Browsing by Author "Ingham, B"

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    Carbide composition and stress measurement in ethylene pyrolysis tubes
    (Australian Institute of Physics, 2010-02-05) Stevens, KJ; Ingham, B; Ryan, M; Luzin, V; Cheong, K
    Ethylene is important in the production of polyethylene, used in thin film packaging, piping and cable sheathing. It is produced by steam cracking of naptha, LPG or ethane at temperatures around 950°C at high flow velocities. Carburisation of ethylene pyrolysis tubes (typically of nominal composition 31%Fe, 37%Ni and 25%Cr) causes a loss in weldability, corrosion resistance and ductility, and provides a source of micro-cracking. Plant operators prefer to replace tubes at planned outages and are interested in remaining life assessments assisted by description and modelling of the progress of carburisation. The powder diffraction beamline at the Australian Synchrotron has been used to radially scan mounted and polished tube sections prepared from ex-service carburised tubes. Radial dependence of carbide phases in the tubes is being quantified using Bruker TOPAS software for whole pattern line fitting. Composition analysis and microscopy is being used to create a representative microstructure in Abaqus Finite Element Analysis (FEA) models and to interpret non-destructive eddy current measurements [1] of carburisation. The austenite diffracting planes give a peak shift response to stress that is anisotropic and is being interpreted with FEA based crystal plasticity models. Neutron diffraction at the Kowari beamline at OPAL (Open Pool Australian Lightwater reactor) was used to measure strain in unsectioned tubes at room temperature. This was compared to FEA models of the strain created by differential thermal expansion between carbide phases and austenite, assuming creep relaxation at normal tube operating temperature.
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    Towards better understanding of atomically precise gold clusters and titania made using surface modifying agents
    (Australian Institute of Physics, 2014-02-04) Golovko, VB; Ruzicka, JY; Abu Bakar, A; Anderson, DP; Adnan, R; Donoeva, B; Ovoshchnikov, D; Metha, GF; Andersson, GG; Thomsen, L; Cowie, B; McNicoll, C; Ingham, B; Kemmitt, T; Fang, V; Kennedy, J
    Controlled synthesis of titania nanoparticles using recently perfected sol-gel methodology, synthesis of atomically precise metal clusters, their deposition and activation on oxide supports and studies of properties of the resulting materials as promising catalysts and sensors will be briefly discussed. Our work on synthesis of titania nanoparticles is focused on careful tuning of the reaction conditions and use of selected surface modifying agents capable of directing and controlling growth of nanoparticles with specific size, phase and even population of Ti+3 sites at the surface. Promising performance of titania made using our methodology as near-IR reflective coating will be briefly highlighted. From pre-historic times gold was known as a chemically inert, “noble” metal until, in 1987, Haruta et al. proved that gold nanoparticles can be catalytically active. Results of research focused on the use of size-controlled, chemically pre-synthesised nanoparticles (colloids and clusters) with core sizes ranging from classical 1.5 nm “Au55” systems to atomically precise, uniquely small clusters (Au9 etc.) including a range of mixed-metal clusters will be presented. Immobilization of such clusters on a variety of supports had been pursued in an attempt to fabricate a family of site-isolated catalysts, where properties of the active site are defined by the nature of the precursor with great precision. Catalytic performance in selected reactions will be highlighted. New insights in the nature of our precisely defined precursors (pure and immobilised onto supports) obtained using relevant materials characterization techniques, such as Synchrotron X-ray Photoelectron Spectroscopy will be presented.
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    XPS and NEXAFS study of fluorine modified TiO2 nano-ovoids reveals dependence of Ti3+ surface population on the modifying agent
    (Royal Society of Chemistry, 2014-04-04) Ruzicka, JY; Bakar, FA; Thomsen, L; Cowie, BCC; McNicoll, C; Kemmitt, T; Brand, HEA; Ingham, B; Andersson, GG; Golovko, VB
    Crystalline titanium dioxide was synthesised under mild conditions by the thermal degradation of peroxotitanic acid in the presence of a number of fluoride-containing surface modifying agents (NH4F, NH4BF4, NH4PF6, NBu4F, NBu4BF4, NBu4PF6). The resulting materials were characterised by PXRD, SEM, HRTEM, XPS and NEXAFS. Particle phase, size, and surface area were noticeably affected by the choice of surface modifying agent. Both the cation and anion comprising the modifying agent affect the surface Ti3+ population of the materials, with two apparent trends observed: F− > BF4− > PF6− and NBu4+ > NH4+. All materials displayed evidence of fluorine doping on their surfaces, although no evidence of bulk doping was observed. © 2014 The Royal Society of Chemistry (Open Access)