Sunkar Orazbek

EPDM is widely used as the polymer matrix for solid rocket motor (SRM) internal thermal protection because of its low density, chemical inertness, and ability to form carbonaceous residue. Practical performance is frequently limited by weak char integrity and barrier properties, char oxidation, mechanical stripping in gas-dynamic flow, and by the poor comparability of published results due to non-uniform test conditions and reporting. This review systematizes studies on 0D nanofillers in EPDM ablatives and harmonizes the key metrics, including linear and mass ablation rates (LAR, MAR), back-face temperature (T_back), and solid residue yield. The major 0D additives-nSiO₂, nTiO₂, nZnO, and carbon black (CB) are compared, and their dominant mechanisms are summarized: degradation-layer structuring, reduced gas permeability, thermo-oxidative stabilization, and effects on vulcanization. Several studies report larger improvements for hybrid systems, where CB enhances char cohesion and retention, while oxide nanoparticles improve barrier performance and resistance to oxidation. Finally, an application-oriented selection matrix is proposed that accounts for thermal protection efficiency, processability, agglomeration limits, and density penalties to support EPDM coating design and improve comparability.

Elastomeric ablative coatings are essential for protecting solid rocket motor (SRM) combustion chambers from extreme thermal and erosive environments, and their performance is governed by both material composition and processing strategy. This review examines the main elastomer systems used for SRM insulation, including ethylene propylene diene monomer (EPDM), nitrile butadiene rubber (NBR), hydroxyl-terminated polybutadiene (HTPB), polyurethane (PU), silicone-based compounds, and related hybrids, and discusses how their rheological behavior, cure kinetics, thermal stability, and ablation mechanisms affect manufacturability and in-service performance. A comprehensive assessment of coating technologies is presented, covering casting, molding, centrifugal forming, spraying, automated deposition, and emerging additive-manufacturing approaches for complex geometries. Emphasis is placed on processing parameters that control adhesion to metallic substrates, layer uniformity, defect formation, and thermomechanical integrity under high-heat-flux exposure. The review integrates current knowledge on how material choice, surface preparation, and application sequence collectively determine insulation efficiency under operational SRM conditions. Practical aspects such as scalability, compatibility with complex chamber architectures, and integration with quality-control tools are highlighted. By comparing the capabilities and limitations of different materials and technologies, the study identifies key development trends and outlines remaining challenges for improving the durability, structural robustness, and ablation resistance of next-generation elastomeric coatings for SRMs.

This study addresses the need for thermomechanically robust materials for high-temperature environments by investigating fabric-reinforced composites produced through polymer infiltration and thermal pressing using phenol-formaldehyde (PF) and epoxy (ER) resins. Experimental validation was required due to the lack of comparative data across different textile reinforcements under identical conditions. Seven technical fabrics—carbon, aramid, basalt, silica, fiberglass, asbestos, and a carbon/aramid hybrid—were used as reinforcements. Mechanical testing revealed that carbon- and hybrid fiber composites exhibited the highest tensile (up to 465 MPa) and compressive strengths (up to 301 MPa), particularly when combined with ER. Conversely, the use of PF generally resulted in a 30–50% reduction in mechanical strength. However, PF-based composites demonstrated superior thermal resistance, with the silica/PF combination showing the lowest back-face temperature (401 °C), up to 37% lower than other pairings. Thermal conductivity ranged from 0.041 to 0.51 W/m·K, with PF-based systems offering 6–12% lower values on average compared to ER-based analogs. Morphological analysis confirmed better interfacial bonding in ER composites, while PF systems showed higher structural integrity under thermal loading. Overall, the results emphasize the trade-offs between mechanical strength and thermal protection depending on the fabric–resin combination. Among all variants, the silica fabric with PF demonstrated the most balanced performance, making it a promising candidate for thermomechanical applications.