DESIGN, ASSEMBLY AND CHARACTERIZATION OF COMPOSITE ...

The above discussion is mainly focused on the sintering behavior of LFBT. On
the other hand, sintering of Ni particles in the composite structure proceeds differently.
As Ni particles are insoluble in the ZnO-B2O3-Li2O liquid phase, and have a sintering
temperature of 900 °C, densification of Ni matrix should follow the solid state sintering
model. Neck formation of the percolating Ni particle network is likely to occur at the
early stage of the sintering process. This is obvious by comparing the specimens fired at
800 °C. The BT:Ni=3:37 Ni'(m) lattice demonstrates a significant sintering strain,
indicating that neck formation of Ni particle network had already occurred at a lower
temperature. Neck formation of Ni particles in lattices of BT:Ni=1:4 and 3:7 Ni'(m) must
have occurred, but their sintering strain is resisted by a higher refractory BT inclusion.
Nevertheless, the expected result is the formation of interlocked Ni particle network in
these lattice specimens. Hence, the structure of Ni'(m) components with a high Ni content
in a composite structure is relatively fixed as compared to the LFBT components, and
stress relaxation during densification must largely be accomplished by particle
rearrangement in the LFBT components.
6.3.4. Fabrication of BT-Ni Composites
Heterogeneous BT-Ni composite structures have been successfully fabricated
with the use of the LFBT ink for ceramic components, and either the BT:Ni=1:4 or 3:7
Ni'(m) ink for metal components. A thorough screen of all possible compositions is not
done, but presumably any composition between BT:Ni=1:4 and 3:7 is compatible to the
LFBT ink. All these composite structures have slight deformation compared to the
original CAD designs, due to the pulling effect by the moving nozzle tips during ink-
printing process and the internal stresses involved throughout the sintering process. The
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