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- ItemGlass improvement by combination with plastics(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1989) Jandeleit, OttoAfter a short survey of the development of laminated safety glass, modern safety and comfort requirements are listed. Problems and properties of such glass-plastic combinations are examplified by the Sekuriflex windshield. In addition, other functions and solutions for security glazings as well as antifogging by moisture and impact resistance are discussed. Fireproof and sound insulating glazings are discussed on the basis of symmetrical glass-plastic combinations with both exterior faces consisting of glass.
- ItemObservations on the process and the products of chemically tempered glass(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1989) Paudice, Ciro; Boattini, Pier Paolo; Bergia, Lucia[no abstract available]
- ItemGlass-ceramics of the system Pb(Zr0.5Ti0.5)O3-GeO2(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1989) Park, Won-Kyu; Yamane, MasayukiΑ thin film of glass-ceramics containing Pb(Zr0.5Ti0.5)O3 has been prepared by rapid quenching of a melt of the system Pb(Zr0.5Ti0.5)O3-GeO2 and subsequent heat treatment for crystallization. The dielectric constant of the glass-ceramics obtained by the heat treatment at 1000 °C for 2 h ranged from 96 to 123. An endothermic peak which is considered to show the ferroelectric-paraelectric transition was observed between 420 and 445 °C on the DTA curve of the glass-ceramics.
- ItemManufacture, properties and application of open-pore sintered glasses and open-pore sintered glass-ceramics(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1989) Siebers, Friedrich B.; Greulich, Norbert; Kiefer, WernerΑ new process was developed for the manufacture of open-pore sintered glass and glass-ceramics with defined porosity according to the filler principle. Fine-grained glass powder is homogeneously mixed with an inorganic salt of specified grain size and sintered. The salt is washed out, its grain size allowing the adjustment of the mean pore diameter between 5 and 350 μm accompanied by a sharp pore size distribution. The quantity of inorganic salt determines the open pore volume between 20 and 80 vol%. The manufacture of an open-pore sintered glass-ceramic requires a crystallizable glass powder. Depending on the choice of glass powder and inorganic salt compositions inert behavior can be maintained, or ion exchange takes place leading to new compositions and properties. Properties are a consequence of defined porosity and the microstructure of the skeleton material. Maximum working temperatures may reach about 750 °C in the case of sintered glasses and up to 1400 °C in the case of sintered glass-ceramics. The application of the open-pore materials results from their selectively adjustable porosity: filtration of gases and liquids; separating processes; storage, conduction and distribution of liquids; electric and thermal insulation; catalyst carriers; biotechnology.
- ItemPrimary measures for the ΝΟx reduction on glass melting furnaces(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1989) Barklage-Hilgefort, Hansjürgen; Sieger, WernerOn a producing horseshoe furnace fired with natural gas experiments were carried out to reduce the NOx emission by primary measures. After optimizing the combustion conditions flue gas recirculation and air staging were tested as new measures. To ensure a complete combustion the CO content of the flue gases was limited to values of less than 1000 mg/m3, measuring the CO content at the top of the regenerator. The recirculated flue gas was used to replace the primary air. The ΝΟx content obtained by flue gas recirculation in combination with other measures was about half of the original value. The air staging was realized by branching a part of the preheated combustion air from the top of the regenerator and feeding the air over existing sight holes to the combustion space. The preheated air was transported using a jet pump. This measure established ΝΟx contents in the flue gas which were less than 1000 mg/m3.
- ItemElectrochromic layers for active optical filters(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1989) Gambke, Thomas; Metz, BerndIn principle, electrochromic materials permit continuous variation of the absorption and reflection characteristics of functional optical components. This has led to a broad range of innovative developments. The important and essential properties of electrochromic applications are presented for the materials used most frequently and various system designs are explained with reference to some examples. Three applications for electrochromic systems are introduced - the electrochromic display, the continuously dimmed automobile mirror and the so-called "smart window".
- ItemInvestigation of the bottom and throat current in a glass melting tank with drainage of contaminated bottom glass(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1989) Treptow, Frank; Woelk, GüntherIn glass melting tanks the formation and/or enrichment of contaminations in the bottom area may occur. By methods of melt circulation and the insertion of drainages it is tried to prevent these contaminations in production glass. The occurring processes, however, are difficult to investigate on real tanks. It is also difficult to carry out a change in the tank design during its operation. Therefore, a mathematical model for the glass melting tank was developed calculating the flow and the temperature distribution in a vertical section. The calculations were carried out for fuel-heated tanks. The result of the drainage and the behavior of the slush (= contaminated bottom glass) were investigated with several variants. It showed that the behavior of the slush is strongly dependent on its layer thickness. From the investigations a submerged drainage proved to be the best solution. Drainage should be positioned in front of the throat or in the throat directly. The insertion of a second submerged drainage in the dead region of flow in the fining tank is favorable.
- ItemGrinding of optical glasses with cup wheels - Α new way to generate polishable surfaces(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1989) König, Wilfried; Koch, NorbertConventionally the machining sequence of optical glass lenses consists of rough grinding, fine grinding and polishing. At this time the research in glass machining techniques concentrates on rough grinding and fine grinding, especially tool and process optimisation. The shown results of rough grinding tests offer the possibility to eliminate the fine grinding process out of the machining sequence. The surface quality which can be reached depends, besides other circumstances like machine parameters, on the glass material. This is described just as the used research methods and measuring techniques.
- ItemEstimation of handling stresses in a 4 m Zerodur blank with the finite element method(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1989) Loch, HorstDuring handling of large Zerodur blanks for astronomical applications, the risk of a break due to an improper procedure is rather high. Using the example of a 4 m Zerodur blank produced by spincasting, this paper demonstrates that the finite element method can be used to estimate the handling stresses in advance. In this way, critical situations can be avoided. Two typical situations are investigated: the position of the blank on 4 or 2 support points, and the moment where the blank is standing vertically during a turning movement. Only static stresses produced by gravity are computed (no further accelerations). The results show the magnitude and distribution of the resulting first principal stresses.
- ItemStructural and chemical properties of glass capillary membranes and their use in protein separation(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1989) Schnabel, Roland; Langer, PeterInorganic materials for membranes become increasingly interesting with respect to applications in pharmaceutics, medicine, biotechnology and other fields where high chemical resistance is mandatory. Among the different kinds of membrane materials, BIORAN® porous glass can be seen as a widely variable and adaptable material because of its broad range of pore sizes and of its changeable surface polarity. In recent years porous glass applications for seawater desahnation, emulsion splitting, hemofiltration, diafiltration, milk concentration and cascade plasmapheresis were evaluated. Ultrafiltration and/or microfiltration in the fields of biotechnology, medicine and pharmaceutics are mainly demanded for the separation, concentration and purification of proteins. Because of only small differences in physical properties like molecular size etc., the individual chemical properties as well as process parameters must be exploited to get satisfactory results. The structure and the properties of porous glass membranes are largely independent from external influences. This leads to cleanable, even heat-sterilizable membrane modules. BIORAN® porous glass membranes are produced as capillaries showing excellent mechanical stability even at high pressures. Due to narrow pore size distribution and variable surface properties they may be tailored to certain applications.