The effects of thermocycle frequency, aging temperature and post-cure conditions on weight loss, microhardness and crack formation of PMR-15 neat resins were investigated. Crack formation was monitored by metallography. The molecular level changes, occurring under the same conditions, were monitored by microscopic FT-IR in reflectance mode on the same samples. FT-IR analysis was carried out in zones 100 μm in diameter, allowing examination of different regions of the aged samples. It was found that weight loss, crack formation and microhardness were highly dependent on aging time and temperature, but not thermocycling frequency. Molecular level changes were also highly correlated to time and temperature of aging. Both the physical effects of aging and the chemical effects were isolated to a thin surface layer. No changes whatsoever to the interiors of the samples were evident by FT-IR, microhardness or microscopy.
We present a design for a continuous-wave (CW) atom laser on a chip and describe the process used to fabricate the device. Our design aims to integrate quadrupole magnetic guiding of ground state 87 Rb atoms with continuous surface adsorption evaporative cooling to create a continuous Bose-Einstein condensate; out-coupled atoms from the condensate should realize a CW atom laser. We choose a geometry with three wires embedded in a spiral pattern in a silicon subtrate. The guide features an integrated solenoid to mitigate spin-flip losses and provide a tailored longitudinal magnetic field. Our design also includes multiple options for atom interferometry: accomodations are in place for laser-generated atom Fabry-Perot and Mach-Zehnder interferometers, and a pair of atomic beam X-splitters is incorporated for an all-magnetic atom Mach-Zehnder setup. We demonstrate the techniques necessary to fabricate our device using existing micro-and nano-scale fabrication equipment, and discuss future options for modified designs and fabrication processes.
Research on the boundary lubrication performance of two perfluoropolyether (PFPE) thin films in the presence of passirated 440C stainless steel is presented. The study used a standard ball‐on‐disc (BoD) tribometer operating in dry nitrogen and a vacuum spiral orbit tribometer (SOT). Stainless steel surfaces were passivated using one of four techniques: a high‐temperature and low‐temperature chromic acid bath, a tricresyl phosphate (TCP) soak, or UV/ozone treatment for 15 min. After passivation, each BoD disc had a 400 Å film of Krytox® 16256 (PFPE) applied to it. The lives of these films were quantified by measuring the number of sliding cycles before an increase in friction occurred. The lubricated life of the 440C couple was not altered as a result of the various passivation techniques. The resulting surface chemistry of each passivation technique was examined using X‐ray photoelectron spectroscopy. The SOT was used to examine the effects of the TCP treatment on the lubricated life of another PFPE, Brayco® 815Z, under rolling conditions. None of the passivation techniques were found to increase dramatically the oxide film thickness or lubricated life.
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