System CaO-SiO

Waseda, Y., and J. M. Toguri (1977). The structure of molten binary silicate systems CaO-SiO, and MgO-SiOj. Metall. Trans. 8B, 563-68. 

Fig. 2.27 The section of the system CaO-SiO -MgO-AljOj-Fe Oj showing stable polymorphic phase of CjS after cooling (after [42]) molar ratio Al20j/Fe20j= 1...

Fig. 2.3 The system CaO-AljOj-SiO. After Muan and Osborn (M19), with later modifications.

Drake M. J., McFarlane E. A., Gasparik T., and Rubie D. C. (1993) Mg-perovsMte/sihcate melt and majorite garnet/ silicate melt partition coefficients in the system CaO-MgO-SiO, at high temperatures and pressures. J. Geophys. Res. 98, 5427-5431. 

As a molten ash cools crystals will be formed. The nature of the crystalline phases formed during cooling are a function of the chemical composition of the ash, and may be made the basis of a predictive technique, as described by Kalmano dtch ei al [1986]. The technique involves the use of high temperature phase diagrams for the system CaO - FeO - - SiO- to provide information on... 

The equilibrium constant calculated from these solubility data agrees reasonably well with that found by Roller and Ervin (23) in a study of the association of silicate ions in the CaO-SiO -HjO system. These authors found at 30 C a value of 1.5 x 10. Thus it is clear that the solubility of silica increases at high pH because of the formation of silicate ion in addition to SKOH) in solution. 

FIGURE 5.12 Phase equilibria and glass formation region in the soda-lime-silica system. (After K. A. Shahid and F. P. Glasser, Phase equilibria in the system Nafi-CaO-SiO, Phys. Chem. Glasses, vol. 12, 1971, p. 50.)... 

Iherzolite boundaries in the system CaO-MgO-Al O -SiO. lated slopes at lOOO C are from thermochemistry and are consis tent with the O Hara et al (1971) determination. 

Tsuru et al. [87] reported that in PDMS-CaO-SiOj hybrids prepared by the sol-gel method, apatite appeared on their surfaces upon immersion into a simulated body fluid (SBF), which suggests that these hybrids can be bioactive. Similarly, Chen et al. [88] synthesized PDMS-CaO-SiO -TiOj hybrids and found that these systems show an apatite-forming ability, while being deformable. It was shown that PDMS-CaO-SiOj hybrids present apatite-forming ability when immersed in SBF and, moreover, these materials exhibit mechanical properties analogous to those of human cancellous bones. 

Figure 1.137. The variations of major element contents in andesite (drilling core. 8-MAHAK-4 and underground samples) away from the vein system (Shikazano et al., 2002), Diamond Hishikari Lower Andesitic tuff (underground samples) square Hishikari Lower Andesitic tuff (drilling core samples) triangle Hishikari Lower Andesitic lava (drilling core samples) x relatively fresh Hishikari Lower Andesitic lava (drilling core samples). (A) SiO content variation. (B) K2O content variation. (C) CaO content variation.

Glass of the system Si02 — CaO — Na20 (the commonest type) when molten can be considered to be dissociated into cations Na", and (SiO ) " or (Sin,On) ... 

To accelerate the approach to equilibrium, the oxide catalysis employed are based on Group 7 metals, exclusively iron in practice (Fe,0 i. A number of promoters help to improve performance, including Al202 which increases the active surface area of the particles, and K20. SiO,. MeO. CaO etc, which improve stability, and increase activity and resistance to poisoning. Systems currently under development make use of ruthenium... 

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