ICOTOM12-Proceedings of the Twelfth International Conference on Textures of Materials, Vol. 2, pp. 1501-1512. Edited by J. A. Szpunar. NRC Research Press, Ottowa, Canada,1999.

MICROSTRUCTURE AND MECHANICAL PROPERTIES OF TEXTURED

ALUMINA

D. KOVAR and P.W. HALL

Texas Materials Institute and Department of Mechanical Engineering

University of Texas at Austin, Austin, TX, USA

Abstract

A method for producing a crystallographically and morphologically textured alumina has been devised using an inexpensive, solvent-based tape casting route. A small percentage of anisometric alumina seed particles and a sintering aid are added to a conventional slurry containing solvents, a polymeric binder, and a fine a-alumina powder. The slurry is tapecast using an extended doctor blade to align the seed platelets within the tapes. After drying, the tapes are cut, stacked and compression molded to form solid billets and then the binder is removed by pyrolysis. During sintering, a grain boundary liquid phase forms that facilitates densification and results in the preferential growth of the seed platelets in directions parallel to the basal plane. X-ray measurements indicate that the sintered alumina exhibits a strong (006) fiber texture and micrographs show that the grain morphology is also elongated in the plane of tape casting. Experiments using Vickers indentations to simulate contact damage show that resistance to cracking is significantly greater in a direction perpendicular to the plane of alignment compared to parallel to the plane of alignment.

Keywords: alumina, microstructure, texture, fracture toughness, contact damage.