Search Results (81)

The continuous advancement of modern weaponry has intensified the pursuit of next-generation ballistic protection systems that integrate lightweight architectures, superior flexibility, and high energy absorption efficiency. This review provides a technological overview of current trends in the design, processing, and performance optimization of metallic, ceramic, polymeric, and composite materials for ballistic applications. Particular emphasis is placed on the role of advanced surface coatings and nanostructured interfaces as enabling technologies for improved impact resistance and multifunctionality. Conventional materials such as high-strength steels, alumina, silicon carbide, boron carbide, Kevlar^®, and ultra-high-molecular-weight polyethylene (UHMWPE) continue to dominate the field due to their outstanding mechanical properties; however, their intrinsic limitations have prompted a transition toward nanotechnology-assisted solutions. Functional coatings incorporating nanosilica, graphene and graphene oxide, carbon nanotubes (CNTs), and zinc oxide nanowires (ZnO NWs) have demonstrated significant enhancement in interfacial adhesion, inter-yarn friction, and energy dissipation. Moreover, multifunctional coatings such as CNT- and laser-induced graphene (LIG)-based layers integrate sensing capability, electromagnetic interference (EMI) shielding, and thermal stability, supporting the development of smart and adaptive protection platforms. By combining experimental evidence with computational modeling and materials informatics, this review highlights the technological impact of coating-assisted strategies in the evolution of lightweight, high-performance, and multifunctional ballistic armor systems for defense and civil protection. Full article

The potential of silicon carbide (SiC) as a promising high-capacity and stable anode material is hindered by poor electronic conductivity and slow lithium diffusion kinetics. Here, we report a one-step laser chemical vapor deposition (LCVD) process to directly synthesize porous graphene@SiC heterostructures on carbon fiber substrates. This in situ method yields an integral, binder-free electrode architecture that enhances mechanical robustness against pulverization. A critical feature of this heterostructure is the built-in electric field at the graphene–SiC interface, which is revealed by theoretical calculations to significantly accelerate charge transport and lithium-ion diffusion. The resulting anode delivers a high reversible capacity of 668 mAh·g⁻¹ after 100 cycles at 0.1 A·g⁻¹. More remarkably, a unique multi-stage activation mechanism is discovered, leading to an unprecedented capacity rebound to 735 mAh·g⁻¹ after cycling at rates up to 5 A·g⁻¹. This activation process is observed to accelerate with increasing current density in the 0.1–2 A·g⁻¹ range. Furthermore, post-cycling analysis via XRD, TEM, and XPS confirms both the structural durability of the electrode and a reversible lithium intercalation mechanism, providing a critical foundation for the future design of high-performance LIB anodes. Full article

The quantum Hall effect is a paradigmatic example of topological order, characterized by precisely quantized Hall resistance and dissipationless edge transport. These edge states are chiral, propagating unidirectionally along the boundary, and their directionality is determined by the external magnetic field. While chirality is a central feature of the quantum Hall effect, directly probing it remains experimentally nontrivial. In this study, we introduce a simple and effective method to probe the chirality of edge transport using two independently controlled current sources in a Hall bar geometry. The system under investigation is monolayer epitaxial graphene grown on a silicon carbide substrate, exhibiting robust quantum Hall states. By varying the configurations of the two current sources, we measure terminal voltages and analyze the transport characteristics. Our results demonstrate that the observed behavior can be understood as a linear superposition of chiral contributions to the edge transport. This superposition enables tunable combinations of longitudinal and Hall resistances and enables additive or canceling behavior of Hall voltages depending on current source configuration. The Landauer–Büttiker formalism provides a quantitative framework to describe these observations, capturing the interplay between edge state chirality and the measurement configuration. This research offers a simple yet effective experimental and analytical approach for probing chiral edge currents and highlights the linear superposition principle in the quantum Hall effect. Full article

Carbide-bonded graphene (CBG) coating, with its unique 3D cross-linked network structure, shows significant potential for protecting silicon substrates. However, a comprehensive understanding of its macroscale tribological properties remains lacking. This study investigated the macroscale friction and wear behaviors of CBG-coated silicon wafers using reciprocating sliding tests against steel balls under various loads and sliding cycles. The CBG coating exhibited excellent friction-reduction and anti-wear performance, reducing the steady friction coefficient from 0.80 to 0.17 and wear rate by an order of magnitude compared to those of bare silicon. Higher loads slightly decreased both friction coefficients and wear rates, primarily due to the formation of denser tribofilms and transfer layers. Re-running experiments revealed three distinct wear stages—adhesive, abrasive, and accelerated substrate wear—driven by the evolution of tribofilms, transfer layers, and unabraded flat areas. Furthermore, comparative experiments confirmed that these “unabraded flat areas” on the wear track play a critical role in sustaining low friction and prolonging coating life. The findings identify CBG as a robust solid lubricant for high-contact-pressure applications and emphasize the influence of tribo-layer dynamics and wear debris behavior on coating performance. Full article

Graphene, a two-dimensional material with remarkable electrical, thermal, and mechanical properties, has revolutionized the fields of electronics, energy storage, and nanotechnology. This review presents a comprehensive analysis of graphene synthesis techniques, which can be classified into two primary approaches: top-down and bottom-up. Top-down methods, such as mechanical exfoliation, oxidation-reduction, unzipping carbon nanotubes, and liquid-phase exfoliation, are highlighted for their scalability and cost-effectiveness, albeit with challenges in controlling defects and uniformity. In contrast, bottom-up methods, including chemical vapor deposition (CVD), arc discharge, and epitaxial growth on silicon carbide, offer superior structural control and quality but are often constrained by high costs and limited scalability. The interplay between synthesis parameters, material properties, and application requirements is critically examined to provide insights into optimizing graphene production. This review also emphasizes the growing demand for sustainable and environmentally friendly approaches, aligning with the global push for green nanotechnology. By synthesizing current advancements and identifying critical research gaps, this work offers a roadmap for selecting the most suitable synthesis techniques and fostering innovations in scalable and high-quality graphene production. The findings serve as a valuable resource for researchers and industries aiming to harness graphene’s full potential in diverse technological applications. Full article

In the process of machining an aluminum matrix silicon carbide (SiCp/Al) composite material using wire electric discharge machining (WEDM), the thermal conductivity and dielectric properties of working fluid, such as discharge medium and cool carrier, directly determine the material removal rate (MRR) and surface roughness (R_a). In this paper, graphene-working fluid is innovatively used as working medium to optimize the discharge process due to its high thermal conductivity and field emission characteristics. The single-factor experiments show that graphene can increase the MRR by 11.16% and decrease the R_a by 29.96% compared with traditional working fluids. In order to analyze the multi-parameter coupling effect, an L16 (4⁴) orthogonal test is further designed, and the effects of the pulse width (T_on), duty cycle (DC), power tube number (PT), and wire speed (WS) on the MRR and R_a are determined using a signal-to-noise analysis. Based on a gray relational grade analysis, a multi-objective optimization model was established, and the priority of the MRR and R_a was determined using an AHP, and finally the optimal parameter combination (T_on = 22 μs, DC = 1:4, PT = 3, WS = 2) was obtained. Full article

Properly refrigerating hard-to-cut alloys during grinding is key to achieve high quality, strict tolerances, and good surface finishing. Nonetheless, literature about the influence of cooling-lubrication conditions (CLCs) on dimensional accuracy of ground components is still scarce. Thus, this work aims to evaluate surface quality, grinding power, and dimensional accuracy of Inconel 718 workpieces after grinding with silicon carbide grinding wheel at different grinding conditions. Four different CLCs were tested: flood, minimum quantity of lubrication (MQL) without graphene, and with multilayer graphene (MG) at two distinct concentrations: 0.05 and 0.10 wt.%. Different radial depths of cut values were also tested. The results showed that the material’s removed height increased with radial depth of cut, leading to coarse tolerance (IT) grades. Machining with the MQL WG resulted in higher dimensional precision with an IT grade varying between IT6 and IT7, followed by MQL MG 0.10% (IT7), MQL MG 0.05% (IT7-IT8), and flood (IT8). The lower tolerances achieved with MG were attributed to the lowering in the friction coefficient of the workpiece material sliding through the abrasive grits with no material removal (micro-plowing mechanism), thereby reducing grinding power and the removed height in comparison to the other CLC tested. Full article

In order to solve the self-heating problem of power electronic devices, this paper adopts a nonequilibrium molecular dynamics approach to study the thermal transport regulation mechanism of the aluminum nitride/graphene/silicon carbide heterogeneous interface. The effects of temperature, size, and vacancy defects on interfacial thermal conductivity are analyzed by phonon state density versus phonon participation rate to reveal their phonon transfer mechanisms during thermal transport. It is shown that the interfacial thermal conductance (ITC) increases about three times when the temperature increases from 300 K to 1100 K. It is analyzed that the increase in temperature will enhance lattice vibration, enhance phonon coupling degree, and thus increase its ITC. With the increase in the number of AlN-SiC layers from 8 to 28, the ITC increases by about 295.3%, and it is analyzed that the increase in the number of AlN-SiC layers effectively reduces the interfacial scattering and improves the phonon interfacial transmission efficiency. The increase in the number of graphene layers from 1 layer to 4 layers decreases the ITC by 70.3%. The interfacial thermal conductivity reaches a minimum, which is attributed to the increase in graphene layers aggravating the degree of phonon localization. Under the influence of the increase in graphene single and double vacancy defects concentration, the ITC is slightly reduced. When the defect rate reaches about 20%, the interfacial thermal conductance of SV (single vacancy) and DV (double vacancy) defects rises back to 5.606 × 10⁻² GW/m²K and 5.224 × 10⁻² GW/m²K, respectively. It is analyzed that the phonon overlapping and the participation rate act at the same time, so the heat-transferring phonons increase, increasing the thermal conductance of their interfaces. The findings provide theoretical support for optimizing the thermal management performance of heterostructure interfaces. Full article

Silylation treatment improves the hydrophobicity of cellulose by reducing the number of hydroxyl groups in the cellulose chains that are available to react with moisture in the surrounding environment. Additionally, silylation increases stress transfer from cellulose to synthetic nanofillers by forming covalent bonds between the hydroxyl groups of cellulose and the oxidized surface of these nanofillers. This study investigates the impact of silane coupling agents on the tensile properties of cellulose nanocomposites. The cellulose nanocomposites are reinforced with four types of C/SiC-based nanofillers: carbon nanotubes, graphene nanoplatelets, silicon carbide nanotubes, and silicon carbide nanoplatelets. Subsequently, the nanofillers are subjected to surface treatment using the silane coupling agent KH550. The mechanical properties of the cellulose nanocomposites are evaluated by molecular dynamics simulations based on the polymer’s consistent forcefield. The results indicate that the reinforcements of silylated silicon carbide nanotubes and carbon nanotubes increase the tensile modulus of cellulose by 18.03% and 24.58%, respectively, compared to their untreated counterparts. Furthermore, the application of silylation treatment on the surface of C/SiC nanofillers increases the yield strength and ultimate tensile strength of cellulose nanocomposites due to enhanced load transfer between cellulose and these reinforcements. Full article

How to solve hydrogen embrittlement (HE) is a key issue that urgently needs to be addressed in the hydrogen energy industry. The use of hydrogen barrier coatings can effectively reduce the occurrence of HE. In this article, we utilized the epoxy resin (ER) as the base coating and the graphene (GN) and the silicon carbide (SiC) as the additives to prepare the (GN-ER)/(SiC-ER)/(GN-ER) sandwich structure composite hydrogen barrier coatings by the spin coating method and investigated the effect of coating composite ways on the hydrogen barrier performance. The GN-ER and the SiC-ER are used as the hydrogen barrier layer and the hydrogen capture layer, respectively, in order to improve the hydrogen barrier performances jointly. The XRD and the SEM were used to characterize their phase compositions and microstructures, and the hydrogen barrier performances were analyzed by the electrochemical hydrogen permeation curves. The adhesive strength was characterized through the pull-out method. Compared to the single-layer and the double-layer structures, sandwich structures can effectively enhance the hydrogen barrier performance of the coatings, such as the relatively low electrochemical hydrogen diffusion coefficient (D_t, 3.88 × 10⁻⁸ cm²·s⁻¹), the relatively high permeation reduction factor (PRF, 59) and adhesive strength (10.9 MPa). This research may provide a theoretical basis for improving the hydrogen barrier performance of coatings. The (GN-ER)/(SiC ER)/(GN-ER) sandwich structures composite hydrogen barrier coatings can be expected to be used in the field of safe hydrogen storage and transportation. Full article

Magnesium-based materials, which are known for their light weight and exceptional strength-to-weight ratio, hold immense promise in the biomedical, automotive, aerospace, and military sectors. However, their inherent limitations, including low wear resistance and poor mechanical properties, have driven the development of magnesium-based metal matrix composites (Mg-MMCs). The pivotal role of powder metallurgy (PM) in fabricating Mg-MMCs was explored, enhancing their mechanical and corrosion resistance characteristics. The mechanical characteristics depend upon the fabrication methodology, composition, processing technique, and reinforcement added to the magnesium. PM is identified as the most efficient due to its ability to produce near-net shape composites with high precision, cost-effectiveness, and minimal waste. Furthermore, PM enables precise control over critical processing parameters, such as compaction pressure, sintering temperature, and particle size, which directly influence the composite’s microstructure and properties. This study highlights various reinforcements, mainly carbon nanotubes (CNTs), graphene nanoparticles (GNPs), silicon carbide (SiC), and hydroxyapatite (HAp), and their effects on improving wear, corrosion resistance, and mechanical strength. Among these, CNTs emerge as a standout reinforcement due to their ability to enhance multiple properties when used at optimal weight fractions. Further, this study delves into the interaction between reinforcement types and matrix materials, emphasizing the importance of uniform dispersion in preventing porosity and improving durability. Optimal PM conditions, such as a compaction pressure of 450 MPa, sintering temperatures between 550 and 600 °C, and sintering times of 2 h, are recommended for achieving superior mechanical performance. Emerging trends in reinforcement materials, including nanostructures and bioactive particles, are also discussed, underscoring their potential to widen the application spectrum of Mg-MMCs. Full article

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

The direct ink writing (DIW) process has been successfully used to prepare SiC-based composites from preceramic polymers due to the porous light weight, lower sintering temperature, and tailored design. However, it still presents challenges in improving the mechanical properties of composites and endowing them with multifunctionality. In this study, we present a 3D-printing strategy for preparing a graphene/SiC_p/SiC composite using the DIW process. A polycarbosilane (PCS)-based slurry containing graphene/SiC_p composite powder was developed and 3D-printed into scaffolds with a lattice structure, which were then pyrolyzed at 1500 °C to obtain a graphene/SiC_p/SiC composite. The weight loss, viscosity, and printability of the graphene/SiC_p/PCS slurry were evaluated, and it was determined that the slurry after 4 h of magnetic stirring was suitable for the DIW process. When heat-treated at above 800 °C in an N₂ atmosphere, PCS was first reacted with SiC_xO_y, which was further transformed into β-SiC and pyrocarbon. The 3D-printed lattice structure achieved porosity and low density, while the SiC_p reduced defects caused by large shrinkage during pyrolysis of PCS. Meanwhile, GNPs provided the composites with better conductivity and lower density. The density was as low as 1.08 g/cm³, the conductivity reached 670 S·m⁻¹, and the compressive strength was 4.3 MPa. Thus, a lightweight and porous SiC-based composite with high conductivity and strength can be prepared. Full article

Engineering ceramics and their composites are widely used owing to their excellent properties, including high wear, corrosion and heat resistance, low friction coefficient, and low thermal conductivity; thus, the current paper presents a comprehensive review of the most common types of engineering ceramics, demonstrating their key properties, advantages, potential applications, and challenges. This paper also provides prevailing methods for tackling the engineering ceramic challenges and maximizing their applicability. This review paper focuses on alumina (Al₂O₃), silicon carbide (SiC), zirconia (ZrO₂), aluminum nitride (AlN), and silicon nitride (Si₃N₄), and explores their usability in automotive, aerospace, and tribological applications. Additionally, the incorporation of reinforcing nanomaterials, i.e., graphene and carbon nanotubes or their combination with second-phase reinforcing nanomaterials in these types of ceramics to improve their physico-mechanical properties is also discussed. By strategically adding these reinforcing materials, the brittleness of ceramics can be mitigated, leading to materials that are more suitable for demanding applications in various high-performance industries. Full article

The potential of semiconducting, corrugated graphene, grown on silicon carbide, as an active element in chemosensors is studied in the present work. For this purpose, the adsorption of benzene, diazepam and 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD) on the material’s surface was modeled. According to the graphene sheet bending and adsorbate–adsorbent distances, the heterostructure favors the ligands in the order of diazepam < benzene < TCDD. The apparent ambiguity in the results for diazepam is easy to explain. The abundance of lone pairs and π-electrons compensates for the low-symmetry, non-planar, far from optimal (adsorption-wise) geometry. The maximum band gap change in the heterostructure, caused by adsorption, is 0.02 eV. Intermolecular binding does not alter the HOMO–LUMO difference in benzene and TCDD by more than 0.01 eV. The completely planar molecules are not expected to undergo significant geometrical changes; hence, the alteration in their frontier orbitals is also minimal. The adsorption of diazepam, however, causes significant changes in the projected density of states of both structures in the complex. In conclusion, corrugated graphene is applicable as an active material in selective chemosensors for non-planar aromatic molecules. Full article