Microstructure and electromagnetic wave absorption property of reduced graphene oxide-SiCnw/SiBCN composite ceramics

In this account, RGO-SiC_nw/SiBCN composite ceramics were fabricated using polymer derived ceramic (PDC) combined with chemical vapor infiltration (CVI) technology. Dielectric property of as-obtained RGO-SiC_nw/SiBCN composite ceramics was significantly enhanced thanks to established conductive pathway through overlapped nanoscale SiC_nw and micro-sized RGO. The minimum RC of composite ceramics with 0.5 wt% GO and 2.29 wt% SiC_nw at thickness of 3.6 mm reached -42.02 dB with corresponding effective absorption bandwidth (EAB) of 4.2 GHz. As temperature rose from 25 to 400 °C, permittivity increased with enhanced charge carrier density and then it decreased due to oxidation process of RGO from 400 to 600 °C. The minimum reflection coefficient (RC) was recorded as -39.13 dB and EAB covered the entire X-band at 600 °C. EMW absorption ability was evaluated after high-temperature oxidation experiment under protective effect of wave-transparent Si₃N₄ coating. RGO-SiC_nw/SiBCN composite ceramics maintained outstanding EMW absorption ability with minimum RC of -10.41 dB after oxidation at 900 °C, indicating RGO-SiC_nw/SiBCN composite ceramics with excellent EMW absorption characteristic even at high temperatures and harsh environments.     

Ultra-light 3D bamboo-like SiC nanowires felt for efficient microwave absorption in the low-frequency region

Nonmagnetic ceramics are ideal microwave absorbing materials used in high-temperature and oxidizing environments. However, low-frequency absorbing properties of this material are rarely reported because low-frequency absorbing requires nonmagnetic materials to have much higher permittivity. In this research, a series of three-dimensional architectures formed by SiC nanowires with different microstructures felt were fabricated to address this issue. The morphology of the SiC_nw (linear, bamboo-shaped, and worm-like) dominated by the VLS growth mechanism can be manipulated by the silicon vapor concentration, which is governed by the vaporization temperature of the mixed silicon source (Si and SiO₂) in different sintering processes. The spontaneously overlapped bamboo-shaped SiC nanowires in these felt enhance the permittivity and conductivity loss and produce multiple scattering effects on the incident EM waves, thus increasing the low-frequency wave absorption ability. The RL_min of the bamboo-shaped SiC_nw felt reaches ?44.3 dB at 3.85 GHz with the corresponding EAB of 0.64 GHz (3.6–4.24 GHz) at a thickness of 3.5 mm. The density of the SiC_nw felt is as low as 0.022 g/cm³ due to the high porosity (99.3%) of 3D networks, which fulfills lightweight requirements and highly efficient electromagnetic wave absorption.     

3D printed SiC nanowire reinforced composites for broadband electromagnetic absorption

SiC nanowire/acrylic resin (SiC_nw/ACR) composites with broadband electromagnetic (EM) absorption capabilities were fabricated by a novel procedure using 3D stereolithography (3D-SL) printing technology. The EM absorption abilities of the composites can be adjusted by tuning the SiC_nw content and the thickness of the printing layer. When the SiC_nw content is 3?wt% and the thickness of the printing layer is 25?μm–50?μm, the SiC_nw/ACR composite has an optimally broad effective absorption bandwidth (EAB) and a high efficiency for EM absorption, whether assessing the C, X or Ku band, because of the high dielectric loss and proper impedance matching between the materials and free space. In the C band (4–8?GHz), the EAB reaches 2.9?GHz, and the reflection loss (RL) reaches ?34.1?dB; in the X band (8–12?GHz), the EAB reaches 4?GHz, which covers the entire X band, and the RL reaches ?34.5?dB; in the Ku band (12–18?GHz), the EAB exceeds 6?GHz, which covers the whole Ku band, and the RL reaches ?34.7?dB. This research is of great importance to the rapid preparation of parts, shells or devices with arbitrarily complex shapes and high efficiency broadband EM absorption abilities.     

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.     

Impedance matching optimization of SiCf/Si3N4–SiOC composites for excellent microwave absorption properties

SiC fiber reinforced ceramic matrix composites (SiC_f-CMCs) are considered to be one of the most promising materials in the electromagnetic (EM) stealth of aero-engines, which is expected to achieve strong absorption and broad-band performance. Multiscale structural design was applied to SiC_f/Si₃N₄–SiOC composites by construction of micro/nanoscale heterogeneous interfaces and macro double-layer impedance matching structure. SiC_f/Si₃N₄–SiOC composites were fabricated by using SiC fibers with different conductivities and SiOC–Si₃N₄ matrices with gradient impedance structures to improve impedance matching effectively. Owing to its unique structure, SiC_f/Si₃N₄–SiOC composites (A3-composites) achieved excellent EM wave absorption performance with a minimum reflection coefficient (RC_min) of ?25.1 dB at 2.45 mm and an effective absorption bandwidth (EAB) of 4.0 GHz at 2.85 mm in X-band. Moreover, double-layer SiC_f/Si₃N₄–SiOC with an improved impedance matching structure obtained an RC_min of ?56.9 dB and an EAB of 4.2 GHz at 3.00 mm, which means it can absorb more than 90% of the EM waves in the whole X-band. The RC is less than ?8 dB at 2.6–2.8 mm from RT to 600 °C in the whole X-band, displaying excellent high-temperature absorption performance. The results provide a new design opinion for broad-band EM absorbing SiC_f-CMCs at high temperatures.     

Construction of compound interface in SiCf/mullite ceramic-matrix composites for enhanced mechanical and microwave absorbing performance

SiC fiber-reinforced mullite ceramic-matrix (SiC_f/mullite) composite is a promising load-bearing and microwave absorption material. However, the strong interfacial bonding strength and low permittivity cause poor mechanical and absorption performance. Herein, we report SiC_f/C-SiC/mullite composite containing a carbon nanosphere network (CNSN) in the SiC interface prepared by precursor infiltration and pyrolysis (PIP). Due to the contribution of CNSN towards interface debonding, fiber slipping, and individual fiber pull-out, the composite shows significant improvement in the flexural strength (by 187%, from 56.23 ± 4.89 MPa to 161.69 ± 13.43 MPa) and the failure displacements (by 238%, from 0.080 ± 0.006 mm to 0.271 ± 0.015 mm). Moreover, the real and imaginary parts of complex permittivity (ε′, ε″) are enhanced from 5.57 to 5.98–6.36–7.11 and from 1.27 to 1.95–2.97–4.69, respectively. Under the synergistic effect of appropriate impedance matching in company with effective conductive loss and multiple polarization loss, the effective absorption bandwidth (EAB) increases from 0.98 GHz to the entire X band, and the minimum reflection loss (RL_min) enhanced from − 14.31 dB to − 41.51 dB.     

Electromagnetic wave absorption of inexpensive C/ZnO composites derived from zinc-based acrylate resins

Based on the abundant and low-cost zinc-based acrylate resins, C/ZnO composites were fabricated via one-step carbonization at 700 °C in a N₂ atmosphere for 2 h. Zinc-based acrylate resins, which were synthesized by free-radical polymerization of butyl acrylate (BA), acrylic acid (AA) and vinyl acetate (VAc) and dehydration condensation of Zn(OH)₂, provided a common source for carbon and ZnO. These materials demonstrate enhanced electromagnetic wave absorption (EMWA) behavior with tunable microwave absorption bands at 2–18 GHz, which is related to the molar ratio (mol%) of Zn(OH)₂ to acrylate monomers in zinc-based acrylate resins. Remarkably, the 0.11 mol% C/ZnO composite exhibits outstanding absorption properties: the minimum reflection loss (RL_min) at 16.7 wt% loading of −34.66 dB is observed at 3.0 mm and 10.32 GHz, and an RL_min of −24.83 dB is observed at a small thickness of 1.5 mm with an effective absorption bandwidth (EAB) of 3.61 GHz. Moreover, the EAB (RL ≤ −10 dB) from the C band to Ku band is achieved by simply adjusting the thickness of the absorbers, which are superior to the other hybrids of organic carbon and ZnO. These results provide a new strategy for the preparation of carbon-based composites containing metal oxides and their application in high-performance microwave absorption.     

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.     

In-situ synthesis of ternary layered Y3Si2C2 ceramic on silicon carbide fiber for enhanced electromagnetic wave absorption

A novel ternary layered ceramic of Y₃Si₂C₂ was successfully in-situ synthesized on the surface of home-made third-generation KD-SA SiC fiber for the first time by molten salt method aimed at improving the electromagnetic wave (EMW) absorption. After in-situ synthesis of Y₃Si₂C₂ ceramic layer on SiC fiber (SiC_f/Y₃Si₂C₂), significantly improved EMW absorption performance was obtained. The minimum reflection loss (RL_min) of ?16.97 dB was reached in SiC_f/Y₃Si₂C₂ composites at the thickness of only 2.19 mm, and the effective absorption bandwidth (EAB) was up to 5.44 GHz (12.56–18 GHz) at a thin thickness of 2.64 mm. The improvement in EMW absorption of SiC_f/Y₃Si₂C₂ is mainly attributed to enhanced dielectric loss and conduction loss resulting from increased heterogeneous interfaces and multiple reflections and scattering originating from net structure. The SiC_f/Y₃Si₂C₂ could be a promising EMW absorber for application in high-performance EMW absorbing materials.     

Enhanced electromagnetic microwave absorption properties of SiCN(Fe) ceramics produced by additive manufacturing via in-situ reaction of ferrocene

SiCN(Fe) ceramics with excellent electromagnetic wave (EMW) absorption performance were successfully prepared from a preceramic polymer doped with ferrocene. Additive manufacturing (Digital Light Processing), providing enhanced structural design ability, was employed to fabricate samples with complex architectures. During pyrolysis, ferrocene catalyzed the in-situ formation of a large amount of turbostratic carbon, graphite and SiC nanosized phases, which formed carrier channels in the electromagnetic field and increased the conductivity loss. Meanwhile, it also increased the dipole polarization, interface polarization and the dielectric properties of the material, which finally enhanced the EMW absorption capacity of SiCN(Fe) ceramics. When containing 0.5 wt% ferrocene, the material showed good performance with EAB 4.57 GHz at 1.30 mm, and RL_min −61.34 dB at 2.22 mm. The RL_min of 3D-SiCN-0.5 ceramics was −6 dB, and the RL of the X-band was lower than −4 dB at 2 mm.     

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.     

The heterointerface of graphene in-situ growth for enhanced microwave attenuation properties in La-doped SiBCN ceramics

The electromagnetic wave (EMW) absorbing materials are widely applied to attenuate the useless and harmful EMW generated from wireless communication and 5G networks, which could protect the human health and electronic device safety. In this study, La-doped SiBCN ceramics with broadband EMW absorption capability were prepared via generating abundance of heterointerfaces, as graphene were in-situ grown by La₂O₃ catalyzing. The graphene in-situ formed in the ceramics can be attributed to the La atom decreasing the potential energy of the free carbon ring nucleation from −760.9 Ha to −8984.3 Ha. Consequently, the electrical conductivity of the SiBCN ceramics improved from 12.360 S/m to 18.025 S/m, the minimum reflection loss (RL_min) obtained was −26.48 dB at 7.2 GHz and the effective absorption bandwidth (EAB) was 6.32 GHz (11.68–18.00 GHz) at a thickness of 1.7 mm. At 700 °C, the RL_min and EAB values reached −43.18 dB and 4.2 GHz, respectively. The enhanced EMW absorbing capability can be attributed to the rationally tailor the heterointerfaces to improve the polarization loss and conduction loss of the SiBCN ceramics. The interfaces between graphene and amorphous phases generate built-in electric fields and space chare regions to strengthen the interface polarization, while the electrons migrating rapidly in the graphene and other crystals improved the electrical conductivity. The positive effect of heterointerfaces regulation of graphene in-situ growth improved the dielectric loss capacity of the SiBCN ceramics; therefore, this study provides a feasible method to enhance the EMW absorption capability of polymer-derived ceramics.     

Enhancement on high-temperature microwave absorption properties of TiB2–MgO composites with multi-interfacial effects

TiB₂–MgO microwave absorbing materials with TiB₂ as the absorber, MgO as the matrix are prepared by spark plasma sintering (SPS). The influences of commercial TiB₂ content and sintering temperature on dielectric and microwave absorption (MA) properties are studied. Besides, to optimize the MA performance, TiB₂–MgO composite containing TiB₂ synthesized by the carbonthermal process is prepared. Meanwhile, its high-temperature dielectric and MA properties are investigated. Indeed, both the commercial TiB₂ content and sintering temperature play key roles in dielectric and MA properties, as they reaching 8 wt% and 1400 °C, the composite presents the optimal MA performance. For composite with synthetic TiB₂ as the absorber, the temperature has a positive effect on dielectric and MA properties. The enhanced high-temperature MA properties with minimum reflection loss (RL_min) of ?52.11 dB at 1.6 mm under 500 °C and effective absorption bandwidth (EAB, RL < ?5 dB) of 4.2 GHz at 1.4–1.6 mm under 800 °C are obtained, which is mainly attributed to the temperature-dependent interfacial polarization compared to the temperature-insensitive conductivity. The excellent mechanical properties (flexural strength = 212.48 MPa), thin absorbing layer (d < 2 mm), enhanced thermal stability and high-temperature MA properties indicate that the TiB₂–MgO composites can be considered as new candidates for high-temperature structure microwave absorbing materials.     

Adjustable iron-containing SiBCN ceramics with high-temperature microwave absorption and anti-oxidation properties

Quaternary siliconboron carbonitride (SiBCN) ceramics show excellent high-temperature stability and oxidation resistance, indicating great potential as high-temperature electromagnetic (EM) wave absorbing materials. In this contribution, an efficient and facile method was developed to prepare bulk iron-containing SiBCN (Fe–SiBCN) ceramics with remarkable EM wave absorption at high temperature by pyrolyzing boron and iron containing precursors (PSZV-B–Fe). The introduction of boron and iron not only improves the high-temperature stability but also influences the complex permittivity and EM wave absorption. The minimum reflection coefficient (RC_min) is −61.05 dB, and the effective bandwidth absorption (EAB) is 3.35 GHz (9.05–12.4 GHz). The RC_min will be decreased to −52.3 dB at 600°C as well as the EAB covers more than 67% of the X band (2.8 GHz). The high-temperature stable Fe–SiBCN ceramics with adjustable dielectric properties can be utilized as high-performance EM wave-absorbing materials in high-temperature and harsh environments.     

Construction of multiple heterogeneous interface and its effect on microwave absorption of SiBCN ceramics

Iron-containing siliconboron carbonitride (SiBCN) ceramics with multiple heterogeneous interfaces were fabricated using the microstructural design and polymer-derived ceramics (PDC) approach. The characterization results revealed the in-situ generation of nanocrystals, including graphite, belt-like silicon nitride (Si₃N₄), and silicon carbide (SiC) whiskers, in amorphous SiBCN matrix after annealing. At the same time, these dielectric lossy phases successfully constructed multiple heterogeneous interfaces and three-dimensional network structures. Consequently, the conductivity of the ceramics increased from 4.49 × 10⁻⁹ (annealed at 800 °C) to 0.67 × 10⁻⁴ S cm⁻¹ (annealed at 1600 °C). The real part of permittivity improved from 4.57–3.36 (annealed at 800 °C) to 10.90–8.38 (annealed at 1600 °C) in the frequency range of 2–18 GHz. The formation of multiple heterogeneous interfaces caused interfacial polarization and increased the multiple relaxations, which ultimately led to a superior microwave absorption property with a minimum reflection loss (RL_min) of −34.28 dB and an effective absorption bandwidth (EAB) of 3.76 GHz (8.64–12.4 GHz).     

Rapid one-pot synthesis of SiO2@SiO2/Carbon@Carbon core-shell composites with efficient microwave absorption in a short time

A carbon-silica nanomaterial for electromagnetic wave (EW) absorption was synthesized using a modified one-pot method. The unique hydrolysis-polymerization process forms a SiO₂@SiO₂/Carbon@Carbon core-shell structure. The growth process of the material was studied by transmission electron microscope (TEM) and thermogravimetric analysis (TGA). Nanoparticles were successfully synthesized with a core-shell structure after 6 h of reaction, and the composite material showed excellent EW absorption performance with a thickness of 3.8 mm. The minimum reflection loss (RL_min) was ?56.3 dB, and the broadest effective absorption bandwidth (EAB) (RL ≤ 10 dB, 90% absorption) covered 5.15 GHz (12.48–17.63 GHz) with 1.8 mm of thickness. There is no significant difference in the EW absorption performance with increasing reaction time. Thus, this study provides a method for synthesizing EW-absorbing materials with shorter reaction time, simpler process, and excellent absorption properties, possibly a candidate for further application.     

Enhanced microwave absorption properties of Fe-doped SiOC ceramics by the magnetic-dielectric loss properties

The combination of multiple loss characteristics is an effective approach to achieve broadband microwave wave absorption performance. The Fe-doped SiOC ceramics were synthesized by polymer derived ceramics (PDCs) method at 1500 °C, and their dielectric and magnetic properties were investigated at 2–18 GHz. The results showed that adding Fe content effectively controlled the composition and content of multiphase products (such as Fe₃Si, SiC, SiO₂ and turbostratic carbon). Meanwhile, the Fe promoted the change of the grain size. The Fe₃Si enhanced the magnetic loss, and the SiC and turbostratic carbon generated by PDCs process significantly increased the polarization and conductance loss. Besides, the magnetic particles Fe₃Si and dielectric particles SiO₂ improved the impedance matching, which was beneficial to EM wave absorption properties. Impressively, the Fe-doped SiOC ceramics (with Fe addition of 3 wt %) presented the minimum reflection coefficient (RC_min) of ?20.5 dB at 10.8 GHz with 2.8 mm. The effective absorption bandwidth (EAB, RC < ?10 dB) covered a wide frequency range from 5 GHz to 18 GHz (covered the C, X and Ku-band) when the absorbent thickness increased from 2 mm to 5 mm. Therefore, this research opens up another strategy for exploring novel SiOC ceramics to design the good EM wave-absorbing materials with broad absorption bandwidth and thin thickness.     

Preparation,mechanical, dielectric and microwave absorption properties of hierarchical porous SiCnw-Si3N4 composite ceramics

Herein, hierarchical porous SiC_nw-Si₃N₄ composite ceramics with good electromagnetic absorption properties were prepared. A porous Si₃N₄ matrix with different pore structures was first prepared by gelcasting-pressureless sintering (G-PLS) and gelcasting combined with particle stabilized foam-pressureless sintering (G-PSF-PLS). SiC_nw was then introduced by catalytic chemical vapor deposition (CCVD). An increase in solid loading (25–40 vol%) decreased apparent porosity (47.7–41.3%) and improved flexural strength (142.19–240.36 MPa) and fracture toughness (2.25–3.68 MPa·m^1/2). The addition of foam stabilizer propyl gallate (PG, 0.5–1.0 wt%) significantly increased apparent porosity (73.2–86.4%) and realized large-sized spherical pores, reducing flexural strength (58.23–38.56 MPa) and fracture toughness (0.75–0.41 MPa·m^1/2). High apparent porosity and large-sized pores facilitated the introduction of SiC_nw. The 25 vol% sample exhibited a reflection loss of ? 14.67 dB with an effective absorption bandwidth of 3.47 GHz, suggesting a development potential in the electromagnetic wave absorption field.     

Construction of Si3N4/SiO2/SiC–Y2Si2O7 composite ceramics with gradual impedance matching structure for high-temperature electromagnetic wave absorption

Good impedance matching is vital in upgrading the performance of electromagnetic (EM) wave-absorbing materials. In this study, Si₃N₄/SiO₂/SiC–Y₂Si₂O₇ composite ceramics were synthesized by sintering and chemical vapor infiltration (CVI) technology with gradual impedance matching. The relationship between the microstructure of the as-prepared composite ceramics and EM wave absorption characteristics was thoroughly explored. It was found that the amorphous Si₃N₄, SiO₂, and SiC layers were constructed with a gradual impedance matching structure, which not only improved impedance matching but also increased the number of nano interfaces. More importantly, SiC nanocrystals effectively increased the conduction loss, and the presence of defects and nanoscale heterogeneous interfaces further increased the polarization loss. Consequently, the as-prepared composite ceramics displayed enhanced EM wave absorption properties, with a minimum reflection coefficient (RC_min) value of less than ?20 dB over a temperature range of 25 °C (RT)-300 °C, and an effective absorption bandwidth (EAB) maintained at 4.2 GHz with the thickness range of 3.75–4.75 mm. These results demonstrated the practical significance of high-performance EM wave absorption materials that can be applied in high-temperature and water vapor environments.     

Nano-SiC-decorated Y2Si2O7 ceramic for enhancing electromagnetic waves absorption performance

To improve the electromagnetic (EM) wave absorption performance of rare earth silicate in harsh environments, this work synthesized dense SiC–Y₂Si₂O₇ composite ceramics with excellent EM wave absorption properties by using the polymer permeation pyrolysis (PIP) process, which introduced carbon and SiC into a porous Y₂Si₂O₇ matrix to form novel composite ceramics. SiC–Y₂Si₂O₇ composite ceramics with different numbers of PIP cycles were tested and analysed. The results show that the as-prepared composites exhibit different microstructures, porosities, dielectric properties and EM wave absorption properties. On the whole, the SiC–Y₂Si₂O₇ composite ceramics (with a SiC/C content of 29.88 wt%) show superior microwave absorption properties. The minimum reflection loss (RL_min) reaches ?16.1 dB when the thickness is 3.9 mm at 9.8 GHz. Moreover, the effective absorption bandwidth (EAB) included a broad frequency from 8.2 GHz to 12.4 GHz as the absorbent thickness varied from 3.15 mm to 4.6 mm. In addition, the EM wave absorption mechanism was analysed profoundly, which ascribed to the multiple mediums of nanocrystalline, amorphous phases and turbostratic carbon distributed in the Y₂Si₂O₇ matrix. Therefore, SiC–Y₂Si₂O₇ composite ceramics with high-efficiency EM wave absorption performance promise to be a novel wave absorbing material for applications in harsh environments.