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Proceedings Paper

Solid particle erosion performance of a new ultradurable AR for silicon
Author(s): Caspar C. Clark
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Paper Abstract

Plasma Assisted Chemical Vapor Deposition (PACVD) boron phosphide (BP) has long been established in service on materials such as germanium and FLIR grade zinc sulfide as a protective coating. As airborne systems are required to fly at higher speeds either coatings must become more protective or substrates must become more durable. For MWIR only systems it is logical to use silicon as a window or dome material as the natural hardness of the substrate provides good resistance to particle and rain erosion. The optical transmittance of uncoated silicon is not particularly good (~53% over the 3-5micrometers for a 5mm substrate and normal incidence, Pol=R, room temperature). Applying low energy multilayers on each surface boosts the transparency but offers no resistance to harsh environmental conditions. Although generally the silicon substrate is unaffected due to its hardness, the coating is eroded on the external surface and the transparency drops. With the deposition of boron phosphide by the improved PACVD process the adhesion is so great that not only does the BP not get removed by the erosion, but it protects the substrate at higher speeds. This paper presents data collected by several methods relating to airborne erosion by solid impact of an IR coating/substrate system.

Paper Details

Date Published: 7 September 2001
PDF: 8 pages
Proc. SPIE 4375, Window and Dome Technologies and Materials VII, (7 September 2001); doi: 10.1117/12.439185
Show Author Affiliations
Caspar C. Clark, Thales Optronics (United Kingdom)

Published in SPIE Proceedings Vol. 4375:
Window and Dome Technologies and Materials VII
Randal W. Tustison, Editor(s)

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