Advanced Thermal Protection Systems Enabled by Additive Manufacturing of Hybrid Thermoplastic Composites

This study investigates seven advanced hybrid composite thermal protection system (TPS) prototypes, featuring an innovative internal air chamber design that reduces heat conduction and enhances overall thermal protection performance. Specimens were manufactured by fused deposition modeling (FDM), an additive manufacturing technique, using a fire-retardant thermoplastic. Selected configurations were reinforced with continuous carbon or glass fibers, coated with ceramic surface layer, or hybridized with carbon fiber reinforced polymer (CFRP) layers or a CFRP laminate disk. To validate performance, a harsh oxy-acetylene torch (OAT) protocol was implemented, deliberately designed to exceed the severity of most reported typical ablative assessments. The exposed surface of each specimen was subjected to direct flame at a 50 mm distance, recording peak temperatures of 1600 ± 50 °C. Two samples of each configuration were tested under 60 and 90 s exposures. Back-face thermal readings at potential payload sites consistently remained below 85 °C, well under the 200 °C maximum standard threshold for TPS applications. Several configurations preserved structural integrity despite the extreme environment. Prototypes 4.1 and 4.2 demonstrate the most favorable performance, maintaining structural integrity and low back-face temperatures despite substantial thickness loss. By contrast, specimen 6.2 exhibited rapid degradation following 60 s of exposure, which served as a rigorous and selective early-stage screening tool for evaluating polymer-based ablative TPS architectures.