Hasil untuk "Mechanical industries"

L. Parry, I. Ashcroft, R. Wildman

M. Shafieifar, Mahsa Farzad, A. Azizinamini

A. Behnood

Abstract The use of recycled materials such as Reclaimed Asphalt Pavement (RAP) and Recycled Asphalt Shingle (RAS) in asphalt pavements is a valuable approach to construct sustainable pavements and to preserve natural resources and energy. However, the use of high amounts of RAP and RAS can potentially cause durability-related distresses such as cracking and raveling due to the presence of severely aged asphalt binders. Rejuvenators have been widely used to overcome this issue and to mitigate the problems associated with the use of aged binders. They can improve the viscoelastic and rheological properties of asphalt mixtures containing RAP and RAS. Much has been learned about various types of rejuvenating agents, techniques to apply these agents, and challenges associated with their applications. This article reviews the literature on the applications of various types of rejuvenators in paving industry and their effects on the properties of the aged binders. The techniques for rejuvenating the aged asphalt binders and the mechanism of rejuvenation are also reviewed. Moreover, methods to determine the optimum rejuvenator content to achieve optimized mechanical and durability properties of the asphalt binders and mixtures are discussed. The findings in this research show that rejuvenators can be successfully used to restore the properties of the aged binders. It is hoped that this review will serve as a guidelines for pavement engineers to better design the asphalt mixtures containing rejuvenators. This review will also help scientists to find future avenues of research on the applications of rejuvenators in asphalt industry.

Yijiao Xue, Jiabing Feng, S. Huo et al.

Abstract The creation of thermostable, flame-retardant, mechanically robust bioplastics is highly desirable in the industry as one sustainable alternative to traditional petroleum-based plastics. Unfortunately, to date there lacks an effective strategy to endow commercial bioplastics, such as polylactide (PLA) with such desired integrated performances. Herein, we have demonstrated the fabrication of a novel MXene-phenyl phosphonic diaminohexane (MXene-PPDA) nanohybrid via the intercalation of PPDA into the MXene interlayer. The interlayer spacing of MXene nanosheets is enlarged and as-prepared MXene-PPDA is homogeneously dispersed in the PLA matrix. Incorporating 1.0 wt% MXene-PPDA enables PLA to achieve a UL-94 V-0 rating, with a ~22.2% reduction in peak heat release rate, indicating a significantly improved flame retardancy. Meanwhile, the 1.0 wt% MXene-PPDA also increases the initial decomposition temperature of PLA composite, giving rise to a ~25-fold enhancement in char yield relative to pure PLA. Additionally, the MXene-PPDA enhances the toughness while retains the mechanical strength for PLA. This work offers an innovative strategy for the design of multifunctional additives and the creation of high-performance polymers with high thermal stability, mechanical robustness and low flammability, expecting to find many practical applications in the industry.

Fu Gu, Jianfeng Guo, Wujie Zhang et al.

Zhenyu Zhang, Junfeng Cui, Jiabo Zhang et al.

Abstract Chemical mechanical polishing slurry of copper usually contains more than four compositions, in which strong acids, alkalis or hazardous chemicals are normally employed. With these slurries, surface roughness less than 1 nm is difficult to obtain on the surface of copper after chemical mechanical polishing. It is a challenge to develop a kind of novel chemical mechanical polishing slurry for copper including three environment friendly compositions. In this study, a kind of novel chemical mechanical polishing slurry is developed consisting of silica, hydrogen peroxide and chitosan oligosaccharide, where all the three compositions are environment friendly. After chemical mechanical polishing, surface roughness Ra and peak-to-valley values are 0.444 and 5.468 nm respectively. Chemical mechanical polishing mechanism is elucidated by infrared and X-ray photoelectron spectra and electrochemical measurements. Firstly, Cu surface is oxidized by hydrogen peroxide, forming CuO and Cu(OH)2. Then, CuO and Cu(OH)2 are dissolved by H+ ions released by the ionization of chitosan oligosaccharide. Subsequently, Cu2+ ions are chelated by chitosan oligosaccharide molecules. Finally, the adsorbed layer is removed by silica nanospheres, generating ultra-smooth surface of copper. The findings propose a new route for fabrication devices of copper and other transition metals used in integrated circuits, graphene, transformers, batteries and electronics industries.

B. Panda, Jian Hui Lim, M. Tan

Abstract Digital construction is gradually opening unlimited possibilities for building and concrete industry. The key secret for a robust print process lies in our understanding of the processing technology and material fresh properties, in addition to developing novel measurement and control techniques. This paper aims to gain a better understanding of early age mechanical properties of 3D printable materials and improve it for the requirement of large scale concrete printing. Experimental investigations were carried out to measure green strength and stiffness of fresh fly ash-cement mortar with applied 3D optical metrology. The compressive green strength was linked with material yield strength evolution and later, modified with nanoclay for higher buildability properties. Nanoclay addition deceased the layer deformation due to significant increase in Young's modulus and to estimate this uncontrolled deformation, a mathematical function was formulated, which subsequently validated by comparison to printing experiments.

Aaron Malone, Alannah Brett, Elisheba Spiller et al.

The global scramble for critical minerals and the US push to increase domestic production have generated interest around the potential for direct lithium extraction from oilfield brines (OB-DLE) in Arkansas. This paper provides an interdisciplinary scoping review to analyze the knowns and unknowns around resource potential, socio-economic, and environmental dynamics. An initial three OB-DLE projects could contribute an estimated 53 100 tons per year lithium carbonate equivalent beginning as soon as 2028, around one-fifth of estimated US consumption at 2024 levels, while additional proposed projects could expand that figure later. However, uncertainties remain around the resource, technology, and economic dimensions, all of which have implications for the eventual impacts for local communities and the environment. The paper reviews geology and reservoir characteristics and unknowns, and summarizes the legal and regulatory advantages that have brought Arkansas to the forefront of a resource that extends across multiple states. However, at 2025 lithium prices, none of the proposed projects would be profitable; viability depends on projected price increases materializing. Impacts to communities would include employment, royalties, and tax revenues, the distribution of which will determine whether existing uneven development in the region is reinforced or disrupted. Finally, we compare OB-DLE’s environmental profile to that of other lithium production methods. The first round of OB-DLE projects will be greenfield, rather than reusing oil and gas infrastructure or produced waters. Freshwater consumption is projected to be higher than in brine evaporation but similar or lower than mining lithium from rock. The paper concludes by identifying areas for future research.

Zhimin Wang, J. Oliveira, Z. Zeng et al.

Abstract Three types of laser beam oscillating welding were applied on 5A06 aluminum alloy sheets. The microstructure and mechanical properties of the welded joints were characterized. The formation and elimination mechanisms of welding pores during laser beam oscillating welding was investigated. The results showed that laser beam oscillating welding using linear, circular and infinity paths allow to reduce the porosity of the welded joint when compared to the joint produced without beam without oscillation. Among the three oscillating paths, the infinity mode was the best in terms of decreasing the porosity in the weld and increasing the tensile strength. The decrease in porosity of the fusion zone was associated with the weld shape and the decrease of the depth-to-width ratio of the weld due to the oscillation of the heat source. Laser beam oscillating welding applied to aluminum alloys can be of significant interest to industry to decrease porosity problems typically encountered during laser welding of these materials.

Parth U Kelkar, Hyun Soo Kim, K. Cho et al.

Recent advances in lithography technology and the spread of 3D printers allow us a facile fabrication of special materials with complicated microstructures. The materials are called “designed materials” or “architectured materials” and provide new opportunities for material development. These materials, which owing to their rationally designed architectures exhibit unusual properties at the micro- and nano-scales, are being widely exploited in the development of modern materials with customized and improved performance. Meta-materials are found to possess superior and unusual properties as regards static modulus (axial stress divided by axial strain), density, energy absorption, smart functionality, and negative Poisson’s ratio (NPR). However, in spite of recent developments, it has only been feasible to fabricate a few such meta-materials and to implement them in practical applications. Against such a backdrop, a broad review of the wide range of cellular auxetic structures for mechanical metamaterials available at our disposal and their potential application areas is important. Classified according to their geometrical configuration, this paper provides a review of cellular auxetic structures. The structures are presented with a view to tap into their potential abilities and leverage multidimensional fabrication advances to facilitate their application in industry. In this review, there is a special emphasis on state-of-the-art applications of these structures in important domains such as sensors and actuators, the medical industry, and defense while touching upon ways to accelerate the material development process.

A. Behnood

Abstract In pavement industry, warm mix asphalt (WMA) technologies provide a wide variety of environmental, technical, and economic benefits. WMA includes a series of technologies to mix and compact asphalt mixtures at temperatures lower than the temperatures normally used in the production of hot mix asphalt (mainly by reducing the viscosity of asphalt binders). Different WMA technologies affect in different ways on the performance of binders and mixtures. Much has been learned about the WMA technologies used in pavement industry and their effects on the thermo-mechanical properties of WMA mixtures and the rheological properties of asphalt binders. The literature on the different WMA technologies and their effects on the performance of WMA binders and mixtures is reviewed in this paper. Moreover, the performance of the WMA technologies in mixtures containing other materials such as reclaimed asphalt pavement, polymers, and crumb rubber is reviewed in here. The findings in this review indicate that, in pavement industry, WMA technologies can reduce the environmental pollution, production cost, and energy usage. Moreover, an appropriate WMA technology can provide several technical benefits. The findings in the current paper can help pavement engineers to better utilize the WMA technologies in designing the asphalt mixtures. It is also hoped that this review will be helpful for asphalt researchers to find future avenues of research about WMA technologies.

Yazhou Tian, Qiong Wang, Lijiao Shen et al.

Abstract Preparing low-flammable biobased epoxy resins with a high glass transition temperature (Tg) and excellent mechanical properties is significant for the rapid growing electronics and microelectronics industry. In this research, a resveratrol-based epoxy resin (REEP) with well-designed chemical structures possessing trifunctional epoxy groups and rigid conjugate structures was prepared through the one-pot method and was then cured by methyl hexahydrophthalic anhydride (MeHHPA). The conventional petroleum-based epoxy resin (DGEBA) was cured by the same kind of curing agent. Results showed that Tg of REEP/MeHHPA was up to 210.8 °C, much higher than that of DGEBA/MeHHPA (only 146.5 °C). The tensile strength and modulus of REEP/MeHHPA were 73.5 MPa and 3.0 GPa, respectively. More importantly, REEP/MeHHPA exhibited exceptional low permittivity (about 3.5) and low flammability with high char yield of 19.0% (800 °C). Therefore, the resveratrol-based epoxy resin could be a promising candidate for DGEBA and has great potential application in electronics and microelectronics industry.

Sinan Ardıç, Gökhan Kunt, Selim Gürgen et al.

Matilde Arese, Beatrice Cavallo, Gabriele Ciaccio et al.

Considering the increasing use of plastics in vehicles, the need for sustainable management is becoming a matter of concern. The reintroduction of plastic originated from post-consumer waste in the vehicle manufacturing loop can also be a solution to meet the recent EU ELVs (end-of-life vehicles) legislation in terms of sustainability. This study focuses on post-consumer polypropylene (PP) compounds destined for automotive applications by assessing their morphological, thermal, and mechanical properties. Field Emission Scanning Electron Microscopy (FE-SEM), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC) techniques were used. Since the ageing of these materials, caused by the thermo-oxidative degradation process, may compromise their performances, a comprehensive study of their behavior, in comparison to the virgin compound counterpart, was necessary to evaluate the fossil replacement possibility. Furthermore, an additional investigation was conducted after subjecting the materials to UV ageing in order to simulate the degradation effect of solar radiation, with the aim of determining the suitability of the recycled materials in long-term applications. In summary, the results support the feasibility of using recycled post-consumer materials mixed with virgin grade in automotive production, highlighting the stability of thermal and mechanical properties, critical for efficient manufacturing. This research underlines the noteworthy progress in the circularity of automotive plastics, providing a sustainable solution for integrating plastic material waste into new vehicle production.

Claudie‐Maude Canuel, Evelyne Thiffault, Nelson Thiffault

ABSTRACT Many jurisdictions within the boreal and temperate biomes have adopted targets to increase the contribution of forest bioenergy for climate change mitigation. Using residual forest biomass as feedstock is considered, but the carbon emission reductions associated with this practice remain controversial. Our study evaluated how intensifying wood procurement for bioenergy production, alongside supplying fiber for conventional wood industries, can support low‐carbon forest management. We used six sites established in eastern Canada as a case study. We compared the carbon balance of four harvesting scenarios with increasing wood procurement intensity (from procuring sawtimber only to procuring sawtimber, pulpwood and biomass) to three scenarios of unharvested forests, two of which experienced natural disturbances. We modeled carbon fluxes over a 100‐year simulation period, considering biogenic and fossil emissions from aboveground forest ecosystems, harvested wood products, and wood supply and manufacturing. We assessed the mitigation potential of procuring biomass to produce bioenergy in the form of stemwood, treetops (including branches) or pulpwood. We found that forest harvesting, regardless of the wood procurement intensity, offered limited carbon benefits compared to the referenced undisturbed mature stands in most cases. However, increasing wood procurement can reduce the carbon footprint of wood supply chains, with pulpwood identified as a key feedstock. Compared with harvesting roundwood for conventional industries only, procuring biomass for bioenergy is likely to increase carbon emissions unless it substitutes high‐emission energy sources on markets or enhances the next‐rotation stand yield, which seems achievable in the context we studied. Bioenergy displacement factors should range from 0.072 to 0.701 tonne of carbon emission reduction per tonne of carbon in the bioenergy product, depending on stand characteristics, biomass feedstock, and cutting cycle length. Our findings provide a foundation for assessing the GHG reduction potential of harvesting activities at a broader scale, considering varying feedstock recovery intensities.

Savan K. Raj, Khushbu Sharma, Vartika Sharma et al.

The design and synthesis of a silicon-integrated MXene-based nanoflower (Si@NFs) architecture using a simple hydrothermal method and thermal treatment are reported in this study. The resulting hierarchical structure creates a multidimensional conductive network by fusing the superior conductivity and mechanical stability of MXenes with the high capacity of nanosilicon. Due to effective ion transport, interfacial contact, and volume expansion buffering, Si@NFs exhibit better cycling stability, as demonstrated by structural and electrochemical characterisation. The strong interface and structural integrity of the nanoflowers indicate high promise for future integration into all-solid-state lithium-ion battery systems, even though solid-state electrolytes are not directly incorporated in this study.

Syed Fouzan Iftekar, Abdul Aabid, Nor Aiman Sukindar et al.

Abstract The high costs associated with metal additive manufacturing methods including expensive feedstock, energy-intensive lasers, and controlled environments have limited their widespread adoption in industries like aerospace and automotive, despite powder bed fusion success in producing intricate and high-precision components. As a cost-effective alternative, material extrusion 3D printing enables the fabrication of metal-polymer composites using simpler equipment. However, challenges remain in optimizing post-processing parameters to enhance mechanical performance and microstructural integrity. This study focuses on improving the post-processing of copper-filled PLA parts fabricated with an Artillery Sidewinder X1 material extrusion printer. A Taguchi design of experiments approach using an L8 orthogonal array was employed to investigate the effects of debinding time, sintering time, and layer thickness. Results showed that shorter debinding compromised structural integrity in 25% of samples, while optimized settings achieved a 30.59% shrinkage and a 12.5% hardness increase. These findings highlight the significance of proper thermal post-processing in controlling dimensional changes and improving part quality.

Yasmeen Magdy, Ahmed Abo-Ahmed, Mohamed Abumandour et al.

Abstract Research on collagen content in donkey skin is limited, necessitating experimental approaches to aid in the economic production of the leather and cosmetics industries. This study aimed to analyze the histomorphometry and ultrastructure of donkey skin and compare collagen fiber zones in various anatomical regions, both objectively and quantitatively. The study was the first to describe the melanosome number in different skin regions of a donkey. Skin biopsies from fourteen mature male donkeys were used in this study. The epidermis and dermis were examined histologically and ultrastructurally, focusing on the dermo-epidermal thickness ratio and collagen bundle arrangement in the dermis. The study revealed that melanin deposits are higher in the limbs and abdomen of donkeys compared to the back, neck, and thorax, and the dermal-epidermal junction of the back skin is longer. The back skin is the thickest, while the limb skin is the thinnest, despite the high collagen content in the thoracic region. The study indicates that the variation in melanin deposits and dermal-epidermal junction lengths in different body regions of donkeys may be due to variations in mechanical stress and environmental factors. The abdomen had the highest melanocyte count, with significant differences compared to the neck, back, and thorax. The neck region had the lowest count, while the limb, back, and thorax had similar counts. The study’s findings could aid in identifying the difference between normal skin features and collagen-diseased skin in donkeys, aiding in diagnosis and providing valuable insights for veterinarians and researchers studying similar conditions.

Onyinyechi Nnamchi, Cyprian Tom, Godwin Akpan et al.

As the world transitions towards green energy sources solar drying has become a vital technology for sustainable agricultural production, offering a cleaner, more efficient alternative to traditional drying methods. Solar drying has been demonstrated to be a sustainable and eco-friendly drying process for drying and preserving agricultural products, offering advantages over traditional methods that include faster drying rates, improved product quality, and reduced energy costs. This review examines the mechanisms and methods applicable to solar drying, including indirect and direct solar drying, hybrid systems combining solar drying with other heating sources, and thermal storage materials to address challenges such as intermittent solar radiation. The designs of solar drying systems include various solar collector configurations, drying chamber geometries, and air conveyance mechanisms crucial for efficient drying. This review therefore explores different design approaches and their effects on drying performance, highlighting the importance of understanding the complex interactions between system components. Additionally, the approach for Energy and exergy analysis of solar drying systems was explored, providing insights into energy utilization and efficiency. Finally, this review elucidates the complex transport phenomena governing solar drying, including moisture diffusion, heat and mass transfer, and airflow patterns. It identifies knowledge gaps in existing models and future research directions in transport modelling phenomena to advance sustainable, efficient, and scalable solar drying techniques.

Mukesh Kumar Nag