Browsing by Author "Walls, P"

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    Immobilisation of cations and anions in geopolymers
    (Materials Science and Technology (MS&T), 2007-09-16) Vance, ER; Perera, DS; Aly, Z; Walls, P; Zhang, YJ; Cassidy, DJ; Griffith, CS
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    Residual stress distribution in steel butt welds measured using neutron and synchrotron diffraction
    (Institute of Physics, 2009-03-25) Paradowska, AM; Price, JWH; Finlayson, TR; Lienert, U; Walls, P; Ibrahim, R
    70 keV synchrotron radiation and thermal neutrons have been employed to investigate the residual stress characteristics in a fully restrained, steel, butt weld. The focus is on the values of the subsurface and through-thickness strain/stress variation in the middle of the weld. The advantages and limitations of the techniques have been addressed, in relation to the gauge volume, the stress-free reference sample and positioning. The measurement of residual stress around the weld achieved in this work significantly improves the resolution at which residual stress in welded components has been determined. © 2009, Institute of Physics
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    Thermal character of geopolymers synthesized from class f fly ash containing high concentrations of iron and α-quartz.
    (Wiley-Blackwell, 2010-01) Rickard, WDA; van Riessen, A; Walls, P
    This article reports the thermal characteristics of geopolymers prepared with a class F fly ash containing 15 wt% iron oxide and 20 wt%α-quartz. The characterization techniques used included dilatometry, TGA, DTA, XRD, and SEM. Geopolymer specimens were prepared with nominal ratios of Si:Al=2.3 and Na:Al=0.85. Iron oxide in the fly ash precursor was found to play a critical role in the thermal expansion and morphology of geopolymers at temperatures >500°C. Volume changes of quartz on either side of the α–β phase transition cause only minor variations in thermal expansion. © 2010, Wiley-Blackwell.