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Journal of Materials
Volume 2014 (2014), Article ID 623832, 5 pages
Research Article

Optical Response of Metakaolin after Ultraviolet and High Energy Electron Exposure

1Department of Aeronautics and Astronautics, Air Force Institute of Technology, Building 640, 2950 Hobson Way, Wright-Patterson AFB, OH 45433-7765, USA
2Metals Branch, Structural Materials Division, Materials and Manufacturing Directorate, Air Force Research Laboratory, 2230 10th Street, Building 655, Wright-Patterson AFB, OH 45433, USA

Received 2 December 2013; Revised 17 March 2014; Accepted 19 March 2014; Published 8 May 2014

Academic Editor: Achim Trampert

Copyright © 2014 B. T. Cesul et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Metakaolin, which is part of a class of inorganic polymers called geopolymers, is being tested currently for its use as a lightweight mirror material in spacecraft applications. Metakaolin, as with most geopolymers, has the advantages of low initial coefficient of thermal expansion, easy preparation at room temperature and pressure, and high specific strength. Even though metakaolin has been known as a structural material for millennia, it has not been properly vetted for use as a material in spacecraft applications, especially with respect to exposure to its environments. This research highlights one particular aspect of response to the space environment; that is, how do the optical properties of metakaolin change after subjugation to bombardment by ultraviolet and high energy electron radiation? These two radiation sources are common in low earth orbit and a primary cause of degradation of organic polymers in space. Photospectroscopic analysis showed that ultraviolet in combination with high energy electrons causes changes in the metakaolin which need to be accounted for due to their potential impacts on the thermal management of a spacecraft and during application in composite mirror structures.