Thermal behavior of an oxide layer on aluminum

Films 16 to 17 μm thick were obtained on the ^#AMg5 alloy by plasma electrolytic oxidation (PEO) in an orthophosphate-borate electrolyte. Air annealing at 250, 300, 400, and 500°C for 4 h did not affect the thickness, weight, and the elemental composition of the resulting films. The contact angle for water changed from 75° to zero. In a temperature range from 250 to 300°C, the content of the crystalline γ-Al₂O₃ phase jumped. Above 300°C, the film surface cracked and became less resistant to corrosion. Original Russian Text ? V.S. Rudnev, A. E. Lysenko, P. M. Nedozorov, T. P. Yarovay, A.N. Minaev, 2007, published in Zashchita Metallov, 2007, Vol. 43, No. 5, pp. 510–514.