INFLUENCE OF OXIDATION ON CONTACT ANGLE BETWEEN LIQUID ALUMINUM AND Al2O3

Aluminum can be easily oxidized at high temperature so that it is difficult to accurately measure the contact angle between the liquid aluminum and Al2O3 substrate. In the current study, the measurement of the contact angle between liquid aluminum and Al2O3 was performed under Ar gas purging and vacuum conditions. The effect of oxidation on the contact angle between liquid aluminum and Al2O3 was investigated. It was observed that aluminum samples in both Ar gas and vacuum condition were oxidized. With further increasing of the temperature, the oxide film gradually reacted with liquid Al and became thinner. The disruption of the thin oxide film caused the mutation of contact angle. The contact angle after mutation was approximately 130 degrees for both cases. The temperature of the turning point was lower under vacuum condition than under Ar gas purging. Under vacuum condition, the final stable contact angle was approximately 63 degrees above 1275 degrees C.