Formation of corrosion resistant plasma electrolytic oxidation coatings on aluminium alloy with addition of sodium tungstate species

Abstract

Plasma electrolytic oxidation (PEO) coatings were formed in silicate based electrolytes without and with the addition of sodium tungstate on AA 6063 aluminium alloy. Microstructure, composition and corrosion resistance of PEO coatings were investigated by scanning electron microscopy, X-ray diffraction and electrochemical impedance spectroscopy and potentiodynamic polarisation test respectively. The effects of additive sodium tungstate were examined. The results showed that the additive containing PEO coatings were of dense structure with additional phase (WO₃) and of less cracks than the additive free PEO coating. In addition, additive containing coatings were of better corrosion resistance than the additive free PEO coating, which was confirmed by electrochemical impedance spectroscopy and potentiodynamic polarisation tests. Furthermore, long time immersion test revealed that the PEO coated alloy with the addition of 12 g L^{− 1} sodium tungstate maintained high impedance over 82 h in 3.5 wt-%NaCl, while the PEO coating without additive was unable to protect the substrate after such long time immersion.

Keywords

Aluminium alloy Plasma electrolytic oxidation Sodium tungstate Corrosion resistance Microstructure

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References

Wang

Z. J.

L. N.

Y. L.

Cai

and Jiang

Z. H.

: ‘Self-lubricating Al₂O₃/PTFE composite coating formation on surface of aluminium alloy’ Surf. Coat. Technol., 2010 204 3315–3318. doi: 10.1016/j.surfcoat.2010.03.049

Yerokhin

A. L.

Nie

Leyland

Matthews

and Dowey

S. J.

: ‘Plasma electrolysis for surface engineering’ Surf. Coat. Technol., 1999 122 73–93. doi: 10.1016/S0257-8972(99)00441-7

Sah

S. P.

Tsuji

Aoki

and Habazaki

: ‘Cathodic pulse breakdown of anodic films on aluminium in alkaline silicate electrolyte - understanding the role of cathodic half-cycle in AC plasma electrolytic oxidation’ Corros. Sci., 2012 55 90–96. doi: 10.1016/j.corsci.2011.10.007

Q. B.

Liang

and Wang

: ‘Plasma electrolytic oxidation coatings on lightweight metals’, in ‘Modern surface engineering treatments’, (ed. Aliofkhazraei

, 75–99; 2013

Rijeka

Intech.

P. B.

X. H.

and Jiang

Z. H.

: ‘Plasma electrolytic oxidation of a low friction casting on ZK60 magnesium alloy’ Mater. Lett 2008 62 3124–3126. doi: 10.1016/j.matlet.2008.02.023

Yerokhin

A. L.

Nie

Leyland

and Matthews

: ‘Characterisation of oxide films produced by plasma electrolytic oxidation of a Ti-6Al-4V alloy’ Surf. Coat. Technol., 2000 130 195–206. doi: 10.1016/S0257-8972(00)00719-2

Hussein

R. O.

Northwood

D. O.

and Nie

: ‘The effect of processing parameters and substrate composition on the corrosion resistance of plasma electrolytic oxidation (PEO) coated magnesium alloys’ Surf. Coat. Technol., 2013 237 357–368. doi: 10.1016/j.surfcoat.2013.09.021

Liang

Bala Srinivasan

Blawert

and Dietzel

: ‘Influence of chloride ion concentration on the electrochemical corrosion behaviour of plasma electrolytic oxidation coated AM50 magnesium alloy’ Electrochim. Acta 2010 55 6802–6811. doi: 10.1016/j.electacta.2010.05.087

Shokouhfar

Dehghanian

and Baradaran

: ‘Preparation of ceramic coating on Ti substrate by plasma electrolytic oxidation in different electrolytes and evaluation of its corrosion resistance’ Appl. Surf. Sci 2011 257 2617–2624. doi: 10.1016/j.apsusc.2010.10.032

10.

Bala Srinivasan

Liang

Blawert

and Dietzel

: ‘Environmentally assisted cracking behaviour of plasma electrolytic oxidation coated AZ31 magnesium alloy’ Corros. Eng. Sci. Technol., 2011 46 706–711. doi: 10.1179/147842210X12722706885968

11.

Jung

Y. C.

Shin

K. R.

Y. G.

and Shin

D. H.

: ‘Surface characteristics and biological response of titanium oxide layer formed via micro-arc oxidation in K₃PO₄ and Na₃PO₄ electrolytes’ J. Alloys Compd 2014 586 S548–S552. doi: 10.1016/j.jallcom.2013.01.060

12.

Ghasemi

Raja

V. S.

Blawert

Dietzel

and Kainer

K. U.

: ‘Study of the structure and corrosion behavior of PEO coatings on AM50 magnesium alloy by electrochemical impedance spectroscopy’ Surf. Coat. Technol., 2008 202 3513–3518. doi: 10.1016/j.surfcoat.2007.12.033

13.

Cheng

Y. L.

Qin

T. W.

L. L.

Wang

H. M.

and Zhang

: ‘Comparison of corrosion resistance of microarc oxidation coatings prepared with different electrolyte concentrations on AM60 magnesium alloy’ Corros. Eng. Sci. Technol., 2011 46 17–23. doi: 10.1179/174327809X409222

14.

Zhang

X. L.

Zhang

Y. F.

Chang

L. M.

Jiang

Z. H.

Yao

Z. P.

and Liu

X. W.

: ‘Effects of frequency on growth process of plasma electrolytic oxidation coating’ Mater. Chem. Phys 2012 132 909–915. doi: 10.1016/j.matchemphys.2011.12.032

15.

Dehnavi

Luan

B. L.

Shoesmith

D. W.

Liu

X. Y.

and Rohani

: ‘Effect of duty cycle and applied current frequency on plasma electrolytic oxidation (PEO) coating growth behavior’ Surf. Coat. Technol., 2013 226 100–107. doi: 10.1016/j.surfcoat.2013.03.041

16.

H. X.

W. J.

Song

R. G.

and Ji

Z. G.

: ‘Effects of different current densities on properties of MAO coatings embedded with and without α-Al₂O₃ nanoadditives’ Mater. Sci. Technol., 2012 28 565–568. doi: 10.1179/1743284711Y.0000000084

17.

Habazaki

Tsunekawa

Tsuji

and Nakayama

: ‘Formation and characterization of wear-resistant PEO coatings formed on β-titanium alloy at different electrolyte temperatures’ Appl. Surf. Sci 2012 259 711–718. doi: 10.1016/j.apsusc.2012.07.104

18.

Shen

D. J.

G. L.

Guo

C. H.

Zou

Cai

J. R.

and He

D. L.

: ‘Microstructure and corrosion behavior of micro-arc oxidation coating on 6061 aluminum alloy pre-treated by high-temperature oxidation’ Appl. Surf. Sci., 2013 287 451–456. doi: 10.1016/j.apsusc.2013.09.178

19.

Montazeri

Dehghanian

Shokouhfar

and Baradaran

: ‘Investigation of the voltage and time effects on the formation of hydroxyapatite-containing titania prepared by plasma electrolytic oxidation on Ti–6Al–4V alloy and its corrosion behavior’ Appl. Surf. Sci 2011 257 7268–7275. doi: 10.1016/j.apsusc.2011.03.103

20.

Fadaee

and Javidi

: ‘Investigation on the corrosion behaviour and microstructure of 2024-T3 Al alloy treated via plasma electrolytic oxidation’ J. Alloys. Compd 2014 604 36–42. doi: 10.1016/j.jallcom.2014.03.127

21.

Zhou

X. J.

Xiao

Liang

and Huo

X. D.

: ‘Preparation and tribological properties of self-lubricating TiO₂/graphite composite coating on Ti6Al4V alloy’ Appl. Surf. Sci 2012 258 8570–8576. doi: 10.1016/j.apsusc.2012.05.051

22.

Lim

T. S.

Ryu

H. S.

and Hong

S. H.

: ‘Electrochemical corrosion properties of CeO₂-containing coatings on AZ31 magnesium alloys prepared by plasma electrolytic oxidation’ Corros. Sci 2012 62 104–111. doi: 10.1016/j.corsci.2012.04.043

23.

Liang

Guo

B. G.

Tian

Liu

H. W.

Zhou

J. F.

and Xu

: ‘Effect of potassium fluoride in electrolytic solution on the structure and properties of microarc oxidation coatings on magnesium alloy’ Appl. Surf. Sci 2005 252 345–351. doi: 10.1016/j.apsusc.2005.01.007

24.

Sreekanth

Rameshbabu

and Venkateswarlu

: ‘Effect of various additives on morphology and corrosion behavior of ceramic coatings developed on AZ31 magnesium alloy by plasma electrolytic oxidation’ Ceram. Int 2012 38 4607–4615. doi: 10.1016/j.ceramint.2012.02.040

25.

Bayatia

M. R.

Golestani-Farda

and Moshfegh

A. Z.

: ‘Visible photodecomposition of methylene blue over micro arc oxidized WO₃-loaded TiO₂ nano-porous layers’ Appl. Catal. A 2010 382A 322–331. doi: 10.1016/j.apcata.2010.05.017

26.

Z. J.

Yuan

Sun

P. P.

and Jing

X. Y.

: ‘Ceramic coatings of LA141 alloy formed by plasma electrolytic oxidation for corrosion protection’ ACS Appl. Mater. Int., 2011 3 3682–3690. doi: 10.1021/am200863s

27.

Tseng

C. C.

Lee

J. L.

Kuo

T. H.

Kuo

S. N.

and Tseng

K. H.

: ‘The influence of sodium tungstate concentration and anodizing conditions on microarc oxidation (MAO) coatings for aluminum alloy’ Surf. Coat. Technol., 2012 206 3437–3443. doi: 10.1016/j.surfcoat.2012.02.002

28.

Zheng

H. Y.

Wang

Y. K.

B. S.

and Han

G. R.

: ‘The effects of Na₂WO₄ concentration on the properties of microarc oxidation coatings on aluminum alloy’ Mater. Lett 2005 59 139–142. doi: 10.1016/j.matlet.2004.06.025

29.

Cao

C. N.

and Zhang

J. Q.

: ‘An introduction to electrochemical impedance spectroscopy’ 2002

Beijing

Science Press.

30.

Yao

Jiang

Xin

Sun

and Wu

: ‘Electrochemical impedance spectroscopy of ceramic coatings on Ti–6Al–4V by micro-plasma oxidation’ Electrochim. Acta 2005 50 3273–3279. doi: 10.1016/j.electacta.2004.12.001

31.

Duan

Yan

and Wang

: ‘Electrochemical corrosion behavior of composite coatings of sealed MAO film on magnesium alloy AZ91D’ Electrochim. Acta 2006 51 2898–2908. doi: 10.1016/j.electacta.2005.08.026

32.

Guo

and Jiang

: ‘Effects of cathode current density on structure and corrosion resistance of plasma electrolytic oxidation coatings formed on ZK60 Mg alloy’ J. Alloys Compd 2009 475 773–777. doi: 10.1016/j.jallcom.2008.08.030

33.

Alcaide

Brillas

and Cabot

P. L.

: ‘EIS analysis of hydroperoxide ion generation in an uncatalyzed oxygen-diffusion cathode’ J. Electroanal. Chem., 2003 547 61–73. doi: 10.1016/S0022-0728(03)00190-6

34.

Zoltowski

: ‘On the electrical capacitance of interfaces exhibiting constant phase element behaviour’ J. Electroanal. Chem 1998 443 149–154. doi: 10.1016/S0022-0728(97)00490-7