Air-processed stable near-infrared Si-based perovskite light-emitting devices with efficiency exceeding 7.5%

Two composite layers are used to enhance the efficiency of Si-based near-infrared perovskite light-emitting devices, which are produced in ambient air, and the external quantum efficiency increased to 7.5%.

Creep Age Forming of Fiber Metal Laminates: Effects of Process Time and Temperature and Stacking Sequence of Core Material

Fiber metal laminates (FMLs) are a type of hybrid materials interlacing composites and metals. In the present work, FMLs with aluminum alloy 6061 as the skin and E-glass fiber-reinforced polypropylene (PP) as the core material are fabricated and formed by the creep age forming (CAF) process. The effects of time and temperature as the process parameters and thickness and stacking sequences of composites layers as the FML parameters are evaluated on the springback of glass-reinforced aluminum laminates (GLARE) FMLs. After the CAF process, the springback of creep age-formed FMLs is calculated. The results show that the FMLs can be successfully formed with the CAF process by considering appropriate time and temperature. In addition, the stacking sequence of composite layers can affect the springback behavior of FMLs significantly.

Fabrication of Novel Chitosan–Hydroxyapatite Nanostructured Thin Films for Biomedical Applications

In this study, we develop chitosan–hydroxyapatite (CS–HAp) composite layers that were deposited on Si substrates in radio frequency (RF) magnetron sputtering discharge in argon gas. The composition and structure of CS–HAp composite layers were investigated by analytical techniques, such as Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), metallographic microscopy (MM), and atomic force microscopy (AFM). On the other hand, in the present study the second order derivative of FT-IR–ATR spectra, for compositional analyses of CS–HAp, were used. The SEM, MM, and AFM data have shown the formation of CS–HAp composite layers. The surface of CS–HAp composite layers showed uniform growth (at an Ar gas working pressure of p = 2 × 10−3 mbar). The surface of the CS–HAp composites coatings became more nanostructured, becoming granular as the gas pressure increased from 5 × 10−3 to 1.2 × 10−2 mbar. However, our studies revealed that the surface morphology of the CS–HAp composite layers varies with the Ar gas working pressure. At the same time, optical properties are slightly influenced by Ar pressure. Their unique physicochemical properties make them suitable for various applications in the biomedical field, if we consider the already proven antimicrobial properties of chitosan. The antifungal properties and the capacity of the CS–HAp composite layers to inhibit the development of fungal biofilms were also demonstrated using the Candida albicans ATCC 10231 (C. albicans) fungal strain.

Effects of Different Types of Interlayers on the Interfacial Reaction Mechanism at the Cu Side of Al/Cu Lap Joints Obtained by Laser Welding/Brazing

The influence of tin foil and Ni coatings on microstructures, mechanical properties, and the interfacial reaction mechanism was investigated during laser welding/brazing of Al/Cu lap joints. In the presence of a Zn-based filler, tin foil as well as Ni coating strengthened the Al/Cu joints. The tin foil only slightly influenced the joint strength. It considerably improved the spreading/wetting ability of the weld filler; however, it weakened the bonding between the seam and the Al base metal. The Ni coating considerably strengthened the Al/Cu lap joints; the highest tensile strength was 171 MPa, which was higher by 15.5% than that of a joint without any interlayer. Microstructure analysis revealed that composite layers of Ni3Zn14–(τ2 Zn–Ni–Al ternary phase)–(α-Zn solid solution)–Al3Ni formed at the fusion zone (FZ)/Cu interface. Based on the inferences about the microstructures at the interfaces, thermodynamic results were calculated to analyze the interfacial reaction mechanism. The diffusion of Cu was limited by the Ni coating and the mutual attraction between the Al and Ni atoms. The microstructure comprised Zn, Ni, and Al, and they replaced the brittle Cu–Zn intermetallic compounds, successfully strengthening the bonding of the FZ/Cu interface.

Final Report for Blood Brain Barrier Opening of Rat by Laser-generated Focused Ultrasound Transducer

A laser-generated carbon nanotube (CNT) transducer has been known to generate a shock wave with large amplitude for lasting sub-microseconds without producing heat. This laser-generated CNT transducer has never been applied to transcranial focused ultrasound (tcFUS) applications. Based on preliminary observation of the Evans blue leaked in the brain tissue of a rat after sonication of the shock wave by a CNT transducer, BBB opening of the rat by the shock wave from the CNT transducer was tried to confirm without damage of vessels. However, peak negative pressure was saturated to -9 MPa which is not enough for cavitation even with all trials of different fabrication processes such as coating methods of the PDMS layer, CNT-PDMS composite layers, backing materials, and CNT solutions. These results and discussion and suggestions were reported. As another application of the CNT transducer for lower peak negative pressure, EEG signals before and after sonication of shock waves for 10 minutes were observed in 3 rats. Shock wave by CNT transducer would be a potential for tcFUS neurostimulation and neuromodulation.

Delamination Behaviour of Embedded Polymeric Sensor and Actuator Carrier Layers in Epoxy Based CFRP Laminates—A Study of Energy Release Rates

Fiber reinforced composites combine low density with high specific mechanical properties and thus became indispensable for today’s lightweight applications. In particular, carbon fibre reinforced plastic (CFRP) is broadly used for aerospace components. However, damage and failure behaviour, especially for complex fibre reinforcement set-ups and under impact loading conditions, are still not fully understood yet. Therefore, relatively large margins of safety are currently used for designing high-performance materials and structures. Technologies to functionalise the materials enabling the monitoring of the structures and thus avoiding critical conditions are considered to be key to overcoming these drawbacks. For this, sensors and actuators are bonded to the surface of the composite structures or are integrated into the composite lay-up. In case of integration, the impact on the mechanical properties of the composite materials needs to be understood in detail. Additional elements may disturb the composite structure, impeding the direct connection of the composite layers and implying the risk of reducing the interlaminar integrity by means of a lower delamination resistance. In the presented study, the possibility of adjusting the interface between the integrated actuator and sensor layers to the composite layers is investigated. Different polymer layer combinations integrated into carbon fibre reinforced composite layups are compared with respect to their interlaminar critical energy release rates GIc and GIIc. A standard aerospace unidirectionally reinforced (UD) CFRP prepreg material was used as reference material configuration. The investigations show that it is possible to enhance the mechanical properties, especially the interlaminar energy release rate by using multilayered sensor–actuator layers with Polyimide (PI) outer layers and layers with low shear stiffness in between.

Icephobic Performance of Combined Fluorine-Containing Composite Layers on Al-Mg-Mn–Si Alloy Surface

This paper presents the results of an evaluation of anti-icing properties of samples obtained by plasma electrolytic oxidation (PEO) with a subsequent application of superdispersed polytetrafluoroethylene (SPTFE) and polyvinylidenefluoride (PVDF). A combined treatment of the samples with SPTFE and PVDF is also presented. It is revealed that impregnation of a PEO layer with fluoropolymer materials leads to a significant increase in surface relief uniformity. Combined PVDF–SPFTE layers with a ratio of PVDF to SPTFE of 1:4 reveal the best electrochemical characteristics, hydrophobicity and icephobic properties among all of the studied samples. It is shown that the decrease in corrosion current density Ic for PVDF–SPFTE coatings is higher by more than five orders of magnitude in comparison with uncoated aluminum alloy. The contact angle for PVDF–SPFTE coatings attain 160.5°, which allows us to classify the coating as superhydrophobic with promising anti-icing performance. A treatment of a PEO layer with PVDF–SPFTE leads to a decrease in ice adhesion strength by 22.1 times compared to an untreated PEO coating.

Comparative Analysis of the Phase Interaction in Plasma Surfaced NiBSi Overlays with IVB and VIB Transition Metal Carbides

Important applications of transition metal carbides (TMCs) are as wear resistant composite layers deposited by plasma transferred arc welding (PTAW) and laser methods. Growing interest in them has also been observed in additive manufacturing and in HEA technology (bulk composite materials and layers), and in the area of energy conversion and storage. This paper presents the results of comparative studies on interfacial interactions in the NiBSi−TMCs system for two border IVB and VIB TM groups of the periodic table. Model (wettability and spreadability) and application experiments (testing of the PTAW-obtained carbide particle−matrix boundaries) were performed. Fe from partially melted steel substrates is active in the liquid NiBSi−TMCs system. It was revealed that the interaction of TMCs with the liquid NiBSi matrix tends to increase with the group number, and from the top to bottom inside individual groups. Particles of IVB TMCs are decomposed by penetration of the liquid along the grain boundaries, whereas those of VIB are decomposed by solubility in the matrix and secondary crystallization. No transition zones formed at the interfacial boundaries of the matrix−IVB group TMCs, unlike in the case of the VIB group. The experimental results are discussed using the data on the TMC electronic structure and the physicochemical properties.

Laser Cladding Cermet Coatings on Niobium Substrate

Pure niobium substrates were coated using laser cladding method. Pure molybdenum, Yttria Stabilized Zirkonia (YSZ) and corundum (Al2O3) powders were used as coating materials. Coatings were deposited on specimens as seperate paths with 3÷10mm width and 40mm of length. Two different laser power 3kW and 4kW were tested during deposition. In order to assess the quality of the Mo-YSZ and Mo-Al2O3 coatings, the light microscopy, Scanning Electron Microscopy (SEM), chemical analysis (EDS) and Vickers hardness test investigation were performed. The surface roughness and wear volume were also measured. As a result of YSZ-Mo powder cladding on the Nb substrate the composite layers were obtained without cracks and porosity not exceeding 1 μm. In addition, an increase in hardness of about 450 HV0.5 was revealed. As a result of Al2O3-Mo powder cladding on the Nb substrate the composite layers with many voids and cracks were obtained for each of the cladding variants.