Surface modelling of crystalline non-metallic inclusions

Non-metallic inclusions such as corundum and spinel-type compounds are crys talline at steelmaking temperatures. The crystal structure and the configur ation of the atoms at the crystal surfaces affect the surface related energ ies and thus the growth forms of the inclusions near equilibrium. Potential growth layers in spinel are described by the application of the Hartman-Pe rdok theory (HPT). Four different periodic bond chains (PBCs) have been fou nd, i.e., [1/2 1/2 0], [0 0 1], [1/2 1/2 1] and [0 1/2 11/2] These PBCs giv e rise to five F faces, which are in order of decreasing slice thickness: { 1 1 1}, {2 2 0}, {1 1 3}, {4 0 0} qand {3 3 1}. Electrostatic point charge computations, taking into account the short-range interactions as well, wer e carried out to compute the attachment energies and specific surface energ ies of the F faces to derive the theoretical growth form and the theoretica l equilibrium form, respectively. For spinel the growth form is an octahedr on, while the equilibrium form is a combination of an octahedron with a min or rhombic dodecahedron. These theoretical forms are rather similar to the growth forms observed as non-metallic inclusions. (C) 2001 Elsevier Science B.V. All rights reserved.