Use of Grafoil in mechanical testing of sapphire at elevated temperatures

Svetlana G. Ivanova; Frederick Schmid; Chandra P. Khattak; Daniel C. Harris

doi:10.1117/12.405296

25 October 2000 Use of Grafoil in mechanical testing of sapphire at elevated temperatures

Svetlana G. Ivanova, Frederick Schmid, Chandra P. Khattak, Daniel C. Harris

Proceedings Volume 4102, Inorganic Optical Materials II; (2000) https://doi.org/10.1117/12.405296
Event: International Symposium on Optical Science and Technology, 2000, San Diego, CA, United States

Abstract

Flexure strength testing of single crystal sapphire was conducted in the 500 - 600 degree(s)C temperature range using thin sheets of Grafoil^TM to reduce failures due to the contact stresses at the loading points. Load-point failures occur often in high temperature testing of sapphire when twinning mechanisms activate above 500 degree(s)C. Bend bars of three different orientations were tested, and the flexure strength was found to be strongly dependent on the orientation type both in Grafoil and non-Grafoil tests. Use of Grafoil increases measured flexure strength up to the factor of three due to the reduction of contact stress. The effect of using Grafoil in mechanical testing of sapphire, including flexure strength, compressive strength and biaxial flexure strength testing is discussed.

Citation Download Citation

Svetlana G. Ivanova, Frederick Schmid, Chandra P. Khattak, and Daniel C. Harris "Use of Grafoil in mechanical testing of sapphire at elevated temperatures", Proc. SPIE 4102, Inorganic Optical Materials II, (25 October 2000); https://doi.org/10.1117/12.405296

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