Issue 6

Self-sealing Polymeric Materials: Mechanism and Applications

Nand Kumar; Dibyendu Sekhar Bag; Krishna Pratap Singh; Akansha Dixit; Shashank Mishra; Durgesh Nath Tripathi; Namburi Eswara Prasad

Advanced Materials Letters, 2020, Volume 11, Issue 6, Pages 1-11
DOI: 10.5185/amlett.2020.061521

Self-sealing polymers possess the virtue to seal small punctures/cracks/damages automatically whenever occurred in the materials/components during their service. This behaviour of self-sealing in polymeric materials is inspired by the biological system in which self-sealing is a usual phenomenon. There are many self-sealing approaches demonstrated by researchers which are being applied in many polymeric components and systems to prevent them from catastrophic failure. The sealant materials in these systems are the main parts which play a crucial role in the sealing phenomenon. This review article describes self-sealing phenomenon, sealant materials and their applications in the various strategic materials and systems namely self-sealing spacecraft structures in the meteoroid environments, self-sealing fuel tank for fighter aircrafts, self-sealing hemostatic syringe to prevent bleeding, self-sealing tires to prevent punctures and concrete structures to prevent water leakages etc. 

Researcher of the Year 2020: Professor Herbert Gleiter, Germany

Ashutosh Tiwari

Advanced Materials Letters, 2020, Volume 11, Issue 6, Pages 1-8
DOI: 10.5185/amlett.2020.061520

Researcher of the year is considered one of the highest honors for a researcher working in a diverse background, either from Physical, Chemical, Biological, Engineering, Mathematical and Medical Sciences along with their substantial contribution towards ‘research perspective, expanding education, promoting materials research and its applications at a global standard’, mentoring professionals and series of advancements on the related topics.

Development of Ruthenium Complex Based Sensitizers, Organic Based Sensitizers, and Co-sensitization System for Dye-sensitized Solar Cells

Chan K.F.; Lim H.N. Huang N.M.; Ahmad H.

Advanced Materials Letters, 2020, Volume 11, Issue 6, Pages 1-12
DOI: 10.5185/amlett.2020.061522

This paper reviews the recent development of ruthenium complex sensitizers, organic sensitizers, and co-sensitizers for dye-sensitized solar cell (DSSC) applications. The development of ruthenium sensitizers has progressed from thiocyanate (NCS) ligands containing bipyridyl, terpyridyl, quarterpyridyl, and cyclometalated ruthenium sensitizers to NCS-free analogs. The integration of organic moieties and ruthenium complex ancillary ligands into a single structure entity was also achieved in the DSSC industry. The development of organic sensitizers as an alternative to ruthenium-based sensitizers was also discussed according to their functional segment: donor, acceptor, and π-spacer. The modification of donor groups has been focused on introducing ancillary groups to increase the molar extinction coefficient and electron recombination resistance. Anchoring groups other than cyanoacrylic acids have been developed to improve the anchoring ability of organic sensitizers while maintaining their light-harvesting properties. A study was performed on π-spacers modified with different conjugation lengths and conjugated side chains in order to enhance the charge transfer within organic sensitizers. Co-sensitization systems, including metal-metal, metal-organic, and organic-organic systems with stepwise and “cocktail” co-sensitization methods will be discussed in this review.

Characterization of a New Copper Paste for Printed Electronics

Ihssan Hendi; Matthieu Blaise; Gaétan Schneider; Manuel Fendler

Advanced Materials Letters, 2020, Volume 11, Issue 6, Pages 1-5
DOI: 10.5185/amlett.2020.061523

Printed electronics can be considered as an additive manufacturing technique allowing the fabrication of circuits and devices such as sensors, MEMS, LEDs, etc. An important research subject in this field is identifying new materials exhibiting low resistivity. In this article, we present a new copper paste interesting for structural electronics, based on additive manufacturing and laser activation. We characterized the structure of this copper paste after laser activation, by SEM, EDS, and FTIR. We also used four probe method to characterize sheet resistance to obtain a resistivity as low as 10 -7 Ω.m, and compared it to other commercial conductive pastes.

Co-Ni Nanowires Arrays with Tunable Properties Obtained by Template Synthesis

Ruxandra Vidu; Andra Mihaela Predescu; Ecaterina Matei; Andrei Berbecaru; Cristian Pantilimon; Claudia Dragan; Mirela Sohaciu; Cristian Predescu

Advanced Materials Letters, 2020, Volume 11, Issue 6, Pages 1-5
DOI: 10.5185/amlett.2020.061524

Co-Ni nanowires arrays were obtained by electrochemical template synthesis in a polycarbonate track etched (PCTE) membrane. To diminish the effects of anomalous deposition observed in the Co-Ni system, the electrochemical deposition was performed from a solution containing nickel and cobalt in an atomic ratio of 3:1. Electrochemical deposition was performed at constant potentials E = -0.8, -0.9, -1.0, -1.1, -1.2 V vs Ag/AgCl for 15 min. The structures were characterized electrochemically via cyclic voltammetry, chronoamperometry, and charge stripping. Co-Ni nanowires were characterized by scanning electron microscopy (SEM/EDAX) to assess the morphology and the composition of the Co-Ni alloy nanowires at different deposition potentials. Electrochemical and structural analysis provided details of their deposition kinetics, structure, and morphology, which would be used to build nanowires array with controlled structure and composition.

Dispersion of Multi-Walled Carbon Nanotubes Using Polyvinylpyrrolidone for Application in Cement - Based Composites to Enhance Electrical Conductivity

Ghimire Prateek; Yulin Wang; Henggan Li; Yuanfu Ban; Hao Luo; Danping Lin; Jinglong Yang; Shuyan Lin; Zhengyang Pan; Qingwei Su

Advanced Materials Letters, 2020, Volume 11, Issue 6, Pages 1-8
DOI: 10.5185/amlett.2020.061525

The purpose of this study is to analyse the effective method of dispersion of MWCNTs for the application in cement-based composites. Efficient dispersion of Carbon Nanotubes (CNTs) is one of the most challenging and crucial aspects for the application in cement-based composite. In this study, two different CNTs, pristine and functionalized (p-MWCNTs and f-MWCNTs) were dispersed in de-ionized water using different surfactants, Polyvinylpyrrolidone (PVP k-30 and PVP k-90) & Sodium Dodecyl Sulfate (SDS) and conducted a comparative investigation of the effects. Dispersion using an ultrasonic, treatment with surfactant and integrated method of both were analysed. The influence of CNTs dispersion on the electrical conductivity of the aqueous solution and to cement composites has been studied. Among the surfactant used PVPk-30 provide the best-dispersing effect while PVPk-30+SDS shows an extraordinary enhancement of conductivity of an aqueous solution. Analysis of electrical conductivity of Various % CNTs’ loaded specimen (0,0.001,0.003,0.025 wt.%) with different curing period (3,7,14,21,28 days) showed that the electrical resistivity decreases with CNTs’ loading. Dispersion effect of surfactant on p-MWCNTs and f-MWCNTs has been characterized by Ultraviolet-visible Spectroscopy (UV-Vis) and electrical resistivity measurement is carried for investigation and comparison on enhancement of electrical conductivity. 

Towards a Physics Based Model of Magnetic Barkhausen Noise in Steel 

Thomas W. Krause; Aroba Saleem; P. Ross Underhill

Advanced Materials Letters, 2020, Volume 11, Issue 6, Pages 1-6
DOI: 10.5185/amlett.2020.061526

Ferromagnetic iron based alloys are used in many important steel products including electrical steels, oil and gas pipelines, naval structures, aircraft landing gear and automotive components. Magnetic properties of these materials are vital for such applications as electrical motors and transformers, where they have direct implications for energy efficiency. Many inspection methods rely on measurement of magnetic response including magnetic particle inspection, magnetic flux leakage, metal magnetic memory, magnetic adaptive testing and magnetic Barkhausen noise (MBN).  Understanding the dependence of magnetic properties on material condition is particularly important for detection of residual stress using MBN. This paper examines MBN response in a high strength naval steel, Q1N, undergoing magnetization, including domain structure, which is modified by application of tensile stress, and its interaction with pinning sites within grains, as provided by impurity elements and carbides, whose density is varied by isothermal tempering treatment. A physical basis for modifying domain structure and experimentally examining its interaction with changing pinning site density via temper embrittlement is presented to investigate stress dependent behaviour of MBN in such steel materials. The introduction of this experimental process will facilitate the potential of MBN sensing technology for advanced monitoring of steel structure condition.

Sustainable Concept and Economic Evaluation of a Solar-Powered Hydrogen Generation Unit

Laura Langenbucher; Lukasz Brodecki; Michael Wiesmeth; Ines Klugius; Heiner Hüppelshäuser; Markus Blesl; Ralf Wörner

Advanced Materials Letters, 2020, Volume 11, Issue 6, Pages 1-7
DOI: 10.5185/amlett.2020.061527

This study focuses on an overall energy consumption prediction for the area of Stuttgart city in Germany and a specific analysis of a solar-fed power-to-gas plant in an industrial area close to Stuttgart. In order to achieve decarbonisation targets, a sustainable concept of hydrogen production and mobility based on renewable energy and a zero-emissions scenario was defined. First, an energy system analysis was conducted to assess the viability of hydrogen as fuel in the system context. Scenario results indicate the increased penetration rate of electric mobility with systematic repercussions on other traffic, power generation and consumption as well as the achievement of the local targets for the reduction of greenhouse gas emissions. As a result, this allows us to make an assessment regarding the relative advantages of hydrogen over alternative propulsion technologies. In a second step, the minimum purchase costs of hydrogen are determined, based on a total-cost-of-ownership calculation for an individual energy plant application. In a last chapter of this work, a study was conducted on a zero-emission bus fleet using the total costs of mobility method. The results of this study serve a pioneering role model in urban areas and shall be transferable to projects throughout Europe. Copyright © VBRI Press.

Macrocell Corrosion and its Countermeasure for Reinforced Concrete after Patch Repair

Shinichi Miyazato;Daishin Hanaoka

Advanced Materials Letters, 2020, Volume 11, Issue 6, Pages 1-6
DOI: 10.5185/amlett.2020.061528

Reinforced concrete has been used in civil infrastructure development for several decades. However, steel bars used in some concrete structures are easily corroded by chlorides. In particular, when an existing concrete structure, after a patch repair, has a large quantity of unremoved chloride, local corrosions are generated in the steel bars. The purpose of this study is to analyze the macrocell corrosion mechanism in a reinforced concrete structure after a patch repair and to determine the influence of corrosion on structural performance. Additionally, a method to continue safely using reinforced concrete after a patch repair is proposed. The results of this study suggest that theoretically, the macrocell corrosion rate is high, based on an intersection point of an anodic and a cathodic polarization curves. It is also found that the macrocell corrosion increases when the chloride ion content exhibits a large difference. Additionally, it can be confirmed that increasing the extent of corrosion decreases the bending fracture load of the beam. Finally, a method is proposed to control macrocell corrosion. 

Modelling the Height of Hydrothermally Synthesized Titanium Dioxide Nanostructures

Alka Jaggessar; Prasad KDV Yarlagadda

Advanced Materials Letters, 2020, Volume 11, Issue 6, Pages 1-6
DOI: 10.5185/amlett.2020.061529

Bacterial infection is a widespread concern for the medical community. With the rise of antibiotic resistant bacteria strains, research has begun to focus on developing bactericidal surfaces as a method of infection control, to reduce society’s dependence on antibiotics. Previous work in this area has established hydrothermal synthesis as an effective method of fabricating bactericidal titanium dioxide nanostructures, with structure height statistically correlated to bactericidal efficiency. This study investigates the effect of NaOH concentration, reaction temperature and reaction time on hydrothermally synthesized TiO2 nanostructures. Various TiO2 nanostructured surfaces, morphologies and dimensions were achieved by altering hydrothermal process conditions. This data was used to develop 3 models to predict nanostructure height, as a function of hydrothermal fabrication conditions. The three models are qualitatively validated using statistical data. These models provide a preliminary basis of modelling TiO2 nanostructure growth during hydrothermal synthesis. The findings of this study are significant for the designing of nanostructured surfaces for antibacterial applications, and users of the hydrothermal method for effective and efficient nanostructure fabrication.

Cellular SiC/Iron Alloy Composite

Barbara Lipowska; Bronisław Psiuk; Mirosław Cholewa

Advanced Materials Letters, 2020, Volume 11, Issue 6, Pages 1-5
DOI: 10.5185/amlett.2020.061530

Cellular SiC/iron alloy composite with a spatial structure of mutually intersecting skeletons created with a porous ceramic preform has not been obtained before, despite promising spectrum of potential uses. We tested the possibility of obtaining such material using a SiC material with an oxynitride bonding and grey cast iron. Porous ceramic preforms were made by pouring the gelling ceramic suspension over a foamed polymer base which was next fired. The obtained samples of materials were subjected to macroscopic and microscopic observations as well as investigations into the chemical composition in microareas. It was found that the minimum width of a channel in the preform, which in the case of pressureless infiltration enables molten cast iron penetration, ranges from 0.10 to 0.17 mm. It was also found that the ceramic material applied was characterized by good metal wettability. Were the channels are wide enough for the metal penetration we observed that the ceramics/metal contact area always has a transition zone in which mixing of both components takes place.

Conceptual Design of the CSP Lead Demonstrator SOLEAD

I. Di Piazza; A. Tincani; R. Marinari; M. Valdiserri; S. Bassini; A. Rinaldi; M. Serra; A. Antonelli; D. Delfino

Advanced Materials Letters, 2020, Volume 11, Issue 6, Pages 1-7
DOI: 10.5185/amlett.2020.061531

The NEXTOWER H2020 EU project investigates the possibility of using liquid lead as heat storage medium for high-temperature Thermal Energy Storage (TES) in concentrated solar power plants. To that end, within such project, a demonstration TES unit named SOLEAD (SOlar LEAd Demonstrator) is being developed and will be coupled with an open volumetric air receiver in a solar tower CSP system. The SOLEAD demonstrator will be built and operated at the Plataforma Solar de Almeria (Spain) as a result of the project effort. In the present paper, the conceptual design of the SOLEAD demonstrator is illustrated in details. Basically, SOLEAD is a single-tank thermocline TES system using a pool of liquid lead as heat storage medium. The receiver collects energy from the solar field and heats atmospheric air up to 900°C; the hot air is then used to thermally charge the SOLEAD system through an air-lead primary heat exchanger located in the lower part of the lead pool. In particular, one of the goals of the design is to reach a temperature stratification from 600°C (lower part) to 750°C (upper part), which cannot be achieved with the common molten salt mixtures used in commercial TES systems for CSP applications. The thermal stratification is obtained by positioning the primary heat exchanger in the bottom part of the pool and by exploiting the buoyancy forces to promote natural circulation in the pool. This method avoids the use of a pump with an impeller and a proper orifice calibration allows to attain in the average the required mass flow rate and temperature drop in the system. The design of the air-lead primary heat exchanger is innovative and challenging due to the poor heat transfer properties of the atmospheric air at 900°C. The Heat exchanger is counter-current bayonet type with the air on the bayonet side and the lead on the shell side. The design of the heat exchanger was performed by a large use of CFD tools and modelling and includes a riser to guide the flow path and to bring the hot fluid in the top part of the pool.

Numerical and Experimental Analyses of Equal Channel Angular Processing of Pure Aluminum

W.H. El-Garaihy

Advanced Materials Letters, 2020, Volume 11, Issue 6, Pages 1-5
DOI: 10.5185/amlett.2020.061532

Nowadays, Equal Channel Angular Processing (ECAP) is one of the most appealing and potentially efficient Severe Plastic Deformation techniques (SPD) for fabricating Ultrafine Grained (UFG) and Nanostructured materials (NS) with sufficiently improved mechanical properties which has enabled this technique to be used in industrial applications. In this study, commercially pure aluminum was processed by ECAP through route A for up to 4 passes. A Finite Element (FE) analysis was carried out and compared to the experimental findings in order to investigate the effects of the geometric and the process’ parameters on the plastic deformation behavior of the work-piece during the ECAP process. The number of passes was selected as an input factor, while hardness values and compressive properties were modeled as the response. The total imposed stresses and strain as a function of the number of passes were examined. The FE analysis were carried out, yielding favorable results, concurring perfectly with the experimental findings and the microstructural evolution.