Search Results (22)

Al₂O₃ with SiC, silver, and graphene nanoplatelets (GNPs) powder mixture was produced by ball milling using ethanol as dispersion media. The GNP-reinforced Al₂O₃-SiC-Ag ceramic–metal composites were densified by spark plasma sintering technology (SPS). A homogeneous dispersion of GNPs in Al₂O₃-SiC-Ag was observed from the sintered samples, and the GNPs were embedded between the grains, which resulted in increasing the contact area. The trans-granular mechanism of crack propagation becomes increasingly dominant by adding GNPs. The hardness reaches 27 GPa, as tested by the Vickers microhardness method, which reflects an increase of 11% compared to Ag-GNPs-free Al₂O₃-SiC. On the other hand, by adding Ag-GNP content, the improvement in density is limited. Wear mechanisms, as determined through ball-on-flat testing, including adhesion, abrasion, and microcracks, are observed and discussed. The composite demonstrated remarkable self-lubricating properties, exhibiting a lower coefficient of friction (COF) and wear rate in an air environment compared to monolithic Al₂O₃-SiC. This improvement is attributed to the formation of a self-lubricating film, enabled by the uniform distribution of Ag and GNPs within the Al₂O₃-SiC matrix. The findings of this study propose a novel material design approach for developing self-lubricating ceramic composites with hybrid solid lubricants. Full article

Hybrid nanocomposites have emerged as a groundbreaking class of materials in the aerospace industry, offering exceptional mechanical, thermal, and functional properties. These materials, composed of a combination of metallic matrices (based on aluminum, magnesium, or titanium) reinforced with a mixture of nanoscale particles, such as carbon nanotubes (CNTs), graphene, and ceramic nanoparticles (SiC, Al₂O₃), provide a unique balance of high strength, low weight, and enhanced durability. Recent advances in developing these nanocomposites have focused on optimizing the dispersion and integration of nanoparticles within the matrix to achieve superior material performance. Innovative fabrication techniques have ensured uniform distribution and strong bonding between the matrix and the reinforcements, including advanced powder metallurgy, stir casting, in situ chemical vapor deposition (CVD), and additive manufacturing. These methods have enabled the production of hybrid nanocomposites with improved mechanical properties, such as increased tensile strength, fracture toughness, wear resistance, and enhanced thermal stability and electrical conductivity. Despite these advancements, challenges remain in preventing nanoparticle agglomeration due to the high surface energy and van der Walls forces and ensuring consistent quality and repeatability in large-scale production. Addressing these issues is critical for fully leveraging the potential of hybrid nanocomposites in aerospace applications, where materials are subjected to extreme conditions and rigorous performance standards. Ongoing research is focused on developing novel processing techniques and understanding the underlying mechanisms that govern the behavior of these materials under various operational conditions. This review highlights the recent progress in the design, fabrication, and application of hybrid nanocomposites for aerospace applications. It underscores their potential to revolutionize the industry by providing materials that meet the demanding requirements for lightweight, high-strength, and multifunctional components. Full article

Enhancing the mechanical properties of conventional ceramic particles-reinforced aluminum (Al 1060) metal matrix composites (AMCs) with lower detrimental phases is difficult. In this research work, AMCs are reinforced with graphene nanosheet (GNS) and hybrid reinforcement (GNS combined with 20% SiC, synthesized by shift-speed ball milling (SSBM), and further fabricated by two-pass friction stir processing (FSP). The effect of GNS content and the addition of SiC on the microstructure and mechanical properties of AMCs are studied. The microstructure, elemental, and phase composition of the developed composite are examined using SEM, EDS, and XRD techniques, respectively. Mechanical properties such as hardness, wear, and tensile strength are analyzed. The experimental results show that the GNS and the SiC are fairly distributed in the Al matrix via SSBM, which is beneficial for the mechanical properties of the composites. The maximum tensile strength of the composites is approximately 171.3 MPa in AMCs reinforced by hybrid reinforcements. The tensile strength of the GNS/Al composites increases when the GNS content increases from 0 to 1%, but then reduces with the further increase in GNS content. The hardness increases by 2.3%, 24.9%, 28.9%, and 41.8% when the Al 1060 is reinforced with 0.5, 1, 2% GNS, and a hybrid of SiC and GNS, respectively. The SiC provides further enhancement of the hardness of AMCs reinforced by GNS. The coefficient of friction decreases by about 7%, 13%, and 17% with the reinforcement of 0.5, 1, and 2% GNS, respectively. Hybrid reinforcement has the lowest friction coefficient (0.41). The decreasing friction coefficient contributes to the self-lubrication of GNSs, the reduction in the contact area with the substrate, and the load-bearing ability of ceramic particles. According to this study, the strengthening mechanisms of the composites may be due to thermal mismatch, grain refinement, and Orowan looping. In summary, such hybrid reinforcements effectively improve the mechanical and tribological properties of the composites. Full article

In this study, the nano-aluminum powder was reinforced with a hybrid of copper and graphene nanoplatelets (GNPs). The ratios of GNPs were 0 wt%, 0.4 wt%, 0.6 wt%, 1.2 wt% and 1.8 wt%. To avoid the reaction between aluminum and graphene and, consequently, the formation of aluminum carbide, the GNP was first metalized with 5 wt% Ag and then coated with the predetermined 15 wt% Cu by the electroless coating process. In addition, the coating process was performed to improve the poor wettability between metal and ceramic. The Al/(GNPs-Ag)Cu nanocomposites with a high relative density of 99.9% were successfully prepared by the powder hot-pressing techniques. The effects of (GNPs/Ag) and Cu on the microstructure, density, hardness, and compressive strength of the Al-Cu nanocomposite were studied. As a result of agitating the GNPs during the cleaning and silver and Cu-plating, a homogeneous distribution was achieved. Some layers formed nano-tubes. The Al₄C₃ phase was not detected due to coating GNPs with Cu. The Cu₉Al₄ intermetallic was formed during the sintering process. The homogeneous dispersion of Cu and different ratios of GNs, good adhesion, and the formation of the new Cu₉Al₄ intermetallic improved in hardness. The pure aluminum sample recorded 216.2 HV, whereas Al/Cu reinforced with 1.8 GNs recorded 328.42 HV with a 51.9% increment. The compressive stress of graphene samples was improved upon increasing the GNPs contents. The Al-Cu/1.8 GNs sample recorded 266.99 MPa. Full article

In recent years, research has focused on developing materials exhibiting outstanding mechanical, electrical, thermal, catalytic, magnetic and optical properties such as graphene/polymer, graphene/metal nanoparticles and graphene/ceramic nanocomposites. Two-dimensional sp² hybridized graphene has become a material of choice in research due to the excellent properties it displays electrically, thermally, optically and mechanically. Noble nanomaterials also present special physical and chemical properties and, therefore, they provide model building blocks in modifying nanoscale structures for various applications, ranging from nanomedicine to catalysis and optics. The introduction of noble metal nanoparticles (NPs) (Au, Ag and Pd) into chemically derived graphene is important in opening new avenues for both materials in different fields where they can provide hybrid materials with exceptional performance due to the synergistical result of the specific properties of each of the materials. This review presents the different synthetic procedures for preparing Pt, Ag, Pd and Au NP/graphene oxide (GO) and reduced graphene oxide (rGO) composites. Full article

With increasing heat accumulation in advanced modern electronic devices, dielectric materials with high thermal conductivity (λ) and excellent electrical insulation have attracted extensive attention in recent years. Inspired by mussel, hexagonal boron nitride (hBN) and graphene oxide (GO) are assembled to construct mhBN@GO hybrids with the assistance of poly(catechol-polyamine). Then, mhBN@GO hybrids are dispersed in carboxy nitrile rubber (XNBR) latex via emulsion coprecipitation to form elastomer composites with a high λ and satisfactory insulating properties. Thanks to the uniform dispersion of mhBN@GO hybrids, the continuous heat conduction pathways exert a significant effect on enhancing the λ and decreasing the interface thermal resistance of XNBR composites. In particular, the λ value of 30 vol% mhBN@GO/XNBR composite reaches 0.4348 W/(m·K), which is 2.7 times that of the neat XNBR (0.1623 W/(m·K)). Meanwhile, the insulating hBN platelets hinder the electron transfer between adjacent GO sheets, leading to satisfactory electrical insulation in XNBR composites, whose AC conductivity is as low as 10⁻¹⁰ S/cm below 100 Hz. This strategy opens up new prospects in the assembly of ceramic and carbonaceous fillers to prepare dielectric elastomer composites with high λ and satisfactory electrical insulation, making them promising for modern electrical systems. Full article

This article reports on the structure and electronic properties of carbon-rich polysilazane polymer-derived silicon carbonitride (C/SiCN) corresponding to pyrolysis temperatures between 1100 and 1600 °C in an argon atmosphere. Raman spectroscopy, X-ray diffraction (XRD), energy dispersive X-ray spectroscopy (EDX), Scanning Electron Microscopy (SEM) and Hall measurements were used to support the structural and electronic properties characterization of the prepared C/SiCN nanocomposites. A structural analysis using Raman spectroscopy showed the evolution of sp² hybridized carbon phase that resulted from the growth in the lateral crystallite size (L_a), average continuous graphene length including tortuosity (L_eq) and inter-defects distance (L_D) with an increase in pyrolysis temperature. The prepared C/SiCN monoliths showed a record high room temperature (RT) electrical conductivity of 9.6 S/cm for the sample prepared at 1600 °C. The electronic properties of the nanocomposites determined using Hall measurement revealed an anomalous change in the predominant charge carriers from n-type in the samples pyrolyzed at 1100 °C to predominantly p-type in the samples prepared at 1400 and 1600 °C. According to this outcome, tailor-made carbon-rich SiCN polymer-derived ceramics could be developed to produce n-type and p-type semiconductors for development of the next generation of electronic systems for applications in extreme temperature environments. Full article

This paper presents an evaluation of the mechanical properties of nanocomposites when a lower concentration of nanoparticles graphene and ceramics are mixed with epoxy to determine the damping and stability characteristics of hybrid epoxy, using vibration techniques to extract accurate results. The effectiveness of the Impact hammer vibration technique is validated with mechanical testing such as three-point bending in terms of Young’s modulus of the nanocomposite. The graphene nanocomposite carries nanoparticle 1 wt.% of epoxy, while the ceramic nanocomposite carries 3 wt.% of epoxy. It is observed that the reduction in frequency under a thermal environment is significantly less for graphene and ceramic reinforced hybrid nanocomposites, whereas the reduction in pure epoxy under a thermal environment is high. Thus, the results show that the addition of nanoparticles to composites shows improvement in the mechanical and thermal stability of elastic properties. The elastic properties obtained from the vibrational analysis are more consistent and economical than the three-point bending test for the evaluation of hybrid nanocomposites. Full article

The incorporation of ceramic nanoinclusions in carbon nanocomposites can induce additional functionality in the field of magnetic properties, piezoelectricity, etc. In this study, series of nanocomposites, consisting of different carbon nanoinclusions (carbon black, MWCNTs, graphene nanoplatelets, nanodiamonds) and magnetite nanoparticles incorporated into a commercially available epoxy resin were developed varying the filler type and concentration. Experimental data from the static tensile tests and dynamic mechanical analysis (DMA) demonstrated that the elastic tensile modulus and storage modulus of hybrid nanocomposites increase with an increase in filler content up to almost 100% due to the inherent filler properties and the strong interactions at the interface between the epoxy matrix and the nanoinclusions. Strong interactions are implied by the increasing values of the glass transition temperature recorded by differential scanning calorimetry (DSC). On the contrary, tensile strength and fracture strain of the nanocomposites were found to decrease with filler content. The results highlight the potentials and capabilities of developing hybrid multifunctional nanocomposites with enriched properties while holding their structural integrity. Full article

The tremendous technological and dental material progress led to a progressive advancement of treatment technologies and materials in restorative dentistry and prosthodontics. In this approach, CAD/CAM restorations have proven to be valuable restorative dental materials in both provisional and definitive restoration, owing to multifarious design, improved and highly tunable mechanical, physical and morphological properties. Thus far, the dentistry market offers a wide range of CAD/CAM restorative dental materials with highly sophisticated design and proper characteristics for a particular clinical problem or multiple dentistry purposes. The main goal of this research study was to comparatively investigate the micro-mechanical properties of various CAD/CAM restorations, which are presented on the market and used in clinical dentistry. Among the investigated dental specimens, hybrid ceramic-based CAD/CAM presented the highest micro-mechanical properties, followed by CAD/CAM PMMA-graphene, while the lowest micro-mechanical features were registered for CAD/CAM multilayered PMMA. Full article

The multiscale hybridization of ceramic nanoparticles incorporated into polymer matrices reinforced with hybrid fibers offers a new opportunity to develop high-performance, multifunctional composites, especially for applications in aeronautical structures. In this study, two different kinds of hybrid fibers were selected, woven carbon and glass fiber, while two different ceramic nanoparticles, alumina (Al₂O₃) and graphene nanoplatelets (GNPs), were chosen to incorporate into a polymer matrix (epoxy resin). To obtain good dispersion of additive nanoparticles within the resin matrix, the ultrasonication technique was implemented. The microstructure, XRD patterns, hardness, and tensile properties of the fabricated composites were investigated here. Microstructural characterization demonstrated a good dispersion of ceramic nanoparticles of Al₂O₃ and GNPs in the fabricated composites. The addition of GNPs/Al₂O₃ nanoparticles as additive reinforcements to the fiber-reinforced polymers (FRPs) induced a significant increase in the hardness and tensile strength. Generally, the FRPs with 3 wt.% nano-Al₂O₃ enhanced composites exhibit higher tensile strength as compared with all other sets of composites. Particularly, the tensile strength was improved from 133 MPa in the unreinforced specimen to 230 MPa in the reinforced specimen with 3 wt.% Al₂O₃. This can be attributed to the better distribution of nanoparticles in the resin polymer, which, in turn, induces proper stress transfer from the matrix to the fiber phase. The hybrid mode mechanism depends on the interaction among the mechanical properties of fiber, the physical and chemical evolution of resin, the bonding properties of the fiber/resin interface, and the service environment. Therefore, the hybrid mode of woven carbon and glass fibers at a volume fraction of 64% with additive nanoparticles of GNPs/Al₂O₃ within the resin was appropriate to produce aeronautical structures with extraordinary properties. Full article

The interfacial structures and interfacial bonding characteristics between graphene and matrix in graphene-reinforced Al₂O₃–WC matrix ceramic composite prepared by two-step hot pressing sintering were systematically investigated. Three interfacial structures including graphene–Al₂O₃, graphene–Al₂OC and graphene-WC were determined in the Al₂O₃–WC–TiC–graphene composite by TEM. The interfacial adhesion energy and interfacial shear strength were calculated by first principles, and it has been found that the interfacial adhesion energy and interfacial shear strength of the graphene–Al₂OC interface (0.287 eV/nm², 59.32 MPa) were far lower than those of graphene–Al₂O₃ (0.967 eV/nm², 395.77 MPa) and graphene–WC (0.781 eV/nm², 229.84 MPa) interfaces. Thus, the composite with the strong and weak hybrid interfaces was successfully obtained, which was further confirmed by the microstructural analysis. This interfacial structure could induce strengthening mechanisms such as load transfer, grain refinement, etc., and toughening mechanisms such as crack bridging, graphene pull-out, etc., which effectively improved mechanical properties. Full article

The remarkable tunability of 2D carbon structures combined with their non-toxicity renders them interesting candidates for thermoelectric applications. Despite some limitations related to their high thermal conductivity and low Seebeck coefficients, several other unique properties of the graphene-like structures could out-weight these weaknesses in some applications. In this study, hybrid structures of alumina ceramics and graphene encapsulated alumina nanofibers are processed by spark plasma sintering to exploit advantages of thermoelectric properties of graphene and high stiffness of alumina. The paper focuses on thermal and electronic transport properties of the systems with varying content of nanofillers (1–25 wt.%) and demonstrates an increase of the Seebeck coefficient and a reduction of the thermal conductivity with an increase in filler content. As a result, the highest thermoelectric figure of merit is achieved in a sample with 25 wt.% of the fillers corresponding to ~3 wt.% of graphene content. The graphene encapsulated nanofibrous fillers, thus, show promising potential for thermoelectric material designs by tuning their properties via carrier density modification and Fermi engineering through doping. Full article

Research activity on ceramic/graphene composites and hybrids has increased dramatically in the last decade. In this review, we provide an overview of recent contributions involving ceramics, graphene, and graphene-related materials (GRM, i.e., graphene oxide, reduced graphene oxide, and graphene nanoplatelets) with a primary focus on applications. We have adopted a broad scope of the term ceramics, therefore including some applications of GRM with certain metal oxides and cement-based matrices in the review. Applications of ceramic/graphene hybrids and composites cover many different areas, in particular, energy production and storage (batteries, supercapacitors, solar and fuel cells), energy harvesting, sensors and biosensors, electromagnetic interference shielding, biomaterials, thermal management (heat dissipation and heat conduction functions), engineering components, catalysts, etc. A section on ceramic/GRM composites processed by additive manufacturing methods is included due to their industrial potential and waste reduction capability. All these applications of ceramic/graphene composites and hybrids are listed and mentioned in the present review, ending with the authors’ outlook of those that seem most promising, based on the research efforts carried out in this field. Full article

Multilayers consisting of graphene oxide (GO) and α-Fe₂O₃ thin layers were deposited on the ceramic substrates by the spray LbL (layer by layer) coating technique. Graphene oxide was prepared from graphite using the modified Hummers method. Obtained GO flakes reached up to 6 nanometers in thickness and 10 micrometers in lateral size. Iron oxide Fe₂O₃ was obtained by the wet chemical method from FeCl₃ and NH₄OH solution. Manufactured samples were deposited as 3 LbL (GO and Fe₂O₃ layers deposited sequentially) and 6 LbL structures with GO as a bottom layer. Electrical measurements show the decrease of multilayer resistance after the introduction of the oxidizing NO₂ gas to the ambient air atmosphere. The concentration of NO₂ was changed from 1 ppm to 20 ppm. The samples changed their resistance even at temperatures close to room temperature, however, the sensitivity increased with temperature. Fe₂O₃ is known as an n-type semiconductor, but the rGO/Fe₂O₃ hybrid structure behaved similarly to rGO, which is p-type. Both chemisorbed O₂ and NO₂ act as electron traps decreasing the concentration of electrons and increasing the effective multilayer conductivity. An explanation of the observed variations of multilayer structure resistance also the possibility of heterojunctions formation was taken into account. Full article