The objective of this study was to create impact welds between a Zr-based Bulk Metallic Glass (BMG) and copper at a laboratory scale and subsequently investigate the relationship between interfacial structure and mechanical properties. Vaporizing Foil Actuator (VFA) has recently been demonstrated as a versatile tool for metalworking applications: impact welding of dissimilar materials being one of them. Its implementation for welding is termed as VFA Welding or VFAW. With 8 kJ input energy into an aluminum foil actuator, a 0.5 mm thick Cu110 alloy sheet was launched toward a BMG target resulting in an impact at a velocity of nearly 600 m/s. For this experiment, the welded interface was straight with a few BMG fragments embedded in the copper sheet in some regions. Hardness tests across the interface showed increase in strength on the copper side. Instrumented peel test resulted in failure in the parent copper sheet. A slower impact velocity during a separate experiment resulted in a weld which had wavy regions along the interface and in peel failure again happened in the parent copper sheet. Some through-thickness cracks were observed in the BMG plate and there was some spall damage in the copper flyers. TEM electron diffraction on a sample, cut out from the wavy weld interface region using a focused ion beam, showed that devitrification of the BMG was completely avoided in this welding process.
Aerosol jet printing of silver inks is a promising approach for 3D printing of electronics, particularly for obtaining very complex circuits with high‐resolution conductive pads and traces. Common silver inks are however not competitive with traditional bulk metal conductors, requiring sintering at high temperatures as well as having significant porosity that can result in early failure. Herein, the possibility of using electroplating to deposit bulk metal copper on aerosol jetted inks is investigated, and more than an order of magnitude reduction in electrical resistivity is shown. The plating rate, resistivity, and adhesion are characterized, along with the morphology of the resulting deposits. This approach is then shown to allow high‐strength soldering to the electroplated metal traces, demonstrating the capability of this technology for integration of soldered surface mount components with aerosol jet‐printed electronics.
Introduction:Percutaneous, transtracheal jet ventilation (percutaneous transtracheal jet ventilation) is an effective way to ventilate both adults and children. However, some authors suggest that a resuscitation bag can be utilized to ventilate through a cannula placed into the trachea.Hypothesis:Percutaneous transtracheal ventilation (percutaneous transtracheal ventilation) through a 14-gauge catheter is ineffective when attempted using a resuscitation bag.Methods:Eight insufflation methods were studied. A 14-gauge intravenous catheter was attached to an adult resuscitation bag, a pediatric resuscitation bag, wall-source (wall) oxygen, portable-tank oxygen with a regulator, and a jet ventilator (JV) at two flow rates. The resuscitation bags were connected to the 14-gauge catheter using a 7 mm adult endotracheal tube adaptor connected to a 3 cc syringe barrel. The wall and tank oxygen were connected to he 14-gauge catheter using a three-way stopcock. The wall oxygen was tested with the regulator set at 15 liters per minute (LPM) and with the regulator wide open. The tank was tested with the regulator set at 15 and 25 LPM. The JV was connected directly to the 14-gauge catheter using JV tubing supplied by the manufacturer. Flow was measured using an Ohmeda 5420 Volume Monitor. A total of 30 measurements were taken, each during four seconds of insufflation, and the results averaged (milliliters (ml) per second (sec)) for each device.Results:Flow rates obtained using both resuscitation bags, tank oxygen, and regulated wall oxygen were extremely low (adult 215 ±20 ml/sec; pediatric 195 ±19 ml/sec; tank 358 ±13 ml/sec; wall at 15 l/min 346 ±20 ml/sec). Flow rates of 1,394 ±13 ml were obtained using wall oxygen with the regulator wide open. Using the JV with the regulator set at 50 pounds per square inch (psi), a flow rate of 1,759 ±40 was obtained.These were the only two methods that produced flow rates high enough to provide an adequate tidal volume to an adult.Conclusions:Resuscitation bags should not be used to ventilate adult patients through a 14-gauge, transtracheal catheter. Jet ventilation is needed when percutaneous transtracheal ventilation is attempted. If jet ventilation is attempted using oxygen supply tubing, it must be connected to an unregulated oxygen source of at least 50 psi.
Over the last decade dual beam FIB has proved increasingly useful in a laboratory setting. Researchers have used dual beam FIB's in a wide variety of experiments, including but in no way limited to fabrication of nano pillars for micromechanical testing, modification of circuits during use, and the creation of tooling for nanoscale machining. The field of high resolution microscopy in particular has seen huge benefits from FIB processing in the form of high quality orientation specific lamella. One drawback of the technique is the formation of damage caused as a result of the impact of fast gallium ions on samples. This damage takes the form of the formation of lattice defects (e.g., dislocation loops) and/or amorphous layers on the surfaces of the FIB'd samples. The latter form of damage can degrade the quality of high resolution images and so the mechanism of its formation has been the subject of considerable study. However, these various studies of amorphization during FIB processing have largely focused on the effect of gallium ions on electronic materials. This concentration of research is likely due to several primary factors, the extensive use of and investment by the semiconductor industry in FIB research and the geometrical factors complicating measurement of amorphous damage. In our research, we have found that there are considerable differences between the amounts of amorphous damage between, on the one hand, semiconductors and, on the other hand, metallic materials. The present paper focuses on attempts to identify the origin for these differences.The main problem in studying the formation of amorphous damage is the consistency in results as a function of the specifics of sample geometry. Most often, thin FIM lamellae are used, and the problem with the use of such samples is the difficulty in distinguishing between "primary" damage and redeposition of material that has been initially milled from the sample surface [1]. In the present study, needle shaped samples have been employed as these allow for consistent measurements of damage formation (as a function of sample thickness, which can be readily determined from the local diameter of the needle), and by positioning of a needle in close proximity to one being milled, the phenomenon of re-deposition can also be examined. Multiple needles may be made using a single FIB trenching operation. In this study one 28 µm * 1.5 µm * 4.5 µm foil was sufficient to create six posts suitable for needle shaping and one slab suitable for creation of a TEM lamella. Redeposition was noted to be a major concern when making closely spaced needles, in Figure 1 . Needles made at 30 kV using NiAl and commercially pure metals such as Ti, Ni, Al, and Fe all contained disordered layers with average thicknesses ranging from a ≈ 2 nm to ≈ 8 nm.
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