K 2 O in molten glass can cause severe corrosion of alumina–zirconia–silica (AZS) refractories at high temperatures 2,3 and induce the defects in glasses 4 . To understand the corrosion mechanism of zirconia‐based AZS refractory and the formation of defects in glass, accurate information on the phase diagram and chemical reaction within the Na 2 O–Al 2 O 3 –SiO 2 –ZrO 2 system is essential.…”

“…1 Alkali oxides such as Na 2 O and K 2 O in molten glass can cause severe corrosion of alumina-zirconiasilica (AZS) refractories at high temperatures 2,3 and induce the defects in glasses. 4 To understand the corrosion mechanism of zirconia-based AZS refractory and the formation of defects in glass, accurate information on the phase diagram and chemical reaction within the Na 2 O-Al 2 O 3 -SiO 2 -ZrO 2 system is essential. However, no accurate phase diagrams of the Na 2 O-Al 2 O 3 -ZrO 2 system and entire quaternary system are available yet.…”

Quantitative evaluation of the improvement of B2O3 for the melting and fining process of high aluminium silicate glass batches under reduced atmospheric pressure

“…Glass with these properties generally requires high alumina content, which will lead to more difficulties in glass melting and fining process, such as the discharge of bubbles. The existence of bubbles is one of the main defects in glass production [8], it will affect the homogeneity and transparency of glass, as well as the mechanical strength and the thermal stability. The fining agent in the glass batch can vaporize or decompose to oxygen, which can promote the escaping of bubbles in the glass liquid [9].…”