Ionic liquids as an additive in fully formulated wind turbine gearbox oils

This work presents the friction and wear behaviour of two fully formulated (polyalphaolefin- and mineral-based) wind turbine gearbox oils separately additivated with two ionic liquids ([Choline][NTf2] and [BMP][NTf2]) at 5wt% concentration. A tribometer using a ball-on-plate reciprocating configuration is adopted for friction and wear experiments. Friction is measured during tests and the worn surface is measured and analysed by confocal microscopy, SEM, EDS and XPS. The friction and wear results show that both ionic liquids used as an additive have a slight friction modifier character but a strong wear reducing performance, with [BMP][NTf2] performing better than [Choline][NTf2]. In addition, EDS and XPS analysis demonstrated the temperature-related chemical interactions and their influence on tribological behaviour

Effect of thermal treatment on the growth, structure and luminescence of nitride-passivated silicon nanoclusters

Silicon nanoclusters (Si-ncs) embedded in silicon nitride films have been studied to determine the effects that deposition and processing parameters have on their growth, luminescent properties, and electronic structure. Luminescence was observed from Si-ncs formed in silicon-rich silicon nitride films with a broad range of compositions and grown using three different types of chemical vapour deposition systems. Photoluminescence (PL) experiments revealed broad, tunable emissions with peaks ranging from the near-infrared across the full visible spectrum. The emission energy was highly dependent on the film composition and changed only slightly with annealing temperature and time, which primarily affected the emission intensity. The PL spectra from films annealed for duration of times ranging from 2 s to 2 h at 600 and 800°C indicated a fast initial formation and growth of nanoclusters in the first few seconds of annealing followed by a slow, but steady growth as annealing time was further increased. X-ray absorption near edge structure at the Si K- and L3,2-edges exhibited composition-dependent phase separation and structural re-ordering of the Si-ncs and silicon nitride host matrix under different post-deposition annealing conditions and generally supported the trends observed in the PL spectra

The Chemical Nature of Oxidized Sulphur in Asphaltenes from X-Ray Absorption Spectroscopy

Bitumen samples have been chosen either from natural oil seepages and outcropping oil-stained reservoirs or archaeological bitumens from excavations in Iraq and Pakistan. Asphaltenes have been extracted from the bitumens. X-ray absorption near edge fine structure (XANES) spectroscopy at the S L-edge and K-edge has been employed to follow the oxidation effects on various sulphur moieties of the asphaltene fractions. Among asphaltenes extracted from archeological bitumens, sulphoxide, sulphone and sulphate are the predominant oxidized forms of sulphur

Laser-induced fluorescence of gaseous vanadium methylidyne, VCH : A triatomic organometallic molecule

M. Barnes, P. G. Hajigeorgiou, R. Kasrai, A J. Merer, and G. F. Meth

Sampling depth of total electron and fluorescence measurements in Si L- and K-edge absorption spectroscopy

High resolution Si L-edge and K-edge X-ray absorption near edge structure (XANES) spectra for SiO2 on Si substrates have been recorded using total electron yield (TEY) and fluorescence yield (FY) techniques. The sampling depths of TEY and FY for Si L-edge and Si K-edge, respectively, have been investigated in the energy range 95-120 eV and 1830-1900 eV. The maximum sampling depth for TEY is found to be ~ 5 nm for the Si L-edge and ~ 70 nm for the K-edge regions. The FY sampling depth at the L-edge is ~ 70 nm whereas for the K-edge, the sampling depth is several hundred nm. Based on these data, and using a theoretical model, electron escape depths for the TEY measurements in both energy ranges have been deduced.NRC publication: Ye