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Proceedings Paper

Advances in spinel ceramic technology for large windows and domes
Author(s): Juan L. Sepulveda; Raouf O. Loutfy; Sekyung Chang; Sharly Ibrahim; Nick Traggis
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Paper Abstract

This paper describes MER's recent advances on the development of high strength, transparent magnesium aluminum spinel technology for large IR windows and domes. The novel spinel material exhibits high optical and IR transparency in the 0.2 - 5.5 μm wavelength, is very resistant to abrasion, with density higher than 99.9% of theoretical, with very fine and uniform grain size, and flexural strength of 300 MPa. Spinel domes technology has been scaled up to produce hemispherical 180° aperture domes in sizes up to 7" in diameter using freeze casting technology to produce the green dome preforms. MER is also pursuing the production of large size spinel windows by either producing monolithic large single windows or by edge bonding several smaller size windows. Both approaches present challenges. Production of monolithic large size windows is limited by equipment size, availability, and investment capital while the edge bonding approach requires perfect transparency and strength at the bonded edge. MER together with Precision Photonics Corp. are developing high strength, edge bonded, transparent magnesium aluminum spinel windows for next generation aircraft and other defense armor applications which require windows as large as 30"x30"x0.5" at an affordable cost. MER has further improved strength of the spinel by accurate control of the average grain size and grain size scatter while remarkable transmission is obtained by elimination of the intergrain/intragrain porosity, and by eliminating all possible contamination. The spinel bonding technology under development consists of chemically activated direct bonding (CADB®), an epoxy-free solution-assisted optical-contacting process developed by Precision Photonics Corporation (PPC).

Paper Details

Date Published: 27 April 2009
PDF: 11 pages
Proc. SPIE 7302, Window and Dome Technologies and Materials XI, 73020E (27 April 2009); doi: 10.1117/12.819222
Show Author Affiliations
Juan L. Sepulveda, Materials and Electrochemical Research Corp. (United States)
Raouf O. Loutfy, Materials and Electrochemical Research Corp. (United States)
Sekyung Chang, Materials and Electrochemical Research Corp. (United States)
Sharly Ibrahim, Materials and Electrochemical Research Corp. (United States)
Nick Traggis, Precision Photonics Corp. (United States)

Published in SPIE Proceedings Vol. 7302:
Window and Dome Technologies and Materials XI
Randal W. Tustison, Editor(s)

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