How edge finish effects the strength of sapphire

Keith T. Jacoby; Steven M. Goodrich

doi:10.1117/12.604085

18 May 2005 How edge finish effects the strength of sapphire

Keith T. Jacoby, Steven M. Goodrich

Proceedings Volume 5786, Window and Dome Technologies and Materials IX; (2005) https://doi.org/10.1117/12.604085
Event: Defense and Security, 2005, Orlando, Florida, United States

Abstract

Exotic Electro-Optics (EEO) has completed a study of how the edge finish of an A-plane sapphire sample affects its flexural strength when tested using the 4-point bend test method. Flexural bar samples were fabricated out of a sapphire panel that was polished to production quality using EEO's standard production methods. All samples were configured to meet the requirements for a C-size sample as defined by ASTM C-1161. The only difference between the three sample groups was the edge finish applied to the sample - conventionally ground, fine ground or a commercial polish edge finish. The edge finish on each sample was quantitatively characterized prior to strength testing. All samples were visually inspected prior to testing to identify any potential fracture initiation points. The samples were then tested using an Instron Universal tester per ASTM C-1161 in the UDRI Ceramics and Glasses Laboratory. After testing, a visual inspection was performed to identify the fracture initiation surface and location. Observations confirmed that all sample data was valid (all fractures initiated inside the two inner load dowels), no fractures were initiated on the edges, and no fractures initiated at any of the suspect sites noted in the pre-test visual inspection. The data was post processed using standard statistical and Weibull analysis methodologies. The results showed no significant difference when comparing the flexural strength of the three edge finish groups. The data suggest that the surface quality of the planar surfaces and the bevels is more critical than the finish of the full edge.

Citation Download Citation

Keith T. Jacoby and Steven M. Goodrich "How edge finish effects the strength of sapphire", Proc. SPIE 5786, Window and Dome Technologies and Materials IX, (18 May 2005); https://doi.org/10.1117/12.604085

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