Dual-matrix fiber-reinforced lightweight ablative thermal protection composites with outstanding micron-scale ablative recession

doi:10.21203/rs.3.rs-3624011/v1

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Dual-matrix fiber-reinforced lightweight ablative thermal protection composites with outstanding micron-scale ablative recession

https://doi.org/10.21203/rs.3.rs-3624011/v1

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Developing lightweight thermal protection materials that can efficiently resist ablation and provide heat insulation in extreme aerodynamic heating environments remains a significant challenge for ensuring aerospace safety. Fiber-reinforced polymer composites (FRPs) are a crucial choice for thermal protection materials due to their lightweight nature and excellent thermal insulation properties. However, the application is limited by ablative recession despite their unique sacrificial thermal protection mechanism.

This study introduces an innovative fiber-reinforced composite with distinct matrices for the upper and lower regions. The upper matrix consists of a silicone-based ceramicizable resin mixed with high-temperature-resistant fillers, while the lower matrix incorporates a porous phenolic aerogel with a high residual carbon rate. In comparison to conventional ablative thermal protection materials, the linear ablation setback can be significantly reduced, reaching levels as low as 0.11 µm/s and 6 µm/s for ablations at 1.5 MW and 3.6 MW, respectively. Furthermore, these materials exhibit exceptional dynamic ablation thermal insulation and repeatability over a certain number of cycles. This approach offers a fresh perspective on the design and preparation of lightweight ablative thermal protection materials, breaking through the limitations of ablation setback and expanding the application scope of such materials in aerospace vehicles.

A. Polymer-matrix composites (PMCs)

A. Structural composites

B. Mechanical properties

B. Thermal properties

Ablative resistance

High-speed, long-range aerospace vehicles designed for near-space missions have been the focus of recent years. These vehicles constantly face harsh aerodynamic heating environments, including high-temperature oxidation and high-speed airflow erosion. Developing thermal protection materials (TPMs) that can efficiently resist ablative recession is crucial for advanced aerospace applications. However, the challenge of ablative recession limits the application of Ablative thermal protection materials (ATPMs) [1–3].

Lightweight fibre-reinforced polymer composites (FRPs) have found extensive use in re-entry spacecraft heat shields and supersonic engine combustors [3]. In such scenarios, the rapid compression of the vehicle with air generates ultra-high temperatures. FRPs offer a significant advantage with their ablative thermal protection mechanism, enabling them to withstand higher temperatures. The pyrolysis of the polymer matrix creates solid carbonaceous products, which possess considerable heat capacity, vaporization energy, and ablation heat. Additionally, pyrolysis gases (such as CO₂, CO, H₂, and CH₄) form a gas boundary layer [4, 5]. Phenolic resins, widely used as a polymer matrix, offer excellent dimensional stability and a high residual char yield. Heat shields for vehicles like "Starship" and "Mars Laboratory" use Phenolic Impregnated Carbon Ablator (PICA) [6], with phenolic resin as the matrix.

Various methods have been explored to reduce ablation recession of FRPs, including optimizing fibre reinforcement, increasing polymer thermal stability, and adding heat-resistant fillers [7]. The fibres anchor the polymer within the composite, reducing delamination risk, such as bonded short-cut fibre preforms [8–12], fibre fabrics [13], continuous fibre felts [14–18], and heterogeneous fibre felts [19]. Typical PICA (0.22 g/cm³) combines short-cut carbon fibres with a phenolic resin matrix, showing a linear ablation setback rate (R_L) of around 0.17 mm/s [20]. Cheng prepared a continuous carbon fibre felt reinforced composite (0.31 g/cm³), with an R_L of 0.04 mm/s [21]. Ceramic oxide fibre reinforced composites have higher oxidation-resistant, with an R_L of 0.03 mm/s [22]. Kubota explored three polymer matrices, with the poly(methyl methacrylate) composite (0.49 g/cm³) showing superior ablative resistance. At 2000℃, it achieved an R_L of 0.024 mm/s and a mass loss rate (R_M) of 0.023 g/s [23]. Amirsardari added multi-walled carbon nanotubes and zirconium diboride fillers to composites (0.95 g/cm³), reducing mass loss by 17% [24, 25]. These traditional methods, however, fail to efficiently concentrate anti-ablation capabilities, resulting in ineffective resistance and undesirable density increase.

Graded ATPMs efficiently balance ablative resistance and thermal insulation by strategically allocating spatial structures. A heterogeneous felt-reinforced composite has achieved an exceptional R_L as low as 0.0067 mm/s [19]. However, this ultra-low ablation recession relies heavily on heterogeneous fiber felts, which can be challenging to acquire. In an alternative approach, Yan et al. developed non-ablative ceramic shells directly on the composite surface, resulting in an ultra-low R_L of 0.38 µm/s at 1900°C [26]. Further advancements have led to the creation of high-density sandwich-like composites by combining non-ablative materials with ablative ones [27–29].

In this study, we present a graded fibre-reinforced polymer composite featuring a dual-matrix structure. The surface region employs a ceramicizable resin as the matrix, enriching its resistance to high-temperature ablation while maintaining shape integrity. The internal region, comprising a porous phenolic aerogel matrix, ensures lightweight and efficient thermal insulation. The research demonstrates that the graded composite exhibits characteristics such as lightweight design, high strength, efficient thermal insulation, and an ultra-low ablation recession under high heat flux flame conditions. To our knowledge, the composite represents the most advanced ATPMs known to date with these unique attributes.

2.1 Materials

Quartz fabric was sourced from Henan Shenjiu Co. Methyl-phenyl-silicone resin (SiR) was procured from Shanghai Resin Factory Co, while Phenolic resin was obtained from Jinan Shengquan Co. ZrB₂ (~ 0.9 um) and SiC particles (~ 700 nm) were purchased from Beijing Huaweruiqi Co. Hexa-methyl-enetetramine (HMTA) and Methyl-trimethoxy-silane (MTMS) were sourced from Shanghai McLean Co. Ethanol (EtOH) and ethylene glycol (EG) were supplied by Harbin Shengze Co.

2.2 Preparation of the gradient fibre-reinforced polymer composite with layered dual-matrix

ZrB₂ and SiC ceramic particles were blended with SiR in specific proportions (as detailed in Table S1) and agitated vigorously for 2 h to create a ceramicizable resin (CR) solution. The quartz fabric was immersed on one side (XY surface) into CR solution, undergoing a shallow impregnation process to achieve approximately 3 mm thickness. This impregnation was facilitated through capillary pressure and solution diffusion. Subsequently, the impregnated fabric was transferred to a 150°C environment for curing over 2 h.

HMTA and MTMS were sequentially introduced into the mixed solution containing phenolic resin and EG. The mixture was stirred with a magnetic stirrer for 2 h to produce the precursor solution (molar ratio HMTA: MTMS: PR = 1: 0.3: 10) for the phenolic aerogel (PRa). The pretreated fabric was subjected to vacuum impregnation in the PRa precursor solution and cured at 180°C for 2 h. Following, solvent replacement was carried out repeatedly over a 24-hour period until no further weight change was observed.

The resulting graded fibre-reinforced polymer composite with a layered dual-matrix, exhibited a density of approximately 0.4 g/cm³. This composite is denoted as S_xQRP, with 'x' representing the specific type of CR formulation used.

2.3 Characterizations.

Microscopic morphology was examined using scanning electron microscopy (SEM, Tescan Amber). Chemical state and structure were characterized using X-ray Photoelectron Spectroscopy (XPS, K-alpha) and Fourier Transform Infrared Spectroscopy (FTIR, Nicolet iS50). Thermal stability in an argon environment, spanning from 25°C to 1100°C, was recorded using a thermal analyzer (TGA/DTG, Netzsch 209C). The crystallographic phases were identified through X-ray Powder Diffraction (XRD, Panalytical Xpert), and pre-static oxidation was performed using a muffle furnace for 2 h. Mechanical properties were assessed using a universal mechanical testing machine (Shimadzu AGX-V2) in accordance with the standard GB/T 1447–1449. Thermal conductivity was measured using the plate method following GB/T10294, with the sample dimensions at φ180 × 30 mm³. Pore structure analysis was conducted using a specific surface and pore size analyzer (BET, Quadrasorb evo). Dynamic ablative insulation and repeated ablative protection were evaluated using a butane flame system with specimens sized at φ30 × 30 mm³, and an Infrared thermographic camera were employed to collect temperature data. High-temperature ablative protection was assessed using an oxyacetylene flame system following GJB 323A, and the specimen dimensions were φ30 × 30 mm³, with heat flow densities of 1.5 MW and 3.6 MW, and backside temperature data measured using thermocouples. Contour was tested by a laser microscope (Keyence VKX150), collection area 1.0 × 1.4 mm².

3.1. Fabrication, structure, and morphology of SQRP

A two-step impregnation-curing process was employed in the fabrication of the SQRPs (Fig. 1 (a)). For reinforcement, a quartz felt with high porosity was chosen. Initially, the reinforcement underwent a shallow impregnation with a pre-mixed CR solution through capillary adsorption, followed by curing to form the surface region matrix. This matrix is crucial for withstanding ablative recession and maintaining shape integrity. Subsequently, the reinforcement underwent a secondary vacuum impregnation using a meticulously formulated precursor solution, resulting in the formation of an internal PRa matrix through polymer-induced phase separation. This internal matrix is instrumental in providing thermal insulation. Macroscopically, the thickness of the surface region matrix is approximately 3 mm (Fig. 1 (b)), and the integrated reinforcement can ensure the absence of significant delamination or cracking at the dual-matrix junction. In contrast to conventional ATPMs, the layered dual-matrix of the SQRPs serves different thermal protection functions, specifically, ablation resistance and thermal insulation (Fig. 1 (c)), as will be elaborated in the following sections. Figure 1 (d-g) illustrate the microscopic structure of the SQRP. The enriched CR matrix effectively occupies the surface region, with tightly bonded micron-sized ceramic particles (Fig. 1 (d)). The interphase interface of the dual matrix integrated well and aerogel particles formed directly on the CR at the junction (Fig. 1 (e)). In sharp contrast to the surface, the interior of the composite contains pores resulting from PRa particles clustering together and forming a highly porous network (Fig. 1 (f)). Further magnified SEM images reveal the presence of nanosized particles.

3.2. Chemical structure and thermal stability of dual matrix

The methyl-phenyl-silicone resin in the CR matrix formed -Si-O-Si- bonds through dehydro-condensation, while vacant hydroxyl groups created weak hydrogen bonds with ceramic particles, facilitating the homogeneous dispersion. Within the internal aerogel matrix, a highly cross-linked phenolic network was formed through various chemical bonds, such as -CH₂- and -Si-O-C- [30]. This polymerization mechanism had been validated through XPS and FTIR. In the XPS spectra (C 1s), the characteristic peak at 284.2 eV for CR corresponded to the -C-Si- bond connecting the methyl and benzene [31], and the peak at 102.5 eV (Si 2p) corresponded to the -Si-O-Si- bond along the molecular main chain [32, 33] (Fig. 2 (b-c)). For PRa, the characteristic peaks at 285.0 and 285.4 eV (C 1s) corresponded to the methylene and -C-O- bonds, and the peak at 103.9 eV (Si 2p) represented the -Si-O-C- bond formed by the reaction between silane and phenol [32, 34, 35] (Fig. 2 (d-e)). FTIR spectrum Fig. 2 (f) reveals the presence of antisymmetric stretching vibration peaks associated with -Si-O-Si- at 1027 and 1135 cm^− 1 for CR. The double peaks provided evidence of the formation of long molecular chains through polycondensation [36]. The spectrum also shows additional phenolic chain linkages, including -CH₂- stretching vibration peaks (2924 and 1466 cm^− 1), -C-N-C deformation vibration peaks (2228 and 1272 cm^− 1), and methylene ether (-CH₂-O-CH₂-) stretching vibration peaks (1109 and 968 cm^− 1) [37]. The thermal stability of CR with ceramic particles under an argon atmosphere surpassed that of the original silicone resin, with a residual weight exceeding 90% at 1100°C. In contrast, the PRa matrix exhibited a 63.1% residual weight (see Fig. 2 (g-h)). Weight loss primarily occurred due to the release of solvents, small terminal molecules, and molecular chain breakdown at high-temperature, with significant losses evident around 550°C. In the case of SiR, the loss was mainly attributed to -Si-O- and -C = C- bond breakage, while for PRa, it resulted from methylene and -C = C- bond breakage. Figure 2 (i-k) illustrates the phases of CR after high-temperature static oxidation treatment. Below 1400°C, the silicone resin was cleaved into amorphous particles, while ZrB₂ particles oxidized to ZrO₂ and SiC particles oxidized to SiO₂ [38, 39]. Importantly, the higher the temperature, the less oxide was generated (Fig. 2 (j)), as the rapid oxidation of ceramic particles at elevated temperatures formed a stable oxide protective layer on their surfaces, thereby reducing ablation recession.

3.3. Evaluation of mechanical strength and thermal insulation

The mechanical properties of the composites were evaluated utilizing a universal mechanical testing machine. Initially, the tensile and flexural response stresses in the XY direction of the SQRPs exhibited linear growth, followed by a rapid decline upon reaching critical points, a behavior consistent with brittle fracture [40] (Fig. 3 (a, c)). During fracture, stress concentrations were particularly pronounced on the densely structured CR matrix at the surface region. The matrix disintegrated and detached from the fibres, leading to failure of the composites. The variations in ceramic particle types had minimal influence on the mechanical strength. The tensile strengths of the composites exceeded 4.62 MPa, and the flexural strengths reached 19.75 MPa (Fig. 3 (b, d)). On the contrary, when subjected to Z-direction compression, the porous PRa matrix experienced compaction rather than fracturing. Consequently, the response stress exhibited a consistent increase (Fig. 3 (e)). The point of offset yield stress at 50% strain defined the maximum compressive strength of the composites, which exceeded 3.07 MPa.

The thermal insulation properties of the dual-matrix composites primarily rely on the internal porous structure. Both surface and internal region thermal conductivities were examined, alongside the high-temperature conductivities within the critical interior. The interior exhibited a low thermal conductivity of only 0.04 at room temperature, which increased to 0.104 at 500°C (Fig. 4 (a)). Heat transfer within the porous interior is governed by the necessity to traverse an intricate network of air-filled pores and an infinitely extended aerogel wall, considerably inhibiting solid-phase and gas-phase conduction [41]. Notably, the pore sizes of both the PRa matrix and the internal composites were predominantly in the range of 30 to 40 nm (Fig. 4 (b-c)). The N₂ adsorption-desorption isotherms conformed to Type IV isotherms and H3 hysteresis lines in accordance with the IUPAC classification of particle stacking structures (detailed pore data refer to Table S3). The dynamic thermal insulation performance of the composites was evaluated using a butane flame ablation, and the cloud diagram illustrating the backside response is presented in Fig. 4 (f). SQRPs featuring various CR matrices exhibited consistent backside response temperatures. During the initial phase, the temperature remained relatively stable, signifying minimal heat transfer to the backside. Subsequently, the pyrolysis of the surface matrix led to a slight increase in response temperature, followed by a second slight increase caused by the pyrolysis of the aerogel matrix. SQRPs demonstrated effective dynamic thermal insulation, maintaining backside temperatures at only 116°C after 600 seconds (as shown in Fig. 4 (g)) and reaching an equilibrium temperature of approximately 450°C after extended exposure to the butane flame (detail in supporting information).

3.4. Evaluation of ablative thermal protection

The thermal protection performance of SQRPs was assessed using oxyacetylene flame ablation, generating heat flows of 1.5 MW (~ 1700°C) and 3.6 MW (~ 2500°C). As depicted in Fig. 5 (b), the ceramicization of the CR matrix resulted in robust surfaces without edge shrinkage. Additionally, the complete vaporization of the pyrolytic carbon exposed voids originating from vertically arranged fibre bundles. Following 90 seconds of exposure to 1.5 MW ablation and 60 seconds of exposure to 3.6 MW ablation respectively, the backside temperatures of the specimens measured approximately 48°C and 75°C (measured depths of 25 mm), as shown in Fig. 5 (c-d), which can be attributed to the exceptional dynamic ablative insulating performance of composites. Notably, the S₂QRP displayed the lowest ablation recession, with a weight loss rate of 9.22 mg/s and a linear ablation setback rate of 0.11 µm/s during 1.5 MW heat flow ablation. At 3.6 MW, the corresponding figures were 18.4 mg/s and 6 µm/s, respectively (Fig. 5 (e-f)). Detailed abaltion data are shown in Table S3 and S4. This remarkable performance derived from the high concentration of nanoscale ceramic particles present in the S₂QRP, which significantly enhanced the resistance to erosion caused by heat and oxygen under flame. Furthermore, the surface-enriched CR matrix resulted in a slight increase of density, effectively reducing the ablative recession of the composites. The pyrolysis products originating from the ceramic particles and silicone resin formed an anti-ablation shielding layer when exposed to the flame. This shielding layer served to protect the internal porous matrix and fibres, thus ensuring the stability of the aerodynamic profile. In addition, the internal phenolic matrix underwent partial pyrolysis, providing thermal protection through mass injection and pyrolysis gas emission. As materials designed for ablative thermal protection, SQRPs offer a competitive combination of low density and exceptionally low linear ablative setback, as shown in Fig. 5 (g) [19, 21–26, 37, 42–48]. Slicing the ablated specimen (1.5 MW ablated S₂QRP, 3 mm thick per layer) in the thickness direction, defined as ablated surface region, charred region, pyrolyzed region, and virgin region [6, 49] (Fig. 5 (h)). It can be observed from the FTIR spectra, the silicone resin at the ablated surface underwent pyrolysis, with the double peak of the long-chain Si-O transforming into a single peak at 1388 cm^− 1. Additionally, the characteristic peaks of the residual -CH₃ were observed at 1388 and 838 cm^− 1. The pyrolysis of the internal phenolic aerogel matrix exhibited regressive characteristics, with the layer (L₂) closest to the ablated surface undergoing complete charring and the disappearance of the characteristic peak of the methylene group connecting the benzene ring bonds at 1466 cm^− 1. The layers of the pyrolysis region (L₂-L₆) did not fully char, with the characteristic peak of the methylene ether -CH₂-O-CH₂- weakly associated with the benzene ring being observed at 968 cm^− 1. The characteristic peaks of the layers in the virgin region (L₇-L₉) remained well preserved and essentially free from pyrolysis. Similarly, the density of the ablated layers exhibited a regressive recession corresponding to the degree of matrix pyrolysis. The ablated surface of the composite contained the expected oxides of the ceramic particles, along with melt crystallization of the quartz fibres.

The micromorphology of the dual-matrix in the ablated S₂QRP was further examined, as depicted in Fig. 6. It is evident that the CR matrix formed an ablative shielding layer on the surface, while the silicone resin underwent pyrolysis and melt, forming a liquid film that encapsulated the ceramic particles and oxides. This ceramic liquid film effectively preventing the intrusion of heat and oxygen, thereby averting significant ablative degradation of the composite. Furthermore, the ceramic particles, resembling islands, were embedded within the liquid film of the silicon phase, which restricted its flow Fig. 6 (b)). Upon inspection, the high-magnification SEM image (Fig. 6 (e)) reveals that the oxides on the surface of the ceramic particles had fused together. In contrast, the oxides in proximity to the charred region exhibited lower response temperatures, causing to melt into small droplets, as seen in Fig. 6 (f). Figure 6 (i-k) provide the micro-morphology of the charred region, the pyrolysis region, and the virgin region, respectively. In the charred region, extensive pyrolysis of the phenolic aerogel resulted in enlarged pores and exposed fibres. Conversely, the aerogel in the pyrolysis and virgin regions remained intact. The high-magnification SEM image clearly shows unchanged aerogel particles.

3.5. Simulation analysis under 1.5MW heat flow ablation

To delve deeper into the ablation process within the composite, a simulation analysis was conducted, and the results are presented in Fig. 7. The simulation model encompasses a dual-matrix composite (S₂QRP) and a graphite sleeve (Fig. 7 (a)), with the temperature collection point positioned at 25 mm depth. Figure 7 (b) demonstrates a consistency between experimental and simulated temperature curves, affirming the precision of model. With prolonged simulated ablation time, the organic resin matrix gradually pyrolyzed and permeated to the bottom (Fig. 7 (c)). Figure 7 (d) illustrates temperature curves at various locations inside the composite, showcasing a rapid rise in surface temperature (above 1700°C) and a gradual increase in internal response temperature due to heat conduction. Notably, the backside temperature at (0,0) surpasses that at (0,5), primarily attributed to the high thermal conductivity of the external graphite sleeve. Figure 7 (e) tracks the pyrolysis rate with time at different depths. At 30 s, the thickness of the fully pyrolyzed region reaches 5 mm, and even after heating ceases at 90 s, the inner phenolic matrix continues to pyrolyze due to accumulated heat. Figure 7 (f) depicts the evolution of pore pressure at various depths over time. One second into ablation witnesses extensive pyrolysis of the surface-enriched CR matrix, resulting in a rapid surge in gas pressure on the ablation surface, peaking at 10,500 Pascals (Pa). Throughout heating, pore pressure within the composite consistently remains above 2000 Pa. Conversely, during cooling, internal pressure drops to approximately 0 Pa, indicating rapid diffusion of pyrolysis gases through the porous structure into the surrounding air. Moving to Fig. 7 (g), a cloud diagram illustrates temperature distribution from left to right at six time points: 1, 45, 90, 91, 135, and 180 seconds. During the heating phase, the high-temperature region concentrates in the upper part of the composite. As the cooling phase progresses, a "heat kernel" region forms as heat continues to transfer inward, but the temperature peak in this region significantly decreases. By 180 seconds, the peak internal temperature of the material stands at 260°C. Figure 7 (h) offers a cloud diagram of pyrolysis ratio distribution at the same time intervals. During heating, the resin at the edge undergoes faster pyrolysis compared to the central region, primarily due to exposure to environmental heat flow. In the cooling phase, heat continues to conduct inward, causing further pyrolysis of the resin. These findings align with the results presented in Fig. 7 (e). Finally, Fig. 7 (i) displays a cloud diagram of pyrolysis gas flow field distribution at the same time intervals. Notably, in the first second of ablation, the flow velocity of pyrolysis gases is substantial, primarily confined to the vicinity of the ablation surface. This phenomenon results from the rapid pyrolysis of resin on the surface induced by environmental heat. As heat propagates inward, the rate of pyrolysis gradually decreases.

3.6. Evaluation of thermal protection under repeated ablation

The S₂QRP underwent a series of repeated ablation tests consisting of 10 cycles, each lasting 300 seconds with a butane flame. Similar to the behavior observed during oxygen-acetylene ablation, the pyrolysis of the composite showed a regression. This behavior created distinct regions within the composite, including the ablated surface, charred region, pyrolyzed region, and virgin area. In the early stages of the ablation cycle, the pyrolysis of the composite was incomplete, leading to a gradual increase in weight loss. After four cycles, the pyrolysis was essentially complete, resulting in only marginal additional weight loss. As a result, the composite retained over 86% of its initial weight. Due to the ablation-resistant CR matrix on the surface, the composite showed slight linear and radial setbacks across repeated ablation cycles. Overall, the composite maintained effective insulation, with backside temperatures remaining below 80°C after 10 ablation cycles. Nevertheless, there was a slight increase in temperature as the number of ablation cycles increased. The ablative setback of ATPMs significantly limits reusability. To assess the surface contour after ten ablation cycles, laser microscopy was employed to observe the flame ablation center, as shown in Fig. 8 (c-f). Figure 8 (d) displays the surface contour at the blue markers on the ablated surface, revealing the presence of high peaks. A height distribution of the surface was also obtained through laser intensity, and 3D surface reconstruction was performed. The combination of Fig. 8 (e) and (f) highlights that the surface peaks consist of warped fibers and ceramicized resin. The arithmetic mean curvature (Spc) of the peak peaks in the collected region measures 3167.231 1/mm, with an arithmetic mean height (Sa) of 8.293 and a maximum height (Sz) of 166.381 µm, respectively. Additionally, observable concave valleys originate from the exposed needled fibre bundles. Overall, the ablation center area of the composite was flat and there was no visible ablation setback.

The dual-matrix fiber-reinforced composite, prepared through two-step surface-internal impregnations, introduces matrices with different thermal protection functions. The surface matrix undergoes ceramicization during ablation, ensuring ablative resistance and shape stabilization, while the internal matrix provides continuous high-temperature thermal insulation. Integrated felt reinforcement prevents delamination in the thickness direction originating from the dual-matrix. Compared to existing Advanced Thermal Protection Materials (ATPMs), these lightweight composites demonstrate outstanding ablation resistance and thermal insulation. The surface ablation setback can be reduced to the micron-level, making it suitable for the thermal protection systems of aircraft in aerodynamically heated environments. In ablation at 1.5 MW for 90 seconds, the linear ablation recession is as low as 0.11 µm/s, the back temperature reduced to 48°C. Under 3.6 MW heat flow ablation for 60 seconds, the linear ablation recession rate is as low as 6 µm/s, with a 60°C back temperature. Additionally, the composite exhibits stable thermal protection through a certain number of repetitive ablation environments. This dual-matrix composite offers new possibilities for ablative thermal protection materials, making it a viable option for future long-duration, long-range, and reusable aerospace vehicles.

Funding: This work was supported by the National Natural Science Foundation of China (51872066,52032003 and U20B2017).

Conflict of Interest: The authors declare no competing interests.

Data Availability statement: No research data were available outside of the submitted manuscript.

Author's contribution: Hebing Wang: Data curation, Formal analysis, Writing - original draft. Xiaojie Yan: Data curation, Formal analysis. He Huang: Methodology. Xiangyu Jin: Methodology. Yiwu Pan: Visualization. Can Wu: Visualization. Changqing Hong: Writing - review & editing. Xinghong Zhang: Conceptualization.

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No competing interests reported.

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Dual-matrix fiber-reinforced lightweight ablative thermal protection composites with outstanding micron-scale ablative recession

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Abstract

Figures

1. Introduction

2. Experimental section

2.1 Materials

2.2 Preparation of the gradient fibre-reinforced polymer composite with layered dual-matrix

2.3 Characterizations.

3. Results and discussion

3.1. Fabrication, structure, and morphology of SQRP

3.2. Chemical structure and thermal stability of dual matrix

3.3. Evaluation of mechanical strength and thermal insulation

3.4. Evaluation of ablative thermal protection

3.5. Simulation analysis under 1.5MW heat flow ablation

3.6. Evaluation of thermal protection under repeated ablation

4. Conclusion

Declarations

References

Additional Declarations

Supplementary Files

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