SiC Composites Research Articles

Mechanical, thermophysical, and ablation properties of C/HfC–SiC composites with various SiC/HfC ratios

AbstractThe mechanical, thermophysical, and ablation properties of 2.5D C/HfC–SiC composites with various SiC/HfC ratios are studied. The S7‐C/HfC–SiC composite with a high SiC/HfC volume ratio of 30.4/15.2 has the highest flexural strength of 203.4 ± 26.8 MPa and fracture toughness of 10.0 ± .5 MPa·m1/2. All C/HfC–SiC composites have a similar low thermal conductivity of ∼2 W·m−1·K−1 and their CTEs are in the range of .45–4.0 × 10−6/K from 30°C to 1400°C. S5‐C/HfC–SiC with medium SiC/HfC ratio possesses the lowest mass ablation rate of .29 ± .02 mg·cm−2·s−1 and linear ablation rate of .003 ± .0002 mm/s. The C/HfC–SiC composites are endowed with a pitting corrosion feature according to the morphology and composition evolution of the ablated surface, which results from both high temperature and stagnation pressure gradients in the radial direction of the oxyacetylene torch.

Using pyrolytic carbon-coated short carbon fiber to fabricate Csf/ZrB2–SiC composites by direct ink writing and precursor infiltration pyrolysis

Direct ink writing (DIW) offers significant advantages for efficient manufacturing of complex ceramic composite components. However, the mechanical properties of short carbon fiber-reinforced ceramic composites fabricated by DIW technology were not ideal, mainly be ascribed to the absence of a suitable coating on the fiber as an interface. In this work, Csf/ZrB2 green bodies were printed by an optimized extrusion process using pyrolytic carbon-coated short carbon fibers (Csf). High-performance Csf/ZrB2–SiC composites were obtained through the infiltration and pyrolysis of SiC precursor six times. With increasing Csf content, the dimensional deviations decreased and the mechanical properties increased. When the Csf content was 30 vol%, the dimensional deviation of the Csf/ZrB2–SiC composite was less than −0.5 % in the X and Y directions and about −2 % in the Z direction. A marked increase in the flexural strength and fracture toughness of the composite was also obtained, reaching 275.0 MPa and 5.26 MPa m1/2, respectively.

Elucidating the effect of whiskers on microstructural, mechanical and wear properties of ceramic-metal composites for sports venues applications

Ceramic whiskers reinforced composites are widely used in electrical, medical, and constructional applications due to their desirable strengths, hardness, and wear characteristics. In this study, to examine the wear and friction characteristics, the pressureless infiltrated Cu–SiC composites with different content of SiC whiskers were roll bonded to Al layer. According to SEM images, the SiC whiskers were distributed across the microstructure although they were aligned along rolling direction. Incorporation of SiC whiskers to Cu matrix led to rise of composites’ strengths, young moduli, and hardness values. The measured values of Al and Cu–SiC layers increased from 50 HV to 135 HV in Al/Cu–SiC (5 wt%) to 57 HV and 159 HV in Al/Cu–SiC (15 wt%). Ductile type of fracture along with dimples, delamination, and debonding of whiskers appeared on fracture surfaces. However, more debonding of SiC whiskers was observed as SiC content increased. Accordingly, mass loss decreased and less adhesive wear mechanism was observed. The mass loss decreased from 6.3 mg in Al/Cu–SiC (5 wt%) to 5.2 mg in Al/Cu–SiC (15 wt%).

ZrB2‐based ultrahigh‐temperature ceramic with various SiC particle size: Microstructure, thermodynamical behavior, and mechanical properties

AbstractThis study investigated the influences of WC and HfB2 additives along with SiC reinforcement (with various particle sizes) on densification, microstructure, and mechanical properties of ZrB2–SiC composites. The results showed that WC and HfB2 addition formed a solid solution of (Zr,W,Hf)B2 with a core–shell structure, whereas the remaining WC transformed into WB. Moreover, nano‐sized SiC caused a much better impact on densification compared to micro‐sized SiC. A small fraction of localized phases like ZrC, HfB, and (Hf,Zr)C in the form of solid solution were also formed. The maximum room temperature flexural strength and the fracture toughness of the sample containing 150 nm SiC and 8.9 wt.% WB were measured to be 682 17 MPa and 6.5 .3 MPa m1/2, respectively.

Effects of Zr/Ti ratios on the structure and ablation characteristics of (Zr,Ti)C–SiC composites

Dense (Zr,Ti)C–SiC composites containing a dual-phase solid solution were fabricated by spark plasma sintering using homemade Mg-modified multiphase ceramic powders as raw materials. The ablation behaviour suggested that the composite with a molar ratio of Zr/Ti = 3:1 exhibited the best ablation resistance, with low mass and linear ablation rates of −2.56 ± 0.89 mg/s and 1.26 ± 0.40 μm/s, respectively, after ablation for 90 s under a plasma flame test at around 2300 °C. It is asserted that the formation of an oxide film consisting of a self-sintered ZrO2 skeleton and a high-viscosity Ti–Mg–Si–O liquid phase was responsible for the excellent ablation resistance, which has remarkable efficacy in resisting the scouring effect of ablative flames and the erosion induced by oxidizing gases on the composite matrix.

Improving TiB2 dispersion in Al-Si composites by interfacial projection: High-throughput first-principles calculations and experimental verification

The dispersion of reinforced particles is crucial in improving the mechanical properties of ceramic particles reinforced Al matrix composites. In this work, a novel interfacial projection strategy was proposed to improve the dispersion of TiB2 particles in Al-Si composites through high-throughput first-principles calculations with the experimental verification. Firstly, the Al(111)/TiB2(0001) interface model was constructed. Then, the pre-substitution of Si at 2 at. % concentration was employed to simulate the solutionized Al matrix. Secondly, alloying behaviors of 55 elements (10 substitution sites per element) in the Si-Al(111)/TiB2(0001) interface were studied by high-throughput first-principles calculations in terms of the relative interface formation energy and the relative work of adhesion. With these values, a theoretical alloying map for evaluating the dispersion ability of these alloying elements was plotted. Accordingly, the copper mold experiments were conducted to validate the theoretical alloying map. Based on the electron analysis, the enhanced interface bonds by alloying primarily attributed to electron accumulations around Si atom, indicating that the pre-substitution Si atom was vital for a reliable simulation result. Generally, this interfacial projection strategy provides a precise and potent approach in designing high-performance Al matrix composites, and should be applicable to other reinforced particles.

Construction of gradient structure C/C–ZrC–SiC composites with good ablation resistance

With the upgrade of aircraft and the increasingly harsh service environment, it is urgent to develop high-performance thermal structural materials. In this study, inspired by foliar and root water uptake of trees, we propose a one-step facile method to achieve an autonomous gradient in C/C–ZrC–SiC sharp leading edge composites. The gradual increase of SiC content from top to bottom is beneficial to improve the heat transfer capacity of the composites. After oxyacetylene ablation for 60 s, the mass and linear ablation rates of the samples with gradient structure are 0.83 mg/s and 0.5 μm/s, 35 % and 83 % lower than conventional samples. The composites with gradient structure of ZrC and SiC are favorable to the formation of a compact and smooth ZrO2 oxide protective layer, which not only protects the composites from further penetration of O2, but also resists the mechanical denudation. The novel gradient structure composites with enhanced ablation resistance show a bright application prospect in next-generation thermal protection systems.

Self‐defending mechanism of C/TaC‒SiC composites under 2100°C cyclic ablation environment

AbstractTo achieve the repeatability of aerospace thermal components, C/TaC‒SiC composites were fabricated. Cycle ablation and bending tests were carried out. After 3 × 60 s of ablation beyond 2100°C, the mechanical property retention rate was 80.9%. Interestingly, a reaction similar to “ouroboros ring,” in which the cyclic reactions of “TaC being oxidized to Ta2O5 and Ta2O5 being reduced to TaC,” occurred in the central ablation region of C/TaC‒SiC composites. On the one hand, the continuous generation of TaC could prevent liquid state Ta2O5 from being blown off central ablation region, playing a similar role in “water and soil conservation.” On the other hand, liquid Ta2O5 covered the surface of C/TaC‒SiC composites during ablation process, contributing to block the inward permeation of oxidized gases. In addition, novel “Grotto” structures were detected in the transitional ablation region of C/TaC‒SiC composites. The formation reason of the “Grotto” structure has also been discussed.

Effect of Diffusion on the Ultimate Axial Load of Complex-Shaped Al-SiC Samples: A Molecular Dynamics Study.

Metal matrix composites (MMCs) combine metal with ceramic reinforcement, offering high strength, stiffness, corrosion resistance, and low weight for diverse applications. Al-SiC, a common MMC, consists of an aluminum matrix reinforced with silicon carbide, making it ideal for the aerospace and automotive industries. In this work, molecular dynamics simulations are performed to investigate the mechanical properties of the complex-shaped models of Al-SiC. Three different volume fractions of SiC particles, precisely 10%, 15%, and 25%, are investigated in a composite under uniaxial tensile loading. The tensile behavior of Al-SiC composites is evaluated under two loading directions, considering both cases with and without diffusion effects. The results show that diffusion increases the ultimate tensile strength of the Al-SiC composite, particularly for the 15% SiC volume fraction. Regarding the shape of the SiC particles considered in this research, the strength of the composite varies in different directions. Specifically, the ultimate strength of the Al-SiC composite with 25% SiC reached 11.29 GPa in one direction, and 6.63 GPa in another, demonstrating the material's anisotropic mechanical behavior when diffusion effects are considered. Young's modulus shows negligible change in the presence of diffusion. Furthermore, diffusion improves toughness in Al-SiC composites, resulting in higher values compared to those without diffusion, as evidenced by the 25% SiC volume fraction composite (2.086 GPa) versus 15% (0.863 GPa) and 10% (1.296 GPa) SiC volume fractions.

Evaluation of surface response of SiC and fly ash-filled Prosopis juliflora fibre-reinforced epoxy composites under dry sliding wear conditions using Taguchi method

Prosopis juliflora (PJ) fibre-reinforced polymer composites are fabricated with fly ash and SiC as fillers with different weight percentages. Jute layers are also sandwiched for added strength in the structure. The wear behaviour is found for the prepared composition of samples. Pin-on-disc wear testing apparatus is used for the wear performance along with the design of experiments approach using orthogonal arrays of Taguchi’s. The effect of the input parameters (load, sliding velocity, speed) is studied on wear resistance. The experimental design creates sliding wear evaluations based on Taguchi’s L9 orthogonal array to identify the most dominating factors influencing the wear rate. This study demonstrates that the most important component affecting the sliding wear rate of the composite materials is followed by the sliding velocity, speed, and load. The result of the wear rate decreases with an increase in filler content and also increases with sliding velocity. The samples with fly ash and SiC fillers reportedly seemed to have the best wear rates.

Hierarchical porous SiCnws/SiC composites with one-dimensional oriented assemblies for high-temperature broadband wave absorption

The research on high-performance electromagnetic wave absorption materials with high-temperature and oxidative stability in extreme environments is gaining popularity. Herein, the lightweight silicon carbide nanowires (SiCnws)/SiC composites are fabricated with in-situ SiC interface on one-dimensional oriented SiCnws skeleton, which collaborative configuration by 3D printing and freeze casting assembly. The constructed porous structure optimizes the impedance matching degree and scattering intensity, the maximum effective absorption bandwidth (EABmax) of 5.9 GHz and the minimum reflection loss (RLmin) of −41.4 dB can be realized. Considering the inherent oxidation resistance of SiC, the composites present well-maintained absorption performance at 600 °C. Even at 1100 °C, the EABmax of 4.9 GHz and RLmin of −30.4 dB also demonstrate the high-temperature absorption stability of the composites, indicating exceptional wave absorption properties and thermal stability. The slight attenuation can be attributed to the decrease in impedance matching capability accompanying the elevated dielectric constant. This work clarifies the impact of structure and component synergy on wave absorption behavior, and offers a novel approach to producing high-performance and high-temperature resistance ceramic-based electromagnetic wave absorption materials suitable for extreme environments.

DRY SLIDING WEAR AND CORROSION BEHAVIOR OF AA7075–SiC COMPOSITES

DRY SLIDING WEAR AND CORROSION BEHAVIOR OF AA7075–SiC COMPOSITES

High-temperature mechanical properties and microstructure of 2.5D C/C–SiC composites applied for the brake disc of high-speed train

This paper uses chemical vapor infiltration method to prepare 2.5D C/C-SiC composites, and conducts various tests to reveal its high-temperature mechanical properties and failure mechanism. The results show that the test temperature significantly affects the mechanical properties. As the test temperature increased from room temperature to 800 °C, the tensile strength of the 2.5D C/C-SiC composite dropped from 127.67 ± 20.87 MPa to 94.74 ± 28.15 MPa, and the performance dropped by 25.79 %. The compressive strength dropped from 326.92±17.37 MPa to 192.31 ± 29.15 MPa, resulting in a performance decrease of 41.18 %. The bending strength dropped from 355.74 ± 40.80 MPa to 235.88 ± 23.52 MPa, and the performance dropped by 33.69 %; the interlaminar shear strength dropped from 9.77 ± 2.79 MPa to 7.80 ± 3.26 MPa, and the performance dropped by 20.16 %. High-temperature oxidation will lead to interface degradation, destroy the composite matrix and carbon fiber structure, change the interface bonding strength, and ultimately lead to a decline in composite performance.

Machinability investigation of grinding 2.5D-SiCf/SiC composites under nanofluid minimum quantity lubrication

SiCf/SiC composites are now the preferred option for the thermal structures of next-generation advanced aero-engines, owing to their high-temperature strength, and creep resistance. Grinding is currently a highly reliable and mature method for SiCf/SiC processing. However, the harsh, dry machining conditions lead to degradation of surface quality, and the dust generated can harm both humans and the environment. Nanofluid Minimum Quantity Lubrication (NMQL) maximizes heat transfer and lubrication in grinding and is environmentally and human-friendly. Based on this, this study thoroughly investigates the effects of dry, flood grinding, minimum quantity lubrication, and different nanofluids (MoS2 and carbon nanotubes (CNTs)) on grinding performance at different grinding depths. Compared with dry grinding, the results show that the normal grinding component force Fn is reduced by 56.9 %, 56.8 %, and 71.6 %, and the tangential grinding component force Ft is reduced by 48.4 %, 50.5 %, and 57.5 % for NMQL-CNTs lubrication condition at grinding depths of 0.2 mm, 0.4 mm, and 0.6 mm, respectively. Meanwhile, NMQL-CNTs can significantly improve the surface quality and help to obtain a surface morphology with fewer surface defects, and the stabilized lubricant film formed by NMQL-CNTs can significantly reduce the specific grinding energy. Although brittle removal was observed in different lubrication methods, NMQL-CNTs could significantly reduce surface damage due to their filling and friction reduction effects. Due to the high viscosity of NMQL-CNTs and the low intermolecular forces, they have strong lubrication stability and wear resistance. This study provides theoretical guidance for the green processing of SiCf/SiC composites.

Mechanical properties and tensile failure behavior of SiCnf/SiC composites with multilayer interphases

SiC fiber-reinforced SiC ceramic matrix composites (SiCf/SiC CMCs) hold potential as thermal structural materials. In this work, SiC nanofibres were coated with multilayer interfaces by magnetron sputtering with the aim to tailor the fiber-matrix interface of SiC nanofibre reinforced SiC composites for superior mechanical properties. The influence of multilayer interface coating and sintering temperature on the density, microstructure, and mechanical properties of SiCnf/SiC CMCs fabricated via a hot-press technique employing ultra-long single-crystal SiC nanofibers as reinforcement were investigated. The composites were characterized by X-ray diffraction (XRD), scanning electron microscopy (SEM), Transmission electron microscopy (TEM), and a universal testing machine. The prepared CMCs were toughened and strengthened by the observed fiber pull-out and bridging. The multilayered SiCnf/SiC CMCs with multiple interface coatings display an identifiable saw-tooth-like pattern in the load-displacement test, suggesting a significant improvement in the toughness of prepared materials through a laminated structure with weaker interface binding brought on by the thicker, denser coating. In comparison to the SiCnf/SiC composites without interface coating, the prepared SiCnf/SiC CMCs with PyC/SiAlC/ZrC interface layers revealed optimum flexural strength (520 ± 28.88 MPa, ↑46.5 %) and fracture toughness (9.95 ± 0.44 MPa m1/2, ↑94.7 %) after an hour of hot pressing at 1800 °C under pressure of 30 MPa. Besides an increase in relative density at high sintering temperatures (1850 °C), further grain coarsening deteriorated mechanical properties.

In-plane compressive properties and failure mechanisms of gradient Cf/ZrB2–SiC composites in high-temperature environment

The gradient Cf/ZrB2–SiC composites can exert the dual advantages of low-density and excellent heat resistance, but which have the complex mechanical properties due to the inhomogeneous geometry characteristics. The in-plane compressive behavior and failure analysis can examine the material integrity and the effect of inhomogeneous characteristics. The in-plane compressive elastic modulus distribution is expressed mathematically by using the superficial elastic modulus, back elastic modulus, and the gradient pore distribution. The superficial elastic modulus and the gradient pore distribution of the gradient materials were characterized by nanoindentation test and Micro-CT statistics. The back of the gradient materials is the porosity needled C/C composites without introducing ZrB2–SiC matrix, whose elastic modulus can be referenced from our previous work. The in-plane compressive experiments of the gradient materials in the high-temperature environment were also conducted to study the failure mechanisms. The strength of the gradient materials is further revealed by the temperature-dependent properties of carbon fibers and thermal residual stress release. The results indicate the gradient structure can effectively eliminate the delamination damage, but the high temperature drastically weakens the ability of needled fibers suppressing delamination damage in the high-porosity region of the gradient materials. This study can be helpful to the material design and evaluation of mechanical properties for the gradient Cf/ZrB2–SiC composites.

Microstructure and mechanical properties of multilayer SiC nanofiber paper‐reinforced SiC composites by the NITE method

AbstractIn this work, stacked SiC fibers paper‐reinforced SiC ceramic matrix composites (SiCnf/SiC CMCs) were prepared by nanoimpregnation and transient eutectic (NITE) process using ultra‐long single‐crystal SiC nanofibers. The effect of the SiCnf surface modification via boron nitride (BN) interphase deposition as well as the sintering additive (Al2O3–Y2O3) content on the density, microstructure, and mechanical properties of SiCnf/SiC CMCs has been investigated systematically. The results revealed that the laminated SiCnf/SiC CMCs feature a significant saw‐tooth‐like curve on the load–displacement test, which indicates that the obtained laminated structure with the weak interlayer binding owning to the BN coating treatment possesses significant toughening to the SiC ceramics. Specifically, the SiCnf/SiC CMCs with the sintering additive content of 12 wt% revealed a fracture toughness of over 10 MPa m1/2 after 60 min of BN interface deposition, which is 104.31% higher than that of the composites prepared without BN coating.

Enhancing performance of silicon/graphene composites by transition lattice interfaces constructed using plasma

The silicon-based (Si) anodes have not widely used due to their low conductivity and severe irreversible volume changes until now. Graphene (G) is considered a promising material for inhibiting volume expansion and enhancing conductivity of Si, a large amount of work has been exploring effective composite of graphene and silicon. A new SiG composite structure (PB-SiG-1) with transition lattice interface is provided by N plasma assisted technique in this work. The phase interface undergoes lattice changes on the atomic scale with silicon, oxygen, and carbon bonding in new chemical bonds (Si-O-C). More importantly, the lattice spacing of Si (111) increases from 0.31 nm to 0.325 nm due to the insertion of carbon or oxygen atom into the Si body, which promotes the diffusion kinetics of lithium ions. This PB-SiG-1 exhibits better electrochemical performance with reversible specific capacity of 2013.9 mAh g−1 after 100 cycles at 0.2 A g−1, high capacity retention of 98.53% and coulombic efficiency of 99.4%. The multiple advanced in situ methods reveal that the PB-SiG-1 not only has the ability to quickly transfer ions, electrons, and form stable SEI, but also has a low irreversible volume expansion of 33.1 %. This proves that the transition lattice interface endows PB-SiG-1 with isotropy characteristic of lithium diffusion, leading to dynamically stable electrodes during cycles. This work proposes a Si-C composite structure with transition lattice interface, which opens a new insight for volume expansion and lithium transmission in Si-C composite.

Fabrication of bamboo-inspired continuous carbon fiber-reinforced SiC composites via dual-material thermally assisted extrusion-based 3D printing

Ceramic matrix composites (CMCs) structural components encounter the dual challenges of severe mechanical conditions and complex electromagnetic environments due to the increasing demand for stealth technology in aerospace field. To address various functional requirements, this study integrates a biomimetic strategy inspired by gradient bamboo vascular bundles with a novel dual-material 3D printing approach. Three distinct bamboo-inspired structural configurations Cf/SiC composites are designed and manufactured, and the effects of these different structural configurations on the CVI process are analyzed. Nanoindentation method is utilized to characterize the relationship between interface bonding strength and mechanical properties. The results reveal that the maximum flexural strength and fracture toughness reach 108.6 ± 5.2 MPa and 16.45±1.52 MPa m1/2, respectively, attributed to the enhanced crack propagation resistance and path caused by the weak fiber-matrix interface. Furthermore, the bio-inspired configuration enhances the dielectric loss and conductivity loss, exhibiting a minimum reflection loss of −24.3 dB with the effective absorption band of 3.89 GHz. This work introduces an innovative biomimetic strategy and 3D printing method for continuous fiber-reinforced ceramic composites, expanding the application of 3D printing technology in the field of CMCs.

Molecular Dynamics Simulation on Solidification Microstructure and Tensile Properties of Cu/SiC Composites.

The shape of ceramic particles is one of the factors affecting the properties of metal matrix composites. Exploring the mechanism of ceramic particles affecting the cooling mechanical behavior and microstructure of composites provides a simulation basis for the design of high-performance composites. In this study, molecular dynamics methods are used for investigating the microstructure evolution mechanism in Cu/SiC composites containing SiC particles of different shapes during the rapid solidification process and evaluating the mechanical properties after cooling. The results show that the spherical SiC composites demonstrate the highest degree of local ordering after cooling. The more ordered the formation is of face-centered-cubic and hexagonal-close-packed structures, the better the crystallization is of the final composite and the less the number of stacking faults. Finally, the results of uniaxial tensile in three different directions after solidification showed that the composite containing spherical SiC particles demonstrated the best mechanical properties. The findings of this study provide a reference for understanding the preparation of Cu/SiC composites with different shapes of SiC particles as well as their microstructure and mechanical properties and provide a new idea for the experimental and theoretical research of Cu/SiC metal matrix composites.