Reinforcing capability of multiwall carbon nanotubes in alumina ceramic hybrid nanocomposites containing zirconium oxide nanoparticle
Zhu, Iftikhar Ahmad, Mohammad Islam, Shahid Parvez, Nuha AlHabis, Adeel Umar, Khurram S. Munir, Nannan Wang, Yanqiu . 2019
In this study, we investigate the reinforcing capability of multiwall carbon nanotubes (mwCNT) in alumina
(Al2O3) ceramic hybrid nanocomposites containing zirconium oxide nanoparticles (ZrO2np). For this purpose,
highly dense hybrid nanocomposites containing well-dispersed ZrO2np (8 vol%) and mwCNT (4 vol%) were
fabricated by the hot-pressing method. The resulting hybrid nanocomposite exhibited a ten-fold finer microstructure
and 116% enhanced fracture toughness as well as 12% greater hardness over the benchmarked
monolithic Al2O3. The superior mechanical performance of the hybrid nanocomposite was attributed to the
synergistic role of ZrO2np and mwCNT in refining the matrix microstructure and inducing unique toughening
mechanisms of micro-cracking by ZrO2np and pull-out as well as crack-bridging by mwCNT. Qualitative and
quantitative approaches were utilized to assess the individual and collective role of the reinforcing constituents
in enhancing the performance of hybrid nanocomposite. The qualitative analysis by electron microscopes demonstrated
strong interfacial adhesion of both reinforcing constituents with the based Al2O3 matrix.
Furthermore, the quantitative analysis verified that the enhanced mwCNT/Al2O3 interfacial shear strength is
caused by the intricate physical arrangement of the mwCNT within the matrix grains besides their chemical
bonding at the interface. The role of fine-grained microstructure in establishing idiosyncratic mwCNT interlocking
with the Al2O3 matrix grains was meticulously investigated. Moreover, the influence of mwCNT/matrix
interlocking on the mwCNT reinforcing ability and toughening mechanisms efficiency in the hybrid nanocomposite
is discussed.
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