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In this scenario, the transition temperature is known as the calorimetric ideal glass transition temperature T 0c. In this view, the glass transition is not merely a kinetic effect, i.e. merely the result of fast cooling of a melt, but there is an underlying thermodynamic basis for glass formation. The glass transition temperature:
Liquidus temperature curve in the binary glass system SiO 2-Li 2 O. For impure substances, e.g. alloys, honey, soft drink, ice cream, etc. the melting point broadens into a melting interval. If the temperature is within the melting interval, one may see "slurries" at equilibrium, i.e. the slurry will neither fully solidify nor melt.
Fused quartz is used for high-temperature applications such as furnace tubes, lighting tubes, melting crucibles, etc. [74] However, its high melting temperature (1723 °C) and viscosity make it difficult to work with. Therefore, normally, other substances (fluxes) are added to lower the melting temperature and simplify glass processing. [75]
Ordinary soda-lime glass, used in windows and drinking containers, is created by the addition of sodium carbonate and lime (calcium oxide) to silicon dioxide. Without these additives, silicon dioxide would require very high temperature to obtain a melt, and subsequently (with slow cooling) a glass.
Fragility characterizes how rapidly the viscosity of a glass forming liquid approaches a very large value approximately 10 12 Pa s during cooling. At this viscosity, the liquid is "frozen" into a solid and the corresponding temperature is known as the glass transition temperature T g. Materials with a higher fragility have a more rapid increase ...
Borosilicate glass is created by combining and melting boric oxide, silica sand, soda ash, [6] and alumina. Since borosilicate glass melts at a higher temperature than ordinary silicate glass, some new techniques were required for industrial production.
The manufacturing process for soda–lime glass consists in melting the raw materials, which are the silica, soda (Na 2 O), hydrated lime (Ca(OH) 2), dolomite (CaMg(CO 3) 2, which provides the magnesium oxide), and aluminium oxide; along with small quantities of fining agents (e.g., sodium sulfate (Na 2 SO 4), sodium chloride (NaCl), etc.) in a glass furnace at temperatures locally up to 1675 ...
The melting point (or, rarely, liquefaction point) of a substance is the temperature at which it changes state from solid to liquid. At the melting point the solid and liquid phase exist in equilibrium. The melting point of a substance depends on pressure and is usually specified at a standard pressure such as 1 atmosphere or 100 kPa.