Study on Scanning Micro-arc Oxidation Technology Applied to 2024 Aluminum Alloy

doi:10.3724/SP.J.1077.2013.12156

Abstract

Abstract:

The ceramic coating was formed on the part of the impaired surface of the 2024 alloy sample by scanning micro-arc oxidation using low pulsating power supply. It proposed a solution for local repairing impaired part of big workpiece using micro-arc oxidation technique. Microstructure and phase composition of coating were characterized by SEM, XRD and EDS. The nano indentation hardness and elastic modulus of coatings were tested by nano indenter. The corrosion resistance properties of coatings were determined by potentiodynamic polarization. The results show that under the continuous current mode, the bath voltage of scanning micro-arc oxidation (SMAO) raise fast and go into micro-arc oxidation stage immediately. The thickness of the coating formed by SMAO is 17 μm after a single scanning, indicating SMAO has high film efficiency. The coating, mainly composed of α-Al₂O₃ and γ-Al₂O₃, is dense in the inner layer and porous in the outer layer. There are a large number of micropores and micro-cracks on its surface. The nano indentation test results show that the nano indentation hardness and elastic modulus of coatings firstly increase and then decrease from interface to surface. The potentiodynamic polarization indicates that the SMAO and MAO coatings all have effective corrosion protective effect to 2024 aluminium alloy. And the MAO coating's performance is better than that of SMAO coating.

Key words: aluminium alloy, scanning micro-arc oxidation, ceramic coating, nano indentation, corrosion

CLC Number:

TQ174

Lü Peng-Xiang, WEI Dong-Bo, GUO Cheng-Bo, LI Zhao-Long, DI Shi-Chun. Study on Scanning Micro-arc Oxidation Technology Applied to 2024 Aluminum Alloy[J]. Journal of Inorganic Materials, 2013, 28(4): 381-386.

Figures/Tables 7

Fig. 1 Schematic of SMAO experiment principle (a) General schematic diagraph; (b) Detailed schematic diagraph of Partial A in (a)

Fig. 2 Ceramic coating formed in local repairing region on 2024 alloy sample by SMAO

Fig. 3 Interpolar voltage curve during SMAO and MAO

Fig. 4 Ceramic coating thickness curve during SMAO and MAO

Fig. 5 Microstructure and constituent of ceramic coating formed on 2024 alloy by SMAO

Fig. 6 Nano indentation hardness and Modulus of SMAO ceramic coating

Fig. 7 Popotetiodynamic polarization curves of SMAO, MAO ceramic coating and 2024 alloy

References 19

[1]	ZHANG Yu. Application of aluminum alloy to aerospace industry. Aluminium Fabrication, 2009, 3: 50-53.
[2]	YAO Si-Tong, SUN Ya-Ru, XU Bing-Hui, et al. Corrosion resistance of anodic oxidation coating on aluminum and its alloys. Materials Protection, 2010, 43(8): 40-41.
[3]	Wang Z A, Chu J B, Zhu H B, et al. Growth of ZnO:Al films by RF sputtering at room temperature for solar cell applications. Solid-State Electronics, 2009, 53: 1149-1153.
[4]	Balcaen Y, Radutoiu N, Alexis J, et al. Mechanical and barrier properties of MOCVD processed alumina coatings on Ti6Al4V titanium alloy. Surface & Coatings Technology, 2011, 206: 1684-1690.
[5]	Gawali Sanjay A, Bhosale C H. Structural and optical properties of nanocrystalline CdSe and Al:CdSe thin films for photoelectrochemical application. Materials chemistry and physics, 2011, 129: 751-755.
[6]	Yerokhin A L, Nie X, Leyland A, et al. Plasma electrolysis for surface engineering. Surface and Coatings Technology, 1999, 122: 73-93.
[7]	Liang J, Bala P, Blawert C, et al. Electrochemical corrosion behaviour of plasma electrolytic oxidation coatings on AM50 magnesium alloy formed in silicate and phosphate based electrolytes. Electrochimica Acta, 2009, 54: 3842-3850.
[8]	Matykina E, Arrabal R, Monfort F, et al. Incorporation of zirconia into coatings formed by DC plasma electrolytic oxidation of aluminium in nanoparticle suspensions. Applied Surface Science, 2008, 255: 2830-2839.
[9]	Teh T H, Erkani A, Mato S, et al. Initial stages of plasma electrolytic oxidation of titanium. Corrosion Science, 2003, 45: 2757-2768.
[10]	JIANG Bai-ling, BAI Li-jing, JIANG Yong-feng. Growth of alumina ceramic coatings on aluminum matrix material surface. The Chinese journal of nonferrous metals, 2001, 11(2): 186-189.
[11]	LAI Yong-chun, DENG Zhi-wei, SONG Hong-wei, et al. Properties of micro arc oxidation films on aluminum alloy substrate. Tribology, 2000, 20(4): 304-306.
[12]	Srinivasan P B, Liang J, Blawert C, et al. Dry sliding wear behaviour of magnesium oxide and zirconium oxide plasma electrolytic oxidation coated magnesium alloy. Applied Surface Science, 2010, 256(10): 3265-3273.
[13]	Yerokhina A L, Shatrov A, Samsonov V, et al. Oxide ceramic coatings on aluminium alloys produced by a pulsed bipolar plasma electrolytic oxidation process. Surface and Coatings Technology, 2005, 199: 150-157.
[14]	CHEN Sui-yuan, YANG Yong-ze, LIANG Jing, et al. Preparation of high-wearability and self-lubricating anode oxide film on aluminum alloy surface. Journal of Northeastern University (Natural Science), 2010, 31(12): 1721-1724.
[15]	Li H X, Rudnev V S, Zheng X H, et al. Characterization of Al2O3 ceramic coatings on 6063 aluminum alloy prepared in borate electrolytes by micro-arc oxidation. Journal of Alloys and Compounds, 2008, 25: 99-102.
[16]	KULEKCI M K. Magnesium and its alloys applications in automotive industry. The International Journal of Advanced Manufacturing Technology, 2008, 39: 851-865.
[17]	Timoshenko A V, Rakoch A G. Method for Microplasma Electrolytic Processing of Surfaces of Electroconductive Materials. US Patent, No. 16238540. 2001.
[18]	WANG Ya-ming, HAN Xiao-dong, GUO Li-xin, et al. Microarc oxidation process with spraying cathode applied to LY12 alloy. Transactions of Materials and Heat Treatment, 2009, 30(2): 121-124.
[19]	XUE Wen-bin, LAI Yong-chun, DENG Zhi-cheng, et al. Phase distribution and microhardness analysis of ceramic coatings formed by microplasma oxidation on aluminum alloys. Materials Science and Technology, 1999, 7(2): 18-21.