Preparation of SiCf/Si–O–C composites by impregnation pyrolysis of polysiloxane and its electromagnetic wave absorption properties

High-temperature structural electromagnetic wave (EMW) absorption materials are increasing in demand because they can simultaneously possess the functions of mechanical load-bearing, heatproof, and EMW absorption. Herein, SiC_f/Si–O–C composites were prepared by precursor impregnation pyrolysis using continuous SiC fibers needled felt as reinforcement and polysiloxane as a precursor, respectively. The phase composition, microstructure, complex permittivity, and EMW absorption properties of SiC_f/Si–O–C composites after annealing at various temperatures were investigated. The annealing at 1400–1500°C affects positively the EMW absorption performance of the composites, because the β-SiC microcrystals and SiC nanowires were generated by the activation of carbothermal reduction reaction in the composites, and the aspect ratio of SiC nanowires increased with the rise of temperature. The composites exhibit optimal EMW absorption performance, with the effective absorption bandwidth covering the entire X-band and the minimum reflection loss (RL_min) of −32.8 dB at 4.0 mm when the annealing temperature is raised to 1500°C. This is because that the impedance matching is improved as the rising of ε′ and decreasing of ε″ due to the conversion of free carbon in the composite into SiC nanowires.     

Effect of SiC interphase on the mechanical,high-temperature dielectric and high-temperature microwave absorption properties of the SiCf/SiC/Mu composites

In this study, SiC interphase was prepared via a precursor infiltration-pyrolysis process, and effects of dipping concentrations on the mechanical, high-temperature dielectric and microwave absorption properties of the SiC_f/SiC/Mu composites had been investigated. Results indicated that different dipping concentrations influenced ultimate interfacial morphology. The SiC interphase prepared with 5 wt% PCS/xylene solution was smooth and homogeneous, and no bridging between the fiber monofilament could be observed. At the same time, SiC interphase prepared with 5 wt% PCS/xylene solution had significantly improved mechanical properties of the composite. In particular, the flexural strength of the composite prepared with 5 wt% PCS/xylene solution reached 281 MPa. Both ε′ and ε′′ of the SiC_f/SiC/Mu composites were enhanced after preparing SiC interphase at room temperature. The SiC_f/SiC/Mu composite prepared with 5 wt% PCS/xylene solution showed the maximum dielectric loss value of 0.38 at 10 GHz. Under the dual action of polarization mechanism and conductance loss, both ε′ and ε′′ of the SiC_f/SiC/Mu composites enhanced as the temperature increased. At 700 °C, the corresponding bandwidth (RL ≤ ?5 dB) of SiC_f/SiC/Mu composites prepared with 5 wt% PCS/xylene solution can reach 3.3 GHz at 2.6 mm. The SiC_f/SiC/Mu composite with SiC interphase prepared with 5 wt% PCS/xylene solution is expected to be an excellent structural-functional material.     

Optimization of the microwave absorptivity of SiCf/Resin composites in the GHz range

The effects of structural factors on the electromagnetic wave absorption properties of SiC fibre reinforced resin composites (SiC_f/Resin) were investigated. Transmission line theory was used to calculate the reflection loss and to tap the potential of SiC fibres as broadband wave absorbents. The structure of the SiC_f/Resin composite was optimized based on a double-layered laminate containing high-resistance SiC fibres (H-SiC_f, ρ = 6.5 × 10⁵ Ω cm) in the upper layer and low-resistance SiC fibres (L-SiC_f, ρ = 109.7 Ω cm) in the bottom layer. The calculation suggests that to achieve a high absorptivity better than ?10 dB, the permittivity of the L-SiC_f/Resin bottom layer must be enhanced to quite a high value with a specific frequency dispersion degree. The desired permittivity was realized by controllable addition of carbon black into L-SiC_f/Resin. Under the optimized thickness combination, the reflection loss of the double-layered composite could be lower than ?13.3 dB in the whole X and Ku bands.     

Mechanical and dielectric properties of SiCf/SiC composites fabricated by PIP combined with CIP process

2D KD-1 SiC fiber fabrics were employed to fabricate SiC_f/SiC composites by an improved polymer infiltration and pyrolysis (PIP) process, combined with cold isostatic pressing (CIP). The effect of CIP process on the microstructure, mechanical and dielectric properties of SiC_f/SiC composites was investigated. The infiltration efficiency was remarkably improved with the introduction of CIP process. Compared to vacuum infiltration, the CIP process can effectively increase the infiltrated precursor content and decrease the porosity resulting in a dense matrix. Thus SiC_f/SiC composites with high density of 2.11 g cm⁻³ and low porosity of 11.3% were obtained at 100 MPa CIP pressure, together with an increase of the flexural strength of the composites from 89 MPa to 213 MPa. Real part (ε′) and the imaginary part (ε″) of complex permittivity of SiC_f/SiC composites increase and vary from 11.7-i9.7 to 15.0-i12.8 when the CIP pressure reaches 100 MPa.     

A high-temperature structural and wave-absorbing SiC fiber reinforced Si3N4 matrix composites

The SiC_f/Si₃N₄ composite with low–high–low permittivity sandwich structure was designed for high-temperature electromagnetic (EM) wave absorption and mechanical stability. The SiC_f/Si₃N₄ possessed the remarkable mechanical properties at room temperature (the flexural strength is 357 ± 16 MPa and the fracture toughness is 10.8 ± 1.7 MPa m^1/2) for the strong fiber strength, moderate interface bonding strength and uniform matrix. Furthermore, the retention rate is as high as 80% at 800 °C. The A/B/C nanostructure and the sandwich meta-structure endowed the SiC_f/Si₃N₄ with an excellent EM absorbing property at room temperature. The SiC_f/Si₃N₄ still absorbed 75% of the incident EM waves energy in X and Ku bands when the temperature increases up to 600 °C, which is only 6% lower than that at room temperature, for the partial compensation of the decreased interfacial polarization loss for the increased conductivity loss and dipole polarization loss.     

Enhancement of the microwave absorption properties of PyC-SiCf/SiC composites by electrophoretic deposition of SiC nanowires on SiC fibers

The employment of coating technique on the silicon carbide fibers plays a pivotal role in preparing SiC fiber-reinforced SiC composites (SiC_f/SiC) toward electromagnetic wave absorption applications. In this work, SiC nanowires (SiCNWs) are successfully deposited onto the pyrolytic carbon (PyC) coated SiC fibers by an electrophoretic deposition method, and subsequently densified by chemical vapor infiltration to obtain SiCNWs/PyC-SiC_f/SiC composites. The results reveal that the introduction of SiCNWs could markedly enhance the microwave absorption properties of PyC-SiC_f/SiC composites. Owing to the increasing of SiCNWs loading, the minimum reflection loss of composites raises up to −58.5 dB in the SiCNWs/PyC-SiC_f/SiC composites with an effective absorption bandwidth (reflection loss ≤ −10 dB) of 6.13 GHz. The remarkable enhancement of electromagnetic wave absorption performances is mainly attributed to the improved dielectric loss ability, impedance matching and multiple reflections. This work provides a novel strategy in preparing SiC_f/SiC composites with excellent electromagnetic wave absorption properties.     

Simultaneous enhancement of mechanical and microwave absorption properties with a novel in-situ synthesis α-Al2O3 fillers for SiCf/SiC composites

The Al and H₃BO₃ mixed powder was introduced into the PCS/Xylene precursor solution as in-situ synthesis α-Al₂O₃ filler by precursor infiltration and pyrolysis (PIP) method. The in-situ synthesis filler can effectively decrease the open porosity of SiC_f/SiC composites and give rise to multiple scattering of microwave and dipolar polarization. Therefore, the mechanical and microwave absorption properties of SiC_f/SiC composites can be simultaneously enhanced. The effects of in-situ synthesis filler on the morphologies, flexure strength and reflection loss values of SiC_f/SiC composites were investigated. With 2 wt% in-situ synthesis filler, the flexure strength of SiC_f/SiC composite was 305 MPa and the maximum reflection loss (RL_m) can reach ? 54.68 dB with the effective absorption band (EAB) of 3.51 GHz in the X band. With 5 wt% in-situ synthesis filler, the flexure strength of SiC_f/SiC composite was 207 MPa and the RL_m was ? 30.91 dB. Due to the inefficient infiltration process, the RL_m of SiC_f/SiC composites with 10 wt% in-situ synthesis filler was only ? 27.36 dB. Nevertheless, the flexure strength of that composite was 259 MPa, owing to the dense matrix. Additionally, the flexure strength of SiC_f/SiC composite without filler was 148 MPa and the RL_m was ? 26.40 dB.     

Simultaneously improving mechanical and microwave absorption properties of a novel SiCf/SiOC & mullite hybrid ceramic matrix composite

For enhanced mechanical and microwave absorption properties at the same time, the SiC_f/hybrid matrix composites were fabricated by precursor infiltration and pyrolysis (PIP) method with polysiloxane (PSO) ethanol solution, alumina sols and silica sols. As the first layer of the hybrid matrix, the SiOC ceramic was pyrolyzed from PSO solution. The remained hybrid matrix was mullite, which sintered from alumina sols and silica sols. The effects of different content of PSO solution on the morphologies, flexure strength and reflection loss values of composites were studied. Additionally, the XRD patterns, Fourier Transform Infrared (FTIR) and Raman spectrum of hybrid matrix were also investigated. With the increasingly content of PSO solution from 0% to 10 % and 20%–60% in the first infiltration-pyrolysis process, the flexure strength of composites was increased from 175.18 MPa to 301.94 MPa and decreased from 263.33 MPa to 221.30 MPa, respectively. The complex permittivity was increased with the increasing content of PSO solution from 0%–40% due to the free carbon conductive network from excessive SiOC. Moreover, the complex permittivity of SiC_f/hybrid matrix composites with 50 % and 60 % content of PSO solution was reduced due to more open porosity and broken free carbon conductive network. Additionally, the maximum reflection loss values of SiC_f/hybrid matrix composite with 50 % PSO solution were over -60 dB and the effective absorption bandwidth (EAB) of this composite reaches 3.89 GHz in the X band.     

Influence of pyrolysis and melt infiltration temperatures on the mechanical properties of SiCf/SiC composites

In order to improve the degree of matrix densification of SiC_f/SiC composites based on liquid silicon infiltration (LSI) process, the microstructure and mechanical properties of composites according to various pyrolysis temperatures and melt infiltration temperatures were investigated.Comparing the microstructures of SiC_f/C carbon preform by a one-step pyrolysis process at 600 °C and two-step pyrolysis process at 600 and 1600 °C, the width of the crack and microcrack formation between the fibers and matrix in the fiber bundle increased during the two-step pyrolysis process. For each pyrolysis process, the density, porosity, and flexural strength of the SiC_f/SiC composites manufactured by the LSI process at 1450–1550 °C were measured to evaluate the degree of matrix densification and mechanical properties. As a result, the SiC_f/SiC composite that was fabricated by the two-step pyrolysis process and LSI process showed an 18% increase in density, 16%p decrease in porosity, and 150% increase in flexural strength on average compared to the composite fabricated by the one-step pyrolysis process.In addition, among the SiC_f/SiC specimens fabricated by the LSI process after the same two-step pyrolysis process, the specimen that underwent the LSI process at 1500 °C showed 30% higher flexural strength on average than those at 1450 or 1550 °C. Furthermore, under the same pyrolysis temperature, the mechanical strength of SiC_f/SiC specimens in which the LSI process was performed at 1500 °C was higher than that of the 1550 °C although both porosity and density were almost similar. This is because the mechanical properties of the Tyranno-S grade SiC fibers degraded rapidly with increasing LSI process temperature.     

Enhanced mechanical and microwave-absorption properties of SiCf/AlPO4 composite with PIP–SiC interphase and the MWCNTs filler

A single-layer radar-absorbing structure in the X-band (8.2 GHz to 12.4 GHz) was designed and fabricated by blending multi-walled carbon nanotubes (MWCNTs) with the binder matrix of SiC fiber/aluminum phosphate matrix (SiC_f/AlPO₄) composite. The SiC interphase was successfully prepared on SiC fibers by a precursor infiltration and pyrolysis (PIP) method. The morphology of as-received interphase was observed by SEM, and its structure was characterized by XRD and Raman spectrum. The effects of PIP–SiC interphase on the mechanical and dielectric properties of the composite were investigated. The influence of MWCNTs content on the dielectric and microwave-absorption properties of coated SiC_f/AlPO₄ composite was discussed. When the content of MWCNTs was between 1.5 wt% and 3.5 wt% and the composite thickness is in the range of 2.5–3.5 mm, the SiC_f/AlPO₄ composite achieved excellent absorbing wave property in X-band.     

Effect of SiC nanowires on the high-temperature microwave absorption properties of SiCf/SiC composites

SiC-nanowire-reinforced SiC_f/SiC composites were successfully fabricated through an in situ growth of SiC nanowires on SiC fibres via chemical vapour infiltration. The dielectric and microwave absorption properties of the composites were investigated within the frequency range of 8.2–12.4 GHz at 25–600 °C. The electric conductivity and complex permittivity of the composites displayed evident temperature-dependent behaviour and were enhanced with increasing temperature. The composites exhibited superior microwave absorption abilities with a minimum reflection loss value of ?47.5 dB at 11.4 GHz and an effective bandwidth of 2.8 GHz at 600 °C. Apart from the contribution of the interconnected SiC nanowire network and multiple reflections, the excellent microwave absorption performance was attributed to dielectric loss that originated from SiC nanowires with abundant stacking faults and heterostructure interfaces. Results suggested that the composites are promising candidates for high-temperature microwave absorbing materials.     

Microstructure and mechanical properties of hot-pressed SiC nanofiber reinforced SiC composites

This study reports on the preparation and mechanical properties of a novel SiC_nf/SiC composite. The single crystal SiC nanofiber(SiC_nf) reinforced SiC ceramic matrix composites (CMC) were successfully fabricated by hot pressing the mixture of β-SiC powders, SiC_nf and Al–B–C powder. The effects of SiC_nf mass fraction as well as the hot-pressing temperature on the microstructure and mechanical properties of SiC_nf/SiC CMC were systematically investigated. The results demonstrated that the 15 wt% SiC_nf/SiC CMC obtained by hot pressing (HP) at 1850 °C with 30 MPa for 60 min possessed the maximum flexural strength and fracture toughness of 678.2 MPa and 8.33 MPa m^1/2, respectively. The nanofibers pull out, nanofibers bridging and cracks deflection were found by scanning electron microscopy, which are believed can strengthen and toughen the SiC_nf/SiC CMC via consuming plenty of the fracture energy. Besides, although the relative density of the prepared SiC_nf/SiC CMC further increased with the sintering temperature rose to 1900 °C, the further coarsend composites grains results in the deterioration of the mechanical properties for the obtained composites compared to 1850 °C.     

Dielectric and microwave absorption properties of polymer derived SiCN ceramics annealed in N2 atmosphere

Porous SiCN ceramics were successfully fabricated by pyrolysis of a kind of polysilazane. The effects of annealing temperature on the microstructure evolution, direct-current electrical conductivity, dielectric properties, and microwave absorption properties of SiCN in the frequency range 8.2–12.4 GHz (X-band) were investigated. With the increase of annealing temperature, SiC, Si₃N₄ and free carbon nanodomains are gradually formed in the SiCN. Both the SiC and free carbon nanodomains lead to the increases of the complex relative permittivity and loss tangent of SiCN. With the increase of the annealing temperature, the average real permittivity, imaginary permittivity and loss tangent increase from 4.4, 0.2 and 0.05 to 13.8, 6.3 and 0.46, respectively. The minimum reflection coefficient and the frequency bandwidth below −10 dB for SiCN annealed at 1500 °C are −53 dB and 3.02 GHz, indicating good microwave absorption properties.     

Microstructure and strengthening behavior in high content SiC nanowires reinforced SiC composites

In this study, the high-content SiC_nw reinforced SiC ceramic matrix composites (SiC_nw/SiC CMC) were successfully fabricated by hot pressing β-SiC and sintering additive (Al₂O₃-Y₂O₃) with boron nitride interphase modification SiC_nw. The effects of sintering additive content and mass fraction (5–25 wt%) of SiC_nw on the density, microstructure, and mechanical properties of the composites were investigated. The results showed that with the increase of sintering additives from 10 wt% to 12 wt%, the relative density of the SiC_nw/SiC CMC increased from 97.3% to 98.9%, attributed to the generated Y₃Al₅O₁₂ (YAG) liquid phase from the Al₂O₃-Y₂O₃ that promotes the rearrangement and migration of SiC grains. The comprehensive performance of the obtained composite with 15 wt% SiC_nw possessed the optimal flexural strength and fracture toughness of 524 ± 30.24 MPa and 12.39 ± 0.49 MPa·m^1/2, respectively. Besides, the fracture mode of the composites with 25 wt% SiC_nw content revealed a pseudo-plastic fracture behavior. It concludes that the 25 wt% SiC_nw/SiC CMC was toughened by the fiber pull-outs, debonding, bridging, and crack deflection that can consume plenty of fracture energy. The strategy of SiC nanowires worked as a main bearing phase for the fabrication of SiC/SiC CMC providing critical information for understanding the mechanical behavior of high toughness and high strength SiC nanoceramic matrix composites.     

Effect of oxidation treatment on KD–II SiC fiber–reinforced SiC composites

Continuous silicon carbide fiber–reinforced silicon carbide matrix (SiC_f/SiC) composites have developed into a promising candidate for structural materials for high–temperature applications in aerospace engine systems. This is due to their advantageous properties, such as low density, high hardness and strength, and excellent high temperature and oxidation resistance. In this study, SiC_f/SiC composites were fabricated via polymer infiltration and pyrolysis (PIP) with the lower–oxygen–content KD–II SiC fiber as the reinforcement; a mixture of 2,4,6,8–tetravinyl–2,4,6,8–tetramethylcyclotetrasiloxane (V4) and liquid polycarbosilane (LPCS), known as LPVCS, was used as the precursor; while pyrolytic carbon (PyC) was used as the interface. The effects of oxidation treatment at different temperatures on morphology, structure, composition, and mechanical properties of the KD–II SiC fibers, SiC matrix from LPVCS precursor conversion, and SiC_f/SiC composites were comprehensively investigated. The results revealed that the oxidation treatment greatly impacted the mechanical properties of the SiC fiber, thereby significantly influencing the mechanical properties of the SiC_f/SiC composite. After oxidation at 1300 °C for 1 h, the strength retention rates of the fiber and composite were 41% and 49%, respectively. In terms of the phase structure, oxidation treatment had little effect on the SiC fiber, while greatly influencing the SiC matrix. A weak peak corresponding to silica (SiO₂) appeared after high–temperature treatment of the fiber; however, oxidation treatment of the matrix led to the appearance of a very strong diffraction peak that corresponds to SiO₂. The analysis of the morphology and composition indicated cracking of the fiber surface after oxidation treatment, which was increasingly obvious with the increase in the oxidation treatment temperature. The elemental composition of the fiber surface changed significantly, with drastically decreased carbon element content and sharply increased oxygen element content.     

Bonding strength and thermal shock resistance of a novel bilayer (c-AlPO4-SiCw-mullite)/SiC coated carbon fiber reinforced CMCs

Mullite coating, SiC whiskers toughened mullite coating (SiC_w-mullite), and cristobalite aluminum phosphate (c-AlPO₄) particle modified SiC_w-mullite coating (c-AlPO₄-SiC_w-mullite) were prepared on SiC coated C/SiC composites using a novel sol-gel method combined with air spraying. Results show that molten SiO₂ formed by the oxidation of SiC whiskers and molten c-AlPO₄ improved the bonding strength between mullite outer coating and SiC–C/SiC composites due to their high-temperature bonding properties. The bonding strength between mullite, SiC_w-mullite, c-AlPO₄-SiC_w-mullite outer coatings and SiC–C/SiC composites were 2.41, 4.31, and 7.38 MPa, respectively. After 48 thermal cycles between 1773 K and room temperature, the weight loss of mullite/SiC coating coated C/SiC composites was up to 11.61%, while the weight losses of SiC_w-mullite/SiC and c-AlPO₄-SiC_w-mullite/SiC coatings coated C/SiC composites were reduced to 7.40% and 5.12%, respectively. The addition of appropriate SiC whiskers can considerably improve the thermal shock resistance of mullite coating owing to their excellent mechanical properties at high temperature. In addition, c-AlPO₄ particles can further improve the thermal shock resistance of SiC_w-mullite coating due to their high-temperature bonding and sealing properties. No obvious micro-pores and cracks were observed on the surface of c-AlPO₄-SiC_w-mullite coating after 48 thermal cycles due to timely healing effect by formation of secondary mullite.     

Microstructural evolution and microwave transmission/absorption transition in polymer-derived SiOC ceramics

Herein, we present the structural evolution of polymer-derived SiOC ceramics with the pyrolysis temperature and the corresponding change in their microwave dielectric properties. The structure of the SiOC ceramics pyrolyzed at a temperature lower than 1200 °C is amorphous, and the corresponding microwave complex permittivity is pretty low; thus, the ceramics exhibit wave transmission properties. The Structural arrangement of free carbon in the SiOC ceramics mainly happens in the temperature range of 1200 °C-1300 °C due to the separation from the Si–O–C network and graphitization, while the structural arrangement of the Si-based matrix mainly occurs in the range of 1300 °C-1400 °C owing to the separation of SiC₄ from the Si–O–C network to form nanocrystalline SiC. In pyrolysis temperature range of 1200 °C-1400 °C, the microwave permittivity of SiOC shows negligible change. At a pyrolysis temperature exceeding 1400 °C, the carbothermal reaction of free carbon and the Si–O backbone becomes significant, leading to the formation of crystalline SiC. The as-formed SiC and residual defective carbon improve the polarization loss of SiOC ceramics. In this case, the SiOC ceramics show significantly increased complex permittivity, exhibiting electromagnetic absorption characteristics. These characteristics promote the application of polymer-derived SiOC ceramics to high-temperature electromagnetic absorption materials.     

SiCnw@SiC foam prepared based on vapor-solid mechanism for efficient microwave absorption

A SiC_nw@SiC foam with highly efficient microwave absorption (MA) performance was successfully synthesized based on Vapor-Solid (V–S) growth mechanism. SiC nanowire (SiC_nw) and SiC foam skeleton efficiently form a double network coupling structure, which gives additional interface polarization and dielectric loss for the SiC foam, significantly enhancing the MA capacity of the foam. In this study, the SiC_nw@SiC foam has a minimum reflection loss (RL_min) of ?86.31 dB and an effective absorption bandwidth (EAB) of 12.55 GHz in room-temperature environment. However, the MA performance of SiC_nw@SiC foam decreases with increasing temperature, which may be due to the thickening of the SiO₂ layer in the SiC_nw at high temperature. At 600 °C, it has no effective absorption bandwidth, while at 1000 °C, the EAB and RL_min were 0.6 GHz and ?13.04 dB, respectively. As the temperature reaches 1000 °C, the defects in the material further increase, leading to a recovery in the MA performance.     

Enhanced high-temperature dielectric and microwave absorption properties of SiC fiber-reinforced oxide matrix composites

Because of outstanding performances of the SiC fiber-reinforced ceramic matrix composites in aircraft/aerospace systems, two silicon carbide fiber-reinforced oxide matrices (SiC_f/oxides) composites have been prepared by a precursor infiltration and sintering method. Results indicate that the flexural strength of the SiC_f/Al₂O₃–SiO₂ composite reaches 159 MPa, whereas that of the SiC_f/Al₂O₃ composite is only 50 MPa. The high-temperature microwave absorption properties of the composite are significantly enhanced due to choosing Al₂O₃ and SiO₂ as the hybrid matrices. Particularly, the minimum reflection loss (RL) value of the SiC_f/Al₂O₃–SiO₂ composite reaches −37 dB in the temperature of 200 °C at 8.6 GHz, and the effective absorption bandwidth (RL ≤ −5 dB) is 4.2 GHz (8.2–12.4 GHz) below 400 °C. The superior microwave absorption properties at high temperatures indicate that the SiC_f/Al₂O₃–SiO₂ composite has promising applications in civil and military areas. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47097.     

Oxidation and ablation behaviours of a SiCnw@SiC–Si coating fabricated for carbon-fibre-reinforced carbon-matrix composites via thermal evaporation and gaseous silicon infiltration

A SiC-nanowire-modified SiC–Si (SiC_nw@SiC–Si) coating was prepared for carbon-fibre-reinforced carbon-matrix (C/C) composites using a two-step method based on thermal evaporation and gaseous silicon infiltration, and the effects of SiC nanowires on the oxidation and ablation behaviours of the coated samples were studied. Oxidation tests conducted at 1500 °C revealed that the weight loss of the SiC–Si-coated C/C composite was 15.85% after 6 h, whereas the SiC_nw@SiC–Si-coated C/C composite experienced a significantly lower weight loss of 1.27% after 50 h. Ablation tests suggested that the mass and linear ablation rates of the SiC_nw@SiC–Si-coated C/C composite were 0.05 mg/s and 0.09 μm/s, respectively; they were reduced by 78.26 and 92.74%, respectively, compared with those of the SiC–Si-coated C/C composite. Careful characterisation suggested that the network structure of the SiC nanowires in the SiC–Si phase can suppress crack propagation and firmly attach to the coating surface to enhance the interfacial adhesion between the coating and substrate, leading to improved anti-oxidation and anti-ablation properties. The SiC_nw@SiC–Si coating could offer a technological foundation for preventing the oxidation and ablation of C/C composites in aerospace engineering.