Continuous Single Crystal Sapphire Filaments and Ribbon.
Abstract
Three techniques for the growth of alpha-Al2O3 and other single crystals from the melt are described, together with their characterization. These techniques are based on the central requirement that controlled growth may be obtained by means of controlled temperature gradients. The first of these, the floating orifice technique (FOT) makes use of a molybdenum disc, pierced at the center, floating in the melt. To overcome various difficulties, a second method was developed, called the self-filling tube (SFT). Here, a fixed molybdenum tube draws liquid from the crucible to the top of the tube in a region of controlled temperature gradients. This arrangement is satisfactory for the growth of several relatively simple shapes of nominal dimensional accuracy. The final innovation, edge-defined, film-fed growth (EFG), combines the use of a platform having a surface outlining the inside and outside edges in the cross section to be grown with the capillary feed system. This system makes possible the growth of virtually any cross-sectional shape, and close dimensional accuracy. Growth of both structural and non-structural shapes of alpha-Al2O3 and of other material types such as interoxide compounds and oxide solid solutions is described. Characterization of the grown materials, chiefly structural sapphires, includes studies of the orientation, microstructure, and mechanical properties.
Document Details
- Document Type
- Technical Report
- Publication Date
- Jun 01, 1969
- Accession Number
- AD0884284
Entities
People
- A. I. Mlavsky
- G. F. Hurley
- H. E. Labelle Jr.