Evolution of insoluble eutectic Si particles in anodic oxidation films during adipic-sulfuric acid anodizing processes of ZL114A aluminum alloys

Abstract

The effects of insoluble eutectic Si particles on the growth of anodic oxide films on ZL114A aluminum alloy substrates were investigated by optical microscopy (OM) and scanning electron microscopy (SEM). The anodic oxidation was performed at 25°C and a constant voltage of 15 V in a solution containing 50 g/L sulfuric acid and 10 g/L adipic acid. The thickness of the formed anodic oxidation film was approximately 7.13 μm. The interpore distance and the diameters of the major pores in the porous layer of the film were within the approximate ranges of 10–20 nm and 5–10 nm, respectively. Insoluble eutectic Si particles strongly influenced the morphology of the anodic oxidation films. The anodic oxidation films exhibited minimal defects and a uniform thickness on the ZL114A substrates; in contrast, when the front of the oxide oxidation films encountered eutectic Si particles, defects such as pits and non-uniform thickness were observed, and pits were observed in the films.

Keywords

aluminum alloys / anodizing / anodic oxidation / thin films / eutectic / silicon / particles

References

[1] Brungs D. Technical Report: light weight design with light metal castings. Mater. Des., 1997, 18(4–6): 285.

[2] Alexopoulos ND, Pantelakis SpG. Quality evaluation of A357 cast aluminum alloy specimens subjected to different artificial aging treatment. Mater. Des., 2004, 25(5): 419.

[3] Ceschini L, Morri A, Morri A, Gamberini A, Messieri S. Correlation between ultimate tensile strength and solidification microstructure for the sand cast A357 aluminium alloy. Mater. Des., 2009, 30(10): 4525.

[4] Roberge PR. Corrosion Engineering: Principles and Practice, 2008, New York, McGraw-Hill, 603.

[5] Mansfeld F, Kendig MW. Evaluation of anodized aluminum surfaces with electrochemical impedance spectroscopy. J. Electrochem. Soc., 1988, 135(4): 828.

[6] Fratila-Apachitei LE, Duszczyk J, Katgerman L. Voltage transients and morphology of AlSi(Cu) anodic oxide layers formed in H₂SO₄ at low temperature. Surf. Coat. Technol., 2002, 157(1): 80.

[7] Fratila-Apachitei LE, Terryn H, Skeldon P, Thompson GE, Duszczyk J, Katgerman L. Influence of substrate microstructure on the growth of anodic oxide layers. Electrochim. Acta, 2004, 49(7): 1127.

[8] Liu Y, Arenas MA, Skeldon P, Thompson GE, Bailey P, Noakes TCQ, Habazaki H, Shimizu K. Anodic behaviour of a model second phase: Al-20at.%Mg-20at.%Cu. Corros. Sci., 2006, 48(5): 1225.

[9] Dimitrov N, Mann JA, Vukmirovic M, Sieradzki K. , Dealloying of Al₂CuMg in alkaline media. J. Electrochem. Soc., 2000, 147(9): 3283.

[10] Liu Y, Arenas MA, Skeldon P, Thompson GE, Habazaki H, Shimizu K, Bailey P, Noakes TCQ. Generation of copper nanoparticles during alkaline etching of an Al-30at.%Cu alloy. Corros. Sci., 2006, 48(8): 1874.

[11] Liu J, Li M, Sheng H, Li S, Chen G, Yu M. A Method of Non-chromium Anodic Oxidation Process to 2XXX and 7XXX Aluminum Alloys, 2009

[12] Yu M, Chen GH, Liu JH, Li SH. Adipic-sulfuric acid anodizing for LY12CZ aluminum alloy. J. Beijing Univ. Aeronaut. Astronaut., 2012, 38(3): 363.

[13] Yu M, Chen GH, Liu JH, Li SM, Li YD, Liu Z. Effect of adipic acid on fatigue performance of sulfuric anodizing for aluminum alloy. Heat Treat. Met., 2011, 36(6): 50.

[14] Liu JH, Liu Z, Yu M, Li SM, Chen GH. Properties of aluminum alloy anodic films formed in three kinds of solutions. Chin. J. Nonferrous Met., 2012, 22(7): 2031.

[15] Curioni M, Saenz de Miera M, Skeldon P, Thompson GE, Ferguson J. Macroscopic and local filming behavior of AA2024 T3 aluminum alloy during anodizing in sulfuric acid electrolyte. J. Electrochem. Soc., 2008, 155(8): C387.

[16] Parkhutik VP, Belov VT, Chernyckh MA. Study of aluminium anodization in sulphuric and chromic acid solutions: II. Oxide morphology and structure. Electrochim. Acta, 1990, 35(6): 961.

[17] Moutarlier V, Gigandet MP, Pagetti J. Characterisation of pitting corrosion in sealed anodic films formed in sulphuric, sulphuric/molybdate and chromic media. Appl. Surf. Sci., 2003, 206(1–4): 237.