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ORGANIZER;CN=ESTAD 2023:mailto:info@metec-estad.com
LOCATION:Room 19b
SUMMARY:Structure of casting powders as a function of basicity
DESCRIPTION:The change in structure in casting powders as a function of their basicity is well known to have important effects on their rheology, and therefore on their success in casting.
Different compositions of casting powders were prepared in the form of glasses, by melting the appropriate mixture and fast quenching. The structure of the glasses was studied by means of neutron total scattering at the spallation neutron source ISIS (UK), at the beamline NIMROD [1]. Even though amorphous materials do not possess a long range order, they do have a short range order, whose variations may be responsible for the change in properties. The total scattering data were corrected for all the scattering not produced by the sample and Fourier transformed into a Pair Distribution Function, which provides peaks in correspondence of interatomic bonds. The figure shows an example for 4 of the samples, with a different fluorine content: sample 10 has the highest fluorine content, while sample 11 has the lowest. The shoulder in the plot, at about 2.3 Å, corresponds to the Ca-F bond length.

 The data were analysed through the software EPSR (Empirical Potential Structure Refinement) [2], which allows the creation of a 3D model of the system under study. From the model, various geometrical and structural information can be gained, such as the distribution of coordination numbers, bond lengths and bond angles. This allows to fully understand the subtle differences in the local structure of the glasses, and therefore to produce casting powders with a better performance.


References
[1] https://www.isis.stfc.ac.uk/Pages/nimrod.aspx
[2] Soper AK (2010) EPSRshell: a users guide. ISIS DisorderedMaterial Group, Didcot

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DTSTART:20230614T100000
DTEND:20230614T102000
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