an investigation into the morphology of short-time oxide films in molten pure aluminum

aluminum is very sensitive to oxidation reactions. if a fresh surface of melt is exposed to air, it oxidizes quickly and an oxide layer covers the melt surface. new oxide films formed in a very short time during casting are thin and folded. the metal surface can be folded and create a double-oxide film as a result of the melt turbulence. the entrance of this double-oxide film into the melt is one of the most important reasons for the formation of crack-like defects during casting. in this work, the characteristics of these new oxide films have been investigated based on the oxide-metal-oxide sandwich technique. to study the futures of new oxide film, the contact area between two adjacent and entrapped bubbles have been examined using scanning electron microscope (sem). results showed that the short time oxide films formed in pure aluminum have a thickness less than 100 nanometer