DESIGN, ASSEMBLY AND CHARACTERIZATION OF COMPOSITE ...

Second, the added LiAC∙2H2O is amenable to the ink preparation concept used in
Robocasting. Salt addition has been a strategy to formulate aqueous colloidal ceramic
gels. Usually, the added salt is either a fugitive composition during heating process, or a
constituent element of the ceramic system, or both. An example is BaCl2 addition for BT
inks, 105 where BaCl2 is used to flocculate the aqueous BT suspension. In this study, the
primary function of added Li + is to serve as a low melting temperature flux that
stimulates mass transfer during the sintering process for the ceramic phase. And the
acetate group is a fugitive content during sintering process. Nevertheless, their effect of
flocculating BT and Ni(m) suspensions is obvious. An increase in viscosity occurs after
LiAC∙2H2O addition, indicating flocculated particle networks. As LiAC is a monovalent
salt and a less effective flocculation agent, 105 the resulting colloidal gels has a low elastic
behavior and requires rheological adjustment. This is achieved by subsequent addition of
polyelectrolyte, i.e. PEI-50K in the LFBT ink, and PAA-240K and Darvan 821A in the
Ni'(m) inks.
Third, the only purpose of LiAC in the Ni'(m) ink is to balance Li + concentration
for the LFBT and Ni'(m) inks. Consider the scenarios when LFBT ink is co-printed with
a Ni(m) ink that contains no LiAC concentration in the form of a composite ensemble,
there would be a concentration gradient of Li + between the LFBT ink and Ni(m). Li + (aq)
will diffuse from the LFBT to the Ni(m) component. The outcome is that the initial
concentration in the LFBT decreases and the final Li concentration in a composite
structure depends on volume ratio of both inks, provided that a homogeneous
concentration of Li + (aq) may be achieved within the as-printed composite ensemble. To
maintain Li2O concentration in the ceramic phase required for liquid phase sintering, this
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