Research Progress on Carbon-Based Materials for Aerospace Applications

Research Progress on Carbon-Based Materials for Aerospace Applications

With the development of aircraft towards lightweight, high reliability, and multifunctionalization, traditional metal materials are facing performance bottlenecks. Carbon-based materials such as carbon fiber, carbon nanotubes (CNTs), graphene, carbon/carbon composites, and carbon aerogels are gradually achieving engineering applications in the aerospace field due to their excellent mechanical, thermal, and electrical properties.

On October 15, 2025, Composites Part B: Engineering published the latest research titled "Research Progress on Carbon-Based Materials for Aerospace Applications" from the School of Equipment Engineering of Shenyang Ligong University, the School of Aeronautic Science and Engineering of Beihang University, the Beijing Key Laboratory of Powder Technology Research and Development of Beihang University, the School of Materials Science and Engineering of Shenyang Ligong University, the College of Aerospace Engineering of Nanjing University of Aeronautics and Astronautics, and the State Key Laboratory of Mechanics and Control of Mechanical Structures of Nanjing University of Aeronautics and Astronautics.

I. Main Carbon-Based Materials

II. Applications in Aerospace

High-Temperature Thermal Protection Systems

In the aerospace field, thermal protection systems are crucial for the safe operation of aircraft. During high-speed flight and atmospheric re-entry, aircraft face extremely high temperatures and oxidative environments, posing severe challenges to the structural integrity and functional stability of materials. With increasing flight speeds and mission durations, thermal protection systems must maintain stable performance under extreme conditions exceeding 1650°C, especially at key parts like space shuttles and hypersonic vehicle nose cones. Materials need to combine excellent thermomechanical properties, thermochemical stability, thermal shock resistance, and lightweight/high-strength characteristics.

1. Key Role of Hf6Ta2O17 in Ablation Resistance of C/C Composites
Wang et al. studied the cross-sectional microstructure of HfC-0HTO, HfC-1.25HTO, and HfC-2.5HTO samples and found that as the HTO content increased, the density of the oxide layer improved, and the interface with the SiC layer maintained good integrity (Figure 2a-f).
After 120 seconds of ablation, a dense oxide layer composed of HfO₂ and ZrO₂ formed on the composite surface, significantly enhancing oxidation resistance and anti-heat flux capability (Figure 2i).

Fig. 2. (a-f) Cross-sectional microstructure images of HfC-0HTO, HfC-1.25HTO, and HfC-2.5HTO samples, showing the density of the oxide layer and the integrity of the interface with the SiC layer. (g) Photograph of the composites after 120 seconds of ablation. (h) SEM image of the composite center after 120 seconds of ablation. (i) Surface microstructure after ablation, where HfO2 and ZrO2 form a dense oxide layer.

2. Excellent Antioxidant Behavior of La2O3-doped ZrB2-SiC Coating

• Lin et al. prepared a ZrB₂-SiC-La₂O₃ composite coating on the surface of C/C composites using atmospheric plasma spraying. The ZSL10 sample containing 10 wt% La₂O₃ performed the best.

• After 10 hours of oxidation in air at 1500°C, the ZSL10 coating showed only a 9.62% mass loss, demonstrating excellent oxidation resistance.

• After 2 hours of oxidation, the coating formed a sandwich structure of "borosilicate glass phase — (La₀.₁Zr₀.₉)O₁.₉₅₊ₘ — ZrO₂ solid solution — original ZSL10 coating" (Figure 3a).

• As the oxidation time extended to 10 hours, the glass phase further melted and expanded, encapsulating oxidized particles and stabilizing the phase transition of La-doped ZrO₂.

• A continuous Zr(La)-O-C low diffusion barrier layer was simultaneously generated, ultimately forming a crack-free, dense protective film that significantly reduced oxygen permeation rate.

3. Self-Healing Protection Mechanism of SiO2 Glass Layer in C/SiC Composites

• Zou et al. found that C/SiC composites can naturally form a continuous glassy SiO₂ protective layer through oxidation during the ablation process.

• When the temperature is below 1500°C, the generated liquid SiO₂ has good fluidity and can automatically fill surface microcracks, achieving a "self-repairing" function (Figure 3c).

• This characteristic effectively isolates external oxygen from contacting the matrix, significantly inhibiting the further development of oxidation reactions, providing a guarantee for the application of carbon fibers in high-temperature environments.

Fig. 3. (a-b) ZSL10 coating after (a) 2 h and (b) 10 h of oxidation, showing the formation of the high-temperature stable phase (La,Zr)O₂ and Zr(La)-O-C compounds. (c) Illustration of the ablation process and its protective mechanism. (d) Surface temperature curves during ablation for C/C-SiC-ZrC-Cu composites with varying Cu content. (e) Schematic of the ablation evolution for the C/C-SiC-ZrC-Cu composite.

4. Preparation of New C/C Composites and Their Excellent Thermal Insulation Performance

• Li et al. successfully prepared a C/C composite with an aerogel-like structure using high-pressure assisted polymerization and ambient pressure drying (APD) technology, incorporating low-crystallinity fiber reinforcement.

• This method avoids complex organic solvent exchange steps, simplifies the process flow, shortens the preparation cycle, and enables large-scale, crack-free production.

• After being heated by an 1800°C acetylene flame for 900 seconds, the backside temperature of the material was only 685–778°C (Figure 4a), demonstrating excellent thermal insulation performance.

• Microstructural design optimization achieved a significant reduction in thermal conductivity while maintaining excellent mechanical properties, overcoming the problems of high thermal conductivity and insufficient strength of traditional C/C materials at high temperatures.

5. Low-Cost and Efficient Preparation and Performance Advantages of Carbon Fiber Reinforced Carbon Aerogel (CF/CA)

• Zhang et al. impregnated a polyacrylonitrile (PAN) fiber felt with a resorcinol-furfural (RF) gel containing ZnCl₂, and obtained carbon fiber reinforced carbon aerogel (CF/CA) through aging and pyrolysis treatments (Figure 4b).

• This process eliminates the solvent exchange and supercritical drying steps in the traditional sol-gel method, enabling the preparation of low-cost, efficient high-temperature insulation materials.

• Under an argon atmosphere at 1800°C, CF/CA maintained a low thermal conductivity of 0.6904 W/m·K (Figure 4c) and a high compressive strength of 6.10 MPa (Figure 4d), combining excellent high-temperature insulation with mechanical stability.

Fig. 4. (a) Temperature changes at the front (Tf) and back (Tb) surfaces of C/C composites heated by an oxyacetylene flame at 1800 °C. (b) Preparation flowchart of carbon fiber-reinforced carbon aerogel (CF/CA). (c) Compressive stress-strain curve of CF/CA. (d) Thermal conductivity of CF/CA in an argon atmosphere at different temperatures.

6. Chitosan-Assisted Preparation of High-Performance Monolithic Carbon Aerogel

• Men et al. successfully prepared morphologically intact, nano-sized, ultra-low density carbon aerogels by optimizing the polymerization reaction and hydrogen bond network between chitosan and the precursor to build a reinforced gel skeleton.

• The preparation process by ambient pressure drying is shown in Figure 5a. Under acidic conditions, resorcinol and formaldehyde generate hydroxymethyl derivatives. Chitosan is protonated under acid catalysis and cross-linked with formaldehyde to form a three-dimensional network structure, which acts as a soft template to guide the sol-gel reaction and connects RF oligomers through hydrogen bonds, enhancing the strength of the gel framework.

• The RF hydrogel was carbonized after drying at 80–100°C under ambient pressure to obtain large-sized monolithic carbon aerogels. Without chitosan, the gel is prone to cracking during drying. Adding chitosan effectively inhibits shrinkage and cracking, resulting in defect-free RF aerogels (Figure 5b).

Fig. 5. Process for preparing nanoporous monolithic carbon aerogel via ambient pressure drying: (a) schematic of the preparation process; (b) schematic of the drying process.

Anti-Atomic Oxygen Protection

1. Threat of Atomic Oxygen Environment to LEO Spacecraft and Protective Potential of Carbon-Based Materials

• In the Low Earth Orbit (LEO) environment, atomic oxygen (AO) is one of the most destructive space environmental factors, generated by the photodissociation of molecular oxygen caused by solar ultraviolet radiation.

• AO is highly oxidative and reacts with spacecraft surface materials, causing severe erosion and performance degradation.

• Carbon-based materials (such as graphene) exhibit excellent resistance to AO erosion due to their unique single-layer structure, making them particularly suitable for LEO environment applications.

2. Effect of Graphene as Nanofiller against Atomic Oxygen Erosion

• Incorporating graphene as a nanofiller into a polymer matrix can significantly improve the AO resistance of the composite material.

• Zhang et al. found that adding 0.5 wt% graphene to epoxy resin reduced mass loss and erosion yield by 46% and 47%, respectively.

• Yi et al. showed that under the same AO flux (4.7×10²⁰ atoms·cm⁻²), just 1 wt% of large-size few-layer graphene (FLG) could reduce the mass loss of PVA by 42%, outperforming small-size FLG (~33%) and graphene oxide GO (~28%).

• The improvement is attributed to the physical barrier effect and chemical bonding effect of FLG and GO, effectively preventing AO penetration into the substrate.

(a-b) Mass loss and erosion yield of epoxy/graphene nanocomposites. (c) Morphology of large FLG flakes, (d) small FLG flakes, and (e) GO flakes after exposure to atomic oxygen (AO). (f) Schematic of bond formation and barrier effect. (g) Schematic of AO permeation through large graphene flakes. (h) Schematic of AO penetration through small graphene flakes. (i) Schematic of AO penetration through graphene oxide flakes. Mass loss relative to PI for composite films with different filler contents under a total AO fluence of 10×10²⁰ atoms/cm²: (j) EGs and (k) EGs/nanoparticles. Schematic of the mechanisms by which (l) EGs and (m) EGs/nanoparticles enhance the AO erosion resistance of PI. (n) Barrier and bonding effects between EGs and AO. (o) Three-point bending strength of C/C and SiC-C/C composites after different AO irradiation times. (p) Mass change rate of C/C and SiC-C/C composites after different AO irradiation times.

3. Application Example of Graphene Coating in Atomic Oxygen Protection

• Depositing a SiC coating on the surface of C/C composites using CVD technology can significantly improve their resistance to AO erosion. Strength retention rate increased by 20.3%, and mass loss rate decreased by 60%.

• The unprotected C/C surface was directly oxidized to CO/CO₂ upon impact by high-speed AO, forming honeycomb-like corrosion pits. In contrast, the SiC-C/C surface generated a dense SiO₂/SiCₓOᵧ protective layer in situ, accompanied by the precipitation of a graphite phase and volume expansion, helping to close cracks and prevent further AO erosion of the internal carbon matrix.

(a-b) Schematic of the damage mechanisms induced by atomic oxygen (AO) in C/C and SiC-C/C composites. (c) Diagram of the atomic oxygen exposure experiment. (d) Ground-based simulation facility for atomic oxygen effects. (e) Schematic illustrating the mechanism of graphene coating protecting Kapton from AO erosion.

4. Structural Integrity and Optical Transparency Advantages of Graphene Composite Coatings

• Cui et al. developed a graphene-modified polysiloxane-60 vol.% SiO₂ (G-PSS) composite coating, uniformly coated on Kapton surface using a sol-gel method combined with multiple dip-coating processes.

• Under simulated LEO AO total fluence of 1.86×10²⁰ atoms/cm², the erosion rate of the G-PSS coating ranged from 9.77×10⁻²⁷ to 1.25×10⁻²⁶ cm³/atom, three orders of magnitude lower than bare Kapton and one order of magnitude superior to the PSS coating without graphene.

• After AO exposure, the bare Kapton surface showed a typical "carpet-like" rough and porous structure, while the G-PSS coating surface remained almost unchanged, without pores or microcracks, proving that graphene effectively compensated for the defects in the PSS coating.

• The G-PSS coating maintained over 90% visible light transmittance before and after AO treatment, combining excellent corrosion resistance with high optical transparency, meeting the optical performance requirements for spacecraft surfaces.

(a) SEM image of Kapton before AO erosion. (c-e) SEM images of Kapton after AO erosion. (b) SEM image of Kapton coated with graphene (loading: 26.0 μg/cm²) before AO erosion. (d-f) SEM images of the same coated Kapton after AO erosion (AO fluence: 7.09 × 10²⁰ atoms/cm²). (g-j) Surface images after AO exposure: (g) Kapton, (h) Graphene, (i) PSS hybrid coating, (j) G-PSS composite coating. (k) Transparency comparison of Kapton and the G-PSS composite coating before and after exposure to an AO fluence of 1.86×10²⁰ atoms/cm².

Electromagnetic Shielding and Wave-Absorbing Materials

1. Structural Optimization and Performance Enhancement of Carbon-Based Materials in Microwave Absorption

• By rationally selecting filler components and optimizing material structure, the microwave absorption capacity of materials can be significantly improved.

• Relevant research results lay a theoretical foundation for the development of electromagnetic compatibility and stealth technology in aerospace and military equipment, and provide effective technical pathways for the engineering application of microwave absorption materials.

• The following figure shows preparation schematics for various advanced microwave absorption materials. These include porous FGS/PS material (compression molding + molten salt method), MSS multilayer structure (epoxy resin, 1 wt% MWCNTs, 4 wt% MWCNTs), three-layer layered nanocomposite and its absorption performance, construction of Ni/MnO-CA material and its electromagnetic wave absorption mechanism, and the electromagnetic shielding structure of LCF/PC-SiC.

(a) Schematic of porous FGS/PS material fabrication via compression molding and salt leaching. (b) MSS multilayer structure: resin-epoxy, 1 wt% MWCNTs, and 4 wt% MWCNTs. (c) Layer sequence of the three-layer nanocomposite. (d) Microwave absorption performance of the three-layer nanocomposite. (e) Schematic of the Ni/MnO-CA preparation process. (f) Schematic of the electromagnetic wave absorption mechanism of Ni/MnO-CA. (g) Schematic of the electromagnetic wave shielding mechanism of LCF/PC-SiC.

2. Application Characteristics Analysis

• Weight Reduction and Energy Saving: Carbon fiber composites can reduce weight by 20%~40% compared to aluminum alloys, significantly improving fuel efficiency, and are widely used in large passenger aircraft.

• Resistance to Extreme Environments: Carbon/carbon composites can work for long periods in high-temperature, oxygen-free environments, suitable for high-temperature zones during atmospheric re-entry.

• Multifunctional Integration: Graphene and CNTs endow materials with functions such as electrical conductivity, thermal conductivity, and sensing, supporting the development of smart structures.

• Efficient Thermal Insulation: Carbon aerogel is one of the solid materials with the lowest known thermal conductivity, suitable for passive insulation design in deep space exploration missions.

Current Challenges
Although carbon-based materials show great potential in aerospace, the following problems still exist:

• Poor Oxidation Resistance: Carbon materials are easily oxidized in high-temperature, oxygen-containing environments and require the use of coatings such as SiC.

• High Manufacturing Cost: The production cost of high-performance carbon fibers and complex structural composites is high, limiting large-scale application.

• Difficulty in Controlling Process Consistency: Nanocarbon materials have poor dispersibility and are prone to agglomeration during the compounding process, affecting performance stability.

Future Development Directions

• Promote multi-scale structural design to achieve synergistic optimization of mechanical and functional properties.

• Establish material structure-property relationship models to guide the rational design of new carbon materials.

• Develop automated, low-cost forming technologies to improve manufacturability.

• Explore green preparation processes to reduce energy consumption and environmental impact.

In summary, carbon-based materials have become core materials driving the development of high-performance aerospace vehicles due to their excellent properties such as lightweight, high strength, resistance to extreme environments, and multifunctional integration. However, their susceptibility to oxidation in high-temperature, oxygen-containing environments remains a key challenge that needs to be overcome. Focusing on this industry pain point, Yinsu Flame Retardant Company, specializing in the research, development, and production of flame retardants, will actively grasp this trend in the future. We are committed to developing new, highly efficient flame retardants compatible with carbon-based materials. Through continuous technological innovation and industry-academia-research collaboration, we aim to provide advanced flame retardant solutions to address the inherent weaknesses of carbon-based materials, contribute core strength to the transformation and upgrading of the entire flame retardant industry towards high performance and multifunctionality, and help propel the aerospace industry to new heights.