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May 16-17, 2019 | Prague, Czech Republic
2
nd
International Conference on
22
nd
International Conference on
Nanomaterials and Nanotechnology
Advanced Nanoscience and Nanotechnology
Joint Event
&
Journal of Materials Science and Nanotechnology | Volume 3
Mater Sci Nanotechnol, Volume 3
Nano-scaled fillers (nanotubes, nanosheets): Do they toughness brittle matrices?
Ivo Dlouhy, Petr Tatarko, Luca Bertolla
and
Zdenek Chlup
Brno and Brno University of Technology, Czech Republic
C
arbonnanotubes(CNTs)havebeenshownhavingexcellent
potential as reinforcements in a wide range of composite
systems, thanks to their exceptional intrinsic mechanical and
other functional properties. There has been growing interest
in using CNTs in ceramic and/or glass matrices as toughening
filler, in the last decade. Also, graphene nanosheets (GNSs)
and graphene oxide nanosheets (GONSs) have attracted
attention thanks to their unique combination of mechanical,
thermal and electrical properties. Graphene thus appears to
be an ideal second phase filler in order tomodify properties of
ceramics. Analogous effects have been newly obtained with
boron nitride nanotubes (BNNTs) and nanosheets (BNNSs).
The aim of this contribution is to provide a snapshot of the
current state of the art on the real effect of nanoscale fillers
incorporated into glass/ceramic matrices on their composite
fracture resistance.
For CNTs in silica matrix the fracture toughness KIC increased
linearly to 100-120% relative to silica monoliths up to high
CNT content (15 wt.%). There was an improvement of
35% in KIC of silica with addition of 2.5% GNSs and GONSs.
Toughening mechanisms including GONSs necking, pull-out,
crack bridging, crack deflection and crack branching were
evidenced for silica matrix composites. Similar effects have
been proven in alumina composites, e.g. when incorporating
0.8 vol. % of GNS the improvement of the KIC was more than
40%. BNNT, cylindrical and bamboo-like, incorporated into
nanostructured tetragonal zirconia stabilized with 3 mol.%
yttria contributed to significant increase of KIC, 2.5 wt. %
addition produced 100% increase in KIC compared to the
monolithic zirconia. Exploitation of BNNSs in borosilicate glass
matrix resulted in about 45% KIC increase.
The main effect of nanoscale filler has to be seen not only
in producing synergy of several toughening mechanisms
active during crack initiation/propagation but also in affecting
microstructures formation during sintering.
Speaker Biography
Ivo Dlouhý has been affiliated with Institute of Physics of Materials,
Czech Academy of Sciences, Brno, as a head of Brittle Fracture Group.
He is employed at Brno University of Technology, Institute of Materials
Science and Engineering, as professor and institute director. He
graduated at Faculty of Metallurgy and Materials, TU Ostrava in 1979.
His got his PhD degree from Institute of Physics of Materials, Czech
Academy of Sciences, in 1984. Since 1992, he is active as senior scientist
at the Department of Mechanical Properties. Since 2008, he is the
professor of materials strength, experimental fracture mechanics and
mechanical testing of materials at Faculty of Mechanical Engineering,
Brno University of Technology. Except for research reports, author 210
papers registered by Web of Science, h-index 19. He is the member
of editorial boards of journals Engineering Fracture Mechanics,
International Journal of Applied Ceramic Technology and Metal Physics
and Advanced Technologies.
e:
idlouhy@ipm.cz