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Showing records 1 to 25 of 157. [First] Page: 1 2 3 4 5 Last
Enhanced Lifetime Cathode for Alkaline Electrolysis Using Standard Commercial Titanium Nitride Coatings
William J. F. Gannon, Daniel R. Jones, Charles W. Dunnill
June 18, 2019 (v1)
Subject: Materials
Keywords: alkaline electrolysis, Energy Storage, stainless steel, titanium nitride
The use of hydrogen gas as a means of decoupling supply from demand is crucial for the transition to carbon-neutral energy sources and a greener, more distributed energy landscape. This work shows how simple commercially available titanium nitride coatings can be used to extend the lifetime of 316 grade stainless-steel electrodes for use as the cathode in an alkaline electrolysis cell. The material was subjected to accelerated ageing, with the specific aim of assessing the coating’s suitability for use with intermittent renewable energy sources. Over 2000 cycles lasting 5.5 days, an electrolytic cell featuring the coating outperformed a control cell by 250 mV, and a reduction of overpotential at the cathode of 400 mV was observed. This work also confirms that the coating is solely suitable for cathodic use and presents an analysis of the surface changes that occur if it is used anodically.
Long-Term Stability of Thin-Film Pd-Based Supported Membranes
Niek de Nooijer, Alba Arratibel Plazaola, Jon Meléndez Rey, Ekain Fernandez, David Alfredo Pacheco Tanaka, Martin van Sint Annaland, Fausto Gallucci
June 10, 2019 (v1)
Subject: Materials
Keywords: fluidized bed, hydrogen production, membrane reactors, membrane stability, Palladium based membranes
Membrane reactors have demonstrated a large potential for the production of hydrogen via reforming of different feedstocks in comparison with other reactor types. However, the long-term performance and stability of the applied membranes are extremely important for the possible industrial exploitation of these reactors. This study investigates the long-term stability of thin-film Pd-Ag membranes supported on porous Al₂O₃ supports. The stability of five similarly prepared membranes have been investigated for 2650 h, up to 600 °C and in fluidized bed conditions. Results show the importance and the contribution of the sealing of the membranes at temperatures up to 500 °C. At higher temperatures the membranes surface deformation results in pinhole formation and a consequent decrease in selectivity. Stable operation of the membranes in a fluidized bed is observed up to 450 °C, however, at higher temperatures the scouring action of the particles under fluidization causes significant deformati... [more]
Evaluation of Conditions Affecting Properties of Gac (Momordica Cocochinensis Spreng) Oil-Loaded Solid Lipid Nanoparticles (SLNs) Synthesized Using High-Speed Homogenization Process
Huynh Cang Mai, Thai Sa Vin Nguyen, Thi Hong Nhan Le, Duy Chinh Nguyen, Long Giang Bach
June 10, 2019 (v1)
Subject: Materials
Keywords: carotenoids, cold homogenization, gac oil, hot homogenization, Momordica cocochinensis Spreng, Naterol SE, Solid lipid nanoparticles (SLNs)
In this study, we attempted the preparation of gac oil-loaded solid lipid nanoparticles (SLNs) by the high-speed homogenization method using Naterol SE solid lipid, a cosmetic self-emulsifying base, and surfactant and investigated the effects of different conditions on the characteristics of the resulting nanoparticles. The suspensions containing 5% active agents (gac-oil, w/w) were dispersed in a surfactant concentration of 5% (w/w) (Span 80:Tween 80 ratio of 28:72 w/w) and 2.5% (w/w) of solid lipid (Naterol SE) concentration. Suitable conditions for hot homogenization were 13,000 rpm, 60 min and 60 °C for speed, time and temperature, respectively. The suitable conditions for the subsequent cold homogenization were 25 min of homogenization time and 5 °C of temperature. The results showed that the mean size of SLNs-gac oil was 107 nm (measured by laser diffraction spectrometry, LDS), and dried size of SLNs-gac oil ranged from 50 to 80 nm (measured by transmission electron microscope, T... [more]
Environmental Sustainability Assessment of Typical Cathode Materials of Lithium-Ion Battery Based on Three LCA Approaches
Lei Wang, Haohui Wu, Yuchen Hu, Yajuan Yu, Kai Huang
June 8, 2019 (v1)
Subject: Materials
Keywords: cathode material, environmental sustainability, LCA, LIBs
With the rapid increase in production of lithium-ion batteries (LIBs) and environmental issues arising around the world, cathode materials, as the key component of all LIBs, especially need to be environmentally sustainable. However, a variety of life cycle assessment (LCA) methods increase the difficulty of environmental sustainability assessment. Three authoritative LCAs, IMPACT 2002+, Eco-indicator 99(EI-99), and ReCiPe, are used to assess three traditional marketization cathode materials, compared with a new cathode model, FeF₃(H₂O)₃/C. They all show that four cathode models are ranked by a descending sequence of environmental sustainable potential: FeF₃(H₂O)₃/C, LiFe0.98Mn0.02PO₄/C, LiFePO₄/C, and LiCoO₂/C in total values. Human health is a common issue regarding these four cathode materials. Lithium is the main contributor to the environmental impact of the latter three cathode materials. At the midpoint level in different LCAs, the toxicity and land issues for LiCoO₂/C, the non-... [more]
Increasing Salt Rejection of Polybenzimidazole Nanofiltration Membranes via the Addition of Immobilized and Aligned Aquaporins
Priyesh Wagh, Xinyi Zhang, Ryan Blood, Peter M. Kekenes-Huskey, Prasangi Rajapaksha, Yinan Wei, Isabel C. Escobar
May 16, 2019 (v1)
Subject: Materials
Keywords: aquaporins, biomimetic, immobilization, nanofiltration
Aquaporins are water channel proteins in cell membrane, highly specific for water molecules while restricting the passage of contaminants and small molecules, such as urea and boric acid. Cysteine functional groups were installed on aquaporin Z for covalent attachment to the polymer membrane matrix so that the proteins could be immobilized to the membranes and aligned in the direction of the flow. Depth profiling using x-ray photoelectron spectrometer (XPS) analysis showed the presence of functional groups corresponding to aquaporin Z modified with cysteine (Aqp-SH). Aqp-SH modified membranes showed a higher salt rejection as compared to unmodified membranes. For 2 M NaCl and CaCl₂ solutions, the rejection obtained from Aqp-SH membranes was 49.3 ± 7.5% and 59.1 ± 5.1%. On the other hand, the rejections obtained for 2 M NaCl and CaCl₂ solutions from unmodified membranes were 0.8 ± 0.4% and 1.3 ± 0.2% respectively. Furthermore, Aqp-SH membranes did not show a significant decrease in salt... [more]
Investigation of Pore-Formers to Modify Extrusion-Spheronized CaO-Based Pellets for CO₂ Capture
Zonghao Zhang, Shuai Pi, Donglin He, Changlei Qin, Jingyu Ran
May 16, 2019 (v1)
Subject: Materials
Keywords: anti-attrition, calcium looping, Carbon Dioxide Capture, chemical sorption, pore-former particle size
The application of circulating fluidized bed technology in calcium looping (CaL) requires that CaO-based sorbents should be manufactured in the form of spherical pellets. However, the pelletization of powdered sorbents is always hampered by the problem that the mechanical strength of sorbents is improved at the cost of loss in CO₂ sorption performance. To promote both the CO₂ sorption and anti-attrition performance, in this work, four kinds of pore-forming materials were screened and utilized to prepare sorbent pellets via the extrusion-spheronization process. In addition, impacts of the additional content of pore-forming material and their particle sizes were also investigated comprehensively. It was found that the addition of 5 wt.% polyethylene possesses the highest CO₂ capture capacity (0.155 g-CO₂/g-sorbent in the 25th cycle) and mechanical performance of 4.0 N after high-temperature calcination, which were about 14% higher and 25% improved, compared to pure calcium hydrate pellet... [more]
Processes of Cracking and Crushing in Hybrid Fibre Reinforced High-Performance Concrete Slabs
Piotr Smarzewski
April 15, 2019 (v1)
Subject: Materials
Keywords: high-performance concrete, non-contact deformation measurements, polypropylene fibres, reinforcement, slab, steel fibres
This paper presents the experimental results obtained with the non-contact three-dimensional deformation measuring system⁻ARAMIS and finite element analysis performed using ANSYS of three slabs made of high-performance concrete (HPC) and hybrid (steel/ST and polypropylene/PP) fibre reinforced high-performance concrete (FRHPC). The research was performed on reinforced concrete (RC) slabs with a web mesh of ϕ8 mm bars. All the slabs had an identical amount of steel bars and differed by the fibre volume content. The main objective of the research was to determine the impact of adding polypropylene and steel fibres on the carrying capacity and ductility of HPC slabs. Analysis of the results was conducted based on load⁻deflection curves, crack distribution, vertical displacements and strains. The research findings indicate that fibres may improve peak strength. The presence of PP and ST hybrid fibres in HPC restricted the propagation of cracks. The energy absorption capacity as well as the... [more]
Study on the Preparation and Hydration Properties of a New Cementitious Material for Tailings Discharge
Yunbing Hou, Pengchu Ding, Dong Han, Xing Zhang, Shuxiong Cao
April 15, 2019 (v1)
Subject: Materials
Keywords: cement-based paste discharge, mechanical behaviors, MIP, new cementitious material, SEM, TG/DTG, XRD
Blast furnace slag (BFS) is often used as a cement-based raw material for underground filling and surface cemented paste discharge of tailings during mining processes. This paper studied a new cement-based material (NCM) with BFS to replace ordinary Portland cement (OPC). A uniaxial compressive strength (UCS) experiment was used to test the mechanical strength of samples; X-ray diffraction and thermal gravity experiments were used to test the crystalline phases and amount of hydration products by samples; a scanning electron microscope experiment was used to observe the influence of the hydration products morphology by samples; mercury intrusion porosimetry experiment was used to analyze the pore size distribution of samples. The samples with NCM had an optimum UCS; the crystalline phases of the hydration products were similar in OPC and NCM. However, the amount of product formed in OPC was less than that in NCM at the same curing time; more ettringite and calcium silicate hydrate were... [more]
The Effect of the Presence of Very Cohesive Geldart C Ultra-Fine Particles on the Fluidization of Geldart A Fine Particle Beds
Abbas Kamranian Marnani, Andreas Bück, Sergiy Antonyuk, Berend van Wachem, Dominique Thévenin, Jürgen Tomas
April 15, 2019 (v1)
Subject: Materials
Keywords: agglomeration, binary mixtures, cohesion, fine particle, fluidization, ultra-fine powders
The effect of the presence of ultra-fines (d < 10 μm) on the fluidization of a bed containing fine particles (d < 100 μm), is the subject of this paper. Practically, it can happen due to breakage or surface abrasion of the fine particles in some processes which totally changes the size distribution and also fluidization behaviour. The materials used in this study are both ground calcium carbonate (GCC); fine is CALCIT MVT 100 (Geldart’s group A) and ultra-fine is CALCIT MX 10 (group C). The experimental results for different binary mixtures of these materials (ultra-fines have 30%, 50%, or 68% of the total mixture weight) show that the physical properties of the mixtures are close to those of pure ultra-fine powders. Using mean values of the bed pressure drop calculated from several independent repetitions, the fluidization behaviour of different mixtures are compared and discussed. The fluidization behaviour of the mixtures is non-reproducible and includes cracking, channelling... [more]
Special Issue on “Transport of Fluids in Nanoporous Materials”
Xuechao Gao, Guozhao Ji, Suresh K. Bhatia, David Nicholson
April 9, 2019 (v1)
Subject: Materials
Understanding the transport behavior of fluid molecules in confined spaces is central to the design of innovative processes involving porous materials and is indispensable to the correlation of process behavior with the material structure and properties typically used for structural characterizations such as pore dimension, surface texture, and tortuosity. [...]
Characterization of Pores and Fractures in Soft Coal from the No. 5 Soft Coalbed in the Chenghe Mining Area
Pan Wei, Yunpei Liang, Song Zhao, Shoujian Peng, Xuelong Li, Ran Meng
April 9, 2019 (v1)
Subject: Materials
Keywords: coalbed methane (CBM), fractal pore characteristics, pore structure, soft coal masses
The characteristics of the pore structure and gas migration in soft coalbeds are the premise of evaluating gas discharge in soft coalbeds. To explore the pore structure characteristics of soft coal masses, the No. 5 soft coalbed in the eastern zone of Chenghe Mining Area, was investigated and compared with the No. 5 hard coalbed in the western zone. By using a mercury intrusion method, low-temperature liquid nitrogen adsorption, and scanning electron microscopy (SEM), the pore structure characteristics of the No. 5 coalbed were explored. Moreover, based on fractal theory, the pore structure of coal was characterized. The results showed the pores in soft coal mainly appeared as small pores and micropores in which the small pores accounted for nearly half of the total pore volume. Mesopores and macropores were also distributed throughout the soft coal. The mercury-injection and mercury-ejection curves of soft coal showed significant hysteresis loops, implying that pores in coal samples w... [more]
Trends in Advanced Functional Material Applications of Nanocellulose
Prachiben Panchal, Emmanuel Ogunsona, Tizazu Mekonnen
April 9, 2019 (v1)
Subject: Materials
Keywords: antimicrobicity, barrier properties, cellulose nanocrystals, functional materials, superhydrophobicity
The need to transition to more sustainable and renewable technology has resulted in a focus on cellulose nanofibrils (CNFs) and nanocrystals (CNCs) as one of the materials of the future with potential for replacing currently used synthetic materials. Its abundance and bio-derived source make it attractive and sought after as well. CNFs and CNCs are naturally hydrophilic due to the abundance of -OH group on their surface which makes them an excellent recipient for applications in the medical industry. However, the hydrophilicity is a deterrent to many other industries, subsequently limiting their application scope. In either light, the increased rate of progress using CNCs in advanced materials applications are well underway and is becoming applicable on an industrial scale. Therefore, this review explores the current modification platforms and processes of nanocellulose directly as functional materials and as carriers/substrates of other functional materials for advanced materials appl... [more]
Influence of Organic Ligands on the Colloidal Stability and Removal of ZnO Nanoparticles from Synthetic Waters by Coagulation
Rizwan Khan, Muhammad Ali Inam, Du Ri Park, Saba Zam Zam, Sookyo Shin, Sarfaraz Khan, Muhammad Akram, Ick Tae Yeom
April 8, 2019 (v1)
Subject: Materials
Keywords: Adsorption, coagulation, organic ligands, stability, water treatment, ZnO NPs
The large-scale production and usage of zinc oxide nanoparticles (ZnO NPs) may lead to their post-release into the aquatic environment. In this study, the effect of hydrophobic/hydrophilic organic ligands on sorption and sedimentation of ZnO NPs has been systematically investigated. In addition, the coagulation efficiency of ZnO NPs, Zn2+, dissolved organic carbon (DOC), and UV254 with varying ferric chloride (FC) dosages in synthetic waters were also evaluated. The results showed that the higher concentration of organic ligands, i.e., humic acid (HA), salicylic acid (SA), and L-cysteine (L-cys) reduced the ζ-potential and hydrodynamic diameter (HDD) of particles, which enhanced the NPs stability. The adsorption of organic ligands onto ZnO NPs was fitted with the Langmuir model, with maximum adsorption capacities of 143, 40.47, and 66.05 mg/g for HA, SA and L-cys respectively. Removal of up to 95% of ZnO NPs and Zn2+ was achieved in studied waters at the effective coagulation zone (ECR... [more]
Basic Dye Removal with Sorption onto Low-Cost Natural Textile Fibers
George Z. Kyzas, Evi Christodoulou, Dimitrios N. Bikiaris
April 8, 2019 (v1)
Subject: Materials
Keywords: characterization, dyes, equilibrium, fibers, reuse, sorption
Over the last several years, the trend of researchers has been to use some very low-cost materials as adsorbents. For this purpose, some already commercially used bast fibers were selected as potential adsorbent materials to remove basic dye from synthetic effluents. The adsorption of basic yellow 37 dye was studied using three different bast fibers under the names of flax, ramie, and kenaf. Their morphological structure was examined using several techniques such as scanning electron microscopy (SEM), crystallinity, X-Ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), as well as those characterizations being a useful tool to propose a mechanism of the whole adsorption process. The adsorption evaluation was achieved by studying at first the pH (12) and temperature effects (25⁻55 °C). Two isotherm models (Langmuir and Freundlich) were also applied to the experimental equilibrium data revealing the superiority of ramie fibers (327, 435, and 460 mg·g−1 (25 °C) for ke... [more]
Mass Transfer in Multiphasic Gas/Liquid/Liquid Systems. KLa Determination Using the Effectiveness-Number of Transfer Unit Method
Éric Dumont
April 8, 2019 (v1)
Subject: Materials
Keywords: Absorption, effectiveness-NTU method, KLa, mass transfer, TPPB, VOC
The Effectiveness-Number of Transfer Unit method (ε-NTU method) was applied to determine the overall mass transfer coefficient, KLa, of operating gas-liquid absorbers treating Volatile Organic Compounds (VOCs). This method requires the knowledge of the operating conditions (gas flow rate, QG; liquid flow rate, QL; scrubber volume V), the measurement of gaseous concentrations at the inlet, CGin, and at the outlet, CGout, of the contactor (in order to determine the effectiveness of the absorber ε) and the calculation of the Henry coefficient of the VOC between the gas and the liquid phases (HVOC). Coupled with the “equivalent absorption capacity„ concept, the ε-NTU method was used to determine KLa of absorbers contacting a gas and a mixture of water and a Non Aqueous Phase, successfully. The method, validated from literature data for configurations countercurrent scrubbers and stirred tank reactors, could be used to simply determine the overall mass transfer coefficient of systems for wh... [more]
Adsorptive Properties of Poly(1-methylpyrrol-2-ylsquaraine) Particles for the Removal of Endocrine-Disrupting Chemicals from Aqueous Solutions: Batch and Fixed-Bed Column Studies
Augustine O. Ifelebuegu, Habibath T. Salauh, Yihuai Zhang, Daniel E. Lynch
April 8, 2019 (v1)
Subject: Materials
Keywords: Adsorption, breakthrough, EDCs, fixed-bed column, PMPS particles
The adsorptive properties of poly(1-methylpyrrol-2-ylsquaraine) (PMPS) particles were investigated in batch and column adsorption experiments as alternative adsorbent for the treatment of endocrine-disrupting chemicals in water. The PMPS particles were synthesised by condensing 3,4-dihydroxycyclobut-3-ene-1,2-dione (squaric acid) with 1-methylpyrrole in butanol. The results demonstrated that PMPS particles are effective in the removal of endocrine disrupting chemicals (EDCs) in water with adsorption being more favourable at an acidic pH, and a superior sorption capacity being achieved at pH 4. The results also showed that the removal of EDCs by the PMPS particles was a complex process involving multiple rate-limiting steps and physicochemical interactions between the EDCs and the particles. Gibbs free energy of −8.32 kJ/mole and −6.6 kJ/mol, and enthalpies of 68 kJ/mol and 43 kJ/mol, were achieved for the adsorption E2 and EE2 respectively The removal efficiencies of the EDCs by PMPS p... [more]
Dopamine Incorporated Forward Osmosis Membranes with High Structural Stability and Chlorine Resistance
Yi Wang, Zhendong Fang, Chaoxin Xie, Shuaifei Zhao, Derrick Ng, Zongli Xie
April 8, 2019 (v1)
Subject: Materials
Keywords: chlorine resistance, dopamine, forward osmosis, interfacial polymerization, structural stability, thin-film composite
The degradation and detachment of the polyamide (PA) layer for the conventional thin-film composite (TFC) membranes due to chemical disinfectants cleaning with chlorine and material difference of PA layer and substrate are two major bottlenecks of forward osmosis (FO) technology. In this study, a new type of FO membranes was first prepared by controlling dopamine (DA) as the sole amine in the aqueous phase and the reaction with trimesoyl chloride (TMC) as the acyl chloride during interfacial polymerization (IP) process. The influence of membrane synthesis parameters such as monomer concentration, pH of the aqueous phase, IP reaction time and IP temperature were systematically investigated. The optimized membrane showed both improved structure stability and chlorine resistance, more so than the conventional TFC membrane. In general, novel DA/TMC TFC membranes could be an effective strategy to synthesize high-performance FO membranes with excellent structural stability and chlorine resis... [more]
Supported Ionic Liquid Membranes for Separation of Lignin Aqueous Solutions
Ricardo Abejón, Javier Rabadán, Silvia Lanza, Azucena Abejón, Aurora Garea, Angel Irabien
April 8, 2019 (v1)
Subject: Materials
Keywords: glucose, lignin, separation, supported ionic liquid membranes, xylose
Lignin valorization is a key aspect to design sustainable management systems for lignocellulosic biomass. The successful implementation of bio-refineries requires high value added applications for the chemicals derived from lignin. Without effective separation processes, the achievement of this purpose is difficult. Supported ionic liquid membranes can play a relevant role in the separation and purification of lignocellulosic components. This work investigated different supported ionic liquid membranes for selective transport of two different types of technical lignins (Kraft lignin and lignosulphonate) and monosaccharides (xylose and glucose) in aqueous solution. Although five different membrane supports and nine ionic liquids were tested, only the system composed by [BMIM][DBP] as an ionic liquid and polytetrafluoroethylene (PTFE) as a membrane support allowed the selective transport of the tested solutes. The results obtained with this selective membrane demonstrated that lignins we... [more]
Experimental Study on Specific Heat of Concrete at High Temperatures and Its Influence on Thermal Energy Storage
Jianwen Pan, Renxin Zou, Feng Jin
March 26, 2019 (v1)
Subject: Materials
Keywords: concrete, high temperature, specific heat, thermal energy storage
Using concrete as a thermal energy storage (TES) material is a promising option for large-scale solar-thermal resource development and utilization. Specific heat is one of the most important characteristics for TES performance. In this paper, the half-open dynamic method based on the mixing principle is proposed and applied to measure concrete-specific heat at temperatures up to 600 °C. Measurement of the specific heat of corundum ceramic (99% Al₂O₃) is first performed, and the test results illustrate the accuracy and efficiency of the proposed test method. Furthermore, concrete-specific heat tests are carried out at high temperatures. It found that the specific heat increases as the temperature rises, especially, linearly in the range of 300⁻600 °C, in which the concrete TES module is expected to be in operation. Finally, the effect of concrete-specific heat changes with temperature on its TES capacity is investigated, demonstrating that specific heat is of great significance for conc... [more]
Mechanical Properties of Longmaxi Black Organic-Rich Shale Samples from South China under Uniaxial and Triaxial Compression States
Yusong Wu, Xiao Li, Jianming He, Bo Zheng
February 27, 2019 (v1)
Subject: Materials
Keywords: anisotropy, bedding, confining pressure, hydraulic fracturing, rock mechanics, shale
With the exploitation of shale gas booming all over the world, more and more studies are focused on the core technology, hydraulic fracturing, to improve commercial exploitation. Shale gas resources in China are enormous. In this research, a series of tests were carried out with samples of black organic-rich shale from the Lower Silurian Longmaxi formation, south China. Samples were drilled from different directions and were subjected to uniaxial and triaxial condition with various confining pressures, aiming at studying its rock mechanics properties, so as to provide basis for research and breakthrough of hydraulic fracturing technology. According to the results of the study, the development and distribution of shale’s bedding planes significantly impact its mechanical properties. Shale samples show obvious brittle characteristics under low confining pressure, and its mechanical behavior begins to transform from brittle to plastic characteristics with increasing confining pressure. Sh... [more]
Membrane Permeability Rates of Vanadium Ions and Their Effects on Temperature Variation in Vanadium Redox Batteries
Liuyue Cao, Anders Kronander, Ao Tang, Da-Wei Wang, Maria Skyllas-Kazacos
February 27, 2019 (v1)
Subject: Materials
Keywords: capacity, crossover, diffusion, ion exchange membrane, permeability rates, side reactions, vanadium redox flow batteries (VRFBs)
The inevitable diffusion of vanadium ions across the membrane can cause considerable capacity loss and temperature increase in vanadium redox flow batteries (VRFBs) over long term operation. Reliable experimental data of the permeability rates of vanadium ions are needed for membrane selection and for use in mathematical models to predict long-term behavior. In this paper a number of ion exchange membranes were selected for detailed evaluation using a modified approach to obtain more accurate permeation rates of V2+, V3+, VO2+ and VO₂⁺ ions. Three commercial ion exchange membranes—FAP450, VB2 and F930—are investigated. The obtained diffusion coefficients are then employed in dynamic models to predict the thermal behavior under specific operating conditions. The simulation results prove that smaller and more balanced permeability rates of V2+ and VO₂⁺ ions are more important to avoid large temperature increases in the cell stack during stand-by periods at high states-of-charge with pump... [more]
Shear Resistance Properties of Modified Nano-SiO₂/AA/AM Copolymer Oil Displacement Agent
Nanjun Lai, Xin Guo, Ning Zhou, Qian Xu
February 27, 2019 (v1)
Subject: Materials
Keywords: enhanced oil recovery, modification degrees, rheological property, shear resistance, the modified nano-SiO2/AA/AM copolymer
To address the problem regarding poor shear resistance of commonly employed polymers for oil displacement, modified nano-SiO₂/AA/AM copolymer (HPMNS) oil displacement agents were synthesized using acrylic acid (AA), acrylamide (AM), and modified nano-SiO₂ of different modification degrees as raw materials. HPMNS was characterized by means of infrared spectroscopy (IR), nuclear magnetic resonance (¹H-NMR, 13C-NMR), dynamic/static light scattering, and scanning electron microscope. A comparative study of the shear resistance properties for partially hydrolyzed polyacrylamide (HPAM) and HPMNS was conducted. Compared to HPAM, the introduced hyperbranched structure endowed HPMNS with good shear resistance, which was quantified from the viscosity retention ratio of the polymer solutions. From the perspective of rheological property, HPMNS also showed great shear stability after shearing by a Mixing Speed Governor and porous media shear model. Furthermore, with a higher degree of modification... [more]
Experimental and Simulation Studies of Strength and Fracture Behaviors of Wind Turbine Bearing Steel Processed by High Pressure Torsion
Ning Wang, Luis V. Wilches Peña, Ling Wang, B. G. Mellor, Yi Huang
February 27, 2019 (v1)
Subject: Materials
Keywords: high pressure torsion (HPT), mechanical properties, microstructure, white etching area (WEA)
White structure flaking (WSF) has been found to be one of the failure modes in bearing steels under rolling contacts through the formation of cracks associated with a microstructural change called white etching area (WEA). In the present research, the effects of the high-pressure torsion (HPT) process on the microstructure and mechanical properties of an AISI 52100 alloy are studied. An annealed AISI 52100 was subjected to high-pressure torsion at room temperature under a pressure of up to ~6 GPa for up to three turns. Finite-element modeling (FEM) was used to simulate the process under high-pressure torsion and quasi-constrained conditions to reveal the material property changes occurring in HPT. Scanning electron microscopy and microhardness testing after processing were used to investigate the microstructural and mechanical property evolution of the steel. Strain induced microstructural transformations occur and affect the mechanical properties in a similar way to the well-known whi... [more]
One-Dimensional TiO₂ Nanostructured Photoanodes: From Dye-Sensitised Solar Cells to Perovskite Solar Cells
Jung-Ho Yun, Lianzhou Wang, Rose Amal, Yun Hau Ng
February 27, 2019 (v1)
Subject: Materials
Keywords: charge transport, dye-sensitised solar cells (DSCs), light harvesting efficiency, one-dimensional (1D) TiO2 nanostructure, perovskite solar cells (PSCs), photoanode
This review presents one dimensional (1D) TiO₂ nanostructured photoanodes for next generation solar cells such as dye-sensitised solar cells (DSCs) and perovskite solar cells (PSCs). Due to the unique morphological properties, 1D TiO₂ nanostructures can act as express electron channels as well as light scattering layer, leading to improved charge transport properties, such as charge separation, electron injection, and electron lifetime, and light harvesting efficiency. As 1D TiO₂ nanostructures are applied to solar cells, 1D TiO₂ nanostructures should be further modified to overcome some drawbacks. In this review, we have described some solutions by introducing various 1D TiO₂ synthetic methods and device fabrication processes for solar cell applications, where we have described some important surface engineering and hierarchical device design strategies that facilitate charge transport and light utilisation in 1D TiO₂ nanostructured photoanode system.
Aluminum⁻Titanium Alloy Back Contact Reducing Production Cost of Silicon Thin-Film Solar Cells
Hsin-Yu Wu, Chia-Hsun Hsu, Shui-Yang Lien, Yeu-Long Jiang
February 5, 2019 (v1)
Subject: Materials
Keywords: aluminum–titanium (AlTi) alloy, contact resistance, silicon thin-film solar cells
In this study, metal films are fabricated by using an in-line reactive direct current magnetron sputtering system. The aluminum⁻titanium (AlTi) back contacts are prepared by changing the pressure from 10 mTorr to 25 mTorr. The optical, electrical and structural properties of the metal back contacts are investigated. The solar cells with the AlTi had lower contact resistance than those with the silver (Ag) back contact, resulting in a higher fill factor. The AlTi contact can achieve a solar cell conversion efficiency as high as that obtained from the Ag contact. These findings encourage the potential adoption of AlTi films as an alternative back contact to silver for silicon thin-film solar cells.
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