Effect of Alumina Ceramics Surface Condition …
481
The Wetting Measurements of Lead Drop
The wetting of liquid lead on different roughness alumina substrates was measured
by a sessile drop method. Details of the experimental apparatus and procedure can
be referenced in our previous work [11, 12]. The apparatus consists of a furnace
(Kanthal line heated), photographic equipment, a digitizer, and a computer analysis
system. A quartz tube was sealed with a quartz cap (inner diameter, 30 mm; outer
diameter, 34 mm; length, 560 mm) as a heating chamber. The tip of the thermocouple
(Fe–CuNi) between quartz pipes was located directly under the alumina substrate
and lead drop. The temperature difference of measurement was negligible. Ar–H 2
5% functioned as protective gas.
The lead block (purity, 99.99 mass%) was cut into a cylinder (5.5 × 5.5 mm).
The polishing cloth was used to remove the oxide layer on the lead surface and
cleaned with acetone using an ultrasonic automatic washer for 20 min. Then the
sample was rinsed with deionized water and dried. The lead cylindrical sample was
set on the alumina substrate, which was made horizontal by two water levels, and
then put into the quartz tube of the furnace by a quartz support. The quartz tube was
sealed and evacuated to 10–3 Pa, then filled with Ar–H 2 5% and evacuated again.
After repeated operations for three times, heating was started, and the flow rate of gas
was maintained at 0.2 L/min. After reaching the target temperature, photographs of
the molten lead drop were taken every 3 min and the corresponding time was recorded
for measuring contact angle, droplet height, contact diameter, and adsorption work.
After cooling, the samples were prepared for microscopic characterization of the
interface.
Results and Discussion
Surface Roughness of Alumina Substrate
Figure 1 shows the 3D morphology map of CLSM analysis for the 1# to 4# alumina
substrates, which shows the mean values of Ra. The surface roughness of four substrates can be easily compared by 3D morphology map, and the roughness value of
four alumina substrates was calibrated by Ra. The surface roughness then increases
in turn. The surface of 1# substrates is a smooth mirror, and there are many pits with
different depths on the surface of other substrates.
481
The Wetting Measurements of Lead Drop
The wetting of liquid lead on different roughness alumina substrates was measured
by a sessile drop method. Details of the experimental apparatus and procedure can
be referenced in our previous work [11, 12]. The apparatus consists of a furnace
(Kanthal line heated), photographic equipment, a digitizer, and a computer analysis
system. A quartz tube was sealed with a quartz cap (inner diameter, 30 mm; outer
diameter, 34 mm; length, 560 mm) as a heating chamber. The tip of the thermocouple
(Fe–CuNi) between quartz pipes was located directly under the alumina substrate
and lead drop. The temperature difference of measurement was negligible. Ar–H 2
5% functioned as protective gas.
The lead block (purity, 99.99 mass%) was cut into a cylinder (5.5 × 5.5 mm).
The polishing cloth was used to remove the oxide layer on the lead surface and
cleaned with acetone using an ultrasonic automatic washer for 20 min. Then the
sample was rinsed with deionized water and dried. The lead cylindrical sample was
set on the alumina substrate, which was made horizontal by two water levels, and
then put into the quartz tube of the furnace by a quartz support. The quartz tube was
sealed and evacuated to 10–3 Pa, then filled with Ar–H 2 5% and evacuated again.
After repeated operations for three times, heating was started, and the flow rate of gas
was maintained at 0.2 L/min. After reaching the target temperature, photographs of
the molten lead drop were taken every 3 min and the corresponding time was recorded
for measuring contact angle, droplet height, contact diameter, and adsorption work.
After cooling, the samples were prepared for microscopic characterization of the
interface.
Results and Discussion
Surface Roughness of Alumina Substrate
Figure 1 shows the 3D morphology map of CLSM analysis for the 1# to 4# alumina
substrates, which shows the mean values of Ra. The surface roughness of four substrates can be easily compared by 3D morphology map, and the roughness value of
four alumina substrates was calibrated by Ra. The surface roughness then increases
in turn. The surface of 1# substrates is a smooth mirror, and there are many pits with
different depths on the surface of other substrates.