Correction to: Transient Stress Relaxation Test to Identify Material Constants in Dislocation Density Model

Metallurgical and Materials Transactions A -     

NiS2@V2O5/VS2 ternary heterojunction for a high-performance electrocatalyst in overall water splitting

Water splitting is regarded as an effective way to produce hydrogen energy to solve the energy crisis all over the world. However, the electrocatalysts suffer from expensive prices, high voltage, and sluggish kinetics. The heterojunction is composed of two semiconductors and can accelerate electron transfer by relying on interface engineering. Herein, we first prepare NiS₂@V₂O₅/VS₂ ternary heterojunction electrocatalyst, showing the low OER overpotential of 333 mV and HER overpotential of 216 mV at 10 mA cm^?2, as well as good stability. Meanwhile, the NiS₂@V₂O₅/VS₂ heterojunction is assembled to the two-electrode system for overall water splitting, exhibiting a very low voltage value of 1.49 V, which is much superior to that of the benchmark RuO₂//Pt/C system. The energy band calculation reveals the mechanism that the NiS₂ and VS₂ lower the Fermi level of V₂O₅, thus promoting the electrons transfer in the electrocatalytic reactions. Our work opens up a novel route for heterojunction application in the electrocatalytic field.     

Coral reef structured cobalt-doped vanadate oxometalate nanoparticle for a high-performance electrocatalyst in water splitting

Facing the energy crisis in the whole world, it is important to decompose water to obtain high-clean hydrogen energy. However, water splitting by electrocatalysis is suffering from high voltage and poor stability. Herein, we synthesize Co₃V₂O₈ coral reef-like nanoparticles in a facile way, showing a low oxygen evolution reaction (OER) overpotential of 318 mV coupled with good stability, which is superior to commercial RuO₂. Besides, the Co₃V₂O₈ shows fast kinetics for hydrogen evolution reaction (HER) and small impedance. Furthermore, the Co₃V₂O₈ nanoparticles are assembled in symmetric two-electrode system, which has a very low overall water splitting voltage of 1.50 V at 10 mA cm^?2, this value surpasses the benchmark RuO₂//Pt/C assembling and most of the other oxometalate-based electrocatalysts. This work provides a novel and facile way of preparing oxometalates nanomaterial electrocatalyst for hydrogen energy.     

Effective Separation of CO2 Using Metal-Incorporated rGO Membranes

Graphene-based materials, primarily graphene oxide (GO), have shown excellent separation and purification characteristics. Precise molecular sieving is potentially possible using graphene oxide-based membranes, if the porosity can be matched with the kinetic diameters of the gas molecules, which is possible via the tuning of graphene oxide interlayer spacing to take advantage of gas species interactions with graphene oxide channels. Here, highly effective separation of gases from their mixtures by using uniquely tailored porosity in mildly reduced graphene oxide (rGO) based membranes is reported. The gas permeation experiments, adsorption measurement, and density functional theory calculations show that this membrane preparation method allows tuning the selectivity for targeted molecules via the intercalation of specific transition metal ions. In particular, rGO membranes intercalated with Fe ions that offer ordered porosity, show excellent reproducible N₂/CO₂ selectivity of ≈97 at 110 mbar, which is an unprecedented value for graphene-based membranes. By exploring the impact of Fe intercalated rGO membranes, it is revealed that the increasing transmembrane pressure leads to a transition of N₂ diffusion mode from Maxwell–Stefan type to Knudsen type. This study will lead to new avenues for the applications of graphene for efficiently separating CO₂ from N₂ and other gases.     

Molded geometry and viscoelastic behavior of film insert molded parts

Virgin injection‐molded tensile specimens without any inserted film and four kinds of film insert molded (FIM) tensile specimens were prepared. They were annealed at 80°C to investigate the effect of residual stresses and thermal shrinkage of the inserted film on thermal deformation of tensile specimens. The FIM specimens with the unannealed film were bent after ejection in such a way that the film side was protruded and the warpage was reversed gradually during annealing and the film side was intruded. Warpage of the FIM specimen with the film annealed at 80°C for 20 days was not reversed during annealing. Processing of the FIM specimens have been modeled numerically to predict thermoviscoelastic deformation of the part and to understand the warpage reversal phenomenon (WRP). Nonisothermal three‐dimensional flow analysis was carried out for filling, packing, and cooling stages. The flow analysis results were transported to a finite element stress analysis program for prediction of deformation of the FIM part. The WRP was caused by the combined effect of thermal shrinkage of the inserted film and relaxation of residual stresses in the FIM specimen during annealing. It is expected that this study will contribute towards the improvement of the FIM product quality and prevention of large viscoelastic deformation of the molded part. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009     

Fabrication of a 3D stamp with the micro- and nano-scale patterns through combined NIL and optical lithography processes

Nanoimprint lithography is in the spotlight of the nano technology field for its ability to produce large area patterning [1], [2], [4]. This kind of lithography is also able to fabricate three-dimensional functional structures all at once. In order to fabricate three-dimensional structures for an entire wafer, simple fabrication of three-dimensional large area stamp that combines micro- and nano-scale patterns is required. This paper proposes, the fabrication process of three-dimensional large area stamp that incorporates both micro- and nano-scale pattern. The three-dimensional stamp, which accounts for areas that range from 70nm to 3um, is fabricated on a Si substrate using nanoimprint lithography and optical lithography.     

Cu Diffusion‐Driven Dynamic Modulation of the Electrical Properties of Amorphous Oxide Semiconductors

The exact role of Cu in the electrical properties of amorphous oxide semiconductors (AOSs) has been unclear, even though Cu has been the key element for the p‐type characteristics of crystalline oxide semiconductors. Here, the dynamic changes, determined by diffusion kinetics, in the effect of Cu on the electrical properties of amorphous In? Ga? Zn? O (a‐IGZO) are revealed. In the early stage of annealing, Cu dominantly diffuses into a‐IGZO through the free volume and acts as a mobile electron donor, which generates a resistive switching (RS) behavior related to the conductive filaments (CFs). With further annealing, substitutional Cu becomes predominant via In sites. After annealing, supersaturated Cu forms nonuniform, crystalline Cu? In? O clusters in a‐IGZO, which decrease the electrical conductivity of a‐IGZO and deteriorate the CF‐based RS performance. The findings reveal Cu diffusion mechanisms and the role of Cu in the electrical properties of AOSs dependent on the structural location and provide guidelines for modulating the RS characteristics of AOSs through Cu diffusion control.     

Tailoring of Mechanical Properties of Indirect Hot Stamping Steel Tubes by Laser Assisted Local Rapid Heating

The effect of laser assisted local heating on the mechanical properties of a hot stamping steel tube was in-vestigated.A heated region with a spiral shape was generated on the surface of the tube by combining the linear movement of the laser and the rotation of the tube.The results of axial crush tests show that the laser assisted local heating can be effectively used to modify the mechanical performance of the tube.A microstructural analysis confirms that the laser locally induces a martensitic phase transformation in the heated region and results in inhomogeneous microstructures along the length of the tube.     

Ballistic impact response of laminated hybrid materials made of 5086-H32 aluminum alloy,epoxy and Kevlar® fabrics impregnated with shear thickening fluid

The ballistic impact behavior of hybrid composite laminates synthesized for armor protection was investigated. The hybrid materials, which consist of layers of aluminum 5086-H32 alloy, Kevlar® 49 fibers impregnated with shear thickening fluid (STF) and epoxy resin were produced in different configurations using hand lay-up technique. The hybrid materials were impacted by projectiles (ammunitions of 150 g power-point) fired from a rifle Remington 7600 caliber 270 Winchester to strike the target at an average impact velocity and impact energy of 871 m/s and 3687 J, respectively. The roles of the various components of the hybrid materials in resisting projectile penetration were evaluated in order to determine their effects on the overall ballistic performance of the hybrid laminates. The effects of hybrid material configuration on energy dissipation during ballistic impacts were investigated in order to determine a configuration with high performance for application as protective armor. The energy dissipation capability of the hybrid composite targets was compared with the initial impact energy of low caliber weapons (according to NATO standards) in order to determinate the protection level achieved by the developed hybrid laminates. Deformation analysis and penetration behavior of the targets were studied in different stages; the initial (on target front faces), intermediate (cross-section), and final stages (target rear layers). The influence of target thickness on the ballistic impact response of the laminates were analyzed. Differences in ballistic behavior were observed for samples containing Kevlar® impregnated with STF and those containing no STF. Finally, mechanisms of failure were investigated using scanning electron microscopic examination of the perforations.     

Effect of carburising on geometrical control during quenching of martensitic sheet steel channels

The impact of component orientation and selective carburising is examined on the distortion during quenching of post-forming heat-treated (PFHT) channels using three different strength martensitic steel grades. The results show that the minimal, though unpredictable distortion that occurred during quenching of uncarburised channels was confined to either an opening or closing of the channel wall angle. It is also shown that selective carburising on a given surface of the channel will cause a significant change in the shape of the channel during quenching, which is related to the depth of carburising.