To overcome the steric effect of norbornene (NB), first-generation Grubbs’ catalyst (GC1) was used as the catalyst to graft NB onto the polypropylene (PP) chain by reactive extrusion. Instead of harsh reaction conditions, such as anhydrous, which was the general method to synthesize NB polymers, this convenient method would be easier to industrialize. The mechanism of grafting was studied by using Fourier Transform InfraRed spectra and differential scanning calorimetry. It was found that GC1 could initiate the ring-opening metathesis polymerization of NB to obtain short NB chain-grafted PP-g-NB. The rheological behavior showed that the grafted NB short chains on PP-g-NB increase the shear thinning of the polymers and decrease the system viscosity.

In this paper, the Lewis base character of 3-aminopropyltrimethoxysilane (3-APTMS), an imine derivative of siloxane, and an indole monomer were shown to enable the reduction of gold cations in acetone. The Lewis acid–base adduct of indole monomers and gold formed a polyindole–gold nanoparticle sol. Similarly, the Lewis acid–base adduct of 3-APTMS and gold enabled the formation of gold nanoparticles in the presence of acetone. The polyindole–gold nanoparticle sol and siloxane–gold nanoparticles underwent self-assembly into a polymeric nanofluid that was suitable for casting membranes. The use of these membranes as a potentiometric ion sensor for both cations and anions was considered; a common nonspecific ion exchange molecule, sodium tetraphenylborate, and the polymeric nanofluid were used to prepare an anion sensor and a cation sensor.

This article presents a comprehensive overview of currently available research on bioimplantable energy harvesters, with a specific focus on their fabrication and issue of biocompatibility. Both the achievements and limitations of the field are pointed out from the standpoint of materials science and engineering as directions for future research. Particular attention is paid to the controversy over the use of lead-based or lead-free piezoelectric ceramics in biomedical applications, which is closely related to different temporalities of research on biological conditions. This report is intended to serve as a reference guide for developing the next generation of piezoelectric biomedical devices.

This research investigates a novel composite of encapsulated paraffin in boron nitride nanotube (BNNT) which is more thermally and chemically stable than carbon nanotube. This composite can achieve high thermal conductivity and, meanwhile, have thermal energy storage capability for efficient thermal management under extreme conditions. Equilibrium molecular dynamics simulations were conducted to study self-diffusion coefficient, thermal conductivity, and specific heat of encapsulated paraffin. The simulation results indicated that the self-diffusion coefficient and thermal conductivity of paraffin could be increased by up to 10 and 7 times, respectively, while specific heat was reduced after encapsulating into BNNT.

In this research, the mechanical alloying (MA) technique was used to study solid solubility in the immiscible Zr–Cr alloy system. At first, Zr and Cr powders were milled, and then, the phase evolution, alloying mechanism, microstructural change, and mechanical properties of the milled powders were investigated by X-ray diffraction technique, scanning electron microscopy along with energy dispersive spectroscopy, transition electron microscopy, and microhardness measurements. Moreover, the solubility limit of Zr in Cr lattice was obtained by Vegard's law. The results showed that the MA was significantly enhanced the solubility of Zr in Cr up to about 21.6 wt% after an optimum milling time of 32 h and led to form an amorphous/nanocrystalline composite of Zr-reach and Cr-reach supersaturated solid solutions with the microhardness value of 503 Hv approximately. Also, the thermodynamic analysis indicated that the Gibbs free energy changes for the amorphous and solid solution were positive, which were provided by the MA process.

In this investigation, the superalloy IN718 has been prepared by additive manufacturing (AM) following a selective laser melting technique, and the post-AM heat treatments have been optimized. The microstructure of additively manufactured (AM) IN718 is characterized by the presence of dendritic and cellular features with large spatial heterogeneity along and across the build plane. Along the build direction, the 〈100〉 fiber texture dominates. Heat treatment involving two-step solution treatment, and subsequently, two-step aging treatment was specifically designed to facilitate the precipitation of δ phase at the grain boundaries to make the material resistant to grain boundary sliding (GBS). The AM IN718 showed dynamic strain aging (DSA) at three different temperatures, while the critical strain for the onset of serration was extended to a higher value after the heat treatment.

The fracture toughness of 617 Ni-based weld metal (WM) under different elevated temperatures was tested with a novel method and its fracture mechanism was investigated in this paper. It was found that the fracture toughness of WM was lower than that of base metal (BM) at the same temperature, which was mainly due to the coarse columnar structure, differences in misorientation, and precipitated phases. For both BM and WM, the fracture toughness was lower at elevated temperature due to decreased strength. Much more micro-voids caused by Ti(C, N) and M23C6 inside grains of BM could be observed adjacent to the crack path, which accounted for the dramatically decreased fracture toughness of BM at elevated temperature. In comparison, fewer micro-voids could be observed in WM due to the lack of those second particles. As a result, the J0.2 value and propagation path morphology both showed that the WM had more stable microstructure even though possessing lower toughness.

Metal additive manufacturing (AM) provides a platform for microstructure optimization via process control, but establishing a quantitative processing-microstructure linkage necessitates an efficient scheme for microstructure representation and regeneration. Here, we present a deep learning framework to quantitatively analyze the microstructural variations of metals fabricated by AM under different processing conditions. The principal microstructural descriptors are extracted directly from the electron backscatter diffraction patterns, enabling a quantitative measure of the microstructure differences in a reduced representation domain. We also demonstrate the capability of predicting new microstructures within the representation domain using a regeneration neural network, from which we are able to explore the physical insights into the implicitly expressed microstructure descriptors by mapping the regenerated microstructures as a function of principal component values. We validate the effectiveness of the framework using samples fabricated by a solid-state AM technology, additive friction stir deposition, which typically results in equiaxed microstructures.

The microstructure evolution, dynamic recrystallization (DRX) and precipitation of the ZM61 alloy sheets prepared with different rolling conditions were studied. The DRX grain sizes (dDRX) at four high strain rate rolling (HSRR) temperatures (275–350 °C) are 1.9, 2.3, 2.6 and 3.1 μm, respectively, while the DRX volume fractions (fVDRX) are 69, 73, 76 and 82%, respectively. 300 °C is selected as the optimal HSRR temperature. The dDRX and fVDRX of the alloys prepared by pre-rolling (PR) at 300 °C + HSRR are 1.0 μm and 91%, respectively. The PR treatment does not change the types of the precipitates but promotes the precipitation. The tensile strength (UTS) of 369 MPa and yield strength (YS) of 261 MPa can be achieved by HSRR at 300 °C, while a further increase in both UTS and YS can be obtained by PR treatment.

This paper reviews the recent development of fabrication methods of porous metals with open-channels. The open-channel metals are fabricated through powder sintering or solidification technique. The template wires are embedded in the sintered or solidified metals, such as aluminum, copper, titanium and its alloys, which are then removed by chemical dissolution or extraction methods. The hole size, hole length and porosity are uniquely controlled by thickness, length and number of template metallic wires, respectively. The pore size ranges from 102 to several 103 μm in diameter. The open-channel metals are characterized by a large aspect ratio of the length to the diameter of the holes in metals. Furthermore, the techniques can fabricate spiral and V-shaped pores in metals. Feasibility and usefulness of each fabrication method are discussed. The methodology for producing the open-channel metals is expected to provide expanded opportunities for application technologies such as functional materials like heat sinks and sound absorbers and light-weight structural materials.

In this paper, CNTs reinforced foam aluminum matrix composites with small pore diameter were prepared by powder metallurgy method. When the mass fraction of CNTs was 0.75%, the tensile strength, flexural strength and compressive yield strength of the materials were 3.4 times, 2.4 times and 2.4 times of pure foam aluminum, respectively, reaching the maximum value, which obviously improved the mechanical properties of aluminum foam. The tensile property model of foam aluminum matrix composites was built to predict the properties of the composites, and the effects of defects and reinforcement on the mechanical properties of the composites were compared. The results show that the tensile fitting is consistent with the measured results when the mass fraction of CNTs is less than 0.75%, but the weakening effect of defects on the strength of aluminum foam is much greater than the enhancement of CNTs. With the increase of CNTs mass fraction, the damping loss factor of foam aluminum composites increases, dislocation damping and grain boundary damping play a role in advance, and the damping peak moves to the low temperature region.

Hydrogen lithography has been used to template phosphine-based surface chemistry to fabricate atomic-scale devices, a process we abbreviate as atomic precision advanced manufacturing (APAM). Here, we use mid-infrared variable angle spectroscopic ellipsometry (IR-VASE) to characterize single-nanometer thickness phosphorus dopant layers (δ-layers) in silicon made using APAM compatible processes. A large Drude response is directly attributable to the δ-layer and can be used for nondestructive monitoring of the condition of the APAM layer when integrating additional processing steps. The carrier density and mobility extracted from our room temperature IR-VASE measurements are consistent with cryogenic magneto-transport measurements, showing that APAM δ-layers function at room temperature. Finally, the permittivity extracted from these measurements shows that the doping in the APAM δ-layers is so large that their low-frequency in-plane response is reminiscent of a silicide. However, there is no indication of a plasma resonance, likely due to reduced dimensionality and/or low scattering lifetime.

This study focuses on binary droplet collisions of equal calcium–magnesium–aluminosilicate (CMAS) droplets formed by the melting of dust and sand ingested by gas turbine engines. Head-on, off-center, and grazing collision of 1 mm CMAS droplets traveling toward each other at a relative velocity of 100 m/s are numerically investigated using a volume-of-fluid-based direct numerical simulation approach at operating pressure and temperature of 20 atm and 1548 K, respectively. It is found that head-on and off-center collisions lead to droplet coalescence, whereas stretching behavior is observed for the grazing configuration. To elucidate the effect of viscosity, a fictitious fluid with all properties the same as CMAS except for viscosity (1/10 of CMAS) is also studied. It is found that the lower viscosity liquid deforms significantly as compared to CMAS for the head-on and off-center cases. These differences are quantified using the budgets of kinetic, surface, and dissipation energies. This paper represents the first study of its kind on the binary collision of CMAS droplets.

Lightweight, inexpensive and flexible electrodes are required for flexible technological applications. As polymers are generally low cost, flexible and have low density, they are potential candidates for use as flexible electrodes. However, polymers are not conductive and thus cannot be used as electrodes or current collectors. Polymers have been coated by metals/alloys to make them conductive for use in various applications including electromagnetic shielding and sensors. In this work, a flexible electrode was successfully fabricated by electrodeposition of Cu and Ni on polyester fabric for an energy storage application. The growth of metals was carried out in non-aqueous ionic liquid electrolyte, with the deposition condition of Cu and Ni studied by means of cyclic voltammetry. Non-electrochemical (FTIR, XRD, SEM and EDAX) characterizations of the metal-coated polyester are also presented. Modified flexible electrodes were transferred to an alkaline electrolyte for electrochemical characterization. The specific capacitance of Cu- and Ni-coated polyester reached 33.4 F/g and 50.2 F/g at the same scan rate of 5 mV/s. These results suggest an inexpensive and straightforward method for the fabrication of a flexible electrode for energy storage applications.