Abstract
The reactive wetting behavior of three types of alumina-silicon carbide composite refractory materials was investigated in contact with molten aluminum (Al) and Al alloy using an optimized sessile drop method at 900oC in a purified Ar-4% H2 atmosphere. The time dependent behavior of contact angle and droplet geometry was monitored and the wetting kinetics was identified. The initial contact angle between the liquid Al/Al alloy and two of the refractory substrates was found to be an obtuse angle, which gradually changed to a 90o angle and then eventually to an acute angle with time. However, the wetting angle for the third refractory substrate was found to stay at an obtuse angle for the entire two-hour duration of the experiment. The difference in wetting properties among three types of refractories is attributed to be due to their microstructural and compositional variations. The significant effect of the alloying magnesium added to the molten Al alloy droplets in regard to the wetting kinetics and the influence on the reaction with the refractory substrates is discussed. The results obtained provide important understanding on the wetting and corrosion mechanisms of alumina and silicon carbide materials in contact with molten aluminum.
