scholarly journals Bio-Inspired Functional Surface Fabricated by Electrically Assisted Micro-Embossing of AZ31 Magnesium Alloy

Materials ◽  
2020 ◽  
Vol 13 (2) ◽  
pp. 412 ◽  
Author(s):  
Xinwei Wang ◽  
Jie Xu ◽  
Chunju Wang ◽  
Antonio J. Sánchez Egea ◽  
Jianwei Li ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Large Scale ◽  
Width Ratio ◽  
Functional Surface ◽  
Metallic Surfaces ◽  
Industrial Sectors ◽  
Electrically Assisted ◽  
Micro Channels ◽  
Thermoplastic Forming ◽  
Current Densities

Developing bio-inspired functional surfaces on engineering metals is of extreme importance, involving different industrial sectors, like automotive or aeronautics. In particular, micro-embossing is one of the efficient and large-scale processes for manufacturing bio-inspired textures on metallic surfaces. However, this process faces some problems, such as filling defects and die breakage due to size effect, which restrict this technology for some components. Electrically assisted micro-forming has demonstrated the ability of reducing size effects, improving formability and decreasing flow stress, making it a promising hybrid process to control the filling quality of micro-scale features. This research focuses on the use of different current densities to perform embossed micro-channels of 7 μm and sharklet patterns of 10 μm in textured bulk metallic glass dies. These dies are prepared by thermoplastic forming based on the compression of photolithographic silicon molds. The results show that large areas of bio-inspired textures could be fabricated on magnesium alloy when current densities higher than 6 A/mm2 (threshold) are used. The optimal surface quality scenario is obtained for a current density of 13 A/mm2. Additionally, filling depth and depth–width ratio nonlinearly increases when higher current densities are used, where the temperature is a key parameter to control, keeping it below the temperature of the glass transition to avoid melting or an early breakage of the die.

Micro texturing on metallic surfaces: State of the art

2016 ◽  
Vol 232 (6) ◽  
pp. 941-964 ◽  
Author(s):  
Divyansh Patel ◽  
VK Jain ◽  
J Ramkumar
Keyword(s):  
Large Scale ◽  
Surface Texturing ◽  
Machining Process ◽  
Electrochemical Micromachining ◽  
Metallic Surface ◽  
Textured Surface ◽  
Textured Surfaces ◽  
Metallic Surfaces ◽  
Area Of Interest ◽  
Micro Channels

The study of surface texturing on a metallic surface has become a great area of interest of researchers in the last few decades. Surface texturing is employed for enhancing the performance of the surface in its working environment. As the characterization techniques have been evolving very fast, researchers have started mimicking the natural surfaces to take the advantages of their characteristics (such as self-cleaning, load capacity, reducing coefficient of friction). Manufacturing of natural inspired surface requires having a great control over the process to achieve the micro or nano features on the natural surfaces. Hence, the selection of the most suitable process and optimum parameters for machining of arrays of micro or nano features at large scale is highly desirable. This study reports an overview of different micromachining processes used for texturing on metallic surfaces and research gaps to be filled in the available literature. Electrochemical micromachining has tremendous potential on account of its versatility in different applications. It is a promising and economically viable machining process for micromanufacturing industries for fabrication of micro textures and micro features on metallic surfaces. Production of textured surface at large scale requires a sustainable technology, which can serve the purpose of enhancing the performance of the surface without changing the original properties of the surface. Indeed, laser surface texturing, through-mask electrochemical micromachining, lithography, micro- or nanocasting and so on are the existing methods which involve multiple steps for generation of textured surfaces. This article also reports some original experimental investigations for generation of different kinds of micro textures on metallic surfaces, namely, arrays of micro dimples, micro channels and micro pillars using a single-step maskless electrochemical micro-texturing process with a pre-patterned micro tool.

scholarly journals Process modelling and techno-economic analysis of natural gas combined cycle integrated with calcium looping

2016 ◽  
Vol 20 (suppl. 1) ◽  
pp. 59-67 ◽  
Author(s):  
María Erans ◽  
Dawid Hanak ◽  
Jordi Mir ◽  
Edward Anthony ◽  
Vasilije Manovic
Keyword(s):  
Natural Gas ◽  
Large Scale ◽  
Combined Cycle ◽  
Process Models ◽  
Capital Costs ◽  
Calcium Looping ◽  
Industrial Sectors ◽  
Natural Gas Combined Cycle ◽  
Before And After ◽  
Economic Analyses

Calcium looping (CaL) is promising for large-scale CO2 capture in the power generation and industrial sectors due to the cheap sorbent used and the relatively low energy penalties achieved with this process. Because of the high operating temperatures the heat utilisation is a major advantage of the process, since a significant amount of power can be generated from it. However, this increases its complexity and capital costs. Therefore, not only the energy efficiency performance is important for these cycles, but also the capital costs must be taken into account, i.e. techno-economic analyses are required in order to determine which parameters and configurations are optimal to enhance technology viability in different integration scenarios. In this study the integration scenarios of CaL cycles and natural gas combined cycles (NGCC) are explored. The process models of the NGCC and CaL capture plant are developed to explore the most promising scenarios for NGCC-CaL integration with regards to efficiency penalties. Two scenarios are analysed in detail, and show that the system with heat recovery steam generator (HRSG) before and after the capture plant exhibited better performance of 49.1% efficiency compared with that of 45.7% when only one HRSG is located after the capture plant. However, the techno-economic analyses showed that the more energy efficient case, with two HRSGs, implies relatively higher cost of electricity (COE), 44.1?/MWh, when compared to that of the reference plant system (33.1?/MWh). The predicted cost of CO2 avoided for the case with two HRSGS is 29.3 ?/ton CO2.

scholarly journals Towards a hydrogen economy – a sustainable pathway for global energy transition

2021 ◽  
Vol 28 (2) ◽  
pp. 102-107
Author(s):  
Jeffrey Kwok
Keyword(s):  
Large Scale ◽  
South Australia ◽  
Energy Transition ◽  
Thermal Engineering ◽  
Hydrogen Economy ◽  
Carbon Abatement ◽  
Electric System ◽  
Industrial Sectors ◽  
The Uk ◽  
Scale Integration

Hydrogen is receiving increasing attention for achieving carbon abatement in various sectors, including transport, logistics, thermal engineering and industrial feedstock, etc. Hydrogen can also support distributed power supply that raises national energy security. Both commercial and industrial sectors share a common vision that increasing the cost-effectiveness of renewable hydrogen represents their strategic achievement towards substantial sustainability. This paper explains how hydrogen can play seven roles in the energy transition which include large-scale integration of renewable energy into the power grid, medium for storing and distributing energy across sectors and/or regions, a buffer to increase the electric system resilience and clean fuel for fuel cell vehicles to decarbonise transport. Besides, hydrogen can decarbonise building energy consumption and serve as feedstock using captured carbon. Power Assets Holdings Limited (PAH), a global investor in energy and utility-related business, has identified a hydrogen economy as a strategic vision in its business plan for zero carbon readiness in 2035 and a carbon-free business model in 2050. In this paper, the features and attributes of different hydrogen projects, such as H21 and InTEGRel in the UK and Hydrogen Park in South Australia, are discussed to demonstrate the commercial deployment of hydrogen power.

scholarly journals A New Method of Manufacturing Thin-Walled Tube Made of AZ61 Magnesium Alloy Including Direct Extrusion And Corrugated Equal Channel Angular Extrusion

2021 ◽  
Author(s):  
H-J Hu ◽  
Ou Zhang ◽  
Gang Hu ◽  
Hui Zhao ◽  
Zhongwen OU
Keyword(s):  
Plastic Deformation ◽  
Magnesium Alloy ◽  
Large Scale ◽  
Equal Channel Angular Extrusion ◽  
Process Conditions ◽  
Workpiece Material ◽  
Plastic Deformation Behavior ◽  
Angular Extrusion ◽  
Thin Walled Tube ◽  
Thin Walled

Abstract Due to demand of strong toughness of thin walled tube, and good secondary forming properties and high-precision dimension, New plastic forming method should be researched to achieve a complete filling, uniform deformation and microstructure evolution during forming process.To obtain the deformation mechanisms of a new composite extrusion for thin walled tube fabricated by tube corrugated equal channel angular extrusion has been researched which is shorten as “TC-ECAE” in this paper. Finite element DEFORMTM-3D software to investigate the plastic deformation behavior of magnesium billet during TC-ECAE process has been employed. Computed parameters including workpiece material characteristics and process conditions have been taken into consideration. The pridictions of strains distributions and damage distributions and effective stress distributions and flow velocities distributions and microstructures evolutions have been explored. The results proved that the TC-ECAE process is a forming method for magnesium alloy tube which is suitable for large scale industrial application. The TC-ECAE process would cause serve plastic deformation and improve the dynamic recrystallization of magnesium alloy during TC-ECAE process.

Functional Surface for Bioresorbable Magnesium Alloy Stents

MEMBRANE ◽  
2021 ◽  
Vol 46 (5) ◽  
pp. 294-299
Author(s):  
Xu Wei ◽  
Makoto Sasaki ◽  
Takuro Niidome
Keyword(s):  
Magnesium Alloy ◽  
Functional Surface

scholarly journals Statistical analysis of the dependence of large-scale Birkeland currents on solar wind parameters

2010 ◽  
Vol 28 (2) ◽  
pp. 515-530 ◽  
Author(s):  
H. Korth ◽  
B. J. Anderson ◽  
C. L. Waters
Keyword(s):  
Magnetic Field ◽  
Solar Wind ◽  
Mach Number ◽  
Electric Field ◽  
Large Scale ◽  
Dynamic Pressure ◽  
Dominant Factor ◽  
Total Current ◽  
Current Densities ◽  
Birkeland Currents

Abstract. The spatial distributions of large-scale field-aligned Birkeland currents have been derived using magnetic field data obtained from the Iridium constellation of satellites from February 1999 to December 2007. From this database, we selected intervals that had at least 45% overlap in the large-scale currents between successive hours. The consistency in the current distributions is taken to indicate stability of the large-scale magnetosphere–ionosphere system to within the spatial and temporal resolution of the Iridium observations. The resulting data set of about 1500 two-hour intervals (4% of the data) was sorted first by the interplanetary magnetic field (IMF) GSM clock angle (arctan(By/Bz)) since this governs the spatial morphology of the currents. The Birkeland current densities were then corrected for variations in EUV-produced ionospheric conductance by normalizing the current densities to those occurring for 0° dipole tilt. To determine the dependence of the currents on other solar wind variables for a given IMF clock angle, the data were then sorted sequentially by the following parameters: the solar wind electric field in the plane normal to the Earth–Sun line, Eyz; the solar wind ram pressure; and the solar wind Alfvén Mach number. The solar wind electric field is the dominant factor determining the Birkeland current intensities. The currents shift toward noon and expand equatorward with increasing solar wind electric field. The total current increases by 0.8 MA per mV m−1 increase in Eyz for southward IMF, while for northward IMF it is nearly independent of the electric field, increasing by only 0.1 MA per mV m−1 increase in Eyz. The dependence on solar wind pressure is comparatively modest. After correcting for the solar dynamo dependencies in intensity and distribution, the total current intensity increases with solar wind dynamic pressure by 0.4 MA/nPa for southward IMF. Normalizing the Birkeland current densities to both the median solar wind electric field and dynamic pressure effects, we find no significant dependence of the Birkeland currents on solar wind Alfvén Mach number.

scholarly journals Engineering active sites on hierarchical transition bimetal oxides/sulfides heterostructure array enabling robust overall water splitting

2020 ◽  
Vol 11 (1) ◽  
Author(s):  
Panlong Zhai ◽  
Yanxue Zhang ◽  
Yunzhen Wu ◽  
Junfeng Gao ◽  
Bo Zhang ◽  
...  
Keyword(s):  
Water Splitting ◽  
Active Sites ◽  
Rational Design ◽  
Large Scale ◽  
Grand Challenge ◽  
Long Term Stability ◽  
Large Current ◽  
Electrode Cell ◽  
Large Current Density ◽  
Current Densities

Abstract Rational design of the catalysts is impressive for sustainable energy conversion. However, there is a grand challenge to engineer active sites at the interface. Herein, hierarchical transition bimetal oxides/sulfides heterostructure arrays interacting two-dimensional MoOx/MoS2 nanosheets attached to one-dimensional NiOx/Ni3S2 nanorods were fabricated by oxidation/hydrogenation-induced surface reconfiguration strategy. The NiMoOx/NiMoS heterostructure array exhibits the overpotentials of 38 mV for hydrogen evolution and 186 mV for oxygen evolution at 10 mA cm−2, even surviving at a large current density of 500 mA cm−2 with long-term stability. Due to optimized adsorption energies and accelerated water splitting kinetics by theory calculations, the assembled two-electrode cell delivers the industrially relevant current densities of 500 and 1000 mA cm−2 at record low cell voltages of 1.60 and 1.66 V with excellent durability. This research provides a promising avenue to enhance the electrocatalytic performance of the catalysts by engineering interfacial active sites toward large-scale water splitting.

Investigation on Two Electrically-Assisted Forming Processes of AZ31B Magnesium Alloy Sheets

2019 ◽  
Vol 24 (4) ◽  
pp. 409-416
Author(s):  
Kai Liu ◽  
Xianghuai Dong ◽  
Wen Shi ◽  
Xinbao Wang ◽  
Guohong Wu
Keyword(s):  
Magnesium Alloy ◽  
Az31b Magnesium Alloy ◽  
Electrically Assisted

scholarly journals Prospects and Challenges of Green Hydrogen Economy via Multi-Sector Global Symbiosis in Qatar

2021 ◽  
Vol 1 ◽  
Author(s):  
Fadwa Eljack ◽  
Monzure-Khoda Kazi
Keyword(s):  
Supply Chain ◽  
Large Scale ◽  
Global Climate ◽  
Clean Energy ◽  
Low Carbon ◽  
Great Opportunity ◽  
Industrial Sectors ◽  
Hydrogen Supply ◽  
Hydrogen Supply Chain ◽  
Infrastructure Investments

Low carbon hydrogen can be an excellent source of clean energy, which can combat global climate change and poor air quality. Hydrogen based economy can be a great opportunity for a country like Qatar to decarbonize its multiple sectors including transportation, shipping, global energy markets, and industrial sectors. However, there are still some barriers to the realization of a hydrogen-based economy, which includes large scale hydrogen production cost, infrastructure investments, bulk storage, transport & distribution, safety consideration, and matching supply-demand uncertainties. This paper highlights how the aforementioned challenges can be handled strategically through a multi-sector industrial-urban symbiosis for the hydrogen supply chain implementation. Such symbiosis can enhance the mutual relationship between diverse industries and urban planning by exploring varied scopes of multi-purpose hydrogen usage (i.e., clean energy source as a safer carrier, industrial feedstock and intermittent products, vehicle and shipping fuel, and international energy trading, etc.) both in local and international markets. It enables individual entities and businesses to participate in the physical exchange of materials, by-products, energy, and water, with strategic advantages for all participants. Besides, waste/by-product exchanges, several different kinds of synergies are also possible, such as the sharing of resources and shared facilities. The diversified economic base, regional proximity and the facilitation of rules, strategies and policies may be the key drivers that support the creation of a multi-sector hydrogen supply chain in Qatar.

scholarly journals Graphene: A new technology for agriculture

2021 ◽  
Vol 10 (2) ◽  
pp. e56610212827
Author(s):  
André May ◽  
Luciana Fontes Coelho ◽  
Evandro Henrique Figueiredo Moura da Silva ◽  
Ronaldo da Silva Viana ◽  
Nilson Aparecido Vieira Junior ◽  
...  
Keyword(s):  
Precision Agriculture ◽  
Food Industry ◽  
Large Scale ◽  
Soil Microorganisms ◽  
New Technology ◽  
Limiting Factor ◽  
Contaminant Removal ◽  
Detection Systems ◽  
Industrial Sectors ◽  
The Cost

This article presents a review on the use of graphene in various segments, elucidating that this product can be used in various industrial sectors. These include mainly agriculture (as in large crops of high relevance, such as coffee), the food industry and the environment, as a plant growth stimulator and in fertilizers, nanoencapsulation and smart-release systems, antifungal and antibacterial agents, smart packaging, water treatment and ultrafiltration, contaminant removal, pesticide and insecticide quantitation, detection systems and precision agriculture. However, some challenges can be overcome before the graphene-based nanoparticle is used on a large scale. In this way, before using the product in the environment, it is necessary to determine whether the technology is safe for the soil-plant system and consumers. Furthermore, the cost of its use can also be a limiting factor depending on the level applied. Therefore, this review proposes to examine the diverse literature to explain the effects of the use of graphene in agriculture, plants and soil microorganisms. Accordingly, this article discusses and presents the possibilities of application of graphene in agriculture, plants and soil microorganisms.

Sign in / Sign up

Export Citation Format

Share Document