Durability Assessment Research Articles

High Efficiency and High Durability Proton Exchange Membrane Water Electrolyzers for Hydrogen Production with Advanced Catalyst Coated Membranes

Water electrolyzers and fuel cells can be used to create a closed loop system for space exploration. Electrolyzers allow for reliable self-sustainable generation of hydrogen and oxygen for energy storage, followed by conversion into electrical energy in a fuel cell. A first-order safety concern for water electrolyzer operation is hydrogen crossover. Transport of hydrogen to the oxygen rich anode in proton exchange membrane (PEM) water electrolyzers poses safety concerns when the hydrogen concentration in the anode flow field approaches the hydrogen lower flammability limit (LFL). Hydrogen storage efficiency relies on high hydrogen pressure, leading to pressure-driven hydrogen crossover. Mitigation of hydrogen crossover through research and development of a platinum metal recombination layer has been demonstrated in high performing, durable PEMWEs.1-4 Ouimet4 explored the use of a novel dual recombination layer configuration to mitigate PEM water electrolyzer hydrogen crossover. In addition, the current state of the art for PEM fuel cells and water electrolyzers rely on perfluoro-sulfonated acid (PSFA) based membranes. There are significant challenges facing the use of PSFA-based membranes; namely, environmental contamination and performance limitations. The use of a hydrocarbon membrane allows for the development of a PSFA-free system that shows higher efficiency and durability. Investigation of hydrocarbon membranes pave way for developing a PEM water electrolyzer that will demonstrate improved gas permeability resistance, mechanical strength, and thermal stability.5-8 There is a need for both hydrogen crossover mitigation strategies and durability testing with hydrocarbon membranes.The research outlined in this work is focused on the development of PSFA-free PEM water electrolyzers with low hydrogen crossover. In this work, the dual recombination layer configuration will be incorporated into a hydrocarbon membrane for PEM water electrolysis. Polarization, electrochemical impedance spectroscopy, electrochemical equivalent circuits, distribution of relaxation times, and materials characterization will be used to investigate the cell performance and durability. References G. Mirshekari, R. Ouimet, Z. Zeng, H. Yu, S. Bliznakov, L. Bonville, A. Niedzwiecki, C. Capuano, K. Ayers, and R. Maric, “High-performance and cost-effective membrane electrode assemblies for advanced proton exchange membrane water electrolyzers: Long-term durability assessment,” international journal of hydrogen energy, vol. 46, no. 2, pp. 1526–1539, 2021.Z. Zeng, R. Ouimet, L. Bonville, A. Niedzwiecki, C. Capuano, K. Ayers, A. P. Soleymani, J. Jankovic, H. Yu, G. Mirshekari, et al., “Degradation mechanisms in advanced meas for pem water electrolyzers fabricated by reactive spray deposition technology,” Journal of The Electrochemical Society, vol. 169, no. 5, p. 054536, 2022.A. Martin, D. Abbas, P. Trinke, T. Böhm, M. Bierling, B. Bensmann, S. Thiele, and R. Hanke-Rauschenbach, “Communication—proving the importance of ptinterlayer position in pemwe membranes for the effective reduction of the anodic hydrogen content,” Journal of The Electrochemical Society, vol. 168, no. 9, p. 094509, 2021.R. J. Ouimet, “Catalyst development by a novel fabrication process for energy applications,” University of Connecticut Doctoral Dissertation, 2021.P. Trinke, P. Haug, J. Brauns, B. Bensmann, R. Hanke-Rauschenbach, and T. Turek, “Hydrogen crossover in pem and alkaline water electrolysis: mechanisms, direct comparison and mitigation strategies,” Journal of The Electrochemical Society, vol. 165, no. 7, p. F502, 2018.P. Trinke, B. Bensmann, and R. Hanke-Rauschenbach, “Current density effect on hydrogen permeation in pem water electrolyzers,” International Journal of Hydrogen Energy, vol. 42, no. 21, pp. 14355–14366, 2017.H. Q. Nguyen and B. Shabani, “Proton exchange membrane fuel cells heat recovery opportunities for combined heating/cooling and power applications,” Energy Conversion and Management, vol. 204, p. 112328, 2020.C. Klose, T. Saatkamp, A. Münchinger, L. Bohn, G. Titvinidze, M. Breitwieser, K. D. Kreuer, and S. Vierrath, “All-hydrocarbon mea for pem water electrolysis combining low hydrogen crossover and high efficiency,” Advanced Energy Materials, vol. 10, no. 14, p. 1903995, 2020.

Durability Assessment of Roll-to-Roll Coated PEM Water Electrolysis Anodes

Widespread adoption of green hydrogen relies on the high-throughput production of key electrolyzer components in a manner yielding acceptable stack manufacturing costs. Roll-to-roll liquid coating methods, such as slot die and gravure coating, are particularly relevant means to produce key components (e.g., membranes and electrodes) at high throughput. In the case of proton exchange membrane water electrolysis (PEMWE), thrifting of expensive iridium-based catalysts poses additional challenges to the implementation of such high-throughput coating methods for iridium-based anode manufacture.Herein, we investigate key challenges around roll-to-roll manufacture of low-loaded (<0.2 mgIr/cm2) iridium-based electrodes for PEMWE. In particular, we highlight fundamental limitations in coating the thin layers required to manufacture low-loaded electrodes, for which the improper choice of coating conditions may lead to macro- and micro-scale heterogeneity. By addressing causes of this heterogeneity, homogeneous slot-die coated iridium oxide anodes of varying iridium loading are produced on decal substrates. Catalyst coated membranes (CCMs) are subsequently produced from these anodes via hot-pressed decal transfer, and 1,000 hour constant current tests are conducted with intermediate diagnostics (polarization curves and impedance spectroscopy). Key effects of loading and homogeneity on electrode durability are highlighted, and future directions are discussed.This work was authored by the National Renewable Energy Laboratory, operated by Alliance for Sustainable Energy, LLC, for the U.S. Department of Energy (DOE) under Contract No. DE-AC36-08GO28308. Funding provided by the U.S. Department of Energy, Office of Energy Efficiency and Renewable Energy, Hydrogen and Fuel Cell Technologies Office and Advanced Manufacturing Office. The views expressed in the article do not necessarily represent the views of the DOE or the U.S. Government. The U.S. Government retains and the publisher, by accepting the article for publication, acknowledges that the U.S. Government retains a nonexclusive, paid-up, irrevocable, worldwide license to publish or reproduce the published form of this work, or allow others to do so, for U.S. Government purposes.

NOx Abatement by a TiO2-Based Coating under Real-Life Conditions and Laboratory-Scale Durability Assessment

In urban environments, various pollutants generated by road traffic, human, and industrial activities degrade outdoor and indoor air quality. Among these pollutants, nitrogen oxides (NOx) are subject to air quality regulations designed to protect human health and the environment. It is therefore crucial to keep their concentration as low as possible. Advanced oxidation processes are a practical choice for the degradation of NOx; among them, heterogeneous photocatalysis has proven to be a viable route. However, while the efficiency of this process has been widely demonstrated on a laboratory scale, it is still the subject of debate for real-life applications. The purpose of this study was to present a new field experiment on the application of a photocatalytic coating to outdoor walls. Air quality monitoring stations were used to evaluate the NOx concentration reduction instead of the chemiluminescent analyzer, in order to increase the number of sampling points. Statistical analysis was carried out to interpret the results. Density probability functions were plotted and showed a positive impact of the coating, leading to lower NOx concentrations. This work was completed by a laboratory-scale assessment of the coating’s durability using abrasion, QUV, and immersion/drying tests. The air depollution capacity of the chosen coating was significantly reduced after QUV testing.

Thickness Characterization of Steel Plate Coating Materials with Terahertz Time-Domain Reflection Spectroscopy Based on BP Neural Network.

Accurate monitoring of steel plate coating thickness is crucial in construction quality control and durability assessments. To address this challenge, this study introduces a terahertz time-domain reflection spectroscopy based on a BP neural network model to achieve a quantitative visualization characterization of coating thickness. The BP neural network eliminates the inherent dependence of terahertz reflection spectroscopy on the refractive index value in thickness calculation. This trained BP neural network model effectively establishes a functional relationship between signal feature parameters and the corresponding thickness values. Additionally, the proposed model can innovatively measure different coating materials' refractive indexes, revealing the corresponding values for the black paint, white paint, epoxy resin, and rubber as 2.212, 1.967, 1.924, and 2.185, respectively. The experimental results demonstrate the trained BP neural network model possesses remarkable accuracy in predicting coating thickness within the scanning area, achieving a precision level exceeding 96%. This method enables the visualization of coating thickness and the extraction of thickness characterization values. Furthermore, using the thickness imaging results as a reference, the method can accurately identify the thickness abnormalities across the scanning area, locating the position and size of potential defects such as internal scratches and foreign object defects. This innovative approach offers a superior means of monitoring and assessing the thickness distribution quality of the steel plate coating layer materials.

Actual Problems of Creating Digital Twins of Machine Engineering Products in Terms of Durability Assessment

Actual Problems of Creating Digital Twins of Machine Engineering Products in Terms of Durability Assessment

Effect of Graphene Quantum Dots (GQDs) on the mechanical, dynamic, and durability properties of concrete

Addressing ecological concerns stemming from concrete usage is paramount, prompting exploration into additives for mitigation. Graphene quantum dots (GQDs) have been recognized for their potential to improve the mechanical attributes of cement composites. Additionally, the electrochemical reduction of a saturated solution of carbon dioxide (CO2) and monoethanolamine (CO2-MEA) effectively removes CO2 from the atmosphere. This study delves into the influence of GQDs on the mechanical and durability aspects of concrete. It is noted that the control mix of concrete without GQDs was specifically designed for concrete railway sleepers. Varied proportions of GQDs, ranging from 0.3 % to 1.2 % at 0.3 % increments, were incorporated to assess their impact on fresh and hardened concrete properties. Mechanical properties such as compressive strength, splitting tensile strength, flexural strength, and dynamic properties were evaluated. Durability assessments encompassing water absorption and chloride ion penetration were conducted. Microstructural analysis via Field Emission Scanning Electron Microscopy (FESEM) imaging and Energy-dispersive X-ray spectroscopy (EDS) elucidated the concrete's internal composition. Notably, an optimal GQDs percentage of 0.3 % was observed, signifying its efficacy in enhancing the performance of concrete. When 0.3 % of GQDs was added to concrete, compressive strength, split tensile strength, and flexural strength were enhanced by 10.8 %, 23 %, and 11 % respectively. The incorporation of GQDs resulted in a notable improvement in the fundamental frequencies and dynamic modulus of elasticity. Concurrently, a decrease in the damping ratio was observed for specimens containing GQDs. Additionally, the porosity and chloride penetration depth were lower by 6 % and 30 % for specimens with 0.3 % GQDs. The improvement in workability, mechanical, and dynamic properties of concrete, along with reducing CO2 from the atmosphere, makes GQDs an ideal eco-friendly material. This study is the first to open new pathways for the development of construction materials that are not only structurally superior but also environmentally responsible, marking a significant step forward in the field of civil engineering materials, especially in railway applications.

Durability evolution of RC bridges under the coupled action of fatigue effect and chloride attack

The main factors affecting the durability of a reinforced concrete bridge are the fatigue effect brought on by continuous traffic loads and chloride ion erosion, but studies on how these two factors interact have been scarce. As a result, concrete structure durability analyses need to be more thorough and accurate. The fatigue model from continuum damage mechanics is used to determine the equivalent stress range of traffic loads, and poroelasticity is used to establish the link between volumetric strain and porosity. Following a change in the porosity's function, the chlorine ion diffusion coefficient is covered. Finally, a proposed coupling analysis method that takes many physics into account is presented. This method takes into account fatigue stress, body strain, porosity, chlorine ion diffusion coefficient, and corrosion rate. The multiphysics finite element program and the associated theoretical equations can be used to simulate the chloride ion diffusion, erosion states, corrosion rate, and bearing capacity of the main sections in various stages. As a result, the reinforced concrete bridge's evolutionary durability can be fully attained. Fatigue loading can accelerate corrosion of reinforcement and chloride ion diffusion, which accelerates the loss of a bridge's flexural strength. The method described in this paper can calculate the flexural load capacity, erosion state, time-varying rust rate, and chloride ion diffusion effect of the main bridge sections at various times, which can show the detailed evolution of reinforced concrete bridge durability and offer useful theoretical and technical support for decisions about bridge durability assessment and maintenance

Impact of fuel starvation–induced anode carbon corrosion in proton exchange membrane fuel cells on the structure of the membrane electrode assembly and exhaust gas emissions: A quantitative case study

Although the durability of proton exchange membrane fuel cells (PEMFCs) is crucial for their broad commercial applications, current durability assessments do not encompass all operational scenarios. Startup/shut-down (SUSD) are among the most significant degradation factors in the city. To bridge this gap, we examine the phenomenon of fuel starvation, which leads to the rapid and irreversible degradation of PEMFC performance, particularly during SUSD, but has not been independently examined in the context of PEMFC durability. A quantitative methodology is used to analyze anode carbon corrosion and establish correlations with critical parameters under fuel starvation conditions. In particular, we quantify carbon loss based on (i) the composition or amount of the anode outlet gas emitted under such conditions and (ii) changes in the anode thickness at three distinct locations. The corresponding carbon losses due to 10 min of fuel starvation ((i): 212.0 μg cm−2, (ii): 189.6 ± 12.9 μg cm−2) agree well with each other. The largest decrease in the anode thickness (81.3 %) is observed near the outlet. The obtained insights provide guidance for the design of high-performance PEMFCs and the development of protective measures against the detrimental effects of fuel starvation.

Reliability modeling to predict in‐service weatherability of polyurethane nanocomposite coatings: Approach, comparison and validation

AbstractThis article addresses the challenge of comparing in‐service weatherability among newly developed coatings. The study aims to compare the durability of three thermoplastic polyurethane‐based coatings specifically formulated for defense inflatables. It introduces a reliability model that incorporates two weathering stresses, namely, ultra‐violet radiation and temperature, to predict the service life of the coatings. A life–stress relationship has been established from the accelerated aging tests, which facilitates the determination of material service life at use level conditions. Notably, the analysis underscores the significant improvement in service lifetime achieved with nanocomposite‐based coatings. The validity of the proposed model is established through comparison with real‐world field test data, emphasizing the effectiveness of the approach in assessing and comparing the performance of the three coated samples. The insights gained from this research will surely contribute to enhancing the durability assessment of coated systems in real‐world conditions for various fields of applications.Highlights Introduces a unique method to compare weatherability of three polyurethane coatings. Reliability model predicts service life under UV and temperature stresses. Life–stress relationship via accelerated aging for accurate service life. Nanocomposite coatings show longer service life than conventional ones. Model validated with field data, confirming practical applicability.

Probabilistic characterization for durability assessment under various road strain loads

Probabilistic characterization for durability assessment under various road strain loads

Durability Assessment of Expansive and Nonexpansive Calcium Sulfoaluminate Belite Cement Concrete in Chloride-Rich Environments

Durability Assessment of Expansive and Nonexpansive Calcium Sulfoaluminate Belite Cement Concrete in Chloride-Rich Environments

Wool fiber as an In situ reducing agent towards ZnO-based surface modified fabric development: Durability assessment in the realm of textile applications

The development of a bio-inspired method to fabricate ZnO nanostructure-modified functional wool fabric represents a substantial challenge in the textile field. This article reports for the first time the use of wool as a reducing agent for the synthesis of ZnO nanoparticles. While previous studies have employed alternative natural reducing agents for surface modification of host materials, this investigation uniquely utilizes the host material, wool, as the reducing agent for in-situ ZnO nanoparticle synthesis. In addition to demonstrating the use of wool as a reducing agent, this literature uniquely reports the durability of the modified fabric, achieved through the use of trimethoxy methyl silane. This silane compound acts as a bridging agent, forming a strong interface between the wool fibers and the synthesized ZnO nanoparticles. This innovative approach enhances the adhesion and stability of the ZnO nanoparticles on the wool fabric, a key aspect that contributes to the overall durability and performance of the modified material. The in situ surface modification process employed a metal oxide precursor (zinc acetate dihydrate), capping agents (hexamethylene tetraamine, sodium carbonate, and sodium sulfate), and a coupling agent (trimethyl methoxy silane). The capping agents were used to control the reaction conditions, while the coupling agent was employed to improve the durability of the surface modification. The impact of three different capping agents on the corresponding synthesis process was assessed, and the findings revealed that the choice of capping agent helped to form ZnO nanoparticles with distinct morphologies. Analytical techniques, such as X-ray diffraction (XRD), scanning electron microscopy (SEM), dynamic light scattering (DLS), and attenuated total reflectance-Fourier transform infrared (ATR-FTIR) spectroscopy, were utilized to characterize the synthesized particles and the treated fabric. The XRD analysis coupled with SEM analysis confirmed the successful formation of ZnO nanoparticles. The ATR-FTIR spectroscopy provided evidence of the formation of Si-O-Zn and Si-O-C bonds, observed at around 920 cm−1 and 1040 cm−1 respectively. These spectroscopic findings indicate that the surface modification involving the silane compound has enhanced the durability of the ZnO-modified fabric. The covalent linkages between the ZnO nanoparticles, the silane compound, and the wool fibers, confirmed by SEM analysis before and after washing cycles, have enabled the durable attachment of the nanoparticles to the fabric surface, even after multiple washing cycles. The results suggest a novel pathway to use wool as a reducing agent for the surface modification of the same material. Detailed mechanistic insights into the surface modification process and the corresponding chemical interactions were also discussed.

Evolution of the microporous structure in cement hydration: A deep learning-based image translation method

Investigating the evolution of the microporous structure is essential for gaining insights into the hydration process of the cementitious materials. However, conventional methods for describing cement hydration rely on complex formulas and idealized assumptions, limiting their accuracy and efficiency in representing hydration kinetics. Here, we present a novel deep learning-based image translation method for modelling the in-situ evolution of the microporous structure during cement hydration. The translated images are of high spatial resolution, which can identify the pores smaller than around 100 nm. The performance of our model was evaluated by comparing various characteristics of the translated microporous structures with the experimental data, including porosity, pore size distribution, pore shape and spatial properties. The results of this comparison indicate our approach exhibits an excellent performance in accurately modelling the evolution of the microporous structures. Furthermore, due to the data-driven nature, our model presented a high efficiency, which is capable of completing the image translation within a few minutes. The findings in this study offer a novel approach to trace or predict the structural development of cement during its hydration, which is crucial for material design, durability assessment, and performance prediction of cementitious composites.

Enhancing GFRP fatigue durability for chassis component applications through glass fiber coupling variation

As the landscape of mobility trends continues to evolve, concerted efforts have been made to incorporate Carbon Fiber Reinforced Plastic (CFRP) into automotive components. However, the substantial increase in cost relative to the achieved weight reduction has limited its widespread adoption. Consequently, research endeavors have focused on exploring alternative composite materials, adapting fibers such as glass fibers, natural fibers, and recycled fibers, to reduce the cost of composite components. Of particular interest in the automotive industry is the utilization of Glass Fiber Reinforced Plastic (GFRP) in chassis components like leaf springs. Nevertheless, the development of GFRP leaf springs encounters a significant challenge related to the adhesive strength at the interface between epoxy resin and glass fibers, which is crucial for enhancing fatigue durability. While glass fibers were traditionally paired with unsaturated polyester or vinyl ester matrices, the pursuit of improved durability has led to the adoption of epoxy matrices. Regrettably, this transition has not consistently yielded the expected gains in interfacial adhesion.In light of these challenges, this study systematically compares the interfacial adhesion strength and fatigue endurance performance. For comparison, two coupling agents widely used commercially, amino silane and epoxy silane, were selected. Glass fibers treated with each coupling agent were purchased commercially, and glass fiber-reinforced plastic (GFRP) specimens were fabricated using the HP-RTM (High-Pressure Resin Transfer Molding) method. Static property evaluations and fatigue durability assessments were conducted using the fabricated specimens. The results showed that when epoxy silane was used as the coupling agent, the interlaminar shear strength (ILSS) increased by approximately 7 %. Furthermore, SEM(Scanning Electron Microscopes) analysis confirmed a significant enhancement in interfacial adhesion, providing support for the ILSS evaluation results. Consequently, the fatigue durability performance improved by approximately six-fold. This confirms that the improvement in interfacial adhesion due to the change in coupling agents led to enhanced fatigue durability performance.

Durability and microstructural characteristics of self-compacting concrete incorporating M-sand

ABSTRACT Self-Compacting Concrete (SCC) is characterized by increased fluidity and enhanced cohesion, leading to its growing prominence within the construction sector. Additive materials such as alccofine and silica fume can enhance the properties of SCC while concurrently mitigating the ecological footprint linked to cement manufacturing. Manufactured sand, also known as M-sand, is finely crushed aggregate sourced from rocks or quarry stones, providing a sustainable substitute for natural river sand in construction. The primary emphasis of this study revolves around evaluating the enduring compressive strength and durability attributes of SCC, wherein M-sand is employed to replace river sand to varying percentages of 0%, 25%, 50%, 75%, and 100%. Durability assessments encompass evaluations at 28, 56, 90, 180, and 365 days for water absorption, Rapid Chloride Penetration Test (RCPT), sorptivity, and Volume of Permeable Voids (VPV), all compared against the benchmarks of control concrete. Microstructural characterization studies entail the utilization of techniques such as Scanning Electron Microscope imagery (SEM), X-ray Diffraction (XRD), and Fourier Transform Infrared Spectroscopy (FTIR). From the results it is observed that M-sand replacement in SCC enhanced durability of the concrete.

Investigating the standard design and production procedure of heritage mortars for compatible and durable masonry restoration

Historic buildings ensure generational knowledge of past events, milestones, construction developments and evolution of materials, architectural designs, and practices throughout the centuries. It is indisputable that heritage buildings' survival against deterioration factors has proven the use of durable materials for their construction. However, they suffer inevitable decay due to ageing. Therefore, restoring the monuments to their original appearance and strength is always necessary for long-term survival. This paper discusses solutions for the design and development methods of new compatible restoration mortars for the architectural heritage, covering four significant aspects, namely: i) visual analysis of the heritage building in question, ii) experimental analysis of the original mortar samples for their physical, mineralogical and chemical properties, iii) characterization of the potential raw materials (available in the study area) that are close to the original, and iv) assessment of the new mortar durability. The mortars collected from the Castle of Good Hope, an important and ancient colonial edifice in the Western Cape Province (South Africa), were earth (samples SK7 to SK9) and hydraulic lime-based (SK1 to SK6), with 21–38 % porosity. The raw materials used on this monument include feldspar aggregates, possibly from the West Coast (Cape Town) and hydraulic lime for SK1, SK3 and SK5 mortars. For the restoration of the lime mortars (SK1, SK3 and, SK5), a hydrated lime-based mortar with a binder-to-aggregate ratio of 1:3, made of west coast sea sand and 5 % seashell additives, with a porosity of 24 %, has proved to be the most durable. The aesthetics for all the restoration mortars M1 to M9 is difficult to achieve considering the original material ageing factor, thus, the use of color-enhancing pigments is recommended.

Visible characteristics and durability assessment of methyl methacrylate-based luminescent road marking using unencapsulated SrAl2O4: Eu2+, Dy3+ under coupling service conditions

Luminescent road markings (LRMs) have attracted growing attention due to the enhanced road visibility in low-light conditions and energy-saving benefits. However, high-performance strontium aluminate phosphors (SrAl2O4: Eu2+, Dy3+) are prone to hydrolyze while the conventional encapsulation methods of phosphors produces luminance loss. This paper presented a novel perspective using methyl methacrylate (MMA)-based two-component resins with unencapsulated phosphor (UP) to prepare LRMs with balanced luminescent properties road durability. Luminescent properties, skid resistance, impact resistance, and abrasion rate were evaluated as the response value to optimize the formulations through design of experimental (DOE) methods. The results show that LRMs exhibit outstanding water resistance and abrasion resistance after soaking for 120 hours coupling with wet-wheel abrasion for 20 minutes due to effective bonding between the carboxylic acid-based resin and phosphors. The luminance loss is less than 5 % after undergoing three-wheel abrasion following 480 hours of ultraviolet aging. Furthermore, the macroscopic performance was integrated with microscopic properties through morphological, elemental, and functional group analysis. The results demonstrated that the addition of plasticizer balanced the relationship among the mechanical properties by transforming the curing structure of the coating from resin-encapsulated granular protrusions into layer-like structures.

Comprehensive study of hydrogen-crossover reducing agents for polymer electrolyte membranes

We explored the efficacy of gas-barrier additives (GBAs) in reducing gas crossover within perfluorosulfonic acid (PFSA) membranes. Nine distinct GBAs were incorporated into Nafion solutions, forming composite membranes for subsequent assessment. Comparative analyses revealed no significant differences in the water sorption and mechanical properties between the GBA composite membranes and pristine Nafion membranes. However, most GBA-incorporated membranes exhibited a notable reduction in hydrogen permeability, indicating an effective decrease in gas crossover. Further validation within a membrane electrode assembly confirmed that GBAs affect the key performance metrics, including hydrogen crossover, overall fuel-cell performance, high-frequency resistance, and electrochemically active surface areas. Long-term durability assessments highlighted TiO2 as an effective additive that significantly extends the Nafion membrane's lifespan. Overall, GBA incorporation promises to mitigate gas crossover while improving the performance and durability of PFSA membranes.

Durability Assessment of Eco-Friendly Bricks Containing Lime Kiln Dust and Tire Rubber Waste Using Mercury Intrusion Porosimetry

The global challenge faced due to the impact of the construction industry on climate change, along with the issues surrounding sustainable waste disposal, has necessitated various research on using waste products as eco-friendly alternatives in construction. In this study, the avoidance of waste disposal through landfills in Australia was encouraged by incorporating lime kiln dust (LKD) and tire rubber waste (TRW) into masonry mixes to manufacture green bricks. Furthermore, the investigations in this article highlight the use of mercury intrusion porosimetry (MIP) to determine the durability of the LKD-TRW bricks when exposed to freeze–thaw (F-T) cycles by examining the pore size distribution within the bricks. The LKD waste was blended with ground granulated blast furnace slag (GGBFS) at a 70:30 blending ratio and combined with the TRW in stepped increments of 5% from 0 to 20% to produce these eco-friendly bricks. The compressive strength (CS), flexural strength (FS), frost resistance (FR), pore size distribution according to mercury intrusion porosimetry (MIP), and the water absorption (WA) properties of the bricks were assessed. The CS and FS values at 28 days of curing were recorded as 6.17, 5.25, and 3.09 MPa and 2.52, 2, and 1.55 MPa for 0, 5, and 10% TRW contents, respectively. Durability assessments using the F-T test showed that the bricks produced with 0% TRW passed as frost-resistant bricks. Furthermore, the results from the MIP test showed a total pore volume of 0.033 mL/g at 3 µm pore size for the 0% TRW content, further confirming its durability. Hence, the 0% LKD-TRW bricks can be utilized in cold regions where temperatures can be as low as −43 °C without deteriorating. Lastly, WA values of 7.25, 11.76, and 14.96% were recorded for the bricks with 0, 5, and 10% TRW, respectively, after the 28-day curing period. From all of the results obtained from the laboratory investigations, the LKD-TRW bricks produced with up to 10% TRW were within the satisfactory engineering requirements for masonry units.

Advancing auxetic materials: Emerging development and innovative applications

Abstract The development of auxetic materials, known for their unique negative Poisson’s ratio, is transforming various industries by introducing new mechanical properties and functionalities. These materials offer groundbreaking applications and improved performance in engineering and other areas. Initially found in natural materials, auxetic behaviors have been developed in synthetic materials. Auxetic materials boast improved mechanical properties, including synclastic behavior, variable permeability, indentation resistance, enhanced fracture toughness, superior energy absorption, and fatigue properties. This article provides a thorough review of auxetic materials, including classification and applications. It emphasizes the importance of cellular structure topology in enhancing mechanical performance and explores various auxetic configurations, including re-entrant honeycombs, chiral models, and rotating polygonal units in both two-dimensional and three-dimensional forms. The unique deformation mechanisms of these materials enable innovative applications in energy absorption, medicine, protective gear, textiles, sensors, actuating devices, and more. It also addresses challenges in research, such as practical implementation and durability assessment of auxetic structures, while showcasing their considerable promise for significant advancements in different engineering disciplines.