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Volume 6, Issue 4 (Suppl) J Material Sci Eng, an open access journal
ISSN: 2169-0022 Materials Congress 2017
June 12-14, 2017
June 12-14, 2017 Rome, Italy
Materials Science and Engineering
9th World Congress on
J Material Sci Eng 2017, 6:4(Suppl)
DOI: 10.4172/2169-0022-C1-068
Self-healing capacity of nuclear glass observed by NMR spectroscopy
Thibault Charpentier
Université Paris-Saclay, France
Borosilicate glasses have been recognized as valuable materials for the conditioning of nuclear wastes. An important issue for
their long-term behavior is radiation effects which may impact their performance and stability. To address these concerns, a
fundamental understanding of the origin at the atomic scale of the macroscopic property evolutions must be established. To this
aim, magic-angle spinning nuclear magnetic resonance (MAS NMR) has firmly established itself as one of the most powerful tool to
investigate glass structure. Recently, using external heavy ions irradiation (Xe, Au and Kr) to simulate alpha decays, dramatic changes
in the local network structure were evidenced: Conversion of tetrahedral BO4 units into planar trigonal BO3 units (11B), appearance of
high-coordination aluminum units (AlO5, AlO6); glass depolymerization (29Si) and changes in the distribution of alkali cations (23Na).
Additionally, the spectra broaden globally which supports the hypothesis of an increased topological disorder after irradiation. All
these structural changes are similar to those observed with increasing the glass temperature or quenching rate and support therefore
the model of ballistic disordering fast quenching events which induce a new glassy state with higher fictive temperature. Until recently,
such studies were limited to externally irradiated samples (enabling the different components of irradiation to be dissociated for their
precise investigation), but recently, the first MAS-NMR experiments could be performed on radioactive glasses (doped with 244Cm 0.1
%mol.) paving the way for future MAS NMR examinations of self-irradiation damages in glasses. Experiments were performed at the
Joint Research Centre Institute for Transuranium Elements (JRC-ITU) where a commercial NMR spectrometer were integrated with
a radioactive glovebox and a MAS commercial probe. First results will be presented. Competitive effects between the recoil nuclei and
alpha decays were evidenced and the high resistance of the nuclear waste glasses corroborated.
Bioinspired wettability-controlled surfaces with gradient micro- and nano-structures
Yongmei Zheng
Beihang University, China
Biological wettability surfaces with various-style gradient micro- and nanostructures (MN) greatly provide with excellent functions
via natural evolvement. In nature, a combination of multiple gradients in a periodic spindle-knot structure take on surface of
spider silk after wet-rebuilding process in mist. This structure drives tiny water droplets directionally towards the spindle-knots
for highly efficient water collection. Inspired by the water collecting ability of spider silk, a series of functional fibers with unique
wettability has been designed by various as-inspired techniques. Various geometrically-engineered thin fibers with the bead-on-string
structures achieve droplet driving, transport of droplet for water collection in efficiency, etc. Besides, inspired by gradient effects on
butterfly wing and lotus leaves, the surfaces with ratchet MN, flexible lotus-like MN are fabricated successfully by improved methods,
which demonstrate that the gradient MN effect rises up distinctly anti-icing, ice-phobic and de-ice abilities. These multifunctional
materials can be designed and fabricated for promising applications such as water-collecting, anti-icing, anti-frosting, or anti-fogging
properties for practical applications in aerospace, industry, etc.