Carbon Matrix Composites Research Articles

Processing characteristics of C/C composites with nanosecond pulse laser

This study investigates the effects of the nanosecond pulse laser parameters on the processing characteristics of carbon fiber-reinforced carbon matrix (C/C) composites through a series of laser cutting experiments. It compares the cutting width, depth, heat-affected zone (HAZ) width, processed surface micro-morphology, as well as the oxidation characteristics of the material under different processing parameters. The HAZ width is analyzed in relation to the variations in the oxygen content. The results indicate that both the cutting width and depth initially increase and then decrease with increasing repetition frequency. Moreover, increasing the laser power and pulse width gradually increases the cutting width, depth, and HAZ width, whereas a higher scanning speed tends to reduce the cutting width and depth. Since changes in the processing power, scanning speed, and pulse width affect the HAZ, the oxygen content exhibits a proportional relationship with the HAZ width. In addition, an increase in the repetition frequency can expand the HAZ while reducing the oxygen content. A careful increase in the repetition frequency aids in lowering the ablation threshold of the material, leading to more material removal. Nevertheless, a continuous increase in energy density can trigger a fiber pull-out phenomenon and cause degradation of the matrix.

NiCo-MOFs derived carbon matrix composites: A promising electrode construction for high-performance supercapacitors

Metal-organic frameworks (MOFs) are great precursors and templates for preparing adsorbents, catalysts and electrodes due to the porous structure and high specific surface area. We report a promising approach to prepare nanocrystalline Co, Ni sulfides (CNS) embedded and N self-doped porous carbon (NPC) matrix composites derived from NiCo-MOFs. The CNS@NPC composite was investigated as electrodes for hybrid supercapacitors (HSCs). The prepared electrode achieved specific capacitance of 2789 F g−1 at 1 A/g, and high capacitance retention of 88.93% after 6000 galvanostatic charge–discharge (GCD) cycles under 10 A/g. The HSC structured with CNS@NPC//AC achieved an energy density of 46.79 Wh kg−1 at power density of 800 W kg−1. Meanwhile, specific capacitance of 131.56 F g−1 at 1 A/g and capacitance retention of 99.17% over 6000 GCD cycles under 3 A/g were obtained. Space confinement by the carbon skeleton effectively prevents the aggregation of the redox active nanocrystalline and improves the durability of the electrode. Meanwhile, the carbon skeleton provides abundant charge transfer channels to enhance the redox reaction. In other words, synergistic effect of the carbon skeleton and the active redox nanocrystalline significantly improves the electrochemical properties of the composite.

Multi-scale modeling and mechanical performance analysis of finger seals with plain woven C/C composite

The application of carbon fibers reinforced carbon matrix (C/C) composite can solve the local wear of metallic finger seals effectively. However, the performance of C/C composite finger seal is complex and variable, which further decreases the sealing performance and life. Therefore, a method of multi-scale modeling and mechanical performance analysis for plain woven C/C composite finger seals was conducted. The circumferential finger beams of C/C composite were modeled by multi-scale structural analysis and weaving simulation. The radial static and dynamic stiffness characteristics of finger beams were investigated. The results showed that the radial static stiffness of the finger beam with three layers was about 3 times that with single layer. The radial stiffness of circumferential finger beams presented a periodic distribution pattern with a period of 90°. The radial dynamic stiffness of C/C composite finger beams increased with the excitation displacement amplitude and rotor speed. But the magnitude and fluctuation degree of dynamic stiffness were greater than those of static stiffness. A large difference in radial stiffness will lead to local wear and hysteretic leakage. This study lays a foundation for the analysis and optimization of the hysteresis and wear characteristics of C/C composite finger seals.

Multi-component attached carbon matrix composites with superior electromagnetic wave absorption performance and multifunctional applications

The preparation of highly absorbing and high-performance electromagnetic wave-absorbing materials remains a significant challenge. In this paper, carbon matrix composites modified with sodium inorganic salts (CMS) have been successfully prepared by using the solvent evaporation method in combination with the hydrothermal treatment and high temperature carbonization processes. The composition of the product can be manipulated by varying the material ratios, which in turn affects the interface and dielectric properties of the material. Sodium carbonate (Na2CO3) was produced as a transition phase between sodium silicate and carbon matrix due to high temperature. According to differential charge density a significant charge accumulation found between the interfacial of Na2CO3 and carbon layer is helpful to polarization. The synergistic effect of polarization and conduction loss due to the formation of multiple heterogeneous interfaces and carbon matrix results in excellent electromagnetic wave absorption performance. The minimum reflection loss (RLmin) is −55.49 dB when the thickness is 3.1 mm. Furthermore, CMS composites exhibit notable flame retardancy and thermal insulation properties, rendering them suitable for a diverse range of applications. These remarkable achievements provide new ideas for the design and development of efficient electromagnetic wave absorption materials.

Atmospheric-pressure plasma jet texturing of C/C composites for improved joint strength

This study explores the use of air-fed atmospheric pressure plasma jets (APPJs) as a pre-joining treatment for 3D carbon fiber-reinforced carbon matrix composites (C/C) with the aim of both creating a textured surface that resembles a brush structure and improving the joint strength.The effects of various treatment time lengths on the mass loss, etching depth, and surface texture were investigated using SEM and confocal microscopy. An optimal process time of 30 s was selected, while keeping the other process parameters fixed (air flow of 1750 l/h and nozzle-sample distance of 5 mm). Wetting tests were conducted at 1000 °C, on both untreated and pre-treated C/C surfaces by means of liquid TiCuNi brazing alloy, and low contact angles of about 20° were measured. C/C–TiCuNi–C/C and C/C–TiCuNi–Cu joints were then produced, and their interfacial reactivity was evaluated. The apparent shear strength measured for the APPJ-treated C/C–Cu joints was 140 % higher than the value recorded for the untreated joints, thus confirming the effectiveness of the treatment.Even though a further investigation is needed in which an optimization of the process parameters should be included, this preliminary study has revealed the viability of APPJ as a promising technique to enhance the bonding of C/C composites in dissimilar assemblies and to improve the joint quality.

Investigation of recycled carbon fiber-reinforced ultrafine-grain carbon-matrix composites

To broaden the usefulness of recycled carbon fibers and develop the high value-added product, the recycled carbon fiber-reinforced carbon-matrix composites were prepared using ultrafine-grain coke as a filler and coal tar pitch as a binder via a liquid mixing process. A comprehensive study and investigation of the microstructures and properties of recycled carbon fibers and composites were conducted. It was found that the recycled PAN-based carbon fiber (rPCF) outperformed the recycled rayon-based carbon fiber (rRCF) in terms of fiber integrity and pitch-coated effect in the recycling and forming processes. By relieving thermal stress, lowering stacking pores, and inhibiting the growth of shrinkage pores, the rCF can promote the sintering of the green body. The flexural strength of rPCF-reinforced carbon-matrix composite (30.70 MPa) and rRCF-reinforced carbon-matrix composite (20.75 MPa) increased by 60.6% and 8.6% than that of pristine carbon-matrix composite (19.11 MPa), respectively. The difference in mechanical properties between rPCF-reinforced carbon-matrix composite and rRCF-reinforced carbon-matrix composite is attributed to the mechanical interlock mechanism and fiber pull-out mechanism. This work provides a propagable, affordable, and environment-friendly idea for recycling waste carbon fiber and producing recycled carbon fiber reinforced composites.

Hydrothermal preparation of N and O-rich porous carbon microspheres and their capacitance properties

In this paper, N and O-rich porous activated carbon (N-O/AC) microsphere with various pore sizes was prepared by thermal and KOH activation of g-C3N4@graphene oxide (CN@GO) microsphere. CN@GO microsphere was pre-prepared through a hydrothermal method directly from glucose and melamine, which resulted into high content and uniform doping of O and N in the final product. CN@GO microsphere was composed of GO/CN/GO sandwich nanochips, forming a porous structure with various pore sizes. The obtained N-O/AC has high energy density (33.19 Wh/kg) and high power density (499.93 W/kg), in company with excellent cyclic stability (remaining 98.64 % after 1000 cycles). The N-O/AC derived from the hydrothermal method provides a low-cost way of constructing porous carbon matrix composites with pseudo-capacitance.

Study on the picosecond laser surface treatment and tribological properties of 3D woven carbon fiber reinforced carbon matrix (Cf/C) composites

Carbon fiber reinforced carbon matrix (Cf/C) composites have demonstrated great significance in many fields, especially in aircraft and automobiles as brake materials. The surface physical/chemical states of Cf/C composites significantly affect their tribological properties. Although ultrafast laser machining technology has been proven to be an effective method for modifying material surfaces, there are some issues concerning the ultrafast laser surface treatment of Cf/C composites and the adjustment of their tribological properties by laser treatment. Here, the 3D woven Cf/C composites were treated with an infrared picosecond laser. The effects of machining parameters on the surface microscopic morphology, chemical compositions, and graphitization degree were investigated. The experiment results indicated that the ultrafast laser treatment could eliminate surface defects, improve surface quality, and reduce the porosity of the Cf/C composites due to photothermal-mechanical ablation. More importantly, the laser-induced photothermal effects led to a graphitization transformation of Cf/C composites from a disordered turbostratic structure into an ordered graphite structure with an increased graphitization degree. The abundant micro-nano structures and the graphitization transformation on the Cf/C composite surface contributed to forming a complete and dense friction film on the Cf/C composites. Therefore, the laser-treated Cf/C composites showed lower COF, higher wear rate, and more stable tribological properties. This study demonstrated a method to adjust the tribological properties of Cf/C composites by ultrafast laser surface treatment, which showed great significance for the surface treatment and tribological property enhancement of Cf/C composites.

Highly Conductive Carbon/Carbon Composites as Advanced Multifunctional Anode Materials for Structural Lithium‐Ion Batteries

AbstractCurrently, structural lithium‐ion batteries (LIBs) typically use carbon fibers (CFs) as multifunctional anode materials to provide both Li+ storage and high mechanical strength. However, due to the obvious volume expansion of CFs in lithiation process, the fiber structure suffers rapid degradation during cycling. Herein, CFs‐reinforced carbon matrix (C/C) composites are proposed as multifunctional anodes for structural LIBs for the first time. The C/C composite presents distinctive core/shell structure, in which CF as the core supplies a fast and continuous electron conduction pathway along with excellent mechanical strength, while the layered pyrolytic carbon shell accommodates the volume change of CF and provides additional ion storage. The impact of the C/C microstructure on the ion/electron transport and the Li+ storage mechanism behind such a unique hybrid structure are explored. Owing to the structural advantages of the C/C composite, the LiFePO4||C/C full cell exhibits surprising electrochemical performances at high electrode mass loadings, which are far superior to those of the present structural LIBs and even surpass the commercial LIBs at the same mass loadings. Moreover, the pouch cell presents excellent mechanical strength and mechanical‐electrochemical coupling characteristics. This work demonstrates great potential of the C/C composites as new multifunctional anodes for high‐performance structural batteries.

A universal strategy towards the fabrication of ultra-high temperature ceramic matrix composites with outstanding mechanical properties and ablation resistance

Materials with both excellent mechanical properties and good ablation resistance are urgently needed for the applications of thermal protection system in extreme high temperature oxidizing environments. However, owing to the lack of efficient fabrication processes, the existing materials suffer from either insufficient mechanical properties or poor ablation resistance. Herein, we report a novel solid–liquid combination fabrication strategy that successfully achieves the efficient incorporation of ultra-high temperature ceramics into 3D continuous carbon fiber performs as well as rapid densification. The relative density of the green body approaches the cubic close packing of spherical particles. Using Cf/ZrB2–SiC as an example, the as-prepared composite exhibits outstanding mechanical properties with a flexural strength surpasses 600 MPa and an unprecedented work of fracture of 11,851 ± 838 J/m2, which is two orders of magnitude higher than that of the currently reported monolithic ultra-high temperature ceramics. Moreover, the high ZrB2 content endows the composites with excellent ablation resistance and is thus capable of maintaining long-term non-ablative conditions at 2500 °C. The strategy possesses remarkable universality and high design flexibility, providing a time-saving and cost-effective universal strategy for the on-demand design and fabrication of high-performance ceramic, carbon, metal, and polymer matrix composites.

Microstructural investigation and performance of carbon matrix composites developed through facile pitch modification route

Increasing demand of high-performance materials lead to development of composites with affordable cost and processing route. Present work involves facile chemical modification (nitric acid and melamine) route to produce carbon matrix composites exhibiting progressive performance. Modified pitches and resultant carbon matrix composites were characterized by FTIR, optical microscopy, SEM, XRD, TGA, TMA, tribological study and compression strength. Chemical treatment given to pitch imparts active functional groups which help to improve affinity between pitch particles. Additionally, to evaluate influence of high temperature treatment, composites were also heated to 1400 °C. Optical images show that microstructure of carbonized (1000 °C) and further heat-treated (1400 °C) composites contain fine isotropic grains and flow domains, attributed to the effective influence of chemical modification. SEM images and Raman spectroscopy also confirmed the similar results of arrangement of carbon layers. TGA analysis revealed that heat-treated composites with acid modified pitch have better thermal stability at 800 °C in zero air. Coefficient of thermal expansion of all composites was measured and found very low i.e. 5 to 10 ppm/°C. Chemical treatment applied to the pitch yielded improved results for tribological performance, coupled with enhanced compressive strength. Notably, up until the present, it was difficult to find reports on fabrication of carbon matrix composites from chemically modified pitch.

Prediction of Thermo-Mechanical Properties of 8-Harness Satin-Woven C/C Composites by Asymptotic Homogenization.

The elasticity matrix and the coefficients of thermal expansion (CTEs) of 8-harness satin-woven (8HS) carbon-fiber-reinforced carbon matrix (C/C) composites at high temperatures were obtained by the asymptotic homogenization method (AHM) and finite element method (FEM). By analyzing the microstructure of the 8HS C/C composites, a representative volume element (RVE) model considering a braided structure was established. The effects of the temperature and component volume fraction on the elasticity matrix and CTEs of the composites were investigated. The sensitivity of model parameters, including the size of RVE model and mesh sensitivity, were studied. The optimal calculation model was employed. In addition, the effects of the 4HS methods and 8HS methods on the elastic constants of the composites were compared. The temperature and variation in the carbon fiber volume fraction were found to have a significant impact on the elasticity matrix and CTEs of composite materials. At the same volume fraction of carbon fibers, some elastic coefficients of the 4HS composite material were slightly lower than those of 8HS composite material. This research affords a computational strategy for the accurate prediction of the themo-mechanical properties of satin-woven C/C composites.

Sugar-Derived Nanocrystalline Graphite Matrix C/C Composites with Excellent Ablative Resistance at 3000°C.

Sugars are renewable resources essential to human life, but they are rarely used as raw materials for the industrial production of carbon-based materials, especially for the preparation of carbon fiber-reinforced carbon-matrix (C/C) composites, which are extremely useful for the semiconductor and aerospace sectors. Herein, a method utilizing sugar-derived carbon to replace petrochemicals as dense matrix to preparing C/C composites is reported. The matrix from sugar-derived C/C (S-C/C) composites has a nanocrystalline graphite structure that is highly thermally stable and effectively bonded to the carbon fibers. The mechanical properties of the S-C/C composite are comparable to those prepared from petrochemical sources; significantly, it exhibits a linear ablation rate of 0.03 mm s-1 after 200 s of ablation at 3000°C in 10 MW m-2 heat flux. This new class of S-C/C is promising for use in a broad range of fields, ranging from semiconductor to aerospace.

Elevating mechanical and biotribological properties of carbon fiber composites by constructing graphene-silicon nitride nanowires interlocking interfacial enhancement

Carbon fiber reinforced dual-matrix composites (CHM) including carbon fiber reinforced hydroxyapatite-polymer matrix composites (CHMP) and carbon fiber reinforced hydroxyapatite-pyrolytic carbon matrix composites (CHMC) have great potential application in the field of artificial hip joints, where a combination of high mechanical strength and excellent biotribological property are required. In this work, the graphene-silicon nitride nanowires (Graphene-Si3N4nws) interlocking interfacial enhancement were designed and constructed into CHM for boosting the mechanical and biotribological properties. The graphene and Si3N4nws interact with each other and construct interlocking interfacial enhancement. Benefiting from the Graphene-Si3N4nws synergistic effect and interlocking enhancement mechanism, the mechanical and biotribological properties of CHM were promoted. Compared with CHMP, the shear and compressive strengths of Graphene-Si3N4nws reinforced CHMP were increased by 80.0% and 61.5%, respectively. The friction coefficient and wear rate were reduced by 52.8% and 52.9%, respectively. Compared with CHMC, the shear and compressive strengths of Graphene-Si3N4nws reinforced CHMC were increased by 145.4% and 64.2%. The friction coefficient and wear rate were decreased by 52.3% and 73.6%. Our work provides a promising methodology for preparing Graphene-Si3N4nws reinforced CHM with more reliable mechanical and biotribological properties for use in artificial hip joints.

Understanding wetting mechanism of pure Cu on C/C composites modified by chromium carbide

Carbon fiber reinforced carbon matrix (C/C) composites are considered one of the key lightweight materials for high-temperature components. Unfortunately, C/C composites are difficult to be wetted by metals, seriously hindering their application in the engineering field. This study obtains a superior wettability of pure Cu on C/C composites modified by chromium carbide (CrC). Owing to CrC surface modification, the contact angle of pure Cu on C/C composites is significantly decreased from 159° to 15°. Notably, the spreading and wetting process in this study occurs once Cu melts, distinguished from the common reactive wetting. High Resolution Transmission Electron Microscope (HRTEM) examination demonstrates a direct interfacial joining between the CrC layer and Cu droplet without transition phases. Superior wettability can be attributed to the interfacial metallic bond of CrC and Cu phases. This work offers a promising surface modification strategy to enhance the wettability of carbon and ceramic substrates.

Carbonaceous materials and carbon matrix composites utilized in heat sinks and heat exchangers: A review

Ceramic matrix composites (CMCs) are often used to make high-value and safety–critical parts, so knowing how they react to different machining processes is essential. Due to their heterogeneous structure, non-uniform mechanical and thermal behaviour, and the hardness of at least one of their sections, machining CMCs can lead to significant mechanical and thermal strains. Because CMC surfaces are orthotropic, brittle, and different, they have unique flaws and need special techniques to remove the material. This study seeks to provide an impartial evaluation of the impact of various machining techniques on the machined surfaces of ceramic matrix composites (CMCs) by conducting a comprehensive analysis of the existing literature on typical and novel machining. This article presents a concise review of contemporary methodologies employed in the characterization of materials, which facilitate the detection, quantification, and accentuation of mechanical and thermal surface and subsurface anomalies. Composites are attracting a lot of attention from the aerospace, automotive, and construction industries because they are more resilient per unit of weight than non-reinforced materials. Various filler materials and unique matrix ingredients are intricately combined to produce a wide variety of composites. These filler ingredients, which may include fibres, particles, or flakes, entwine intricately with the matrix to produce a composite material that possesses the distinctive qualities of both of its components.

In situ constructing Co/Co-Ox/Co-Nx diverse active sites on hollow porous carbon spheres derived from Co-MOF for efficient bifunctional electrocatalysis in rechargeable Zn-air

Earth-rich, durable, and efficient bifunctional electrocatalysts for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) is vitally important for the wide application of zinc-air batteries in the future. However, due to the single active site, traditional commercial benchmark catalysts typically exhibit selective activity in only one of the two reactions (ORR or OER), making it difficult to meet the dual functional catalytic requirements. Developing efficient oxygen electrocatalysts that achieve diverse active sites on a single catalyst and understanding their internal synergistic reaction activity remain a challenge. Herein, spherical hollow porous carbon matrix composites (s-Co/CoNC) with the coexistence of diverse intrinsic active sites including Co-Nx and Co-Ox species and metal Co nanoparticles were prepared by pyrolysis with oxygen-enriched Co-MOFs as precursor in the presence of melamine. Owing to the combined advantages of the catalyst including the great specific surface area, good conductivity, abundant diverse intrinsic active sites towards ORR and OER, and the electronic interaction among active sites and the optimized the adsorption/desorption process of oxygen species at the catalyst surface, s-Co/CoNC exhibits desirable electrocatalytic activity for both ORR and OER with an ORR half-wave potential of 0.81 V, an OER potential of 1.53 V(vs. RHE at 10 mA cm−2), providing a small reversible potential difference of 0.72 V, superior to the commercial noble-metal catalysts and the most reported cobalt based ORR/OER catalysts. The assembled s-Co/CoC-based rechargeable Zn-air batteries possess high peak power density of 101.7 mW cm−2. This work provides a significant strategy for constructing high-performance dual functional catalysts for secondary Zn-air batteries.

A focused review on the tribological behavior of C/SiC composites: Present status and future prospects

Silicon carbide-based ceramic matrix composites have received extensive attention in recent years. Many excellent reviews have reported on the tribological behavior of carbon fiber-reinforced carbon and silicon carbide dual matrix (C/C-SiC) composites. However, a systematic overview of the tribological properties of carbon fiber-reinforced silicon carbide (C/SiC) composites does not exist. This review focuses on C/SiC composites and summarizes the key factors, including internal factors (constituent content, graphitization process, material structure and fiber direction), and various test conditions (pressure and speed, dry and wet, temperature, and counterparts) that affect their tribological behavior. Their wear mechanisms under different conditions are elaborated. Finally, some potential future development directions for improving the performance of C/SiC composites are proposed to provide high-quality ceramic matrix composites for engineering applications. These directions include structural modification, matrix modification, coating technology, laser surface texturing, and material genome method.

Achieving excellent wetting of inactive Ag on C/C composites by a low-temperature surface modification strategy

Carbon fiber reinforced carbon matrix (C/C) composites are one of the most promising thermal lightweight materials. However, the inferior wettability of inactive metals on C/C composites severely limits their application for joining alloys in industrial structures. In this study, successful wetting of inactive Ag on C/C composites is achieved via a low-temperature surface modification strategy. After surface modification using a chromium carbide (CrC) layer, the contact angle of Ag droplets on C/C substrates decreases significantly from 158° to 26°. Results of microstructure analysis indicate that no new reaction phases are generated during the wetting process. The wetting and spreading process of Ag droplets on CrC modified C/C substrates are promoted by the diffusion from Ag to CrC layer, which is found for the first time in this study. This study provides a novel surface modification concept for the wetting of C/C composites and other carbon materials.

Three-dimensional conductive network constructed by in-situ preparation of sea urchin-like NiFe2O4 in expanded graphite for efficient microwave absorption

Expanded graphite (EG) is a modified conductive lamellar carbon that has been widely studied in the field of electromagnetic wave absorption due to its low density, good electrical conductivity, and unique structure. However, its application is limited because the interlayer gap cannot match microwave wavelength, and its single composition has less microwave loss. In this study, sea urchin-like NiFe2O4/EG composites are prepared in situ between expanded graphite layers by microwave treatment. The sea urchin-like NiFe2O4 grows between the expanded graphite to form a three-dimensional conductive network structure, which enhances conductive loss of composites and further increases the interlayer distance of EG. The extended interlayer distance promotes multiple reflections and scattering of electromagnetic waves in composites and improves dielectric properties. In addition, EG with a large specific surface area provides many active sites, further promoting interface and dipole polarization. Benefiting from synergistic effect of NiFe2O4 and EG, magnetic loss and dielectric loss of NiFe2O4/EG composites have been improved and impedance matching is further enhanced. The results indicate that the minimal reflection loss of NiFe2O4/EG-4 reaches −53.47 dB at 2.69 mm, and the effective absorption bandwidth reaches 2.97 GHz. In addition, based on the computer simulation technology results, NiFe2O4/EG can attenuate microwave energy under experimental conditions. This work provides a strategy for synthesizing carbon matrix composites with adjustable dielectric parameters and electromagnetic wave properties.