Accelerated growth of oxide film on aluminium alloys under steam: Part I: Effects of alloy chemistry and steam vapour pressure on microstructure

作者：Din Rameez Ud^*; Gudla Visweswara C; Jellesen Morten S; Ambat Rajan

来源：Surface and Coatings Technology, 2015, 276: 77-88.

DOI：10.1016/j.surfcoat.2015.06.059

• Steam
• Vapour pressure
• Aluminium alloys
• Oxide growth
• Boehmite
• Intermetallic particles

Aluminium alloys were treated with steam of varying vapour pressures which resulted in the growth of aluminium oxyhydroxide layers of an average thickness of similar to 450-825 nm. The microstructure and composition of the generated layers were characterised by GD-OES, FEG-SEM, GI-XRD and TEM. The thickness of the oxide layer as well as the compactness increased with steam vapour pressure. The increase in vapour pressure also resulted in a better coverage over the intermetallic particles. Oxide layer showed a layered structure with more compact layer at the Al interface and a nano-scale needle like structure at the top. The kinetics of formation of film under steam was rapid; approx. 350 nm thick layers were generated within 5 s of steam treatment, however increase in thickness of the oxide retarded further growth. The enrichment or depletion of different alloying elements at the surface of aluminium as a result of alkaline etching pre-treatment influenced the thickness and growth of the oxide. Moreover the steam treatment resulted in the partial oxidation of second phase intermetallic particles present in the aluminium alloy microstructure.

• 出版日期2015-8-25