use of metal templates for microcavity formation in alumina

CHAPTER 5
CONCLUSIONS
Densification behavior of the alumina powders was investigated using vertical
dilatometers. It is observed that the relative density and densification rate curves of
them are similar to each other. There were two distinct peaks at the densification rate
versus temperature plots at 1125 o C for 5 o C/min of heating rate. These two peaks, which
belong to alumina CR15 and CR30F, were the densification rate curves of these
alumina powders as different from alumina CR6 powder densification behavior. The
behavior of relative density of alumina ALCOA is similar to alumina CR6. In addition,
the densification rate of alumina AKP50 is higher than that of the other alumina
powders. The relative shrinkage, relative density and densification rate of the CR6
alumina powder were investigated at 1500 o C for 1min. According to the result of this
test, it is observed that the relative density of the CR6 increases parabolically and with
the densification rate of CR6 is higher than the performed tests for 1350 o C.
BET analysis of the powders indicated surface area values between 4 and 22
m 2 /g, respectively.
The SEM micrographs of the alumina powders were investigated, and initial
particle size of the alumina CR6, CR15 and CR30F powders were finer than 50nm,
while the particle size of alumina CT3000SG was finer than 300nm, and alumina
AKP50 had an initial particle size of 200nm. Also, EDS analysis of the metal templates
were done and it was observed that the metal templates had high purity.
Densification behavior of the alumina samples, which had titanium wire, was
investigated using vertical dilatometer. It is understood that the diffusion of titanium
into alumina decreases the final density of the samples, while the diffusion of titanium
increases the densification rate of the samples at 1350 o C. The titanium wires are still
present in the alumina. Titanium proceeded in alumina approximately 100µm at 1350 o C
in four hours of soaking time.
Sintered microstructures of the alumina samples that had Ti wire were
investigated from fractured surfaces as well as polished surfaces. It is clear that titanium
advanced through alumina about 100µm at 1350 o C during four hour soaking time. In
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