Effect of Load on Tribological Characteristics of H-AlSi24Cu3.8Mg0.8 Alloy Under Dry, Lubricated, and Coated (a–c: H) Sliding ConditionsRead the full article
Advances in Materials Science and Engineering publishes research in all areas of materials science and engineering, including the synthesis and properties of materials, and their applications in engineering applications.
Chief Editor, Amit Bandyopadhyay, is based at Washington State University and is interested in the fields of additive manufacturing or 3D printing of advanced materials. His current research is focused on metal additive manufacturing, biomedical devices and multi‑materials structures.
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Combined Performance of Polyethylene Terephthalate Waste Plastic Polymer and Crumb Rubber in Modifying Properties of Hot Mix Asphalt
Nowadays, the use of recycled waste materials in road pavement is regarded not only as a positive option in terms of sustainability but also as an appealing option in terms of providing improved service performance. The current study aimed at evaluating the performance of crumb rubber and polyethylene terephthalate plastic polymer in asphalt mixture in modifying the mechanical properties of asphalt pavement. Experimental tests were carried out both for asphalt binder and asphalt mixture. Different proportions of mix for crumb rubber and polyethylene terephthalate plastic polymer were used to systematically investigate the effect of mix ratio on performance of the asphalt material. The experimental analysis reveals that the combined application of 10% by weight of crumb rubber chips and 2% polyethylene terephthalate plastic polymer are the ideal mix ratios found effective in modifying properties of the asphalt mixture. The asphalt binder test results indicate that adding 10% crumb rubber to asphalt binder reduced penetration by 1.56% along with increment of the softening point by 4.33%. Furthermore, the indicated optimum mix amount resulted in 0.17% rise, 20.07% drop, and 20.71% increase in Marshal stability, flow, and stiffness, respectively. Besides, tensile strength of the asphalt mixture was enhanced with addition of the filler and binder materials. It was witnessed that the combined application of the additives performs better than their separate use in modifying properties of the asphalt mix.
MoWS2 Nanosheet Composite with MXene as Lithium-Sulfur Battery Cathode Material
Due to their superior theoretical specific capacity and energy density, lithium-sulfur (L‒S) batteries are gaining popularity in order to achieve the growing terms for more power generation. However, drawbacks such as low electrical conductivity of the active ingredient sulfur, severe volume expansion and shuttle effect of polysulfides, rapidly decaying battery capacity, and short battery life have hampered their development. A MoWS2@MXene@CNT composite material is used as the main cathode material for L-S batteries in this study. MoWS2 can improve the electrochemical reaction rate by accelerating polysulfide conversion, whereas MXene can suppress electrode volume expansion. Furthermore, the addition of carbon nanotubes (CNT) with high electrical conductivity improves the rate of the electrochemical reaction. Therefore, the MoWS2@MXene@CNT composites have good capacity and versatility as cathode materials and enhance the behavior of L-S batteries.
Evaluating the Influence of Carbon Fiber on the Mechanical Characteristics and Electrical Conductivity of Roller-Compacted Concrete Containing Waste Ceramic Aggregates Exposed to Freeze-Thaw Cycling
Traditional methods of removing snow and ice from pavements using chemicals are combined with mechanical removal that involves a lot of manpower, advanced machinery, chemicals that are harmful to the environment, and damage to pavements. Furthermore, annually, large quantities of ceramic materials become waste due to their fragile nature during processing, transport, and installation, and their accumulation in the nature has brought about environmental and health-related concerns. Therefore, the study aims to investigate the effect of using waste ceramic as a replacement for fine aggregate in roller compacted concrete (RCC) and the application of carbon fiber to improve the mechanical properties and electrical conductivity of RCC. To achieve this goal, several tests such as compressive strength, indirect tensile strength, electrical resistance, chloride ion penetration, specific gravity, and skid resistance tests were carried out on the fabricated samples before and after freeze-thaw cycling exposure. The experimental results illustrated that replacing waste ceramics with fine-grained aggregate increased the compressive strength and tensile strength of RCC. Furthermore, carbon fiber increased tensile strength but had no noticeable influence on compressive strength. Freeze-thaw conditioning led to a reduction in the compressive and tensile strength regardless of the aggregate type and carbon fiber utilization. In the samples containing waste ceramic aggregate, the electrical conductivity was reduced, and by adding carbon fiber, its electrical conductivity was increased. Exposure to freeze-thaw cycling resulted in an increase in electrical resistance and the passing charge. Waste ceramic incorporation created a similar mixture in terms of skid resistance, while in contrast, the carbon fiber slightly reduced the skid resistance. In addition, freeze-thaw conditioning resulted in an increase in the skid resistance. Besides, in this study, kernelized support vector regression (KSVR) and radial bias function (RBF) neural network models were proposed to estimate the indirect tensile strength (ITS) and compressive strength (CS) values. The results showed that both models have high performance in estimating these values, but RBF was a more efficient model.
Effect of Exfoliation Corrosion on the Mechanical Properties of Friction Stir Spot Welded 2024-T3 AA Joints
This study aims to detect the impact of preexfoliation corrosion on the efficiency of 2 mm thick 2024-T3 aluminum alloy friction stir spot welded (FSSW) joints. Five specimens of FSSW joints, welded with 620 r·min−1 rotational speed and a dwell time of 10 seconds, were immersed in an exfoliation corrosion solution for five different times: 10 h, 20 h, 30 h, 40 h, and 50 h. The tensile shear load for the noncorroded joint was 3.5 kN. The results showed that the degradation of mechanical properties increased with increasing exposure time, and the joint efficiency drop reached 62% for specimens exposed for 50 h to the corroded solution. As welded FSSW 2024-T3 AA joints exhibited a nugget debonding failure mode and a mixed-mode tensile-shear fracture, in the corroded specimens, only a shear fracture could be seen. The results were attributed to a reduction in the bonding area between the upper and lower sheets due to corrosion.
Investigation of Magnesium and Chromium Fillers FSW Dissimilar Joint of AA6063 and AA 5154
Friction stir welding (FSW) is a solid-state metal joining process. There is no melting and recasting of metal while welding is used. Some of the defects commonly encountered in FSW are tunnel defect, bond, cracks, pin holes, and pipping defects. The defects occur because of improper metal mixing and less heat input in the weld nugget zone. In the fusion welding process, a filler rod is employed to form a quality weld with superior mechanical properties. In this work magnesium and chromium powders are used as filler materials. The purpose of this study is to ascertain whether filler materials and manufacturing processes have an impact on the weld nugget zone spot weld joint formation as well as the mechanical and abrasive properties of welded joints. This study's FSW filler materials mixing ratio and process parameters were improved by using the Central Composite Design (CCD) idea, which is discussed in more detail below Response Surface Methodology (RSM). The best empirical relationship between the parameters was provided by the CCD. The mathematical relationships were established to forecast the maximum tensile strength, maximum weld nugget hardness, and minimum corrosion rate by incorporating filler materials with process parameters. The optimal processing factors combination is predicted by conducting the validation test. The optimum parameters were the tool rotatory speed 600–1000 revolution per minute, welding speed 60 to 180 mm/min, plunge depth of 0.05 to 0.25 mm, center distance between the sample is 0–4 mm, as well as powder mixing ratio of 90 : 10, 92.5 : 7.5, 95 : 5, 97.5 : 2.5, and 100 : 0, the tensile test, microhardness, and corrosion rate analysis were conducted on the weld specimen. The welded test specimen provides better joint strength, weld nugget hardness, and enhanced corrosion resistance properties. The microstructure analysis shows the fine grain structure and homogeneous distribution of filler material with the base metal in the welded area.
Tribological Characterization of Epoxy Hybrid Composites Reinforced with Al2O3 Nanofiller
The addition of fillers to polymer composites induces a positive influence on the mechanical and tribological properties of the hybrid composites. These properties can be validated for possible uses such as automobile, construction, shipping, aerospace, sports equipment, electronics, and biomedical domains. In the present research, epoxy matrix reinforced with nylon-6 fibers and glass fibers were prepared using the solution blend technique. Alumina nanoparticles are added as fillers to enhance the properties of epoxy hybrid composites. The large surface area of interaction of nanofillers exhibits better adhesion between matrix and fibers of composites, and it significantly affects the various properties of composites. The tribological characteristics of fabricated epoxy hybrid composites were evaluated under various parameters and conditions. The results revealed that the addition of nanofiller significantly reduces the wear loss of epoxy hybrid nanocomposites. The wear resistance of epoxy hybrid composites increased with increase in addition of nanofiller up to 1.0%, and it slightly decreased with the further addition of filler. The Taguchi analysis was carried out for the least coefficient of friction and specific wear rate. The analysis found that the specific wear rate and coefficient of friction mainly depend on load, followed by speed and nanofiller. The fractured and worn surface of Al2O3-filled epoxy hybrid composites was analysed using SEM.