Interfacial relations in slag/metal systems

Bruce, R. H (1959) Interfacial relations in slag/metal systems. PhD thesis, University of Glasgow.

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Abstract

The reader is briefly introduced to the subject of surface thermodynamics, and to the relationship of interfacial free energies in poly-phase systems of particular interest in metallurgy. The second part accurately defines an average surface free energy of crystalline materials, from the surface free energy of crystalline materials, from the surface free energies of individual crystals faces, and a ratio is described which is applicable to any member of a given crystal system. This ratio is calculated for the Simple Cubic, F.C.C. and B.C.C. systems, for ideal crystals, and figures are constructed for those systems showing the variation of specific surface free energy with orientation. From consideration of the Tamman temperature, of sintering and of diffusion, temperature is show to have little or no irreversible effect on the average ratio for refractory oxides, with some possible exceptions such as MgO. The mechanism of recrystallization is briefly considered in terms of surface energy. Such crystal defects as growth faces, grain boundaries, dislocations and mosaic crystals are shown to have negligible effect on total surface free energy. Calculations are made of the average ration for some polycrystalline materials with varying degrees of preferred orientation, such as compacts and vires. The third part is involved with the calculation of the surface free energy of refractory substances. Graphite is dealt with at length, and found to have a surface free energy at absolute zero of about 3,100 org/cm to over 5,000 org/cm depending on the orientation of the surface: its surface entropy is also considered. The crystal structure, the sublimation energy and the critical temperature form the basis of these calculations; and they are contended to fourteen oxides and B SiC. The solid/liquid transformation is also considered, and the surface free energy of some of these substances is calculated from absolute zero to their critical temperatures. The method used is simple and it seems to be at least as reliable as any other yet developed. Finally, some experimental work is described, which was designed to measure contact angles continuously over long periods at high temperatures in order to estimate various interfacial parameters. The solids employed were graphite, pure and composite oxides, silicon carbide and pure iron, and the liquids were oxide slags, pure iron and iron/carbon alloys; various atmospheres were also used. Three distinct types of graphite surfaces were examined, the preparation of these and other specimens is described. Slags made from CaO, MgO, Al2O3, and SiO2 showed contact angles on graphite of 125

Item Type: Thesis (PhD)
Qualification Level: Doctoral
Additional Information: Adviser: Robert Hay
Keywords: Materials science, Thermodynamics
Date of Award: 1959
Depositing User: Enlighten Team
Unique ID: glathesis:1959-72591
Copyright: Copyright of this thesis is held by the author.
Date Deposited: 11 Jun 2019 11:06
Last Modified: 11 Jun 2019 11:06
URI: http://theses.gla.ac.uk/id/eprint/72591

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