Thermodynamic properties and vaporisation processes of ternary glass forming silicate systems: CaO–Al2O3–SiO2, CaO–TiO2–SiO2 and BaO–TiO2–SiO2
A high temperature mass spectrometric method is used for the identification of vapour species over the CaO–Al2O3–SiO2, CaO–TiO2–SiO2 and BaO–TiO2–SiO2 systems in the concentration
range where the mole ratio of CaO(BaO):SiO2 is equal to unity at 1800–1950 K. The vaporisation processes are similar to those in the individual oxides contained in the systems studied. Activities of components in these systems were obtained by the ion current comparison method.
Negative deviations from the ideality were observed in the CaO–Al2O3–SiO2 systems and changes of the sign from the ideal behaviour are found in the CaO–TiO2–SiO2 and BaO–TiO2–SiO2
systems. Thermodynamic properties of the systems under consideration are also calculated using the generalised lattice theory of associated solutions. Suitable agreement was shown between experimental and calculated results. The numbers of the various types of bonds in these melts were calculated
using the same theory. The dependence of the number of Ca–O–Ca, Al–O–Al, Si–O–Si, Ti–O–Ti, Ba–O–Ba, Ca–O–Al, Ca–O–Si, Ca–O–Ti, Ba–O–Si, Ba–O–Ti, Al–O–Si, Ti–O–Si
bonds as a function of the concentration of oxides in the CaO–Al2O3–SiO2, CaO–TiO2–SiO2 and BaO–TiO2–SiO2 systems is in good agreement with the deviations from ideality of their
thermodynamic functions.
Document Type: Research Article
Publication date: 01 April 2005
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