Glass devitrification

Irreversible transformations are those in which reactants do not reform from products upon cooling. Generally one of the reactants is in a metastable state, and only requires thermal agitation or the presence of a catalyst to initiate the transformation. Examples would be combustion of a fossil fuel or glass devitrification. Power-compensated DSC has a distinct advantage over heat-flux DSC in determining the kinetics of transformation from metastable phases. In these type of reactions,... 

In the 1930s, Chamot and Mason defined the state of chemical microscopy (6) by detailing their work on the physical methods and chemical analysis involved with chemical microscopy. In the U.K. in 1954, Welch described a simple microscope attachment for the observation of high-temperature phenomena (7). The small, electrically heated thermocouple could hold a microscopic sample for single-crystal growth assays, melting-point determinations, and glass devitrification studies. 

Glass devitrification Formation of crystals (seeds) in a glass melt, usually occurring when the melt is too cold. These crystals can appear as defects in glass fibers. 

Defining the most appropriate frit particle size (average size and size distribution) through thermal and thermomechanical characterization. Particle size can influence the initiation and subsequent rate of glass devitrification [25]. 

Slags Recrystallize glass-devitrification Unknown stability long term Quenched slags, low solubility Low efficiency, high volume High production cost can theoretically get energy back (Broadbent Warner 1985) ... 

The last two methods, based on a soft chemistry approach, have two main advantages over the glass devitrification ... 

Oxyfluoride Transparent Glass Ceramics 275 9.2.1 Synthesis by Glass Devitrification... 

Some germanate and silicate glass-ceramics have been synthesized with / -PbF2 as the crystalline phase. Similarly to the CaF2 system presented before, these glass-ceramics are made by glass devitrification. 

Glass devitrification induces changes in the optical properties of the materials. First, it provides a crystalline environment for the Ln " " ions, inducing a reduction of their optical... 

Efficient glass devitrification induces the segregation of Ln into the fluoride phase, which usually represents between 5 to 20 % (mol) of the material. The local Ln concentration in the crystallites of the glass-ceramics is between 5 and 20 times higher than in the initial glass. This high local concentration in the crystallites favours Ln —Ln interactions and has an effect on the optical properties, as it is described below. 

The distinction made here between industrial ceramics and glasses lies in the method of preparation, not in the difference between crystalline solids and amorphous solids. In fact, some ceramics are mainly made up of vitreous (amorphous) phases, whereas vitroceramics are obtained by crystallizing a glass (devitrification). 

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