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Various near-atom-thickness two-dimensional (2D) van der Waals (vdW) crystals with unparalleled electromechanical properties have been explored for transformative devices. Currently, the availability of 2D vdW crystals is rather limited in nature as they are only obtained from certain mother crystals with intrinsically possessed layered crystallinity and anisotropic molecular bonding. Recent efforts to transform conventionally non-vdW three-dimensional (3D) crystals into ultrathin 2D-like structures have seen rapid developments to explore device building blocks of unique form factors. Herein, we explore a "peel-and-stick" approach, where a nonlayered 3D platinum sulfide (PtS) crystal, traditionally known as a cooperate mineral material, is transformed into a freestanding 2D-like membrane for electromechanical applications. The ultrathin (∼10 nm) 3D PtS films grown on large-area (cm

Two-dimensional (2D) molybdenum disulfide (MoS2) layers are suitable for visible-to-near infrared photodetection owing to their tunable optical bandgaps. Also, their superior mechanical deformability enabled by an extremely small thickness and van der Waals (vdW) assembly allows them to be structured into unconventional physical forms, unattainable with any other materials. Herein, we demonstrate a new type of 2D MoS2 layer-based rollable photodetector that can be mechanically reconfigured while maintaining excellent geometry-invariant photo-responsiveness. Large-area (>a few cm2) 2D MoS2 layers grown by chemical vapor deposition (CVD) were integrated on transparent and flexible substrates composed of 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO)-oxidized cellulose nanofibers (TOCNs) by a direct solution casting method. These composite materials in three-dimensionally rollable forms exhibited a large set of intriguing photo-responsiveness, well preserving intrinsic opto-electrical characteristics of the integrated 2D MoS2 layers; i.e., light intensity-dependent photocurrents insensitive to illumination angles as well as highly tunable photocurrents varying with the rolling number of 2D MoS2 layers, which were impossible to achieve with conventional photodetectors. This study provides a new design principle for converting 2D materials to three-dimensional (3D) objects of tailored functionalities and structures, significantly broadening their potential and versatility in futuristic devices.

A number of implantable biomedical devices have been developed, and wireless power transfer (WPT) systems are emerging as a way to provide power to these devices without requiring a hardwired connection. Most of the WPT has been based on conventional conductive materials, such as metals, which tend to be less biocompatible and stiff. Herein, we describe a development of an ionic wireless power transfer (IWPT) system using hydrogel receivers that are soft and biocompatible. Although the hydrogel receiver has a lower conductivity than metal (ρ

In this study, the relationship between viscosity of synthetic polymer rubberized gel (SPRG) used for waterproofing and adhesive strength on varying degrees of wetted surfaces is examined. First, SPRG specimens of different ratios of viscosity modifiers were prepared (3% to 10%, interval of 1% per specimen type). These specimens were installed onto substrate surfaces of varying degrees of humidity ratio (0%, 10%, 20%, 30%, 50%, 70% and 100%). Upon following the standard installation procedure of the SPRG specimens, standard pull-off tests were conducted. Results of the test showed that a consistent relationship exists between the viscosity of synthetic polymer rubberized gel (SPRG) and its adhesive strength on different degrees of wetted surfaces. Linear regression analysis and subsequent calculation of the respective coefficient of determination leads to the result that viscosity is a relevant factor for achieving stable adhesion when it comes to the usage of SPRG waterproofing. The findings of this study could have significant implications for the development and application of adhesive gel waterproofing materials in various industries.

Yield stress parameter derivation was conducted by stress-strain curve analysis on four types of grout injection leakage repair materials (GILRM); acrylic, epoxy, urethane and SPRG grouts. Comparative stress-strain curve analysis results showed that while the yield stress point was clearly distinguishable, the strain ratio of SPRG reached up to 664% (13 mm) before material cohesive failure. A secondary experimental result comprised of three different common component ratios of SPRG was conducted to derive and propose an averaged yield stress curve graph, and the results of the yield stress point (180% strain ratio) were set as the basis for repeated stress-strain curve analysis of SPRGs of up to 15 mm displacement conditions. Results showed that SPRG yield stress point remained constant despite repeated cohesive failure, and the modulus of toughness was calculated to be on average 53.1, 180.7, and 271.4 N/mm2, respectively, for the SPRG types. The experimental results of this study demonstrated that it is possible to determine the property limits of conventional GILRM (acrylic, epoxy and urethane grout injection materials) based on yield stress. The study concludes with a proposal on potential application of GILRM toughness by finite element analysis method whereby strain of the material can be derived by hydrostatic pressure. Comparative analysis showed that the toughness of SPRG materials tested in this study are all able to withstand hydrostatic pressure range common to underground structures (0.2 N/mm2). It is expected that the evaluation method and model proposed in this study will be beneficial in assessing other GILRM materials based on their toughness values.

Modern electronics have been geared toward exploring novel electronic materials that can encompass a broad set of unusual functionalities absent in conventional platforms. In this regard, two-dimensional (2D) transition metal dichalcogenide (TMD) semiconductors are highly promising, owing to their large mechanical resilience coupled with superior transport properties and van der Waals (vdW) attraction-enabled relaxed assembly. Moreover, 2D TMD heterolayers based on chemically distinct constituent layers exhibit even more intriguing properties beyond their mono-component counterparts, which can materialize only when they are manufactured on a technologically practical wafer-scale. This mini-review provides a comprehensive overview of recent progress in exploring wafer-scale 2D TMD heterolayers of various kinds. It extensively surveys a variety of manufacturing strategies and discusses their scientific working principles, resulting 2D TMD heterolayers, their material properties, and device applications. Moreover, it offers extended discussion on remaining challenges and future outlooks toward further improving the material quality of 2D TMD heterolayers in both material and manufacturing aspects.

Nanostructured cellulose fabric with an air-bubble-enhanced anti-oil fouling property is introduced for quick oil-cleaning by water even with the surface fouled by oil before water contact under a dry state. It is very challenging to recover the super-hydrophilicity because once the surface is oil-fouled, it is hard to be re-wetted by water. Anti-oil-fouling under a dry state was realized through two main features of the nanostructured, porous fabric: a low solid fraction with high-aspect-ratio nanostructures significantly increasing the retracting forces, and trapped multiscale air bubbles increasing the buoyancy and backpressure for an oil-layer rupture. The nanostructures were formed on cellulose-based rayon microfibers through selective etching with oxygen plasma, forming a nanoscale open-pore structure. Viscous crude oil fouled on a fabric under a dry state was cleaned by immersion into water owing to a higher water affinity of the rayon material and low solid fraction of the high-aspect-ratio nanostructures. Air bubbles trapped in dry porous fibers and nanostructures promote oil detachment from the fouled sites. The macroscale bubbles add buoyancy on top of the oil droplets, enhancing the oil receding at the oil-water-solid interface, whereas the relatively smaller microscale bubbles induce a backpressure underneath the oil droplets. The oil-proofing fabric was used for protecting underwater conductive sensors, allowing a robot fish to swim freely in oily water.

Two-dimensional transition-metal dichalcogenide (2D TMD) layers are highly attractive for emerging stretchable and foldable electronics owing to their extremely small thickness coupled with extraordinary electrical and optical properties. Although intrinsically large strain limits are projected in them (i.e., several times greater than silicon), integrating 2D TMDs in their pristine forms does not realize superior mechanical tolerance greatly demanded in high-end stretchable and foldable devices of unconventional form factors. In this article, we report a versatile and rational strategy to convert 2D TMDs of limited mechanical tolerance to tailored 3D structures with extremely large mechanical stretchability accompanying well-preserved electrical integrity and modulated transport properties. We employed a concept of strain engineering inspired by an ancient paper-cutting art, known as kirigami patterning, and developed 2D TMD-based kirigami electrical conductors. Specifically, we directly integrated 2D platinum diselenide (2D PtSe2) layers of controlled carrier transport characteristics on mechanically flexible polyimide (PI) substrates by taking advantage of their low synthesis temperature. The metallic 2D PtSe2/PI kirigami patterns of optimized dimensions exhibit an extremely large stretchability of ∼2000% without compromising their intrinsic electrical conductance. They also present strain-tunable and reversible photoresponsiveness when interfaced with semiconducting carbon nanotubes (CNTs), benefiting from the formation of 2D PtSe2/CNT Schottky junctions. Moreover, kirigami field-effect transistors (FETs) employing semiconducting 2D PtSe2 layers exhibit tunable gate responses coupled with mechanical stretching upon electrolyte gating. The exclusive role of the kirigami pattern parameters in the resulting mechanoelectrical responses was also verified by a finite-element modeling (FEM) simulation. These multifunctional 2D materials in unconventional yet tailored 3D forms are believed to offer vast opportunities for emerging electronics and optoelectronics.

A practical dual-scale finite element model is developed to enable the formability prediction in the hole expansion of a hyper-burring steel sheet. This numerical approach resorts to the isotropic macroscale hole expansion simulation for calculating the deformation histories near the hole edge, since they are known to be the potential fracture initiation site. The deformation histories are used as boundary conditions in the lower microscale model for calculating the local fracture of the steel sheet. The microscale simulation utilizes the dislocation density based constitutive model and a microstructure-based representative volume element (RVE), with realistic grain morphology taken from experimental microscopy. The fracture initiation at the hole edge region is evaluated from the microscale simulation using four frequently employed uncoupled ductile fracture models, which enable the definition of the critical fracture strain. The proposed dual-scale model can better predict the failure initiation and location near the hole edge when the modeling parameters are calibrated taking into account not only the deformation histories of the hole edge, but also the local stress triaxiality. Moreover, the proposed dual-scale model is applied to analyze the microstructure effect on the hole expansion ratio by providing the insights into the effect of grain size and grain boundary characteristics.

Facility walls with high relative humidity, such as bathrooms or kitchens installed with tiles by spot-bonding methods, become far more prone to defect or adhesion failure when using large or heavy tiles and insufficient application area of adhesive but is still continued to be practiced due to their low costs in the material. Most importantly, if this practice is to be continued, the changes in adhesion strength of the tiles based on different adhesive application areas of adhesives must be clarified such that the very least secure application can be achieved even by using spot-bonding methods. In this regard, an experiment was conducted in this study where tile-adhered specimens with different adhesive-applied area ratios (AR) of 60 ± 2%, 80 ± 2%, and 100% were prepared. Tile adhesion strength was subsequently measured, after sectioning the entire surface of the tile into 40 pieces. Experimental results showed that the adhesion strength above the standard criteria could be achieved for about 75% of the entire tile with AR 100% conditioning, followed by 30% of the entire tile with AR 80 ± 2% conditioning, and 20% of the entire tile for AR 60 ± 2% conditioning. Further analysis showed that with AR 80 ± 2% and AR 60 ± 2% conditions, the overall adhesion strength decreased by the range of about 59–67% compared to the AR 100% application conditions. The results of the study intended to provide an analytical basis of guidelines and risks with the potential usage of spot-bonding and should only be used if AR 100% application is planned.

Two-dimensional (2D) molybdenum disulfide (MoS

We explored the feasibility of wafer-scale two-dimensional (2D) molybdenum disulfide (MoS

Two-dimensional (2D) transition metal dichalcogenide (TMD) layers have gained increasing attention for a variety of emerging electrical, thermal, and optical applications. Recently developed metallic 2D TMD layers have been projected to exhibit unique attributes unattainable in their semiconducting counterparts; e.g., much higher electrical and thermal conductivities coupled with mechanical flexibility. In this work, we explored 2D platinum ditelluride (2D PtTe2) layers - a relatively new class of metallic 2D TMDs - by studying their previously unexplored electro-thermal properties for unconventional window applications. We prepared wafer-scale 2D PtTe2 layer-coated optically transparent and mechanically flexible willow glasses via a thermally-assisted tellurization of Pt films at a low temperature of 400 °C. The 2D PtTe2 layer-coated windows exhibited a thickness-dependent optical transparency and electrical conductivity of106 S m-1 - higher than most of the previously explored 2D TMDs. Upon the application of electrical bias, these windows displayed a significant increase in temperature driven by Joule heating as confirmed by the infrared (IR) imaging characterization. Such superior electro-thermal conversion efficiencies inherent to 2D PtTe2 layers were utilized to demonstrate various applications, including thermochromic displays and electrically-driven defogging windows accompanying mechanical flexibility. Comparisons of these performances confirm the superiority of the wafer-scale 2D PtTe2 layers over other nanomaterials explored for such applications.

High capacity all-solid-state Li-ion battery anodes were prepared using an industrially scalable solution coating process. Employing commercially available polyacrylonitrile as a mixed conducting binder, we have demonstrated stable cycling, high capacity electrodes with large mass loadings of tin active material. This is, to our knowledge, the first time a high capacity lithium-alloying material has been utilized in a slurry-coated sheet-style all-solid-state Li-ion battery anode. Optimization of this new electrode architecture resulted in a sheet-style anode capable of retaining an electrode specific capacity of 643.5 mAh/g after 100 charge-discharge cycles at a 0.1C rate. We believe that this work represents a step forward for slurry-coated electrodes intended for use with sulfide solid electrolytes and that the continued development of these high capacity sheet-style anodes will be critical to the commercialization of the all-solid-state Li-ion battery.

Platinum diselenide (PtSe

A simple, inexpensive and scalable method to prepare silicon‑carbon composite particles for use in all-solid-state Li-ion battery anodes is presented. The composite's electrochemically active soft-carbon matrix is formed through the pyrolysis of coal-tar-pitch, an abundant industrial waste material. Various techniques are used to characterize the physical and electrochemical properties of this pitch derived carbon. Optimization of the Si-C composite anode resulted in an all-solid-state Li-ion half-cell displaying stable specific capacities of 653.5 mAh/g (per mass electrode) and 1089.2 mAh/g (per mass Si-C composite) after 100 discharge-charge cycles. Cross sectional images of cycled electrodes, prepared via FIB milling, were taken in order to investigate the effect of silicon particle expansion on their composite microstructures.

We investigated the semiconductor-catalyzed formation of semiconductor nanowires (NWs) – silver sulfide (Ag2S)-catalyzed zinc sulfide (ZnS) NWs – based on a vapor-liquid-solid (VLS) growth mechanism through metal-organic chemical vapor deposition (MOCVD) with a Ag thin film. The Ag2S-catalyzed ZnS NWs were confirmed to have a wurtzite structure with a width and length in the range of ∼30 nm to ∼80 nm and ∼1 μm, respectively. Using extensive transmission electron microscopy (TEM) and energy-dispersive X-ray spectroscopy (EDS) analyses from plane and cross-sectional viewpoints, the ZnS NWs were determined to have a c-axis, [0001] growth direction. In addition, the catalyst at the top of the ZnS NWs was determined to consist of a Ag2S phase. To support the Ag2S-catalyzed growth of the ZnS NWs by a VLS reaction, an in situ heating TEM experiment was conducted from room temperature to 840 °C. During the experiment, the melting of the Ag2S catalyst in the direction of the ZnS NWs was first observed at approximately 480 °C along with the formation of a carbon (C) shell. Subsequently, the Ag2S catalyst melted completely into the ZnS NWs at approximately 825 °C. As the temperature further increased, the Ag2S and ZnS NWs continuously melted and vaporized up to 840 °C, leaving only the C shell behind. Finally, a possible growth mechanism was proposed based on the structural and chemical investigations.

A voidless Cu/PET substrate is fabricated by producing a superhydrophilic PET surface comprised of nanostructures with large width and height and then by Cu electroless plating. Effect of PET surface nanostructure size on the failure mechanism of the Cu/PET substrate is studied. The fabricated Cu/PET substrate exhibits a maximum peel strength of 1300 N m −1 without using an interlayer, and virtually no increase in electrical resistivity under the extreme cyclic bending condition of 1 mm curvature radius after 300 k cycles. The authors find that there is an optimum nanostructure size for the highest Cu/PET adhesion strength, and the failure mechanism of the Cu/PET flexible substrate depends on the PET surface nanostructure size. Thus, this work presents the possibility to produce flexible metal/polymer electronic substrates that have excellent interfacial adhesion between the metal and polymer and high fatigue resistance against repeated bending. Such metal/polymer substrates provides new design opportunities for wearable electronic devices that can withstand harsh environments and have extended lifetimes.

This study demonstrates the application of Si/C composite fibers as anode materials for all-solid-state lithium-ion batteries. Using polyacrylonitrile as the carbon precursor, Si/C fibers were prepared through electrospinning and subsequent heat-treating processes. To investigate the correlation between fiber diameter and electrochemical performance, we prepared three electrodes (A, B, C), containing Si/C fibers with ~2 μm, ~1 μm and ~0.1 μm diameters, respectively. Our results revealed that although the composition of all three electrodes was nearly the same, the Si/C fiber based electrodes exhibited better capacity retention when their fiber diameters were smaller. Normalized to the total mass of electrode composite, the solid-state half-cell prepared with the smallest diameter (~0.1 μm) Si/C fibers achieved a reversible specific capacity of ~700 mAh g−1 (normalized to electrode mass) over 70 cycles. We believe that this report can serve as an informative approach toward the utilization of electrospun Si/C fibers as anode materials for all-solid-state lithium-ion batteries.

Nanostructured transparent glass surfaces with self-cleaning and anti-fogging properties were fabricated using a non-lithographic, anisotropic etching technique. The superhydrophilic glass surface was achieved by nanostructuring pre-deposited SiO2 film in a glow discharge chamber. For superhydrophobicity, the surface energy of the nanostructured glass was lowered by treatment with 1H,1H,2H,2H-perfluorooctyl trichlorosilane. The self-cleaning and anti-fogging behavior was compared for glasses with different wettabilities by measuring the optical transmittance as well as the surface morphology and contact angles. In measuring the anti-fogging behavior, we included the effects of air flow impinging on the glass surface to emulate many practical situations. The superhydrophobic glass was superior to the superhydrophilic glass when considering both the self-cleaning and anti-fogging behavior with durability, particularly under air flow. The work can be used to fabricate transparent glass products for which minimizing surface contamination is crucial, e.g., eyeglasses, solar cells, and optical instruments.

The aging behavior and orientation relationships in Fe–31.4Mn–11.4Al–0.89C low-density steel were investigated with respect to constituent phases and precipitates, including γ-austenite matrix, β-Mn, and α-precipitate. After aging treatment at 550 °C for various periods of time, the microstructural changes and corresponding mechanical response were characterized by Vickers hardness measurement combined with EBSD and TEM observations. The precipitation sequence during the aging treatment showed that nano-sized κ-carbides firstly precipitated within the γ-austenite matrix at the incipient stage of aging, and induced the primary age hardening. After aging for 300 min, the lath-type β-Mn phase was formed, leading to the dramatic secondary hardening response. The α-precipitates with partial D0 3 order were subsequently produced at the β-Mn interior, grain/phase boundary region, and the γ-austenite interior after further aging over 10,000 min. The misorientation-angle distribution, Rodrigues–Frank vector space, and orientation relationship stereogram (OR stereogram) from EBSD measurements were employed for analyzing γ-matrix/β-Mn and β-Mn/α-precipitate interphase boundaries, respectively. The OR stereograms showed that the preferred orientation relationships were represented as ( 111 ) γ / / ( 221 ) β − M n , ( 01 1 ¯ ) γ / / ( 01 2 ¯ ) β − M n , ( 2 ¯ 11 ) γ / / ( 5 ¯ 42 ) β − M n for γ-matrix/β-Mn interface, and ( 012 ) β − M n / / ( 001 ) α , ( 02 1 ¯ ) β − M n / / ( 010 ) α , ( 100 ) β − M n / / ( 100 ) α for β-Mn/α-precipitate interface, respectively. The orientation relationships obtained from the OR stereograms were clarified by checking the deviation angle distributions of interface segments from the ideal orientation relationships, as well as the TEM diffraction patterns at the interface boundaries. In addition, the misorientation distribution between γ-matrix and α-precipitate was examined and compared to conventional fcc/bcc orientation relationships.

The tensile deformation behavior of Al-Mg-Si alloy under a pulsed electric current has been investigated. Specimens subjected to three types of heat treatment, solution treatment, natural aging, and artificial aging, are prepared. In solution treated specimens, elongation and flow stress increase when pulsed electric current is applied during plastic deformation; also, the Portevin–Le Chatelier (PLC) phenomenon, which is observed in the tensile test without electric current, nearly disappears when the pulsed electric current is applied. In naturally aged specimens, the flow stress decreases and the elongation significantly increases when pulsed electric current is applied during the tensile test. In artificially aged specimens, both elongation and flow stress decrease under pulsed electric current. The result of XRD analysis shows that thermal and electric current–induced annealing occurs in all specimens subjected to the electric current. Especially in the solution treated specimen, the formation of early stage precipitates from a supersaturated state might be accelerated by the electric current, in an effect distinct from Joule heating; this effect would explain the observed increase in flow stress and the disappearance of the PLC phenomenon. Microstructural observation shows that electric current accelerates the formation of microvoids around the precipitates at the grain boundary, resulting in earlier fracture in the artificially aged specimen. A constitutive model based on dislocation density model and precipitation hardening model is proposed to describe the uniaxial tensile behavior for the age hardening alloys. Based on the experimental findings, the proposed constitutive model is modified to describe the upper boundary of the ratchet shape stress-strain curve under a pulsed electric current. Thermal and electric current-induced annealing with precipitation hardening is considered simultaneously in the modified constitutive model. Phenomenological descriptions of each parameter are demonstrated considering the microstructural features observed in experiments. The modified model is capable of predicting the experimental results very well.

Platinum ditelluride (PtTe

Two-dimensional (2D) transition-metal dichalcogenides (2D TMDs) in the form of MX

We have examined a potential new and simple method for patterning a copper circuit on PET substrate by copper electroless plating, without the pretreatment steps (i.e., sensitization and activation) for electroless plating as well as the etching processes of conventional circuit patterning. A patterned mask coated with a catalyst material, Ag, for the reduction of Cu ions, is placed on a PET substrate. Subsequent oxygen plasma treatment of the PET substrate covered with the mask promotes the selective generation of anisotropic pillar- or hair-like nanostructures coated with co-deposited nanoparticles of the catalyst material on PET. After oxygen plasma treatment, a Cu circuit is well formed just by dipping the plasma-treated PET into a Cu electroless plating solution. By increasing the oxygen gas pressure in the chamber, the height of the nanostructures increases and the Ag catalyst particles are coated on not only the top but also the side surfaces of the nanostructures. Strong mechanical interlocking between the Cu circuit and PET substrate is produced by the large surface area of the nanostructures, and enhances peel strength. Results indicate this new simple two step (plasma surface modification and pretreatment-free electroless plating) method can be used to produce a flexible Cu circuit with good adhesion.

Pseudocapacitive materials offer an opportunity to bridge the energy storage gap between supercapacitor and battery technologies. Herein is chronicled the first report of pseudocapacitance in a system devoid of liquid electrolytes, using the cathode material LiTiS2. It is demonstrated that due to extreme crystallite reduction to less than 3 nm, additional charge storage is derived by reducing surface Ti3+ to Ti2+ at higher voltages and more reversibly than traditionally shown. Due to facile diffusion pathways in 3-fold coordinated lithium along the TiS2 surfaces, disordered LiTiS2 can be used as a singular cathode without conductive additives. The result is a system exhibiting nearly 300 mA h g−1 at a rate of C/2 for 1000 cycles. Whereas active materials in liquid cells typically have size limitations before irreversibilities appear, the high pseudocapacitance demonstrated in this report indicates that active materials used in the solid-state could benefit from size reduction. Hopefully, a new avenue of research stems from this work to investigate mixed conductor nano-domains for solid-state battery/capacitor hybrids. The prospect of a solid-state pseudocapacitor unlocks a series of new applications that offer long shelf life, high temperature capabilities, and enhanced safety.

Mechanically induced martensitic transformation (MIMT) and consequent plastic flow behavior with respect to austenitic texture were investigated in a lean duplex stainless steel. Different grain sizes and textures with fixed phase fractions were obtained via varying the thermomechanical processes. Nearly random distribution of austenitic orientation exhibited a distinguished flow curve from the others with a major D {4 4 11}〈11 11 8〉 component due to more gradual enhancement of hardening by less martensitic transformation. In order to compare the susceptibility to the transformation with respect to individual austenitic orientations and the experimental textures, interaction energy between the imposed stress and transformation strain was calculated by a classical transformation and a crystal plasticity model. The results indicated that a larger stress imposed on the D component led to higher interaction energy and a steeper progress of MIMT observed in the textured materials.

Welded pipes containing corrosion may lead to catastrophic situations during transportation of gas. Appropriate methods are needed to assess defective pipelines for integrity assessment. Corroded girth and seam welds were studied for the effect of corrosion length and depth on the burst pressure of API X70 pipe. Full-scale hydrostatic burst pressure tests and finite element analysis (FEA) were performed to investigate the burst pressure resulting from the corroded girth and seam welds. The experimental results were used to validate the finite element model, which considered the 3D elastic–plastic behavior. The FEA predicted burst pressures were compared with the ASME B31G, Modified ASME B31G, DNV RP-F101, and PCORRC standards in order to derive a proper equation for evaluation of corroded seam and girth welds.

〈100〉 axes of the rod-shaped grains of laser irradiated cold-rolled 3.04%-Si steel sheets are parallel to either solidification direction or normal direction of the steel sheet. The portion of desirable textures was enhanced by controlling of atmosphere and the direction of heat flow. The area fraction of the texture, which has 〈100〉 axis parallel to normal direction of the steel sheet, in the laser-affected steel sheets in air and argon atmosphere increased up to 23.4% and 26.3%, respectively, compared to a conventionally annealed steel sheet (8.2%).

We investigate the influence of the contact interface on the electrical properties of a ZnO microwire (MW) with silver (Ag) paste electrodes. The ZnO MW devices that are produced by dropping Ag paste on the ZnO MW surface followed by a curing step at an elevated temperature exhibit linear current-voltage characteristics, whereas the devices with Ag paste electrodes dropped upon a heated ZnO MW exhibit a non-linear electrical behavior. The results of electron microscopy and cathodoluminescence show the effect of the contact interface properties, such as interfacial defects and/or charge trap sites, between the ZnO MW and Ag paste electrodes. An energy band model is suggested to explain the charge transport mechanism for different types of Ag contacts on the ZnO MW.

The feasibility controlling the morphology of retained austenite in TRIP steel was investigated utilizing double bainitic transformation which is two-step isothermal heat treatment. The change in morphology of the retained austenite from a blocky to film type improved the tensile properties owing to higher mechanical stability of film-like retained austenite.

Soft and still responsive Transparent touch screens, from large-panel interactive information maps to advanced cell phones, have become a part of daily life. However, such devices all use hard materials. Kim et al. have developed a soft touch panel based on polyacrylamide hydrogels (cross-linked polymers swollen with water) that are highly transparent and contain trapped LiCl to enhance conductivity. The hydrogels are soft and can be stretched extensively while still maintaining touch sensitivity. Science , this issue p. 682

Ultrafine grained austenitic oxide dispersion strengthened steel was prepared by mechanical alloying of the elemental metal powders and Y 2 O 3 powders, then by hot isostatic pressing, hot rolling and solution annealing. The average grain size of the sample was about 260 nm, and the grain structure was stable after isothermal heat treatment at 1150 °C (~ 0.8 T m ) for 1000 h. The high thermal stability of the grain structure is mainly attributed to the uniformly dispersed semi-coherent Y 2 Ti 2 O 7 particles of about 5 nm in diameter. The particles appear to have a strong pinning effect on grain boundaries due to the semi-coherent interface character between particles and the matrix at 1150 °C. A decrease of the number density of Y 2 Ti 2 O 7 particles and coarsening of the particles on the grain boundaries was observed during heat treatments at 1200 °C and 1250 °C, resulting in a steady grain growth at these temperatures.

We report the results of tensile experiments on 900 nm sputter-deposited films of ZrB 2 , performed at temperatures ranging from ambient to 1016 K. The ZrB 2 samples were tested using micromachined sample frames with integrated micro-heaters. Transmission electron microscopy shows that both as-deposited films and films heated above 1000 K consist of two distinct layers, an amorphous layer and a crystalline layer with a very fine columnar structure. The ZrB 2 films have a room-temperature tensile strength in excess of 1.2 GPa, far exceeding the tensile strength of bulk ZrB 2 , but their stiffness is lower and decreases significantly with increasing temperature. The reduction in stiffness is attributed to the presence of the amorphous phase and the high density of transverse grain boundaries in the crystalline region. The fracture toughness of the ZrB 2 films was measured by introducing pre-cracks in the tensile specimens with a focused ion beam, and was found to be 2.57 ± 0.03 MPa√m, similar to values reported for bulk ZrB 2 .

316L stainless steel based austenitic oxide dispersion strengthened (AODS) steel was fabricated by mechanical alloying (MA) and hot isostatic pressing (HIP). The AODS sample exhibited an ultrafine-grained (UFG) structure with a bimodal grain size distribution (large grains of about 1200 nm and fine grains of about 260 nm). Two groups of oxide particles were observed; fine Y2Ti2O7 of about 7.7 nm and coarse Cr2O3 particles of about 200 nm in diameter. Tensile tests of the hot-rolled AODS steel samples showed yield strength of up to 890 MPa at room temperature, which is nearly four times higher than that of conventional 316L stainless steel. Micro-indentation and hardness tests indicated even higher yield strength of up to 1200 MPa, which shows a good agreement with the calculated value by combining of the grain refinement strengthening by the Hall–Petch relation and the dispersion strengthening by the Orowan mechanism. The lower strength from tensile tests should be attributed to the formation of micro-cracks at the interfaces between coarse Cr2O3 particles and the matrix. Coarse Cr2O3 particles were also frequently observed inside the fracture surface dimples of the creep ruptured sample at 923 K (650 °C) and 140 MPa. It is thus suggested that the yield strength and elongation could be further improved by controlling the coarse Cr2O3 particles.

Three central themes in the study of the phenomenon of resistive switching are the nature of the conducting phase, why it forms, and how it forms. In this study, the answers to all three questions are provided by performing switching experiments in situ in a transmission electron microscope on thin films of the model system polycrystalline SrTiO

We measure stresses that develop in sputter-deposited amorphous Ge thin films during electrochemical lithiation and delithiation. Amorphous LixGe electrodes are found to flow plastically at stresses that are significantly smaller than those of their amorphous LixSi counterparts. The stress measurements allow for quantification of the elastic modulus of amorphous LixGe as a function of lithium concentration, indicating a much-reduced stiffness compared to pure Ge. Additionally, we observe that thinner films of Ge survive a cycle of lithiation and delithiation, whereas thicker films fracture. By monitoring the critical conditions for crack formation, the fracture energy is calculated using an analysis from fracture mechanics. The fracture energies are determined to be Γ = 8.0 J m−2 for a-Li0.3Ge and Γ = 5.6 J m−2 for a-Li1.6Ge. These values are similar to the fracture energy of pure Ge and are typical for brittle fracture. Despite being brittle, the ability of amorphous LixGe to flow at relatively small stresses during lithiation results in an enhanced ability of Ge electrodes to endure electrochemical cycling without fracture.

Alginates can be crosslinked with multivalent cations, leading eventually to hydrogel formation. The properties of alginate gel depend on its lock structure, monomeric composition, concentration of polymer and cross linker. Among these, the properties of ionically crosslinked alginate gel can be greatly affected by multivalent cations as cross-linker. Knowledge of gelation dynamics by multivalent cations allows control over gelation characteristics, such as modulus of gel and the time required for equilibrium state, and healing properties. We have studied gelation dynamics of ionically crosslinked alginate gel. According to different types of anions bound with cations, gelation time and equilibrium viscosity was changed due to the solubility kinetics of the cation. The equilibrium viscosity is increased as the size of the cations increased even though the cations have same valency. A theoretical model is introduced to interpret dynamic change of viscosity during gelation. Open image in new window

Gas pipes invariably develop defects. Assessment and repairing methods vary depending on the defect type. When evaluating corrosion in the base metal of a pipe, the burst pressure is usually calculated using conventional evaluation equations, and the possibility of operating the pipe is determined. These equations are applied differently depending on the pipe's physical properties and environment. Therefore, in this study, the failure behavior and burst pressure of a pipe are determined through a full scale hydrostatic burst test; the results are used to simulate the lengths and depths of defects through the finite element method for the shapes and physical properties identical to those of a full-scale pipe. Thus, the corrosion in the base metal of an API X70 pipe was assessed by a stress-based method, and an evaluation equation suitable for use was proposed.

We have measured the fracture energy of lithiated silicon thin-film electrodes as a function of lithium concentration using a bending test. First, silicon thin-films on copper substrates were lithiated to various states of charge. Then, bending tests were performed by deforming the substrate to a pre-defined shape, producing a variation of the curvature along the length of the electrode. The bending tests allow determination of the critical strains at which cracks initiate in the lithiated silicon. Using the substrate curvature technique, we also measured the elastic moduli and the stresses that develop in the electrodes during electrochemical lithiation. From these measurements, the fracture energy was calculated as a function of lithium concentration using a finite element simulation of fracture of an elastic film on an elastic–plastic substrate. The fracture energy was determined to be Γ = 12.0 ± 3.0 J m−2 for amorphous silicon and Γ = 10.0 ± 3.6 J m−2 for Li3.28Si, with little variation in the fracture energy for intermediate Li concentrations. These results provide a guideline for the practical design of high-capacity lithium ion batteries to avoid fracture. The experimental technique described in this paper also provides a simple means of measuring the fracture energy of brittle thin-films.

Nanostructure formation was explored for various carbon-based materials, such as diamond, carbon fiber, polyethylene terephthalate and poly (methyl methacrylate), which have different levels of crystallinity, ranging from perfect crystal to polymeric amorphous. After treatment of oxygen plasma glow discharge, the nanostructures on these carbon-based materials were found to evolve via preferential etching due to the co-deposition of metal elements sputtered from the metal cathode plate. Local islands or clusters formed by the metal co-deposition have a low etching rate compared to pristine regions on each material, resulting in anisotropic patterns on the carbon-based materials. This pattern formation mechanism was confirmed by covering the cathode or preventing the co-deposition of metallic sources with a polymeric material. Regardless of the level of crystallinity of the carbon-based materials, no patterns were observed on the surfaces covered with the polymeric material, and the surfaces were uniformly etched. It was found that the materials with low crystallinity had a high etching rate due to low carbon atom density, which thus easily formed high-aspect-ratio nanostructures for the same plasma treatment duration.

High Mn TWIP steel is regarded as a promising material for the next generation automobile steel because of its high strength and good ductility. Most of the rolling and recrystallization texture studies of TWIP steels have been made at relatively low rolling reductions (50–60%). In this study, the rolling and recrystallization textures of 60–80% cold-rolled Fe-18% Mn- x Al-0.6% C steel with x being 0–3% have been investigated. The α fiber connecting Goss {110} and brass {110} orientations in the Euler space developed in the cold-rolled sheets, whose orientation density tended to increase with increasing rolling reduction and Al content. The α fiber rolling texture transformed into the recrystallization texture consisting of the main Goss component and minor brass component after annealing for 10 min at 800 °C, implying that the brass orientation transformed into the Goss orientation during recrystallization. The orientation transition was discussed in terms of the strain-energy-release-maximization theory for the recrystallization texture evolution.

The crystallography of monoclinic YTaO4 particles and the atomic structure at the particle/ferrite matrix interface in Ta-containing 12Cr ODS steel have been examined by means of SAD and HRTEM. Three different peaks in size distribution of oxide particles were detected by SANS, with the peak positions at 1.5 nm, 9 nm, and 100 nm in size. The results show that many YTaO4 particles are semi-coherent with the matrix, and the habit plane determined in most cases is { 0 5 1 } O / / { 0 1 1 } M . Orientation relationships of ( 0 5 1 ) O / / ( 1 ¯ 1 ¯ 0 ) M , [ 7 1 5 ¯ ] O / / [ 1 ¯ 1 1 ] M ; ( 1 2 1 ) O / / ( 1 1 0 ) M , [ 2 ¯ 1 0 ] O / / [ 0 0 1 ] M ; ( 0 5 1 ) O / / ( 0 1 1 ) M , [ 7 1 5 ¯ ] O / / [ 0 1 ¯ 1 ] M and ( 0 5 ¯ 1 ) O / / ( 1 ¯ 1 ¯ 0 ) M , [ 3 ¯ 1 5 ] O / / [ 1 ¯ 1 3 ] M were found. These orientation relationships provide a very small misorientation between the specific planes of YTaO4 particles and {1 1 0} close packed planes of ferrite. Fine particles of around 4 nm in size exhibited incoherent relationship with the misfit angle of around 10° with the matrix. Observation on particles ranging from 7 to 50 nm in size revealed that the crystallographic relationship is semi-coherent between oxide particles and the matrix.