Title: Evaluation of Ultra-Performance Polymers to Use as Thermal Protection Systems for Space Vehicle Application

Authors: Abdullah Kafi, Hao Wu, Jon Langstron, Ozen Atak, Haewon Kim, Steven Kim, William Fahy, Roderick Reber, John Misasi, Stuart Bateman, and Joseph H. Koo

DOI: 10.33599/nasampe/c.19.0813

Abstract: As additive manufacturing (AM) increasingly gains commercial and academic interest, government agencies, such as NASA seek to produce thermal protection systems (TPS) using Fused Filament Fabrication (FFF) method. The purpose of this study is to test and evaluate several ultra-performance polymers, such as polyetherimide (PEI), polyetheretherketone (PEEK), and polyetherketoneketone (PEKK) for thermal, flammability, and ablative properties while maintaining compatibility with commercially available FFF machines. The four neat ultra-performance polymers used were SABIC ULTEM™ 9085, Roboze PEEK, Smartmaterials3D PEEK, and Arkema Kepstan® 7002 PEKK, and a modified PEI (ULTEM™ 1010) material. These five polymers were characterized with thermogravimetric analysis (TGA) for char yield and microscale combustion calorimeter (MCC) to determine flammability properties. After obtaining and analyzing TGA and MCC results, test specimens were then fabricated using 1.75 mm diameter FFF filaments using commercially available high-temperature capable printers. Ablation test models were printed via FFF using oxy-acetylene test bed (OTB) (dome-shaped 20 mm diameter cylinders) and inductively coupled plasma (ICP) (dome-shaped 30 mm diameter cylinders) aerothermal ablation testing.

These FFF ablation test models were then evaluated for ablation and thermal properties using the OTB at realistic test conditions simulating reentry conditions, such as 100 W/cm2 for 15s and 30s. From these ablation tests, the materials’ recession, mass remainder, surface temperature, and backside heat-soaked temperature were recorded. Furthermore, microstructural analysis was performed using scanning electron microscopy (SEM) to study the microstructures of printed test specimens. In order to fully exploit the experimental data provided by the OTB, the flowfield generated during aerothermal testing using this heat source was recently modeled by the Koo Research Group. CFD analysis using Ansys/Fluent 19.1 code is currently being used to analyze the heat transfer between the ablative surface and the combustion gases generated by the OTB and compared with experimental results. Finally, after analyzing these test results, a recommendation of the top performing formulation will be submitted to NASA Johnson Space Center for further testing and evaluation.

References: 1. H. Wu, M. Sulkis, J. Driver, A. Saade-Castillo, A. Thompson, and J. H. Koo. Multi-functional ULTEM™1010 composite filaments for additive manufacturing using Fused Filament Fabrication (FFF). Additive Manufacturing, 2018, 24:298-306. 2. B. Graybill, Development of a predictive model for the design of parts fabricated by fused deposition modeling. MS thesis, University of Missouri-Columbia; 2010, May. 3. H. Li, G. Taylor, V. Bheemreddy, O. Iyibilgin, M. Leu, K. Chandrashekhara, Modeling and characterization of fused deposition modeling tooling for vacuum assisted resin transfer molding process. Additive Manufacturing, 2015; 7:64-72, https://doi.org/10.1016/j.addma.2015.02.003 4. Technical data sheets provided by Smart materials 3D, Spain. 5. P. Wang, B. Zou, H. Xiao, S. Ding, and C. Huang, Effects of printing parameters of fused deposition modeling on mechanical properties, surface quality, and microstructure of PEEK. Journal of Materials Processing Technology, 2019, 271:62-74. 6. O. B. Searle and R. H. Pfeiffer, Victrex® poly(ethersulfone) (PES) and Victrex® poly(etheretherketone) (PEEK), Polymer Engineering and Science, mid-June 1985, Vol. 25, No. 8. 7. Material properties were provided by Arkema Inc., King of Prussia, PA, USA. 8. Modified ULTEM 1010. Formulation and raw materials were provided by KAI, LL, Austin, TX, USA. Filaments and test models were produced at Western Washington University, Bellingham, WA, USA. 9. Material properties were characterized at UT Austin. 10. O. Atak, J. H. Koo et al. Three-dimensional modeling of ablative materials exposed to oxy-acetylene test bed. International Journal of Energetic Materials and Chemical Propulsion, (2019), in review. 11. K. J. Schellhase, J.H. Koo, H. Wu, J. J. Buffy. Experimental Characterization of Material Properties of Novel Silica/Polysiloxane Ablative. Journal of Spacecraft and Rockets. 2018;55:1401-13. 12. S. Kim et al. Evaluation of a modified fused filament fabrication material for use as thermal protection. Proc. 2019 SAMPE Technical Conference, May 20-23, 2019, Charlotte, NC.

Conference: CAMX 2019

Publication Date: 2019/09/23

SKU: TP19-0813

Pages: 17

Price: $34.00