Additive Manufactured Dielectrics for Aerospace Electrical Insulation Applications

This paper investigates if there are inherent limitations with Additive Manufactured (AM) materials to preclude their use in electrical insulation applications, and if any anisotropic behavior exists with respect to print orientation. Two different AM processes, stereolithography (SLA) and selective laser sintering (SLS), were utilized to produce dielectric samples. Conductivity, Dielectric Relaxation Spectroscopy, bulk partial discharge, and dielectric breakdown tests were performed on samples printed in different orientations. Dielectric characterization was performed over a wide range of frequencies (DC to 1 MHz) and temperatures (-60C to +200C; material permitting). To help address the lack of meaningful electrical information in AM materials, this paper proposes a methodology for evaluation and dielectric quantification of basically "unknown" materials. Generally, the materials studied exhibited acceptable dielectric behavior but no clear advantages other than enabling complex multifunction designs (dielectric, structural and thermal). Dielectric strengths exceeding 30 kV/mm for a 1.0 mm thickness were exhibited in both SLA and SLS samples, with strength scaling laws explored over a range of thicknesses from 300 µm to 5.0 mm. For differing print orientations (XY-plane, YZ-pane, 30-degree inclined XY-plane) no discernible anisotropic dielectric behavior was observed. Motivations for the use of AM produced dielectrics in a civil aerospace context is also treated.