1,101 research outputs found
Ionic liquids at electrified interfaces
Until recently, âroom-temperatureâ (<100â150 °C) liquid-state electrochemistry was mostly electrochemistry of diluted electrolytes(1)â(4) where dissolved salt ions were surrounded by a considerable amount of solvent molecules. Highly concentrated liquid electrolytes were mostly considered in the narrow (albeit important) niche of high-temperature electrochemistry of molten inorganic salts(5-9) and in the even narrower niche of âfirst-generationâ room temperature ionic liquids, RTILs (such as chloro-aluminates and alkylammonium nitrates).(10-14) The situation has changed dramatically in the 2000s after the discovery of new moisture- and temperature-stable RTILs.(15, 16) These days, the âlater generationâ RTILs attracted wide attention within the electrochemical community.(17-31) Indeed, RTILs, as a class of compounds, possess a unique combination of properties (high charge density, electrochemical stability, low/negligible volatility, tunable polarity, etc.) that make them very attractive substances from fundamental and application points of view.(32-38) Most importantly, they can mix with each other in âcocktailsâ of oneâs choice to acquire the desired properties (e.g., wider temperature range of the liquid phase(39, 40)) and can serve as almost âuniversalâ solvents.(37, 41, 42) It is worth noting here one of the advantages of RTILs as compared to their high-temperature molten salt (HTMS)(43) âsister-systemsâ.(44) In RTILs the dissolved molecules are not imbedded in a harsh high temperature environment which could be destructive for many classes of fragile (organic) molecules
Development of a novel electrophotographic additive layer manufacturing machine
PhD ThesisThe aim of this research was to develop a low-cost, desktop Additive Layer
Manufacturing (ALM) system. A review of commercial ALM systems, a number of
which are also called 3D printers, has been undertaken with the intention of
identifying a suitable technology to embody within a system demonstrating low-cost
and desktop characteristics. The review resulted in a commercially unexploited
powder deposition technology, electrophotography, being identified. The significant
barriers to implementation of this technology were the limitation of build height in the
Z-axis due to electric field depletion and the formation of part material fringing due to
the non-uniform electric field present at the boundaries of printed artefacts.
Initial trials were undertaken using a laser printing system to determine the printing
characteristics of low-cost sacrificial and recyclable materials such as Mica, flour and
sugar as well as an engineering polymer, Nylon 12. Mixed results were seen due to the
large distribution of particle sizes and their tribocharging characteristics. The
identified limiting phenomena were recreated and analysed in order to develop
possible solutions, and further testing on the electrostatic behaviour and print
acceptance of substrate transfer materials was undertaken with standard styrene co-
polymer based toner. Consolidation techniques were investigated and powder layer
transfer mechanisms were trialled, culminating in the development of the novel
thermal transfer system, eliminating both the build height phenomena and artefact
fringing issues. Development of a complete prototype system was undertaken,
producing a compact desktop system with novel process architecture. The system
functioned through the electrostatic deposition of a polymeric thermoplastic material
onto the surface of a registered PTFE transfer substrate. The powder image present on
the transfer substrate, was brought into close proximity to a build platform, where the
powder layer was heated, consolidated and mechanically transferred using a single
moving mechanism. Later concepts describe the novel continuous printing process,
exhibiting high productivity while maintaining accuracy and resolution.
This work demonstrates a significant step forwards in the apparatus for use in an
electrophotographic ALM system. In doing so, solutions to fundamental electrostatic
transfer problems, and a clear route for the further development of a commercial
electrophotography ALM process have been demonstrated. The system
conceptualised, designed and produced within this research holds much novel value
and provides a basis and direction for further development
Process techniques study of integrated circuits Final scientific report
Surface impurity and structural defect analysis on thermally grown silicon oxide integrated circui
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