use of metal templates for microcavity formation in alumina

3.2.1. Co-Pressing with Single-action Mode of Uniaxial Pressing
The alumina pellets were prepared by single-action mode of uniaxial pressing
(UP) at two different pressures: 90MPa and 150MPa (Yıldız Hydraulic Press). The co-
pressing method is shown in Figure 3.3. This procedure was used in single-action-mode
of UP. The alumina powder was poured into die cavity (Φ= 15mm) and was placed
down at its bottom by touching with a metal rod. The metal wire (8mm long) was
placed on this alumina powder on top of which more alumina powder was poured and
the whole pellet was co-pressed at desired pressure.
Figure 3.3. Schematic illustration of uniaxial single action co-pressing method.
3.2.2. Sintering Samples and Preparation for Analysis
The samples were sintered at 1350°C for 4 hours in air in the box kiln
(Nabertherm, 30 – 1750 o C). Heating rate was 5 o C/min and cooling rate was 10 o C/min.
Archimedes method was used to measure densities of all samples. Then, all of the
samples were cut with diamond disc, and the surfaces of all sintered samples were
machined to produce a straight ground and polished surface. 1200, 800, 600, 320, 180
grit grinding paper (Presi, Megaprex, France) and 9 µm, 3 µm and 1 µm diamond
suspensions were used for grinding and polishing to obtain uniform surface (Buehler,
Metadi). Finally, samples around 13mm of diameter and 7mm of thickness, were
obtained. These samples were then ready for SEM analysis.
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