3 results
Search Results
Now showing 1 - 3 of 3
- ItemLong-range granular feature of silicate glasses and its relation to glass properties(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2005) Wang, ChunNumerous experimental results show that silica and silicate glasses consist of higher density granules about 20 to 50 nm sized and lower density linkages. Such long-range feature should originate from the long-range density fluctuation of the glass-forming liquid. Due to the highly coordinated network structure of glass the lower density regions may be under strain. Following this assumption many phenomena of glass observed here and reported in the literature can be explained well, e.g. anomalous conductivity, brittleness, granular boundary contour of crack, high conductivity on the fracture surface, cloudy damage after dishwashing, corrosion products on glass surface, distribution pattern of Ag colloidal particles in float glass bath side, disproportional large influence of water on glass properties, the unusual increase in expansion coefficient with increasing modifier content, etc.
- ItemThree different reasons for surface damages of glasses after machine dishwashing(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2005) Wang, Chun; Krausch, Georg; Decker, Markus; Martinek, Klaus-PeterΑ variety of glass eups has been investigated after treatment in a machine dishwasher. Three types of surface damages were found. The first type consists of clouding on the inner and outer surfaces appearing after about 1000 washing cycles. It can be related to the long range granular structure of glass, which is believed to be formed by thermal density fluctuation. During washing both water and detergents act as weak etchants, first eroding the smooth glass skin, then revealing the granular structure. As soon as the linkages between the granules are entirely broken by the etching, holes will manifest themselves at these sites. When the size of the holes (the hole width) reaches the half of the light wavelength, light scattering occurs and the glass seems cloudy. The second type is the sheet clouding on the outer surface appearing after about 100 washing cycles. It can be related to holes on the surface, which are formed by the loss of the sphere domain phase from the SiO2-rich matrix during washing. These domains result from phase separation induced by round-meldng of the sharp cutting edge, which is responsible for local clouding of glass. The third type is a golden film on the inner surface. These films are probably formed by complex formation between the glass surface and the organic compounds in the drinks. All of the damages studied here are irreversible.
- ItemLocal clouding of glass after machine dishwashing(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2005) Martinek, Klaus-Peter; Wang, Chun; Krausch, Georg; Rädlein, EddaThe local clouding of glasses after dishwashing near the mouth rims on a coffee pot made from borosilicate glass, on a wine cup made from lead crystal glass and near the stem base on a wine cup made from barium Silicate glass has been found to be due to damage during manufacture. The examined clouding is different from the two well known types of filming and etching cloudiness related to the reactions of glass with water and detergent in the dishwasher. The intensive study on the wine cup of lead crystal glass shows that a phase Separation was induced during the flame treatment on the sharp rim and base. The aggregates of Pb-rich spheres scaled off when the thin covering of SiO2 rich skin was eroded away and consequently holes were formed on the glass surface on the micrometre scale, which resulted in light scattering and the clouding of the glassware. Evaporation species from warmer regions onto the colder areas of the glass surface could be observed, but they are not the reason for the local clouding in this study. Dendritic thin corrosion products caused by air exposure could be detected on the undisturbed glass surface as well.