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EFFECTS OF VACUUM-ULTRAVIOLET ENVIRONMENT OF THE OPTICAL PROPERTIES OF BRIGHT ANODIZED ALUMINUM.
AIR FORCE MATERIALS LAB WRIGHT-PATTERSON AFB OHIO
The rapid increase in space vehicle design reliability and lifetime requirements has created a serious problem in the selection of materials for passive temperature control. The major difficulty is the prediction of the degradation of the thermal radiation properties of these materials under the space environment. Bright anodized aluminum coatings are known to possess the desired optical properties for passive temperature control and are being considered for space vehicle application. The effects of the vacuum-ultraviolet environment on the optical properties of bright anodized aluminum have been determined. The optical properties of the bright anodized aluminum system are only slightly altered by ultraviolet radiation in air. However, the combined vacuum-ultraviolet radiation is the most detrimental to the reflectance of bright anodized coatings prepared by the sulfuric acid process. The color centers formed during exposure causes a gradual increase in absorption up to 120 hours exposure. This increase in solar absorption causes the alpha sub sepsilon ration to increase to 0.42 after approximately 120 hours exposure, but after this change, very little further change is noted, unlike most organic and inorganic coatings. Author
Rept. for 1 Jan 63-1 Aug 64,