Sealing Effect of KAl(SO₄)₂ Solution on the Corrosion Resistance of Anodized Aluminum Alloy

Abstract

The 2024 anodized aluminum alloy film was sealed by KAl(SO₄)₂ solution and the effect of sealing on corrosion resistance was investigated by means of potentiodynamic polarization curves, electrochemical impedance spectroscopy, and X-ray photoelectron spectroscopy. The experimental results show that the optimal parameters for KAl(SO₄)₂ sealing are 35 °C, with the pH value of 8, the concentration of 8 g/L, and the sealing time of 3 min. The corrosion resistance of the KAl(SO₄)₂ sealed sample can be significantly improved than that of unsealed one, and is obviously superior to that of the conventional hydrothermal sealed sample. Furthermore, X-ray photoelectron spectroscopy demonstrates that more Al(OH)₃ will be formed in the process of KAl(SO₄)₂ sealing, which will shrink the diameter of the microporous and therefore results in the excellent corrosion resistance.

Keywords

aluminum alloy / anodic oxidation / KAl(SO₄)₂ solution / sealing / corrosion resistance

References

[1] Song Y F, Ding X F, Xiao L R, et al. Effects of Two-stage Aging on the Dimensional Stability of Al-Cu-Mg Alloy. J. Alloys Compd., 2017, 701: 508-514.

[2] Khaled K F, Al-Qahtani M M. The Inhibitive Effect of Some Tetrazole Derivatives towards Al Corrosion in Acid Solution: Chemical, Electrochemical and Theoretical Studies. Mater. Chem. Phys., 2009, 113: 150-158.

[3] Curioni M, De Miera M S, Skeldon P, et al. Macroscopic and Local Filming Behavior of AA2024 T3 Aluminum Alloy during Anodizing in Sulfuric Acid Electrolyte. J. Electrochem. Soc., 2008, 155: C387-C395.

[4] Lee J, Jung U, Kim W, et al. Effects of Residual Water in the Pores of Aluminum Anodic Oxide Layers Prior to Sealing on Corrosion Resistance. Appl. Surf. Sci., 2013, 283: 941-946.

[5] Lee W, Ji R, Gösele U, et al. Fast Fabrication of Long-range Ordered Porous Alumina Membranes by Hard Anodization. Nature Mater., 2006, 5: 741-747.

[6] Stępniowski W J, Bojar Z. Synthesis of Anodic Aluminum Oxide (AAO) at Relatively High Temperatures. Surf. Coat. Technol., 2011, 206: 265-272.

[7] Kim Y C, Park H H, Chun J S, et al. Compositional and Structural Analysis of Aluminum Oxide Films Prepared by Plasma-enhanced Chemical Vapor Deposition. Thin Solid Films, 1994, 237: 57-65.

[8] Celebioglu A, Vempati S, Ozgit-Akgun C, et al. Water-soluble Non-polymeric Electrospun Cyclodextrin Nanofiber Template for the Synthesis of Metal Oxide Tubes by Atomic Layer Deposition. RSC Adv., 2014, 4: 61 698-61 705.

[9] Kuznetsov B, Serdechnova M, Tedim J, et al. Sealing of Tartaric Sulfuric (TSA) Anodized AA2024 with Nanostructured LDH Layers. RSC Adv., 2016, 6: 13 942-13 952.

[10] Wang S, Peng H, Shao Z, et al. Sealing of Anodized Aluminum with Phytic Acid Solution. Surf. Coat. Technol., 2016, 286: 155-164.

[11] Bautista A, Gonzalez J A, Lopez V. Influence of Triethanolamine Additions on the Sealing Mechanism of Anodised Aluminium. Surf. Coat. Technol., 2002, 154: 49-54.

[12] Yang Y S, Cheng J, Liu S L, et al. Effect of NaAlO₂ Sealing on Corrosion Resistance of 2024 Aluminum Alloy Anodized Film. Mater. Corros., 2019, 70: 120-127.

[13] Whelan M, Cassidy J, Duffy B. Sol-gel Sealing Characteristics for Corrosion Resistance of Anodised Aluminium. Surf. Coat. Technol., 2013, 235: 86-96.

[14] Yang J, Yang Y, Balaskas A, et al. Development of a Chromium-Free Post-Anodizing Treatment Based on 2-Mercaptobenzothiazole for Corrosion Protection of AA2024T3. J. Electrochem. Soc., 2017, 164: C376-C382.

[15] Rajguru D, Keshwal B S, Jain S, et al. Alum [KAl (SO₄)₂·12H₂O]: A Green and Efficient Catalyst for Synthesis of Pyrano [4, 3-b] Pyrans in Water Under Conventional and Microwave Conditions. Monatsh Chem., 2013, 144: 1 411-1 416.

[16] Liu Z, Xu Z X, Geng H, et al. Study on Fluoride Removal Performance of Activated Alumina Modified by Potassium Aluminum Sulfate. China Water & Wastewater, 2014, 19: 65-71.

[17] Zhang C Y. A Sealing Method for Photosensitive Material Plate[P]. CN Patent CN106997157 A, 2017 Aug.1

[18] Wang S, Peng H, Shao Z, et al. Sealing of Anodized Aluminum with Phytic Acid Solution. Surf. Coat. Technol., 2016, 286: 155-164.

[19] Moutarlier V, Gigandet M P, Ricq L, et al. Electrochemical Characterisation of Anodic Oxidation Films Formed in Presence of Corrosion Inhibitors. Appl. Surf. Sci., 2001, 183: 1-9.

[20] Gonzalez J A, Lopez V, Bautista A, et al. Characterization of Porous Aluminium Oxide Films from Ac Impedance Measurements. J. Appl. Electrochem., 1999, 29: 229-238.

[21] López V, Gonzalez J A, Otero E, et al. Atmospheric Corrosion of Bare and Anodised Aluminium in a Wide Range of Environmental Conditions. Part II: Electrochemical responses. Surf. Coat. Technol., 2002, 153: 235-244.

[22] Tian L P, Zhao X H, Zhao J M, et al. Electrochemical Behaviors of Anodic Alumina Sealed by Ce-Mo in NaCl Solutions. Trans. Non-ferrous Met. Soc. China, 2006, 16: 1 178-1 183.

[23] Hitzig J, Jüttner K, Lorenz W J, et al. AC-impedance Measurements on Porous Aluminium Oxide Films. Corros. Sci., 1984, 24: 945-952.

[24] Hu N, Dong X, He X, et al. Effect of Sealing on the Morphology of Anodized Aluminum Oxide. Corros. Sci., 2015, 97: 17-24.

[25] Lee J, Kim Y, Jang H, et al. Cr₂O₃ Sealing of Anodized Aluminum Alloy by Heat Treatment. Surf. Coat. Technol., 2014, 243: 34-38.

[26] Kim Y C, Park H H, Chun J S, et al. Compositional and Structural Analysis of Aluminum Oxide Films Prepared by Plasma-enhanced Chemical Vapor Deposition. Thin Solid Films, 1994, 237: 57-65.

[27] Celebioglu A, Vempati S, Ozgit-Akgun C, et al. Water-soluble Non-polymeric Electrospun Cyclodextrin Nanofiber Template for The Synthesis of Metal Oxide Tubes by Atomic Layer Deposition. RSC Adv., 2014, 4: 61 698-61 705.

[28] He H, Alberti K, Barr TL, et al. ESCA Studies of Aluminophosphate Molecular Sieves. J. Phys. Chem., 1993, 97: 13 703-13 707.

[29] Crist B V. Handbooks of Monochromatic XPS Spectra. Volume 2-Commercially Pure Binary Oxides, 2005 California: XPS International, LLC.

[30] Hess A, Kemnitz E, Lippitz A, et al. ESCA, XRD, and IR Characterization of Aluminum Oxide, Hydroxyfluoride, and Fluoride Surfaces in Correlation with Their Catalytic Activity in Heterogeneous Halogen Exchange Reactions. J. Catal., 1994, 148: 270-280.