Lightweight Properties Research Articles

Enabling boosting abrasion resistance of titanium alloy matrix via B4C particles doping micro arc oxidation coating strategy

Abstract Titanium alloy is recognized as the future metal due to its remarkable advantages, including high strength, lightweight properties, and corrosion resistance. Meanwhile, there are a series of technical challenges hindering its development, such as poor abrasion resistance. Herein, we propose a direct strategy by combining micro arc oxidation (MAO) technology with B4C particles doping that can effectively ameliorate the contact mechanics at the interface and regulate the microporous structure of the MAO coating. Exhilaratingly, compared to the titanium alloy and undoped samples, the modified B4C-doped alloy (B0.9) exhibited high hardness of 706.2 HV (increased by 121.9% and 15.8%, respectively) and low friction coefficient of 0.3435 (ameliorated by 40.6% and 39.6%, respectively). Utilizing in X-ray diffraction, scanning electron microscopy, and Image Pro Plus analysis, we found that B0.9 exhibited lower surface porosity and average pore size (8.7% and 3.0 μm, respectively), which are attributed to the regulation of the microporous structure. Specifically, B4C particles are successfully incorporated into the MAO coating by mechanical stirring and electrophoresis, filling the surface micropores and resulting in a denser and more uniform coating. This study emphasizes the compatibility between B4C doping and MAO technology, which effectively provides guidance for the inadequate abrasion resistance of titanium alloy.

Friction Stir Welding in Aircraft Structures: Current and Future Prospects

Friction stir welding (FSW) has significant potential to enhance the efficiency of air transportation systems; however, determining and applying its parameters continues to pose challenges. This article review explores current and future challenges, trends, and practices that facilitate the integration of competitive production into new aircraft structure joints. An overview of friction stir welding techniques used for the design and manufacture of aircraft structures are presented, focusing on product optimization through lightweight and high-strength properties. The implementation of various design solutions and advanced manufacturing technologies can enhance metallic fuselage systems’ performance without compromising risk and cost. The paper presents examples of successfully addressed challenges and those driving the development of new practices, design solutions, methods, and tools. Ultimately, aircraft structure joints become more integrated when systems engineering approaches are linked with various design solutions and advanced manufacturing technologies (e.g., Vertical Compensation Friction Stir Welding) in a reusable manner, balancing product performance and producibility. Nevertheless, the field remains in active development, posing challenges for research, development, and practice.

A Parametric Study of GFRP Composite Beams with Encased I-Section using 3D Finite Element Modeling

Glass Fiber Reinforced Polymer (GFRP) materials play a crucial role in the construction industry due to their lightweight properties, corrosion resistance, and high strength. Furthermore, the GFRP reinforcement ratio is a significant factor in the strength design philosophy that governs the design of flexible members. This study presents a parametric investigation of the performance of concrete composite beams reinforced and encased with pultruded GFRP. This study investigates the effect of concrete compressive strength and GFRP reinforcement ratio on the structural behavior of composite beams with encased GFRP sections under static loads. To achieve this objective, five simply supported models were numerically simulated using the Abaqus software. The reference model comprised normal concrete with a 30 MPa compressive strength, 0.42% GFRP longitudinal reinforcing ratio, and transverse steel rebars, with the GFRP I-section encased in the center of the cross-section. The other models maintained similar properties and geometries but varied in reinforcement ratio (0.85% and 1.2%) and compressive strength (25 MPa and 20 MPa). The results showed that increasing the reinforcement ratio in composite beams with encased GFRP sections improved the ultimate capacity by approximately 29% and 41% for 0.85% and 1.2% ratios, respectively, compared to the reference beam. Conversely, reducing compressive strength below 30 MPa decreased maximum load by about 16% and 23% for 25 MPa and 20 MPa values, respectively, in relation to the reference beam.

Synthesis and characterisation of ZnO nanoparticles and its influence on the engineering properties of lightweight foamed concrete

Synthesis and characterisation of ZnO nanoparticles and its influence on the engineering properties of lightweight foamed concrete

Construction of Nanocellulose Aerogels with Environmental Drying Strategy without Organic Solvent Displacement for High-Efficiency Solar Steam Generation.

Solar desalination is one of the effective means to alleviate water scarcity, in which aerogel-like evaporators have attracted extensive attention in the field of efficient desalination. However, the current preparation methods for aerogels still mainly rely on high-cost solutions, such as freeze-drying or supercritical drying. Herein, a preparation scheme for aerogels that can be realized under atmospheric pressure conditions is reported. In this paper, a foam skeleton template (FST) strategy is proposed, in which flake graphite is entangled by cellulose nanofibers (CNFs) and codispersed between the foam cell walls, and subsequently connected with the nascent Ca2+ in the inner wall to form a tough and stable three-dimensional network structure, which can effectively avoid the structural collapse caused by atmospheric drying. The cellulose/graphite aerogel (CGA) prepared using the FST strategy possesses lightweight (36 mg cm-3) and porous (porosity >97%) properties. The 3D porous structure and wetting characteristics of the CGA provided excellent energy management, rapid water transport capability, and a reduced enthalpy of evaporation, which enabled it to achieve a fast water evaporation rate of 3.8 kg m-2 h-1 with 98.4% energy efficiency. This FST strategy provides a solution for the low-cost development of aerogel and desalination.

Superstrong Lightweight Aerogel with Supercontinuous Layer by Surface Reaction.

Breaking the thermal, mechanical and lightweight performance limit of aerogels has pivotal significance on thermal protection, new energy utilization, high-temperature catalysis, structural engineering, and physics, but is severely limited by the serious discrete characteristics between grain boundary and nano-units interfaces. Herein, a thermodynamically driven surface reaction and confined crystallization process is reported to synthesize a centimeter-scale supercontinuous ZrO2 nanolayer on ZrO2-SiO2 fiber aerogel surface, which significantly improved its thermal and mechanical properties with density almost unchanged (≈26 mgcm-3). Systematic structure analysis confirms that the supercontinuous layer achieves a close connection between grains and fibers through Zr─O─Si bonds. The as-prepared aerogel exhibits record-breaking specific strength (≈84615 Nmkg-1, can support up to ≈227272 times aerogel mass) and dynamic impact resistance (withstanding impacts up to 500 times aerogel mass and up to 200 cycling stability at 80% strain). Besides, its temperature resistance has also been greatly optimized (400°C enhancement, stability at 1500°C). This work will provide a new perspective for exploring the limits of lightweight, high strength, and thermal properties of solid materials.

Sustainability metrics targeted optimization and electric discharge process modelling by neural networks

Aluminium and its alloys, especially Al6061, have gathered significant interest among researchers due to its less density, great durability, and high strength. Due to their lightweight properties, the precise machining of these alloys can become expensive through conventional machining operations for intricate products. Therefore, non-traditional machining such as electric discharge machining (EDM) can potentially be opted for the cutting of Al6061. EDM is often criticized due to its low machining rates, therefore, in the current work, cryogenic treatment (CT) has been performed on the brass electrode to evaluate the improvement in the machining rates. In addition, kerosene oil (KO) has been engaged in traditional EDM which is replaced with the deionized water (DI) based dielectric as a sustainable alternative. The machining variables such as spark voltage (SV), pulse-on-time (PON), peak current (IP), and Al2O3 powder concentration (CP) have been chosen to determine the material removal rate (MRR), surface roughness (SR), and specific energy consumption (SEC) while comparing non-treated (NT), and cryogenically treated (CT) brass electrodes during EDM. The results were analyzed through optical micrographs, scanning electron microscopy (SEM) analysis, energy dispersive x-ray (EDX) examination, and 3D surface plots. An artificial neural network (ANN) has been constructed for the better prediction of output responses. Moreover, multi-response optimization through the non-dominated sorting genetic algorithm (NSGA-II) has also been performed. The magnitudes of MRRCT, SRCT, and SECCT obtained by multi-response optimization are 64.82%, 27.45%, and 46.60% are better than the values obtained by un-optimized settings of CT brass electrodes. However, the optimal magnitudes of processing parameters are IP = 24.85 A, SV = 2.18 V, PON = 119.11 µs, and CP = 1.05 g/100 ml.

The Impact of Differently Prepared Mixed Plastic Waste Granules on the Structure and Properties of Concrete

The relatively low production cost and short lifespan of plastic products contribute significantly to the annual accumulation of plastic waste, raising serious environmental concerns. Conventional disposal methods like landfill and incineration not only waste valuable resources but also result in substantial secondary pollution. In response to the imperatives of sustainable development and environmental protection, in this work, different preparation methods (mechanical processing; heating and covering with milled sand and glass; covering plastic granules with polymers and then mineral materials such as microsilica and waste metakaolin; using other chemical additives) for plastic granules from waste and their influence on the properties of cementitious materials were studied. Lightweight concrete properties such as density, ultrasound pulse velocity, flexural and compressive strength, water absorption, and the interaction zone between the cement matrix and plastic granules were analyzed. It was determined that one-third by volume of natural aggregate can be replaced with specially prepared plastic granules from waste, obtaining a bending strength of the lightweight concrete of about 5 MPa, a compressive strength at 28 days of approximately 30 to 35 MPa, a density of about 1850 kg/m3, and an ultrasound pulse velocity of 3900 m/s.

Optimizing Biomimetic 3D Disordered Fibrous Network Structures for Lightweight, High-Strength Materials via Deep Reinforcement Learning.

3D disordered fibrous network structures (3D-DFNS), such as cytoskeletons, collagen matrices, and spider webs, exhibit remarkable material efficiency, lightweight properties, and mechanical adaptability. Despite their widespread in nature, the integration into engineered materials is limited by the lack of study on their complex architectures. This study addresses the challenge by investigating the structure-property relationships and stability of biomimetic 3D-DFNS using large datasets generated through procedural modeling, coarse-grained molecular dynamics simulations, and machine learning. Based on these datasets, a network deep reinforcement learning (N-DRL) framework is developed to optimize its stability, effectively balancing weight reduction with the maintenance of structural integrity. The results reveal a pronounced correlation between the total fiber length in 3D-DFNS and its mechanical properties, where longer fibers enhance stress distribution and stability. Additionally, fiber orientation is also considered as a potential factor influencing stress growth values. Furthermore, the N-DRL model demonstrates superior performance compared to traditional approaches in optimizing network stability while minimizing mass and computational cost. Structural integrity is significantly improved through the addition of triple junctions and the reduction of higher-order nodes. In summary, this study leverages machine learning to optimize biomimetic 3D-DFNS, providing novel insights into the design of lightweight, high-strength materials.

Thermally conductive polymer foams with sodium-dodecyl-benzenesulfonate-surface-modified graphene nanoplatelets and carbon nanotubes: supercritical CO2-induced foaming

Lightweight composite foams with high thermal conductivities are difficult to obtain owing to the trade-off between thermal conductivity and porosity. In this study, to improve the dispersion of graphene nanoplatelets (GNP) and multi-walled carbon nanotubes (MWNT) and the uniformity of pore size, sodium dodecyl benzenesulfonate (SDBS) can be used, which acts as a surface modification agent on GNP and MWNT and as a foam stabilizer on supercritical carbon dioxide (scCO2) foaming. The mixed morphology composite (MMC) network leads to improved thermal conductivity, which is not significantly reduced after scCO2 foaming. This may be attributed to the fact that the SDBS-assisted MMC networks of GNP and MWNT in polyamide 6 (PA6) are maintained after foaming with the homogeneous pores by scCO2 and the SDBS stabilizer. Thus, the density of the composite decreases to 1.249g/cm3 after foaming. The resulting high-heat-dissipation composites possess lightweight properties and high thermal conductivities, which are promising for application as battery pack components in next-generation automobiles.

Enhancing photovoltaic efficiency in BDTF-based donor polymer solar cells: insights from structural modifications

Polymer solar cells (PSCs) have gained attention for their flexibility, low cost, lightweight properties, and suitability for large-scale production of renewable energy. Typically, PSCs utilize bulk heterojunction (BHJ) active layers composed of blended electron donor and acceptor materials. Improving the efficiency of PSCs involves developing new donor polymers through precise monomer design and optimizing side-chain engineering to enhance properties such as solubility, molecular packing, and electron affinity. Fluorinated benzodithiophene (BDTF) and thiophene-dione-based acceptor units have demonstrated exceptional performance in non-fullerene PSCs with Y6BO as the acceptor. This study focuses on incorporating a linear alkyl chain, 5-((4,5-dioctylthiophen-2-yl)methylene)-4H-cyclopenta[c]thiophene-4,6(5H)-dione (TIND-DOT), into BDTF-based polymers to evaluate their photovoltaic properties using devices structured as ITO/ZnO/TIND-DOT-BDTF:Y6BO/MoO3/Ag giving maximum PCE of 6.55%. The research explores D-A combinations to assess their impact on optoelectronic and photovoltaic performance, highlighting the potential of modifying thiophene-dione core units as acceptors in promising donor materials for advancing PSCs.

Static/quasi-static thermomechanical analysis of 3D thin-walled beam structures based on CUF considering radiation dissipation condition

Thin-walled structures are widely applied in spacecraft as structural components due to their lightweight property. Extreme thermal environment in space may cause highly unfavorable thermal responses in thin-walled structures. Therefore, accurately predicting the thermal-coupling responses of thin-walled structures is of great engineering significance. In order to avoid the disadvantages of 3D finite element model caused by an abundance of computational degrees of freedom, the present paper proposes a thermo-mechanical coupling model based on Carrera Unified Formulation (CUF) for the static and quasi-static thermal response of space thin-walled structures. The longitudinal direction of the structures is discretized by one-dimensional linear and cubic finite elements (B2 and B4), whereas Lagrange expansion functions are used for the description of temperature fields and displacement fields within the cross-section. The governing differential equations of thermal-coupling problems are derived in a unified form according to the principle of virtual displacement and the weighted residual method. In order to demonstrate the accuracy of the numerical results, a convergence analysis is conducted on both beam elements and expansion forms. The results reveal that piece-wise quadratic beam theories approximated with B4 elements are accurate enough for the prediction of thermally-induced displacements, while the high-order cubic cross-sectional expansion is required for the description of stresses. Finally, influences of factors like angle of solar radiation, local shadows, emissivity and thermal conductivity on static and quasi-static displacement distributions are discussed. This research may pave a high-efficiency computational method for solving static/quasi-static thermally induced response of space thin-walled structures.

MECHANICAL AND MICROSTRUCTURAL BEHAVIOR OF ZE41 MAGNESIUM ALLOY REINFORCED WITH INCONEL FOR HIGH-PERFORMANCE APPLICATIONS

Abstract Magnesium alloys are known for their lightweight and desirable properties, as they hold significant potential for innovative engineering applications. The present study investigated the mechanical and microstructural characteristics of a magnesium alloy (ZE41) reinforced with Inconel ceramic particulates. The Magnesium Metal Matrix Composites (MMMC) were fabricated using the stir casting method, with varying weight percentages (wt. %) of Inconel (0, 2, 4, 6, 8, 10, 12 wt. %). The microstructural examinations of the MMMC specimens were performed using SEM, SEM+EDS analyses, and Optical Microscopy (OM), which revealed a strong interfacial bond well-defined between the Magnesium matrix and the Inconel particulates. This uniform distribution of reinforcement particulates significantly enhanced the mechanical properties of the composite materials. The tensile tests showed that the Ultimate Tensile Strength (UTS) improved progressively with up to 8% Inconel reinforcement, achieving a maximum UTS of 202.56 MPa, a 24.47% improvement compared to the base Magnesium alloy. However, the UTS decreased beyond 8% Inconel due to increased brittleness. Hardness tests indicated that the highest hardness value of 76.1 HV was achieved for the composite containing 12 wt.% Inconel, marking an 18.85% increase over the base alloy. Additionally, the wear rate decreased with increasing Inconel reinforcement, demonstrating improved wear resistance. Specifically, the wear rate dropped from 2.58 × 10-7 g/mm at 0% Inconel to 0.84 × 10-7 g/mm at 12% Inconel, showing a 67.44% reduction in wear rate compared to the pure AA6082 matrix. The findings from the present work, indicate the potential of Inconel-reinforced ZE41 composites towards achieving optimized strength and hardness levels for applications requiring high-performance materials. The present research is a contribution to the body of knowledge on the development of magnesium composites and highlights the importance of reinforcement compositions for enhancing their mechanical and microstructural characteristics.

Dynamic analysis of porous fiber‐reinforced sandwich composite panel with variable angle

AbstractDamped sandwich composite structures are increasingly used in the aerospace, automotive and energy sectors due to their high damping and lightweight properties. Here, a novel porous fiber‐reinforced sandwich composite structure is proposed, by punching holes in fiber cloth with impregnated damping solution, and resin flows through the holes during the formation of the composite structure, connecting the upper and lower prepreg layers. This paper focuses on the theoretical study of the free vibration behavior of simply supported composite porous multilayer fiber‐reinforced sandwich composite structures with arbitrary delamination angles. The vibrational differential equation including the orientation angle was established and solved using Rayleigh‐Ritz method and Navier method. Subsequently, the Abaqus finite element method and modal test analysis were used to evaluate the dynamic performance of the structure with different orientation angles, verify the proposed theoretical model and solution strategy, and perform structural optimization based on a genetic algorithm. The results show that the panel with the area ratio of the damping layer of 94.854% and a fiber orientation angle of multiples of 45° has excellent dynamic performance. This model has significant advantages in improving structural stiffness and provides a theoretical basis for practical engineering applications.Highlights A dynamic model of porous multilayer damping plate is established. The effect of different fiber orientation angle on porous plate is studied. An experimental platform is constructed to corroborate the theoretical accuracy. Structural optimization of porous plate is conducted using a genetic algorithm. The influence of structural parameters on the porous plate is analyzed.

Amplifying the Sensitivity of Electrospun Polyvinylidene Fluoride Piezoelectric Sensors Through Electrical Polarization Process for Low-Frequency Applications

Piezoelectric sensors convert mechanical stress into electrical charge via the piezoelectric effect, and when fabricated as fibers, they offer flexibility, lightweight properties, and adaptability to complex shapes for self-powered wearable sensors. Polyvinylidene fluoride (PVDF) nanofibers have garnered significant interest due to their potential applications in various fields, including sensors, actuators, and energy-harvesting devices. Achieving optimal piezoelectric properties in PVDF nanofibers requires the careful optimization of polarization. Applying a high electric field to PVDF chains can cause significant mechanical deformation due to electrostriction, leading to crack formation and fragmentation, particularly at the chain ends. Therefore, it is essential to explore methods for polarizing PVDF at the lowest possible voltage to prevent structural damage. In this study, a Design of Experiments (DoE) approach was employed to systematically optimize the polarization parameters using a definitive screening design. The main effects of the input parameters on piezoelectric properties were identified. Heat treatment and the electric field were significant factors affecting the sensor’s sensitivity and β-phase fraction. At the highest temperature of 120 °C and the maximum applied electric field of 3.5 kV/cm, the % β-phase (F(β)) exceeded 95%. However, when reducing the electric field to 1.5 kV/cm and 120 °C, the % F(β) ranged between 87.5% and 90%. The dielectric constant (ɛ′) of polarized PVDF was determined to be 30 at an electric field frequency of 1 Hz, compared to a value of 25 for non-polarized PVDF. The piezoelectric voltage coefficient (g33) for polarized PVDF was measured at 32 mV·m/N at 1 Hz, whereas non-polarized PVDF exhibited a value of 3.4 mV·m/N. The findings indicate that, in addition to a high density of β-phase dipoles, the polarization of these dipoles significantly enhances the sensitivity of the PVDF nanofiber mat.

Experimental and numerical analysis of pGFRP and wood cross-arm in latticed tower: a comprehensive study of mechanical deformation and flexural creep

The adoption of pultruded glass fibre-reinforced polymer (pGFRP) composites as a substitute for traditional wooden cross-arms in high transmission towers represents a relatively novel approach. These materials were selected for their high strength-to-weight ratio and lightweight properties. Despite various studies focusing on structures improvement, there still have a significant gap in understanding the deformation characteristics of full-scale cross-arms under actual operational loads. Existing study often concentrate on small coupon scale and laboratory condition, leaving a gap in understanding how the cross-arm behavior in full-scale acting on actual weather condition. This study aims to investigate the load-deflection and long-term creep behavior of a pGFRP cross-arm installed in a 132 kV transmission tower. The pGFRP cross-arm was load-tested on a customized rig in an open environment. Using the cantilever beam concept, deflection was analyzed and compared to wood cross-arms. Finite element analysis validated results, and long-term deformation under high-stress loads was assessed. The pGFRP cross-arms showed lower deflection at working loads compared to Balau wood, due to the latter’s higher elastic modulus and flexibility specifically at Point Y3, the critical issues necessitated reinforcement strategies. pGFRP cross-arms withstood higher bending stress, showing 32% less deflection under normal conditions and 15% less under broken wire conditions than Balau wood. Additionally, the creep strength of wood was 34% lower than that of pGFRP cross-arms. Besides that, the pGFRP cross-arm have highest elastic modulus than Balau-wood, shows that the composite cross-arm have better structural strength, resisting deformation and higher flexibility materials. Finite element analysis (FEA) confirmed these results with the relative error between them less than 1%. Consequently, the investigation into pGFRP cross-arm deformation behavior in this paper serves as a foundational framework for future research endeavors specifically for high transmission tower and other structural application.

Preparation and Application of Nature-inspired High-performance Mechanical Materials.

Natural materials are valued for their lightweight properties, high strength, impact resistance, and fracture toughness, often outperforming human-made materials. This paper reviews recent research on biomimetic composites, focusing on how composition, microstructure, and interfacial characteristics affect mechanical properties like strength, stiffness, and toughness. It explores biological structures such as mollusk shells, bones, and insect exoskeletons that inspire lightweight designs, including honeycomb structures for weight reduction and impact resistance. The paper also discusses the flexibility and durability of fibrous materials like arachnid proteins and evaluates traditional and modern fabrication techniques, including machine learning. The development of superior, multifunctional, and eco-friendly materials will benefit transportation, mechanical engineering, architecture, and biomedicine, promoting sustainable materials science. STATEMENT OF SIGNIFICANCE: Natural materials excel in strength, lightweight, impact resistance, and fracture toughness. This review focuses on biomimetic composites inspired by nature, examining how composition, microstructure, and interfacial characteristics affect mechanical properties like strength, stiffness, and toughness. It analyzes biological structures such as shells, bones, and exoskeletons, emphasizing honeycomb strength and lightness. The review also explores the flexibility and durability of fibrous materials like arachnid proteins and discusses fabrication techniques for biomaterials. It highlights impact-resistant materials that combine soft and hard components for enhanced strength and toughness, as well as lightweight, wear-resistant biomimetic materials that respond uniquely to cyclic stress. The article aims to advance sustainable materials science by exploring innovations in multifunctional and eco-friendly materials for various applications.

Highly Crystalline Contorted Coronene Homologous Molecule as Superior Organic Anode Material for Full-Cell Li-Ion Batteries.

Organic anode materials have garnered attention for use in rechargeable Li-ion batteries (LIBs) owing to their lightweight, cost-effectiveness, and tunable properties. However, challenges such as high electrolyte solubility and limited conductivity, restrict their use in full-cell LIBs. Here, we report the use of highly crystalline Cl-substituted contorted hexabenzocoronene (Cl-cHBC) as an efficient organic anode for full-cell LIBs. By employing an antisolvent crystallization method, the crystallinity of the Cl-cHBC materials has been significantly enhanced, achieving superior electrochemical performance in a half-cell configuration. Furthermore, when incorporated with the conventional lithium iron phosphate (LFP) cathode, the Cl-cHBC||LFP full-cell delivers a high discharge cell voltage of 3.0 V, surpassing the voltages of conventional lithium-titanium oxide anodes and offering improved power densities. In addition, a full cell with high-voltage lithium cobalt oxide and single-crystal high-nickel-based cathodes demonstrates enhanced electrochemical characteristics, including elevated discharge voltages, stable C-rate performance, and cycle endurance. Thus, the proposed highly crystalline Cl-cHBC anode is a promising next-generation solution for LIB applications.

Timber Bridges in Modern Japan

In Japan, timber has been used for not only traditional building but also bridge construction since olden times. At least until the 1950s, various types of bridge were in service, including trestle, truss, suspension, etc. for forest railways. However such timber bridges were replaced with concrete or steel bridges, which were thought to be, and were called, “permanent bridges” in those days. Government policy represented by the Five-Year Plan for Road Construction in 1954 facilitated the replacements, and a large percentage of timber bridges disappeared from Japan. Since the late 1980s, new types of timber bridge, so-called “modern timber bridges”, began to be constructed in Japan. The development of materials such as glulam (glue-laminated timber) with a large section, curved glulam, etc. treated with preservative made it possible to construct roadway bridges with several ten-metre spans. The longest span bridge in Japan is Karikobozu Bridge, which was completed in 2003 and has three king post truss spans (the longest span being 48 m). Construction of modern timber bridges reached its peak around 2000 and decreased significantly after that. As budget allocations for public works projects were decreasing, it became difficult to construct symbolic timber road bridges with higher costs. From the 2010s onwards, new approaches have been tried for timber bridges, utilizing the lightweight properties and easy workability of timber but avoiding high-specification road bridge requiring higher costs. Typical examples are illustrated and recent directions discussed.

Performance Enhancement of Aluminum Alloy Bipolar Plates with Polypyrrole Coatings Infused with Titanium Nitride Nanoparticles for PEMFC

Abstract Proton exchange membrane fuel cells (PEMFCs) are energy conversion devices that are both extremely efficient and ecologically beneficial. They are commonly utilized in transportation and stationary power generation. A key component in PEMFCs is the bipolar plate (BP), which provides electrical conductivity, gas distribution, and water management. 6061 aluminium alloy (AA) is often used for BPs due to its lightweight and conductive properties, but it is susceptible to corrosion. This study evaluates polypyrrole (PPy) coatings infused with titanium nitride (TiN) nanoparticles on 6061 AA. The coatings significantly enhance corrosion resistance, polarization resistance (Rp), and protection efficiency (Pi). The PPy-TiN0.05 coating showed outstanding performance, with a Rp value of 32,876.13 Ω/cm² and a Pi of 58.02%. It also achieved a maximum Impedance value (Z) of 5,021.38 Ω/cm², indicating strong resistance to corrosive ions. Electrochemical impedance spectroscopy confirms the coating's effectiveness in PEMFC settings. Further analysis using X-ray diffraction, Fourier-transform infrared spectroscopy, scanning electron microscopy, and contact angle measurements. These thorough analyses will offer a more in-depth understanding of the structural and functional properties of the PPy-TiN0.05 coatings of 6061 AA BPs, making them a highly promising option for advanced PEMFC applications.