N152-104 TITLE:  Manufacturing Near-Net-Shape Conformal Electro-optic Sensor Window Blanks from Spinel

TECHNOLOGY AREAS:  Air Platform, Materials/Processes, Sensors

ACQUISITION PROGRAM:  UCLASS, The Carrier Unmanned Aviation Program Office PMA-268

The technology within this topic is restricted under the International Traffic in Arms Regulation (ITAR), 22 CFR Parts 120-130, which controls the export and import of defense-related material and services, including export of sensitive technical data, or the Export Administration Regulation (EAR), 15 CFR Parts 730-774, which controls dual use items. Offerors must disclose any proposed use of foreign nationals

(FNs), their country(ies) of origin, the type of visa or work permit possessed, and the statement of work (SOW) tasks intended for accomplishment by the FN(s) in accordance with section 5.4.c.(8) of the solicitation. Offerors are advised foreign nationals proposed to perform on this topic may be restricted due to the technical data under US Export Control Laws. 

OBJECTIVE:  Demonstrate a manufacturing process for near net shape spinel blanks for large conformal sensor windows. A related topic NSMA-152-918 will address methods to manufacture large conformal sensor windows that could be made from these blanks in the future.

DESCRIPTION:  Electro-optic sensor windows that conform to the local shape of an aircraft mold-line are desirable for future air platforms to allow for a large sensor angle of regard. Conformal shapes may have little to no symmetry depending upon their location. Spinel is an excellent material candidate as it is both durable and multi-spectral (ultraviolet through mid-wave infrared). Spinel is more erosion resistant than multispectral zinc sulfide, which is another logical candidate for a large conformal window. The availability of blanks currently limits the size and curvature for potential window applications. The objective of this project is to develop and demonstrate new manufacturing processes to provide near net shape blanks to improve upon current state of the art processes which start with a thick, planar blank and grind them to the desired shape. Currently, the thickness of the planar blank limits the maximum sag (height of window from highest to lowest point) that can be obtained to approximately one inch. Although actual shapes will be chosen by mutual agreement with the government, it is expected that the approximate conformal shape for Phase II will be 16x16 inches with a sag of six inches. A small grain spinel is preferred for enhanced strength, which is a desired property. 

PHASE I:  Demonstrate feasibility to manufacture near net shape conformal electro-optic sensor window blanks from spinel. To prove feasibility, produce a minimum of two uncracked, fully dense spinel window blanks having final fired dimensions of at least a 6x6inch footprint, sag of three inches, and thickness of ½ inch. A toroid is a possible demonstration shape. Measure the transmission spectrum of the material using polished flat specimens cut from one of the window blanks. Desired transmission is within 4% of the theoretical value for spinel at a wavelength of 0.63 microns and within 2% of the theoretical value for spinel at a wavelength of 4 microns.

PHASE II:  Scale up to produce a minimum of two uncracked, fully dense spinel window blanks having final fired dimensions of at least a 16x16inch footprint, sag of six inches, and thickness of one inch. Demonstration shape may be a toroid or other free-form shape mutually agreed upon with the government. Measure the transmission spectrum and flexure strength of the material using polished flat specimens cut from one of the window blanks. Desired transmission is within 4% of the theoretical value for spinel at a wavelength of 0.63 microns and within 2% of the theoretical value for spinel at a wavelength of 4 microns. A material strength of greater than 200MPa is desirable, as measured by ring-on-ring flexure testing.

PHASE III:  Implement manufacturing processes for commercial production and commence full rate production in order to support Navy requirements. Assist the Navy in transitioning this technology to identified platforms.

REFERENCES:  

1.   Ganesh, I. “Aqueous slip casting of MgAl2O4 spinel powder,” Bull. Mater. Sci., Vol. 34, No. 2, April

2011, pp. 327–335. Retrieved from: http://www.ias.ac.in/matersci/bmsapr2011/327.pdf

2.   Janney M A, Nunn S D, Walls C A, Omatete O O, Ogle R B, Kirby G H and McMillan A D, 1998 Gelcasting; in The handbook of ceramic engineering (ed.) M N Rahman (New York: Marcel Dekker) pp 1– 15.

3.   Patel P J, Gilde G A, Dehmer P G and McCauley J W, “Transparent Armor” 2000 The AMTIAC Newsletter Retrieved from: http://infohouse.p2ric.org/ref/34/33126.pdf

KEYWORDS:  Spinel; transparent ceramics; slip casting; conformal window; transparent armor; sensor window; infrared window

** TOPIC AUTHOR (TPOC) **

DoD Notice:   Between April 24 and May 25, 2015 you may talk directly with the Topic Authors (TPOC) to ask technical questions about the topics. Their contact information is listed above. For reasons of competitive fairness, direct communication between proposers and topic authors is not allowed starting May 26, 2015 , when DoD begins accepting proposals for this solicitation.

However, proposers may still submit written questions about solicitation topics through the DoD's SBIR/STTR Interactive Topic Information System (SITIS), in which the questioner and respondent remain anonymous and all questions and answers are posted electronically for general viewing until the solicitation closes. All proposers are advised to monitor SITIS (15.2 Q&A) during the solicitation period for questions and answers, and other significant information, relevant to the SBIR 15.2 topic under which they are proposing.

If you have general questions about DoD SBIR program, please contact the DoD SBIR Help Desk at 800-348-0787 or [email protected].