use of metal templates for microcavity formation in alumina

4.3.5. Stainless Steel Diffusion into Alumina
Figure 4.31 shows that the stainless steel wire has almost completely diffused
into the surrounding alumina leaving behind a cylindrical void. The control of the void
diameter shows that it is larger than the original wire diameter. It is the expected result
of sintering densification (Goodshaw et al., 2009).
(a) (b)
A B
Figure 4.31. SEM micrographs of alumina CR15-St that used stainless steel wire
(a) 5 o C/min at magnification of 500X (b) 5 o C/min at magnification
of 5000X.
According to Figure 4.31, it is observed approximately 100µm expansion for
stainless steel in alumina for 4 hours as soaking time.
The phase diagram of Fe2O3 - Al2O3 system is shown in Figure 4.32. According
to this diagram, it is clear that Al2Fe2O6 (heamatite structure) occured at 1350 o C.
51