Science and technology of polymeric ablative materials for thermal protection systems and propulsion devices: A review

Functionally graded materials (FGMs) are a broad research area and attract considerable tremendous attention today in the materials science and engineering society. In recent years, FGMs have experienced remarkable developments in manufacturing methods. FGMs can be produced using several well-known processing techniques from conventional to advanced. This research provides an overview of manufacturing methods for FGMs, thus describing the fundamental difficulties and strengths of these methods based on the available literature over 30 years. Besides, this critical review gives a comprehensive summary of the various applications and the future trends for research required for the design and production of these materials properly with a smooth graded. The anticipated findings of the current paper can be considered as a milestone for future production and analysis investigations for FGMs and are beneficial for researchers, designers, and manufacturers in this scope.

30 Years of functionally graded materials: An overview of manufacturing methods, Applications and Future Challenges

Carbon/carbon (C/C) composites are considered as one of the most promising materials in structural applications owing to their excellent mechanical properties at high temperature. However, C/C composites are susceptible to high-temperature oxidation. Matrix modification and coating technology with ultra-high temperature ceramics (UHTCs) have proved to be highly effective to improve the oxidation and ablation resistance of C/C composites. In this paper, recent advances in oxidation and ablation resistance of C/C composites were firstly reviewed, with attention to oxidation and ablation properties of C/C composites coated or modified with UHTCs. Then, several new methods in improving oxidation and ablation resistance were discussed, such as by using nanostructures to toughen UHTCs coatings or carbon matrix and the combination of matrix modification and coating technology. In addition, relevant ablation tests with scaled models were also briefly introduced. Finally, some open problems and future challenges were highlighted in the development and application of these materials.

Advances in oxidation and ablation resistance of high and ultra-high temperature ceramics modified or coated carbon/carbon composites

The control of the nanostructure and the addition of nanoparticles to polymers have led to structural and functional property enhancements in a number of polymeric systems as a material answer to continuous requirements from advanced industrial sectors. The availability of new nanoparticles with extraordinary properties (i.e. carbon nanotubes, graphenes, but also nanoclays, nanocellulose, metals and ceramics) have determined new and exciting possibilities for a continuous enlargement of polymer markets. However, the potentialities of these new materials are still strongly dependent on the development and scaling-up of reliable processing routes. Therefore, the purpose of this report is to review the main processing approaches for nanostructured polymers and nanocomposites starting with a brief review of available nanoparticles and on their functionalization to promote a better polymer–particle interaction. Regarding processing, the review firstly addresses the bottom-up approaches typically adopted for nanostructured polymers, blends and copolymers. Then, the different technologies required by the top-down processing of thermoplastic and thermosetting polymer matrix systems are reviewed. Finally, the report addresses the recent applications of nanostructured polymers and nanocomposites as matrices of advanced composite materials. In all cases, the main processing approaches and the main structural and functional properties characterizing these materials and their potential and current industrial applications are specifically addressed.

Processing of nanostructured polymers and advanced polymeric based nanocomposites

https://onlinelibrary.wiley.com/doi/pdf/10.1002/admt.201900981

A Review on Functionally Graded Materials and Structures via Additive Manufacturing: From Multi-Scale Design to Versatile Functional Properties

Nano silica modified carbon–phenolic composites for enhanced ablation resistance

Development and characterization of polymer–ceramic continuous fiber reinforced functionally graded composites for aerospace application

C–SiC composite Jet-Vanes were fabricated using liquid silicon infiltration and tested in a plume of aluminum based solid propellant to study erosion resistance. The Jet-Vanes showed excellent resistance to thermo-oxidative erosion; average linear and mass erosion rates were 1 mm/s and 5 g/s, respectively. Morphology of the eroded surfaces suggests that alumina particles in the plume hit the leading edge of the Jet-Vane, damage it and some material is eroded away. Residual silicon melts and reacts with oxygen to form silica which in turn reacts with SiC matrix. The matrix of SiC, silicon and un-reacted carbon is loosened and erode by high shear forces. Once carbon fibers get exposed directly to the plume, these may be both eroded and oxidized.

Fabrication and erosion studies of C–SiC composite Jet Vanes in solid rocket motor exhaust

Effect of siliconization conditions on thermal diffusivity of 3D-stitched fiber architecture-based C–SiC composites was investigated to select desired conditions. Several 3D-stitched C–SiC composite blocks were prepared using coal–tar pitch as a carbon precursor and siliconization was carried out at 1450 and 1650 °C for 10 and 120 min. Thermal diffusivity of blocks was investigated using laser-flash equipment in in-plane and through-thickness directions. It varies from 77 mm 2 /s at room-temperature to 14.7 mm 2 /s at 1500 °C in in-plane and 36–6.1 mm 2 /s in through-thickness direction. A model was developed to estimate thermal diffusivity in in-plane and through-thickness directions based on the volume fraction of the constituents and porosity of the composite blocks. The estimated thermal-diffusivity values were compared with the measured values. The values were found to be close to the experimental values in entire testing temperature range at all the siliconization conditions.

Thermal-diffusivity measurement of 3D-stitched C–SiC composites

3D-orthogonal-woven-C–SiC composite blocks were fabricated using liquid–silicon-infiltration and were characterized for thermal and mechanical properties. Coefficient of thermal expansion (CTE) and thermal-diffusivity of the blocks were determined in the three mutually perpendicular directions. CTE was found to lie in the range −0.5 × 10 −6 to 0.9 × 10 −6 /°C over the temperature range 25–1050 °C while thermal diffusivity was found to be in the range 37.0–7.0 mm 2 /s over the temperature range 25–1200 °C. The composites were subjected to sudden heating at a heat flux of 0.9 W/mm 2 for 20 s and cooling by a blast of air, upto 5 times. Three point bend test of the specimens was carried out. After five thermal shocks the composites retained about 59% of the initial strength (190 MPa); after each thermal shock, the composite retained 85–90% of the previous strength. The composites showed excellent resistance to thermal shock and chemical erosion necessary for re-usable aerospace applications.

G. Rohini Devi

Papers

Nano silica modified carbon–phenolic composites for enhanced ablation resistance

Development and characterization of polymer–ceramic continuous fiber reinforced functionally graded composites for aerospace application

Fabrication and erosion studies of C–SiC composite Jet Vanes in solid rocket motor exhaust

Thermal-diffusivity measurement of 3D-stitched C–SiC composites

Preparation of 3D orthogonal woven C―SiC composite and its characterization for thermo-mechanical properties