Liquid silicates

Physical and chemical properties of glassy and liquid silicates... 

The viscosity of liquid silicates such as drose containing barium oxide and silica show a rapid fall between pure silica and 20 mole per cent of metal oxide of nearly an order of magnitude at 2000 K, followed by a slower decrease as more metal oxide is added. The viscosity then decreases by a factor of two between 20 and 40 mole per cent. The activation energy for viscous flow decreases from 560 kJ in pure silica to 160-180kJmol as the network is broken up by metal oxide addition. The introduction of CaFa into a silicate melt reduces the viscosity markedly, typically by about a factor of drree. There is a rapid increase in the thermal expansivity coefficient as the network is dispersed, from practically zero in solid silica to around 40 cm moP in a typical soda-lime glass. 

It follows that since the addition of metal oxides has such a profound effect on the properties of liquid silicates such as the viscosity, that the Reynolds number of liquid silicates in metal-silicate liquid two-phase systems will influence the boundary layer thickness to a greater extent than in the liquid metals and alloys, mainly because of the higher viscosity of the silicate. 

As in die case of die diffusion properties, die viscous properties of die molten salts and slags, which play an important role in die movement of bulk phases, are also very stiiicture-seiisitive, and will be refeiTed to in specific examples. For example, die viscosity of liquid silicates are in die range 1-100 poise. The viscosities of molten metals are very similar from one metal to anodier, but die numerical value is usually in die range 1-10 centipoise. This range should be compared widi die familiar case of water at room temperature, which has a viscosity of one centipoise. An empirical relationship which has been proposed for die temperature dependence of die viscosity of liquids as an AiTlienius expression is... 

Enhancement of Ion Mobilities in Liquid Silicates from Computer-Simulation Studies to 800-Kilobars. 

Bockris J. O M., Kitchener J. A., and Davies A. E. (1952a). Electric transport in liquid silicates. Trans. Faraday Soc, 48 536-548. 

Bottinga Y. and Weill D. F. (1970). Densities of liquid silicates systems calculated from partial molar volumes of oxide components. Amer. Jour. Scl, 269 169-182. 

Masson C. R. (1965). An approach to the problem of ionic distribution in liquid silicates. Proc. Roy. Soc. London, A287 201-221. 

Masson C. R. (1968). Ionic equilibrium in liquid silicates. J. Amer. Ceram. Soc., 51 134-143. 

Richet P. and Bottinga Y. (1985). Heat capacity of aluminium-free liquid silicates. Geochim. 

Fig. 2. Energy of activation for electrical conduction in binary liquid silicates 28).

Fig. 3. Effects of metal oxides on the viscosity of binary liquid silicates 37).

Some important features regarding the structures of liquid silicates are revealed by recent volumetric studies of both alkali (9) and alkaline earth systems 55). First, the partial molar volume of silica in the alkali silicates is nearly equal to that of pure fused silica and is independent of the cation over wide compositional ranges. Second, at about 10 15 mole-% metal oxides, the thermal expansions show a sudden increase. The results for the alkali silicates are shown in Fig. 5. A similar behavior is found in the system... 

Although electrical measurements have confirmed the ionic nature of borate melts, viscous flow and volumetric studies clearly indicated their difference from liquid silicates. Shartsia and co-workers (4 ) have suggested that an equilibrium exists in the melt between BOj triangles and B04 Letrahedra, this being both temperature and composition dependent. The only ionic model for the borates is that of Bockris and Mellors (8) which... 

Polycomponcnt systems of liquid oxides studied have mostly been silicates. Detailed discussions of these systems are beyond the scope of the present review. Perhaps the most important feature regarding polycomponcnt liquid silicates is their ionic nature. This may be conveniently illustrated by recent studies on the viscosity of some of these melts. 

The calculated and experimental curves deviate considerably in shape, and it seems that the simple diffusion model is not adequate to describe the kinetics of the uptake process in this case. Also the value of D (9.25 X 10"9 cm.2/sec.) required to make the two curves coincide at early times seems to be much smaller than expected. The only data available on the diffusion of molybdenum oxide in liquid silicates is from a report by Norman et al. (11), who measured the diffusion constant of... 

Blend the components one at a time in the given order with continuous stirring. Be sure the tetrasodium EDTA is totally dissolved before adding the liquid silicate. 

Pluronic, Plurafac, and Industrol surfactant Other ratios of Si02 can be used. Liquid silicates can also be used in place of powders. 

Spray a mixture of the surfactant and water (or surfactant, water, and liquid silicate) onto the phosphate builders, soda ash, or mixture thereof. Stir continuously while spraying. 

Of greatest interest is the study of pressure-induced transformations in such an archetypical glass as a-Si02. Besides the fundamental importance of research on transformations in disordered media, a deeper insight into the transitions that occur in a-Si02 and other amorphous and liquid silicates is of much importance for the physics of the Earth and planetary interiors. Thus, we pay the most... 

Neutron diffraction has been applied to the chloroaluminate melts to determine the shape and structure of a number of anions there. They turn out to have chain and ring structures in the higher members similar to those in liquid silicates and borates (Fig. 5.62). 

However, this reorganization is precisely what is not quickly accomplished by the entities in the broken-down networks in liquid silicates. The entities resulting from... 

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