The strengths of sapphire disks of two different crystallographic orientations and bars of three different orientations were measured as a function of temperature in ring-on- ring flexure or 4-point bending. One set of disks (OO cut) had the crystallographic C -axis normal to the flat surface which contained the crystallographic a- and m -axes. The average strength of these disks dropped from 154 ksi at 20°C to 21 ksi at 800°C. In another set of disks (900 cut), the crystallographic c- and m -axes were parallel to the flat surface. The average strength of these disks dropped from 84 ksi at 20°C to 48 ksi at 800°C. The strength of sapphire bars whose tensile axis was the crystallographic m axis dropped from 103 ksi at 20°C to 86 ksi at 1400°C. The strength of sapphire bars whose tensile axis was the crystallographic a-axis dropped from 113 ksi at 20°C to 74 ksi at 1400°C. The strength of sapphire bars whose tensile axis was the crystallographic c-axis dropped from 153 ksi at 20°C to 35 ksi at 1400°C.

Date Published: 1 October 1990
PDF: 12 pages
Proc. SPIE 1326, Window and Dome Technologies and Materials II, (1 October 1990);

Published in SPIE Proceedings Vol. 1326:
Window and Dome Technologies and Materials II
Paul Klocek, Editor(s)