Engineered thin films with ultra-low thermal expansion coefficient for deployable or deformable space structures

Abstract

We developed micro-structured thin films with ultra-low coefficient of thermal expansion. These low-weight, flexible, thermally stable films are expected to be a useful tool in aerospace applications, for example, as a reflective layers of deformable space telescope mirrors. The low-CTE films are composed of a Ti frame supporting hexagonal Al plates arranged in a two-dimensional periodic lattice. The effective CTE of these materials can be controlled by selecting the appropriate constitutent material properties of the frame and plates, and the geometry of the lattice. Aluminum and titanium were selected as constituent materials to create thin films with a CTE close to zero. The 2D bi-metallic lattice was microfabricated, and characterized for its thermal and optical functionalities. The effective CTE was confirmed to be ultra-low (-0.6×10^(-6)/°C), and the imaging capability of this metallic layer was evaluated in the range of temperature from room temperature to 150 °C.

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