Electrochemical trepanning of blades made of Inconel 625

In the aerospace field, difficult-to-machine materials are used widely to improve engine performance. As a nickel-based material that performs well in all aspects, Inconel 625 is used for the blisks of aircraft engines, and electrochemical trepanning (ECTr) is used widely to fabricate such blisks because of its unique advantages regarding ruled surface parts. In this study, to investigate the performance of Inconel 625 in ECTr, measurements were made of the electrochemical characteristics firstly, specifically the anodic polarization curve and the actual volumetric electrochemical equivalent curve. Then, via dynamic electric-field simulations, the processes for forming Inconel 625 blades using ECTr were examined under direct voltage (DV) and pulsed voltage. The contours and current density distributions of formed blades at different times were obtained under different duty cycles. With decreasing duty cycle, the forming accuracy improved gradually and the stray current was reduced. To verify the simulation results, ECTr experiments with Inconel 625 were performed under different voltage conditions. With DV and 90% and 80% duty cycle, the taper angles of the machined blades were 7.784°, 6.278°, and 5.191°, respectively, and the surface roughness ( Ra) values were 0.95, 0.81, and 0.72 μm, respectively. With DV, there were obvious flow marks and gullies on the microscopic surface. With decreasing duty cycle, stray corrosion was reduced effectively and the state of the flow field was improved. Overall, the simulation results were verified effectively.

Mesoscopic electrodynamics at metal surfaces

Plasmonic phenomena in metals are commonly explored within the framework of classical electrodynamics and semiclassical models for the interactions of light with free-electron matter. The more detailed understanding of mesoscopic electrodynamics at metal surfaces is, however, becoming increasingly important for both fundamental developments in quantum plasmonics and potential applications in emerging light-based quantum technologies. The review offers a colloquial introduction to recent mesoscopic formalism, ranging from quantum-corrected hydrodynamics to microscopic surface-response formalism, offering also perspectives on possible future avenues.

Synthesis of Phosphonated Carbon Nanotubes: New Insight into Carbon Nanotubes Functionalization

Carbon nanotubes were successfully functionalized for the first time in a free radical phosphonylation reaction. Three synthetic protocols were proposed. Carbon nanotubes and diethylphosphite reacted in the presence of known radical initiator, such as azobisisobutyronitrile, single electron oxidant—Mn(OAc)3, or under UV radiation. The functionalized material was fully characterized by means of spectroscopic methods, together with microscopic, surface area and thermogravimetric analyses. UV-illumination was found to be the most effective approach for introducing phosphonates onto carbon nanotubes. X-ray photoelectron spectroscopy analysis showed 6% phosphorus in this sample. Moreover, the method was performed at room temperature for only one hour, using diethylphosphite as a reactant and as a solvent. The functionalized carbon nanotubes showed an improved thermal stability, with a decomposition onset temperature increase of more than 130 °C. This makes it very promising material for flame retarding applications.

Compression Molding and Nickel Molds for Directional Gecko-Inspired Adhesives

In the fabrication of directional gecko-inspired adhesives, a new capability made possible by the availability of metal molds is hot compression molding. This molding process allows the use of elastomers with much higher toughness than those cast at ambient temperature and pressure, as has been the common case in fabricating adhesives. In addition, it permits fast cycle times (minutes instead of hours), which is useful for volume manufacturing. We present the results of hot compression molding of elastomers in metal molds created with overhanging and tapered microscopic surface features, which give rise to anisotropic adhesion. We show that the adhesive performance so obtained is equivalent to that obtained earlier with PDMS.

Life in a Droplet: Microbial Ecology in Microscopic Surface Wetness

While many natural and artificial surfaces may appear dry, they are in fact covered by thin liquid films and microdroplets invisible to the naked eye known as microscopic surface wetness (MSW). Central to the formation and the retention of MSW are the deliquescent properties of hygroscopic salts that prevent complete drying of wet surfaces or that drive the absorption of water until dissolution when the relative humidity is above a salt-specific level. As salts are ubiquitous, MSW occurs in many microbial habitats, such as soil, rocks, plant leaf, and root surfaces, the built environment, and human and animal skin. While key properties of MSW, including very high salinity and segregation into droplets, greatly affect microbial life therein, it has been scarcely studied, and systematic studies are only in their beginnings. Based on recent findings, we propose that the harsh micro-environment that MSW imposes, which is very different from bulk liquid, affects key aspects of bacterial ecology including survival traits, antibiotic response, competition, motility, communication, and exchange of genetic material. Further research is required to uncover the fundamental principles that govern microbial life and ecology in MSW. Such research will require multidisciplinary science cutting across biology, physics, and chemistry, while incorporating approaches from microbiology, genomics, microscopy, and computational modeling. The results of such research will be critical to understand microbial ecology in vast terrestrial habitats, affecting global biogeochemical cycles, as well as plant, animal, and human health.