Abstract
Although magnesium alloys have the advantage of high specific strength, they have poor atmospheric corrosion resistance. An important method of improving the corrosion resistance is by applying a coating layer. In this work, the physical vapor deposition (PVD) technique is used for coating a magnesium (Mg) AZ31 sheet substrate with a thin layer of high purity aluminum (Al) and Al–12.6% Si. Aluminum is expected to be suitable as a coating layer on Mg sheets, due to its corrosion resistance and its formability. Before coating, the substrate was subjected to several consecutive surface preparations, including sand-blasting, mechanical grinding, mirror-like polishing, ultrasonic etching, and finally ion etching by magnetron sputtering (MS). PVD coating was conducted using a PVD machine with max electron beam power and voltage of 100 kW and 40 kV, respectively. This was either with or without plasma activation, and with variable substrate speeds ranging between 10 and 70 mm/s. During MS ion etching and coating, the substrate temperature increased. The substrate temperature increased with the application of plasma activation and with lower substrate speeds. The coating-layer thickness varied inversely with substrate speed. A thinner coat with finer morphology was obtained in the case of plasma activation. Other results included coating layer characteristics, diffusion between the AZ 31 substrate and the Al coating layer, adhesion of the coating layer to the substrate, and corrosion resistance by a humidity test.
Similar content being viewed by others
References
Landkof, B. “Magnesium Applications in Aerospace and Electronic Industries.” In: Kainer, KU (ed.), Proceedings of Magnesium Alloys and their Applications, pp. 168–172. Wiley VCH Verlag, Weinheim (2000)
Sharma, AK, Uma Rani, R, Giri, K, “Studies on Anodization of Magnesium Alloy for Thermal Control Applications.” Met. Finish., 95 (3) 43–46, 48–51 (1997)
Sharma, AK, Suresh, MR, Bhojraj, H, Narayanamurthy, H, Sahu, SP, “Electroless Nickel Plating on Magnesium Alloy.” Met. Finish., 96 10–18 (1998)
El Mahallawy, N, Palkowski, H, Shoeib, M, Maamoun, M, “Electro and Electroless Coating of Magnsium AZ31 Sheets: A Comparative Study.” Steel Grips, 2 (2) 130–139 (2004)
El Mahallawy, NA, Palkowski, H, Shoeib, M, Maamoun, MA, Neubert, V, Bakkar, A, “Corrosion Protection of Mg Alloy by Nanostructure Deposits of Ni-P by Electroless Technique.” Steel Grips, 4 (3) 212–216 (2006)
El Mahallawy, N, Bakkar, A, Shoeib, M, Palkowski, H, Neubert, V, “Electroless Ni–P Coating of Different Magnesium Alloys.” Surf. Coat. Technol., 202 (21) 5151–5157 (2008)
Yamamoto, A, Watanabe, A, Sugahara, K, Tsubakino, H, Fukumoto, S, “Improvement of Corrosion Resistance of Magnesium Alloys by Vapour Deposition.” Scr. Mater., 44 1039–1042 (2001)
Yamamoto, A, Tsubakino, H, “A New Technique for Surface Modification in Magnesium Alloys by Applying Magnesium Oxide Coating.” Mater. Sci. Forum, 419–422 903–908 (2003)
Langelfeld, S, Jonschker, G, Schmidt, H, “Neue Sol-Gel-Beschichtungen als Korrosions- und Verschleißschutz für NE- Metalle: New Sol-Gel Based Coatings as Corrosion- and Wear-Protection on Non-Ferrous Metals.” Materialwissenschaft und Werkstofftechnik, 29 23–29 (1998)
Weisheit, A, Lenz, U, Mordike, B, “Thermal Spraying on the Magnesium Alloys AZ91.” Metallurgica, 51 (9) 470–474 (1997)
Tsubakino, A, Yamamoto, A, Watanabe, A, Fukumoto, S, “Coating on Rugged Surfaces of Magnesium Alloy with High-Purity Magnesium Film.” Proc. Int. Congress on Advanced Materials, their Processes and Applications, Materials Week 2001, Munchen, 2001, pp. 1–6
Gray, JE, Luan, B, “Protective Coatings on Magnesium and Its Alloys—A Critical Review.” J. Alloys Compd., 336 88–113 (2002)
El-Mahallawy, N, “Surface Treatment of Magnesium Alloys by Electroless Ni-P Technique with Emphasis on Zinc Pre-Treatment: A Review.” In: El-Mahallawy N, Zhang, M (eds.), Progress in Surface Treatment, vol. 384, pp. 241–262. Key Engineering Materials, Trans Tech Publications (2008)
Bakkar, A, Galun, R, Neubert, V, “Microstructural Characterization and Corrosion Behaviour of Laser Cladded Al–12Si Alloy onto Magnesium AS41/Carbon Fibre Composite.” Mater. Sci. Technol., 22 (3) 353–362 (2006)
Chiu, LH, Lin, HA, Chen, CC, Yang, CF, Chang, CH, Wu, JC, “Effect of Aluminium Coatings on Corrosion Properties of AZ31 Magnesium Alloy.” Mater. Sci. Forum, 419 (422) 909–914 (2003)
Kainer, U, Horst, N, “Thermal Spraying of Magnesium Alloys for Corrosion and Wear Protection Magnesium.” In: Kainer, KU (ed.), Proceedings of the 6th International Conference on Magnesium Alloys and their Applications, pp. 860–868, DGM/Wiley-VCH Verlag GmbH (2004)
Metzner, C, Roegner, F, Heinss, J, Scheffel, B, “PVD Coating of Metallic Sheets and Strips.” Steel Grips, 2 (2) 124–129 (2004)
Hoche, H, Allebrandt, D, Scheerer, H, Broszeit, E, Berger, C, “Design of Wear and Corrosion Resistant PVD-Coatings for Magnesium Alloys.” J. Maetrialwissenschaft und Werkstofftechnik, 38 365–371 (2007)
Hoche, H, Scheerer, H, Fritsche, R, Thissen, A, Flege, S, Broszeit, E, Berger, C, Ortner, H-M, Jaegermann, W, “Untersuchung des Sputter-Ätzens auf die Eigenschaften von PVD-CrN-Hartstoffschichten auf Magnesium AZ91hp.” J. Maetrialwissenschaft und Werkstofftechnik, 33 132–141 (2002)
Shigematsu, I, Nakamura, M, Saitou, N, Shimojima, K, “Surface Treatment of AZ91D Magnesium Alloy by Aluminum Diffusion Coating.” J. Mater. Sci. Lett., 19 473–475 (2000)
Wu, G, “Fabrication of Al and Al/Ti Coatings on Magnesium Alloy by Sputtering.” J. Mater. Lett., 61 3815–3817 (2007)
Acknowledgments
The authors acknowledge Dr. Christoph Metzner and the cooperation by the Fraunhofer Institute for Electron Beam and Plasma Technology (FEP) in Dresden, Germany where the experimental work was conducted.
Author information
Authors and Affiliations
Corresponding author
Rights and permissions
About this article
Cite this article
Taha, M.A., El-Mahallawy, N.A., Hammouda, R.M. et al. PVD Coating of Mg–AZ31 by Thin Layer of Al and Al–Si. J Coat Technol Res 7, 793–800 (2010). https://doi.org/10.1007/s11998-010-9252-7
Published:
Issue Date:
DOI: https://doi.org/10.1007/s11998-010-9252-7