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- ItemAdvanced oxygen burner for the glass industry(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Legiret, Thierry; Philippe, Louis; Tsiava, Remi; Marié, Bruno[no abstract available]
- ItemKonventionell beheizte Glasschmelzöfen für die Hohl- und Flachglasherstellung im deutschsprachigen Raum - Ergebnisse einer HVG-Umfrage - Teil 1. Beheizung, bauliche Merkmale, Schmelzleistung(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Fleischmann, Bernhard[no abstract available]
- ItemIn-situ investigations of sintering and crystallization of lithium aluminosilicate glass-ceramics(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Zimemr, José; Raether, Friedrich; Müller, GerdThe sintering and crystalhzation behaviour of a Li₂O-Al₂O₃-SiO₂ glass powder containing TiO₂ and ZrO₂ was investigated by the in-situ measuring methods of high-temperature dilatometry, high-temperature X-ray diffractometry and differential thermal analysis at heating rates between 0.5 a n d 20 K/min. By comparing the results of the different methods the shrinkage could be explained as an overlap of sintering and crystallization processes. When increasing the heating rate, the sintering and crystallization processes are separated mor e sharply, so that higher final densities of the sintered samples can be achieved.
- ItemVergleich verschiedener Kunststoffbeschichtungen zur Verbesserung der Bruch- und Auslaufsicherheit von Chemikalienflaschen aus Glas(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Lochner, Karl H.[no abstract available]
- ItemInvestigations into the existence of hexavalent chromium in industrial glasses(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Dusdorf, Wolfgang; Müller-Simon, HayoIn several melting experiments the existence of hexavalent chromium in soda-lime-silica glasses depending on the oxidation conditions and the presence of iron have been investigated by means of a recently proposed wet chemical analysis procedure. The observed dependence of the concentraüon of hexavalent chromium on the iron content can be explained by means of an electron exchange between iron and chromium during cooling. The results have been applied to the conditions of industrial glass melting. Under sufficiently reducing conditions and high portions of iron the existence of hexavalent chromium can be excluded. These conditions are fulfilled for all commercial container glasses investigated.
- ItemInterface phenomena accompanying the early stages of glass batch reactions - Α model study(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Storch, Leszek; Kraishan, SamiInterface phenomena accompanying the early stages of reactions in the batch compacted by pressing are considered. The interactions between slowly reacting components of batch, i.e. quartz, potash feldspar and AI₂O₃ (corundum), and alkali carbonates, below the melting temperature of the carbonates, were investigated. The investigations were carried out on quartz, potash feldspar and corundum monocrystals pressed into compacted Na₂CO₃ and K₂CO₃ tablets. The study of the interface reactions on monocrystals was supplemented with the investigation of mixtures of fme-grained (0.1 to 0.3 mm) minerals and alkalies carbonates. The corrosion of the mineral surface takes place due to the interface chemical reaction with alkalies as well as the transportation of free SiO₂ and AI₂O₃ inside the carbonate layer above 580 C for quartz and potash feldspar and above 600 °C for corundum. The mechanism of interaction of quartz and corundum with solid carbonates resembles simple dissolution. In the case of potash feldspar a deep migration of Na⁺ ions to the inside of the mineral structure occurs and its melting begins already above 800 °C. The interface processes determine, to a considerable degree, the effectiveness of the process of prereacting by heat treatment of the compacted glass batches.
- ItemMathematical modeling in the glass industry: An overview of status and needs(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Choudhary, Manoj K.; Huff, Norman T.The paper presents an overview of mathematical modeling in the field of glass manufacturing. It reviews the principal categories of mathematical models used in the glass industry, examines their current Status, and identifies critical needs in the various areas of mathematical modeling. The segments reviewed include process, environmental, control, property-composition, and molecular models. The paper describes not only gaps in the knowledge in the various segments but also identifies ways in which the models may be made more effective in meeting the needs of the glass industry.
- ItemModeling of bubble removal from glassmelts at fining temperatures(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Itoh, Eiji; Yoshikawa, Hidemi; Kawase, YoshinoriΑ new model based on the quasi-stationary approximation is developed for removal of gas bubbles from glassmelts due to buoyant rise of bubbles. The growth and rising of multicomponent gas bubbles in glassmelts are examined from the view point of interfacial mass transfer. It is shown that the models for rising bubbles in glassmelts available in the literature are based on the quasi-steady approximation which is not very reasonable. The growth of a gas bubble initially consisting of nitrogen only is studied in a glassmelt whose diffusing gases are oxygen, water, carbon dioxide, sulfide and nitrogen. The proposed model based on the unsteady-state mass transfer (the quasi-stationary approximation) is compared with the model based on the steady-state mass transfer (the quasisteady approximation). The former, which provides more rational and better descriptions of bubble behavior in refming processes compared with the latter, predicts rather shorter refming times than the latter.
- ItemCondensation on the outer surface of window glazings - Causes, effect on heat loss and method for prevention(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Gläser, Hans JoachimFogging on the outside surfaces of window glazings increases if the thermal insulation of the glazing is improved, i.e., the k value is decreased as realized in the heat-insulating glasses currently on the market. The main reason for this is the radiation exchange with the open sky. The most endangered Windows for fogging are the sky lights and glazings in the skin of buildings, e. g. structural glazing facades, because they are exposed to the largest portion of the open sky. The conditions of fogging are investigated and discussed, as well as its influence on the heat loss of glazings is demonstrated. By radiation exchange with the open sky, the heat loss of window glazings can be increased by more than a factor 2 in comparison to the standardized k value. However, fogging reduces heat losses in dependence on the outside air humidity. Fogging and heat loss can be considerably reduced by a low-emissive coating on the outer surface of glazings. The demands on such a coating are discussed. Also a method of double coating consisting of a low-emissive subcoating and a hydrophobic and anti-sticking top-coating is presented, which has a self-cleaning effect. Lowemissive and, at the same time, self-cleaning coatings, deposited on the outer surface of glazings are a new function of flat glass and may be a challenge to the glass industry in the next years.
- ItemCharacterization of glass surfaces by X-ray reflectivity(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Anderson, Olaf; Bange, KlausSurfaces of soda-lime and borosilicate glasses produced by the float technique as well as polished BK-7, fused silica and aluminosilicate glasses are investigated by means of grazing incidence X-ray reflectometry Thin layers are found at all surfaces with properties which differ significantly from the bulk properties of the respective material. Fused silica surfaces exhibit a hydrated layer with a thickness of approximately 17 nm and a slightly reduced density Α thin leached layer with a density of approximately 2 g*cm⁻³ is analyzed on BK 7 glass. Α variadon in the rms roughness between 0.7 and 1.5 nm is found for aluminosilicate glasses depending on the polishing procedure. Pronounced differences are obtained between the air and the tin bath side of soda-lime float glass, whereas for borosilicate float glass only small differences in density between the two sides of the glass are measurable. The evolution of the initial stages of corrosion is demonstrated on soda-lime glass in dependence on the storage time.