Advanced Materials Processing Research Articles

Excitation and propagation of surface plasmon polaritons on a non-structured surface with a permittivity gradient.

Accompanied by the rise of plasmonic materials beyond those based on noble metals and the development of advanced materials processing techniques, it is important to understand the plasmonic behavior of materials with large-scale inhomogeneity (such as gradient permittivity materials) because they cannot be modeled simply as scatterers. In this paper, we theoretically analyze the excitation and propagation of surface plasmon polaritons (SPPs) on a planar interface between a homogeneous dielectric and a material with a gradient of negative permittivity. We demonstrate the following: (i) free-space propagating waves and surface waves can be coupled by a gradient negative-permittivity material and (ii) the coupling can be enhanced if the material permittivity variation is suitably designed. This theory is then verified by numerical simulations. A direct application of this theory, ‘rainbow trapping’, is also proposed, considering a realistic design based on doped indium antimonide. This theory may lead to various applications, such as ultracompact spectroscopy and dynamically controllable generation of SPPs.

Microstructure and Corrosion Resistance of Laser Additively Manufactured 316L Stainless Steel

Additive manufacturing (AM) of metal alloys to produce complex part designs via powder bed fusion methods such as laser melting promises to be a transformative technology for advanced materials processing. However, effective implementation of AM processes requires a clear understanding of the processing–structure–properties–performance relationships in fabricated components. In this study, we report on the formation of micro and nanoscale structures in 316L stainless steel samples printed by laser AM and their implications for general corrosion resistance. A variety of techniques including x-ray diffraction, optical, scanning and transmission electron microscopy, x-ray fluorescence, and energy dispersive x-ray spectroscopy were employed to characterize the microstructure and chemistry of the laser additively manufactured 316L stainless steel, which are compared with wrought 316L coupons via electrochemical polarization. Apparent segregation of Mo has been found to contribute to a loss of passivity and an increased anodic current density. While porosity will also likely impact the environmental performance (e.g., facilitating crevice corrosion) of AM alloys, this work demonstrates the critical influence of microstructure and heterogeneous solute distributions on the corrosion resistance of laser additively manufactured 316L stainless steel.

Holographic femtosecond laser manipulation for advanced material processing

Abstract Parallel femtosecond laser processing using a computer-generated hologram displayed on a spatial light modulator, known as holographic femtosecond laser processing, provides the advantages of high throughput and high-energy use efficiency. Therefore, it has been widely used in many applications, including laser material processing, two-photon polymerization, two-photon microscopy, and optical manipulation of biological cells. In this paper, we review the development of holographic femtosecond laser processing over the past few years from the perspective of wavefront and polarization modulation. In particular, line-shaped and vector-wave femtosecond laser processing are addressed. These beam-shaping techniques are useful for performing large-area machining in laser cutting, peeling, and grooving of materials and for high-speed fabrication of the complex nanostructures that are applied to material-surface texturing to control tribological properties, wettability, reflectance, and retardance. Furthermore, issues related to the nonuniformity of diffraction light intensity in optical reconstruction and wavelength dispersion from a computer-generated hologram are addressed. As a result, large-scale holographic femtosecond laser processing over 1000 diffraction spots was successfully demonstrated on a glass sample.

Hybrid Perovskites for Photovoltaics: Charge-Carrier Recombination, Diffusion, and Radiative Efficiencies.

Photovoltaic (PV) devices that harvest the energy provided by the sun have great potential as renewable energy sources, yet uptake has been hampered by the increased cost of solar electricity compared with fossil fuels. Hybrid metal halide perovskites have recently emerged as low-cost active materials in PV cells with power conversion efficiencies now exceeding 20%. Rapid progress has been achieved over only a few years through improvements in materials processing and device design. In addition, hybrid perovskites appear to be good light emitters under certain conditions, raising the prospect of applications in low-cost light-emitting diodes and lasers. Further optimization of such hybrid perovskite devices now needs to be supported by a better understanding of how light is converted into electrical currents and vice versa. This Account provides an overview of charge-carrier recombination and mobility mechanisms encountered in such materials. Optical-pump-terahertz-probe (OPTP) photoconductivity spectroscopy is an ideal tool here, because it allows the dynamics of mobile charge carriers inside the perovskite to be monitored following excitation with a short laser pulse whose photon energy falls into the range of the solar spectrum. We first review our insights gained from transient OPTP and photoluminescence spectroscopy on the mechanisms dominating charge-carrier recombination in these materials. We discuss that mono-molecular charge-recombination predominantly originates from trapping of charges, with trap depths being relatively shallow (tens of millielectronvolts) for hybrid lead iodide perovskites. Bimolecular recombination arises from direct band-to-band electron-hole recombination and is found to be in significant violation of the simple Langevin model. Auger recombination exhibits links with electronic band structure, in accordance with its requirement for energy and momentum conservation for all charges involved. We further discuss charge-carrier mobility values extracted from OPTP measurements and their dependence on perovskite composition and morphology. The significance of the reviewed charge-carrier recombination and mobility parameters is subsequently evaluated in terms of the charge-carrier diffusion lengths and radiative efficiencies that may be obtained for such hybrid perovskites. We particularly focus on calculating such quantities in the limit of ultra-low trap-related recombination, which has not yet been demonstrated but could be reached through further advances in material processing. We find that for thin films of hybrid lead iodide perovskites with typical charge-carrier mobilities of ∼30cm(2)/(V s), charge-carrier diffusion lengths at solar (AM1.5) irradiation are unlikely to exceed ∼10 μm even if all trap-related recombination is eliminated. We further examine the radiative efficiency for hybrid lead halide perovskite films and show that if high efficiencies are to be obtained for intermediate charge-carrier densities (n ≈ 10(14) cm(-3)) trap-related recombination lifetimes will have to be enhanced well into the microsecond range.

Study on Preparation of Flexible Semiconductor Electrode for Dye-sensitized Solar Cells by EPD

In recent years, the development of DSSC produced considerable research interest, including improving efficiency, packaging and flexible possibilities. Flexible possibility has great potential for all kinds of applications. Researches on the bendability of the solar cell thin sheets are mostly focus on the making the soft substrate or electrodes. Previous studies showed that coating method of TiO2 semiconductor electrodes cracked after bending. This phenomenon makes the DSSC efficiency and lifetime substantially decline. The electrophoretic deposition (EPD) technique with a wide range of novel applications in the processing of advanced materials and coatings, has recently gained increasing interest both in academia and industrial sector not only because of the high versatility of its use with different materials and their combinations but also because of its cost-effectiveness requiring simple apparatus. This study used a flexible conductive material (ITO-PEN) as substrate. The semiconductor electrode was prepared by eletrophoresis deposition (EPD) method. After bending test, we observe the morphology and electrical properties of semiconductor electrodes. The photocurrent-voltage characteristics of assembled the DSSC were measured by Luzchem Solar Simulator (standard AM 1.5). Results of flexible DSSC indicated that feature enables the flexible solar cells after bending to avoid fragmentation of semiconductor electrodes, and the efficiency doesn't decrease.

To spin or not to spin: spider silk fibers and more.

Spider silk fibers have a sophisticated hierarchical structure composed of proteins with highly repetitive sequences. Their extraordinary mechanical properties, defined by a unique combination of strength and extensibility, are superior to most man-made fibers. Therefore, spider silk has fascinated mankind for thousands of years. However, due to their aggressive territorial behavior, farming of spiders is not feasible on a large scale. For this reason, biotechnological approaches were recently developed for the production of recombinant spider silk proteins. These recombinant proteins can be assembled into a variety of morphologies with a great range of properties for technical and medical applications. Here, the different approaches of biotechnological production and the advances in material processing toward various applications will be reviewed.

Various categories of defects after surface alloying induced by high current pulsed electron beam irradiation

High current pulsed electron beam (HCPEB) is an attractive advanced materials processing method which could highly increase the mechanical properties and corrosion resistance. However, how to eliminate different kinds of defects during irradiation by HCPEB especially in condition of adding new elements is a challenging task. In the present research, the titanium and TaNb-TiW composite films was deposited on the carburizing steel (SAE9310 steel) by DC magnetron sputtering before irradiation. The process of surface alloying was induced by HCPEB with pulse duration of 2.5μs and energy density ranging from 3 to 9J/cm2. Investigation of the microstructure indicated that there were several forms of defects after irradiation, such as surface unwetting, surface eruption, micro-cracks and layering. How the defects formed was explained by the results of electron microscopy and energy dispersive spectroscopy. The results also revealed that proper energy density (∼6J/cm2) and multi-number of irradiation (≥50 times) contributed to high quality of alloyed layers after irradiation.

ChemInform Abstract: Recent Approaches for the Direct Use of Elemental Sulfur in the Synthesis and Processing of Advanced Materials

AbstractReview: [recent physical processing methods and synthetic procedures involving the direct use of elemental sulfur; 93 refs.

Erratum to: Evaluation of the Mechanical Properties of AA 6063 Processed by Severe Plastic Deformation

DAVOUD MASHHADI JAFARLOU, Researcher, and NOOR AZIZI BIN MARDI, Senior Lecturer, are with the Department of Mechanical Engineering, Faculty of Engineering, University of Malaya, 50603 Kuala Lumpur, Malaysia, and also with the Centre of Advanced Manufacturing & Material Processing (AMMP), 50603 Kuala Lumpur, Malaysia. ERFAN ZALNEZHAD, Assistant Professor, is with the Department of Mechanical Convergence Engineering, Hanyang University, 222 Wangsimni-ro, Seongdong-gu, 133-791 Seoul, Korea. Contact e-mail: erfan@hanyang.ac.kr ABDELMAGID SALEM HAMOUDA, Professor, is with the Mechanical and Industrial Engineering Department, College of Engineering, Qatar University, P.O. Box 2713, Doha, Qatar. GHADER FARAJI, Assistant Professor, is with the School of Mechanical Engineering, College of Engineering, University of Tehran, 11155-4563 Tehran, Iran. MOHSEN ABDELNAEIM HASSAN MOHAMED, Associate Professor, is with the Department of Mechanical Engineering, Faculty of Engineering, University of Malaya and Centre of Advanced Manufacturing & Material Processing (AMMP), and also with the Department of Mechanical Engineering, Faculty of Engineering, Assiut University, Assiut 71516, Egypt. The online version of the original article can be found under doi:10.1007/s11661-015-2806-7. Article published online April 7, 2015

Recent Approaches for the Direct Use of Elemental Sulfur in the Synthesis and Processing of Advanced Materials

Elemental sulfur is an abundant and inexpensive material obtained as a by-product of natural-gas and petroleum refining operations. Recently, the need for the development of new energy-storage systems brought into light the potential of sulfur as a high-capacity cathode material in secondary batteries. Sulfur-containing materials were also shown to have useful IR optical properties. These developments coupled with growing environmental concerns related to the global production of excess elemental sulfur have led to a keen interest in its utilization as a feedstock in materials applications. This Minireview focuses on the recent developments on physical and chemical methods for directly processing elemental sulfur to produce functional composites and polymers.

Recent applications of microwaves in materials joining and surface coatings

The conventional methods of manufacturing and materials processing are getting obsolete owing to the higher energy consumptions, large processing times and poor characteristics of processed components. The limitations of conventional processing techniques for processing of large varieties of advanced materials which includes metal matrix composites, ceramics, cermets, metallic alloys, functionally graded materials and fiber-reinforced plastics forced researchers to find alternative and novel methods of manufacturing and material processing, which can overcome the limitations of conventional methods. Hence, it is mandatory to develop a new concept for processing advanced materials, which can provide better mechanical properties, reduced defects and economic advantages in terms of power and time savings. Microwave material processing emerged as one of the novel methods of material processing which can satisfy the present requirements and can yield a better product at reduced costs and processing time. This article discusses some of the novel recent applications of microwaves in the area of manufacturing.

In Situ Synchrotron Radiography and Spectrum Analysis of Transient Cavitation Bubbles in Molten Aluminium Alloy

The melt processing of conventional and advanced metallic materials with high-intensity ultrasonic vibrations significantly improves the quality and properties of molten metals during their solidification. These improvements are primarily attributed to ultrasonic cavitation: the creation, growth, pulsation, and collapse of bubbles in the liquid. However, the development of practical applications is limited by the lack of fundamental knowledge on the dynamics of the cavitation bubbles; it is very difficult to directly observe ultrasonic cavitation using conventional techniques in molten metals due their high temperature and opaqueness.In this study, an in situ synchrotron radiography experiment was performed to investigate bubble dynamics in an Al-10wt.% Cu alloy under an external ultrasound field at 30kHz. Radiographs with an exposure time of 78ms were collected continuously during the sonication of molten alloys at temperatures of 660±10°C. To the best of our knowledge, this is the first time that transient cavitation bubbles have been observed in liquid aluminium. Quantification of bubble parameters such as average size and time of collapse were evaluated from radiographs using advanced image analysis. Additionally, broadband noise associated with the acoustic emissions from shock waves of transient cavitation bubbles and estimation of the real-time acoustic pressure at the driving frequency were assessed using an advanced high-temperature cavitometer in separate bulk experiments.

Integrated Computational Materials Engineering: A Multi-Scale Approach

Computational materials science and engineering has a strong potential for developing robust simulation-based designs for optimizing materials, components, and engineering structures. Integrated computational materials engineering (ICME) provides practical solutions for engineering design tasks and has been recognized by the National Academy of Engineering (NAE Report 2008). The vital role of materials in design as well as the importance of computation in materials engineering necessitate understanding structure, properties, processing, and performance of materials and designed components. Thus, multiscale modeling has extended into solid mechanics, fluid mechanics, materials science, physics, mathematics, biology, and chemistry. ICME couples quantum scales with macroscales. It also allows the integration of materials processing and product performance for simulation-based manufacturing. These advances are analogous to transistor models that have led to complex logic operations and concurrent multilevel simulations. ICME can reduce product development time and costs by minimizing design cycles and facilitating cost-effective design optimization. These benefits have the potential to drive the utilization of multiscale modeling in various industrial sectors. The ‘‘integrated’’ part of ICME strongly emphasizes synergistic systems and interdisciplinary thinking accompanied by multiscale modeling methods. However, a key challenge is to link the various disciplines. Mathematics and statistics play a critical role and form a strong basis for modeling strategies. The terms ‘‘bottom-up’’ and ‘‘top-down’’ are of particular interest. The following characteristics are critical for these approaches: (I) length scales, (II) degrees of freedom and boundary conditions, (III) geometric and energy constraints, (IV) suitable numerical model implementation, (V) determining right sequence of calculations to be performed, (VI) determining variables and equations describing structure–property function, (VII) analyzing the cause–effect relationships using numerical methods, (VIII) verifying effects by experimental approaches before using the developed theory for next higher scales, and (IX) estimating the uncertainty in simulations and experiments to help develop a concrete multiscale modeling approach. This issue of JOM presents nine invited research and review articles. These articles discuss the importance of the ICME approach in refining conventional material and component processing methods as well as advanced materials processing. The article by Ghosh et al. discusses multiscale modeling of heterogeneous metals and alloys. They comprehensively address the problems related to hierarchical-concurrent multilevel or multiscale modeling methods for ductile fracture and nested dual-stage homogenization method for microstructure-based models for cast Al alloys. The two articles by Horstemeyer and colleagues detail the development and deployment of the modified embedded atom method (MEAM). The authors focus on the MATLAB-based MEAM potential calibration tool and interface with LAMMPS. The technique is used for studying aluminum system. To further define the ICME in ‘‘completeness,’’ the article by Liu et al. discusses case studies focused on three examples, where experiments are integrated with computation aspects. The modeling methods described include artificial neural networks, dislocation dynamics, and CALPHAD approach. Asadi et al. discuss the phase-field crystal model and multiscale analysis of solid–liquid structures. The article also compares various phase-field models for calculating solid–liquid interfaces. Bryan et al. demonstrate alloy design using the ICME-based Nitin Chopra is the Guest Editor for the ICME Committee of the TMS Materials Processing & Manufacturing Division, and coordinator of the topic Multi-Scale Modeling: Concurrent and Hierarchical Methods in this issue. JOM, Vol. 67, No. 1, 2015

Industrial plasmas in academia

The present review, written at the occasion of the 2014 EPS Innovation award, will give a short overview of the research and development of industrial plasmas within the last 30 years and will also provide a first glimpse into future developments of this important topic of plasma physics and plasma chemistry. In the present contribution, some of the industrial plasmas studied at the CRPP/EPFL at Lausanne are highlighted and their influence on modern plasma physics and also discharge physics is discussed. One of the most important problems is the treatment of large surfaces, such as that used in solar cells, but also in more daily applications, such as the packaging industry. In this contribution, the advantages and disadvantages of some of the most prominent plasmas such as capacitively- and inductively-coupled plasmas are discussed. Electromagnetic problems due to the related radio frequency and its consequences on the plasma reactor performance, and also dust formation due to chemical reactions in plasma, are highlighted. Arcing and parasitic discharges occurring in plasma reactors can lead to plasma reactor damages. Some specific problems, such as the gas supply of a large area reactor, are discussed in more detail. Other topics of interest have been dc discharges such as those used in plasma spraying where thermal plasmas are applied for advanced material processing. Modern plasma diagnostics make it possible to investigate sparks in electrical discharge machining, which surprisingly show properties of weakly-coupled plasmas. Nanosecond dielectric barrier discharge plasmas have been applied to more speculative topics such as applications in aerodynamics and will surely be important in the future for ignition and combustion.Most of the commonly-used plasma sources have been shown to be limited in their performance. Therefore new, more effective plasma sources are urgently required. With the recent development of novel resonant network antennas for new advanced large area or large volume plasma sources, an important step towards high performance plasmas and new fast processes is made.

The Role of Dry Aero-acoustical Lubrication and Material Softening in Ultrasonically Assisted Milling of Difficult-to-Cut AISI 304 Steels

A recent and promising technique in advanced material processing techniques is the use of ultrasonic assistance in almost all cutting, forming and shaping processes. Optimizing manufacturing costs through reducing process forces and tool wears, improving machinability through enhancing surface finish and quality with minimal production time and energy, and delivering products with prolonged service life are some of the most important features of the vibration assisted manufacturing methods. To study the effect of ultrasonic vibrations on the milling process of the stainless steels, a series of experiments was designed and then implemented on a difficult-to-machine material. The result of the surface roughness and the cutting force tests has been comprised with and without processing by ultrasonic assistance. Experiments prove that under ultrasonic assistance, cutting forces are reduced, surface quality is improved and in all, a better machinability is achieved. It is concluded that dry aero-acoustical lubrication conditions and materials softening are of crucial importance in the machinability of difficult-to-cut AISI 304 materials.

Environmental impacts of hybrid, plug-in hybrid, and battery electric vehicles—what can we learn from life cycle assessment?

The purpose of this review article is to investigate the usefulness of different types of life cycle assessment (LCA) studies of electrified vehicles to provide robust and relevant stakeholder information. It presents synthesized conclusions based on 79 papers. Another objective is to search for explanations to divergence and “complexity” of results found by other overviewing papers in the research field, and to compile methodological learnings. The hypothesis was that such divergence could be explained by differences in goal and scope definitions of the reviewed LCA studies. The review has set special attention to the goal and scope formulation of all included studies. First, completeness and clarity have been assessed in view of the ISO standard’s (ISO 2006a, b) recommendation for goal definition. Secondly, studies have been categorized based on technical and methodological scope, and searched for coherent conclusions. Comprehensive goal formulation according to the ISO standard (ISO 2006a, b) is absent in most reviewed studies. Few give any account of the time scope, indicating the temporal validity of results and conclusions. Furthermore, most studies focus on today’s electric vehicle technology, which is under strong development. Consequently, there is a lack of future time perspective, e.g., to advances in material processing, manufacturing of parts, and changes in electricity production. Nevertheless, robust assessment conclusions may still be identified. Most obvious is that electricity production is the main cause of environmental impact for externally chargeable vehicles. If, and only if, the charging electricity has very low emissions of fossil carbon, electric vehicles can reach their full potential in mitigating global warming. Consequently, it is surprising that almost no studies make this stipulation a main conclusion and try to convey it as a clear message to relevant stakeholders. Also, obtaining resources can be observed as a key area for future research. In mining, leakage of toxic substances from mine tailings has been highlighted. Efficient recycling, which is often assumed in LCA studies of electrified vehicles, may reduce demand for virgin resources and production energy. However, its realization remains a future challenge. LCA studies with clearly stated purposes and time scope are key to stakeholder lessons and guidance. It is also necessary for quality assurance. LCA practitioners studying hybrid and electric vehicles are strongly recommended to provide comprehensive and clear goal and scope formulation in line with the ISO standard (ISO 2006a, b).

Visualization of arc and plasma flow patterns for advanced material processing

Results are presented for physical experiments that illustrate the possibilities and efficiency of visualization for studying the effect of operating conditions (backward-facing stepped forming nozzle, exit diameter of anode, mass flow, and composition of working gas) on plasma flows at low Reynolds numbers for advanced coating and powder processing. In particular, the shadow method, based on adaptive visualization transparency, is used for imaging electric arc and plasma jet flow patterns for different operating conditions. Because of visualization, the optimal geometrical characteristics of the backward-facing stepped forming nozzle, mass flow rate of the working gas, and its composition were found. These provide: (1) the absence of micro-shunting of the arc inside the backward-facing stepped nozzle for a transfer arc and twin arcs; and (2) compared to transient and turbulent jets, a higher density for the heat flux from a quasi-laminar flow to the surface of a flat substrate and the powder material to be treated, for nontransfer arc DC (direct current) torches and DC–RF (direct current and radio frequency) hybrid plasma flow system.

Special issue of the 12th International Symposium on Novel and Nanomaterials 2012

The 12th International Symposium on Novel and Nano Materials 2012, ISNNM2012, was held in Istanbul, Turkey, from 26 to 30 August 2012. Unlike previous series of nanocomposite materials symposia, this symposium was focused on all nanomaterials research, for example Advanced Powder Metallurgy, Advanced Material Processing, Novel Functional Materials, Nanocomposites and Nanoporous materials, Energy and Nuclear Materials, Characterization and Modeling, Resources and Recycling, Rare Metals, and Mechanical Alloying and Mechanochemistry. Approximately 190 participants from nine countries attended the symposium and 241 papers were presented—3 plenary lectures from Korea, Turkey, and Japan, 49 other oral presentations, and 170 poster presentations. After the reviewing process,

Ultrafast lasers—reliable tools for advanced materials processing

The unique characteristics of ultrafast lasers, such as picosecond and femtosecond lasers, have opened up new avenues in materials processing that employ ultrashort pulse widths and extremely high peak intensities. Thus, ultrafast lasers are currently used widely for both fundamental research and practical applications. This review describes the characteristics of ultrafast laser processing and the recent advancements and applications of both surface and volume processing. Surface processing includes micromachining, micro- and nanostructuring, and nanoablation, while volume processing includes two-photon polymerization and three-dimensional (3D) processing within transparent materials. Commercial and industrial applications of ultrafast laser processing are also introduced, and a summary of the technology with future outlooks are also given. Scientists in Asia have reviewed the role of ultrafast lasers in materials processing. Koji Sugioka from RIKEN in Japan and Ya Cheng from the Shanghai Institute of Optics and Fine Mechanics in China describe how femtosecond and picosecond lasers can be used to perform useful tasks in both surface and volume processing. Such lasers can cut, drill and ablate a variety of materials with high precision, including metals, semiconductors, ceramics and glasses. They can also polymerize organic materials that contain a suitable photosensitizer and can three-dimensionally process inside transparent materials such as glass, and are already being used to fabricate medical stents, repair photomasks, drill ink-jet nozzles and pattern solar cells. The researchers also explain the characteristics of such lasers and the interaction of ultrashort, intense pulses of light with matter.

Manufacture and processing of advanced composite materials

The article is devoted to modern composite materials. The article contains the information about various technologies of the production of mechanical and thermal processing of composite materials.