The atmospheric pressure plasma sources with a coaxial geometry were used for generation of the radio frequency, microwave and pulsed dc plasmas inside water and aqueous solutions. Pulsed dc plasma generated in ethanol-water mixtures leads to production of the hydrogen-rich synthesis gas with hydrogen content up to 65 %. The effect of various plasma generation regimes on the performance of plasma, on the hydrogen production efficiency and on the hydrogen-rich synthesis gas production was examined. A role of the composition of the ethanol-water mixture was investigated.

The objective of this study was to investigate the relationship between the thickness of N radical irradiated InN template with crystallographic quality and electrical properties of InN film grown with the previously proposed method, in situ surface modification by radical beam irradiation. In this study, three InN samples were grown with this method on different thickness of irradiated templates. The crystallographic quality of InN films was analyzed by X-ray diffraction and the electrical properties were studied by Hall effect measurement. InN grown on 100 nm thick irradiated template shows lower full-width at half-maximum of X-ray rocking curves and lower carrier concentration compared to InN grown on 200 nm and 450 nm thick irradiated templates. Transmission electron microscopy revealed that threading dislocation density in the InN film decreased by an order of magnitude to ∼4.6×109cm-2. These results suggest that this method is possible for reduction of threading dislocation density in InN and the thickness of irradiated template should be minimized for higher crystallographic quality and electrical properties of the entire InN film.

An investigation of the effect of experimental parameters on the temperature and uniformity of material deposition by atmospheric pressure dielectric barrier discharge (DBD) planar plasma reactors was conducted. The apparatus consisted of a pulsed AC high voltage power source with various electrode materials (aluminum, copper wire mesh, and aluminum/copper wire mesh) operating under a range of load resistances. Possible effects of non-ideal interfacial conditions for the contact surface between the electrode and the substrate were also studied with various modified surface thermal conditions. It was found that a hybrid electrode design with a fine copper (Cu) wire mesh attached to an aluminum plate of approximately 3 mm thickness produced the most visually uniform deposit, presumably as a result of both the superior conductivity provided by the Al metal plate and the stable plasma resulting from the relatively low breakdown voltage by using helium (He) as the dilution gas. Although the experimental conditions of plasma-enhanced chemical vapor deposition (PECVD) are often specific to particular systems and applications, this work provides insights on technical details which can be applied to various plasma DBD reactors.

Nanosized Platinum (Pt) nanocrystals (NCs) have been extensively investigated in catalytic fields because of their high reactivity due to the unique electron structure. However, the rarity and the high cost of Pt limit its applications in industry. To reduce the usage of Pt in catalytic industry, research interests have been extended to Pt-based nanoalloys. Among various nanostructures, nanoframes (NFs) showed promising catalytic performance even with a lower metallic loading dose. Herein, we report a facile and robust method to transfer the Pt-Ni tetrahexahedral (THH) NCs into THH NFs in which carbon monoxide (CO) plays a role of the “etching reagent”. The driving force of the etching is a formation of gaseous metallic complex, Ni(CO)4, known as Mond Process, preferentially dealloying nickel atoms along <100> directions of the Pt-Ni THH NCs. It is determined that the resultant Pt-Ni THH NFs possess an open, stable and high-index preserved nanostructure, in which the outside atomic layers are composed of only Pt atoms with surface strains. Compared to a solution-based etching process, this approach requires less etching time and generates a well-defined structure. The associated thermal annealing operation also releases extra internal stress, making the NFs more stable with fewer surface defects. Such Pt-Ni THH NFs show interesting potentials in the improvement of stability and activity as advanced catalysts.

In this paper, a multilayer CNx/TiN composite film on high-speed steel substrate was prepared by using a multi-arc assisted DC reactive magnetron sputtering system. The cross-section observations of the fracture surface reveal that the films show a pure cleavage fracture due to its super-high hardness, and the interfacial strength between the film and substrate is associates with the film thickness, i.e., 2μm is a critical thickness for the present deposition. That is to say, there is no disbonding or cracking at the interface when the film thickness is less than 2μm, while the interfacial failure is generated if the film thickness is larger than 2μm. This direct SEM observation of the fracture surface provides a distinct image for evaluating the mechanical property and also analyzing the failure mechanism of the films.

Nacre is a hierarchical multi-composite matrix consisting of mineral plate-like structures stacked up similar to brick and mortar. When impacted with a projectile this type of structure is expected to reduce the overall shock loading into the system as well as projectile velocity as a consequence of variations in structural stiffness between the composite plates and the organic interlayers. Bio-mimicked nacre derived from alumina as the base ceramic is also shown to have increased fracture toughness over an alumina monolith. One challenge to building the nacre alumina structure is the design and processing of the composite mineral plates which should be comprised of roughly 90-95% nano-filler and 5-10% organic binder. In order for these plates to accurately mimic the nacre mineral plates they must also emulate aspect ratios on the order of 1:10 to 1:20. This paper will discuss the design and processing of nacre-alumina plates for studies into the impact behavior of nacre composites.

Copper growth for the development of electroplating technique as a low-temperature soldering procedure represents a useful method for the formation of metal deposits, allowing modification of the thickness and morphology of the soldering joints. The approach is particularly useful for soldering electronic components to a plastic 3D printed substrate. To accelerate the soldering process hydrogen assisted electroplating (HAE) method was employed at room temperature. The experiments were designed by making a small electrochemical cell around the gap on a printed circuit board (PCB) or a 3D printed conductive track. During the experiment, water electrolysis was observed, which released hydrogen bubbles. The hydrogen bubbles caused the structure of the electroplated layer to be more porous, but with a similar conductivity as solid copper and a remarkable mechanical strength suitable for use as interconnects on an electronic circuit. Our electrochemical data and video recorded images show a fast and reliable copper electrodeposition in less than 1 minute. The morphology of copper deposits on a 3D printed structure was studied with the scanning electron microscopy (SEM). A reliable soldering process was demonstrated for a surface mount light emitting diode (LED) on a PCB. Further experiments are required to optimize the soldering process for faster and more reliable electroplating, particularly for 3D printed substrates.

Alpha-alumina is a ceramic with excellent chemical stability, mechanical property, high melting point, and insulating property; however, it shows poor workability due to its low fracture toughness. There are a lot of molding processes for α-alumina, such as press molding and extrusion methods. 3D printing is rapidly growing technology to make complex and precious moldings. However, there are still only a few descriptions on 3D ink-jet powder laminating printings for α-alumina due to no self-hydration hardening property. To achieve α-alumina moldings with the 3D ink-jet printers, powder fluidity of α-alumina powders and binders for bonding the powders should be investigated. The powders mixed with α-alumina at 20, 3.4 and 0.4 μm in sizes were adjusted to improve powder fluidity and packing density. Polyvinyl alcohol (PVA) or polyallylamine (PAA) including other additives was used as an ink. The addition of PVA on the adjusted powders made no chemical interaction of powders and no retention of shapes, but that of PAA formed the printed moldings. The relative packing density and compressive strength of the printed moldings were 40 % and 8.2 kPa, which was clearly depended on the printed directions due to the nozzle structure of printer head. Sintering the moldings at 1500°C caused near-net zero shrinkage and improved the maximum compressive strength at 3.6 MPa.

Thermocapillary dewetting of liquids and molten films has recently emerged as a viable alternative to conventional microprocessing methods. As this thermal gradient-induced mechanism is universal, it can be applied to any material. This work explores the sequential dewetting of materials with varying melting points, including polymers and metals, to create aligned morphologies. The variation in melting point allows for the dewetting of single layers at a time or mobility-limited simultaneous dewetting. As a result, a variety of multimaterial structures can be produced with built-in alignment, such as arrays of concentric circles, lines with periodic segmentation, or islands on holes. This approach employs photothermal methods to induce the necessary thermal gradient, manipulating several variables in order to influence the consequent structures. Adjusting laser power and light intensity allows for the control of temperature for selective dewetting of films; altering beam size and exposure time affects the extent of dewetting in terms of diameter size; overlap effects and simultaneous dewetting can result in complex architectures. This controlled writing of patterns also presents a technique to create both masks at low temperatures for conductive multilayers as well as templates for electrospray deposition.