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Z. Qi and Z. F. Yuan
Fig. 3 a Heating curve for wetting experiment of molten lead and b changes for contact angle of
lead drop on alumina substrate of different roughness at various temperatures
diameter of Ra = 2.02 µm exceeds that of Ra = 2.16 µm. At the same time, the
contact angle (Fig. 3b) and the drop height (Fig. 4b) also change correspondingly.
On the basis of Wenzel equation [16], according to the above results, the increase
of surface roughness of alumina substrates means that the actual surface area of
alumina substrates increases. In molten lead/alumina systems, lead tends to reduce
the contact area with alumina substrates. At the same time, the pits on the surface
of the substrate hindered the movement of the three-phase line, forming a pinning