Investigating the effect of silicon content on structure and corrosion resistance by plasma electrolytic oxidation on aluminum-silicon alloys

Subject Areas : journal of New Materials

Masoud Moshrefifar ¹

1 - Assistant prof. Department of Mining and Metallurgical Engineering, Yazd University, 8915818411, Yazd, Iran

Received: 2024-01-28 Accepted : 2024-04-04 Published : 2023-10-23

Keywords: Coating, Corrosion Resistance, Aluminum-Silicon alloy, Plasma electrolytic oxidation,

Abstract :

Abstract Introduction: Plasma electrolytic oxidation is a new and upgraded method of anodizing process to improve the corrosion resistance of aluminum alloys by creating a ceramic coating on their surface. Methods: One of the parameters affecting of PEO process as well as the performance of the prepared coatings is the composition of the substrate. In this study, the effect of increasing the percentage silicon of substrate on the plasma electrolytic oxidation process with bipolar pulse current in a silicate-based electrolytic bath was investigated. Scanning electron microscopy was used to evaluate the morphology and structure of the coating and X-ray diffraction test was used for phase detection. Coating corrosion behavior was evaluated by electrochemical tests after 1 hour immersion in 3.5% NaCl solution with the adjustment of pH 4. Findings: coatings had a pancake structure with craters with irregular micro-cracks and micro-porosity. Investigations showed that with an increase in the percentage of silicon in the substrate, the thickness and porosity of the coatings decreased, and the volcanic morphology prevailed over the pancake morphology in the growth of the coating. Analysis showed the coatings mainly contain a mixture of γ- Al₂O₃, η- Al₂O₃, δ-Al₂O₃, SiO₂, a small amount of mullite and some amorphous phases. Tofel polarization test revealed, in addition to reducing the corrosion current density up to 9% of the substrate silicon, we have seen an increase in the polarization resistance with the increase in the silicon percentage of the substrate after coating. The electrochemical spectroscopy test revealed that with the increase in the silicon percentage of the substrate, the coating forms a physical barrier against charge transfer substrate and the resistance of the outer layer decreases, but the resistance of the inner layer increases.

References:

 References

1. Dahle, A., et al., Eutectic modification and microstructure development in Al–Si Alloys. Materials Science and Engineering: A, 2005. 413: p. 243-248.
   
   


2. Wang, Q., Microstructural effects on the tensile and fracture behavior of aluminum casting alloys A356/357. Metallurgical and materials Transactions A, 2003. 34: p. 2887-2899.
   
   


3. Dai, L., et al. Anti-corrosion and wear properties of plasma electrolytic oxidation coating formed on high Si content Al alloy by sectionalized oxidation mode. in IOP Conference Series: Materials Science and Engineering. 2017. IOP Publishing.
   
   


4. Dong, H., Surface engineering of light alloys: Aluminium, magnesium and titanium alloys. 2010.
   
   


5. Picas, J.A., et al., HVOF thermal sprayed coatings on aluminium alloys and aluminium matrix composites. Surface and Coatings Technology, 2005. 200(1-4): p. 1178-1181.
   
   


6. Revilla, R.I., H. Terryn, and I. De Graeve, Role of Si in the anodizing behavior of Al-Si alloys: additive manufactured and cast Al-Si10-Mg. Journal of The Electrochemical Society, 2018. 165(9): p. C532.
   
   


7. Hakimizad, A., K. Raeissi, and F. Ashrafizadeh, A comparative study of corrosion performance of sealed anodized layers of conventionally colored and interference-colored aluminium. Surface and Coatings Technology, 2012. 206(22): p. 4628-4633.
   
   


8. Raj, V. and M.M. Ali, Formation of ceramic alumina nanocomposite coatings on aluminium for enhanced corrosion resistance. Journal of Materials Processing Technology, 2009. 209(12-13): p. 5341-5352.


9. Bajat, J., et al., Corrosion stability of oxide coatings formed by plasma electrolytic oxidation of aluminum: optimization of process time. Corrosion, 2013. 69(7): p. 693-702.
   
   


10. Gu, W.-C., et al., Characterisation of ceramic coatings produced by plasma electrolytic oxidation of aluminum alloy. Materials Science and Engineering: A, 2007. 447(1-2): p. 158-162.
    
    


11. Hussein, R., et al., Spectroscopic study of electrolytic plasma and discharging behaviour during the plasma electrolytic oxidation (PEO) process. Journal of Physics D: Applied Physics, 2010. 43(10): p. 105203.
    
    


12. Hussein, R., X. Nie, and D. Northwood, Influence of process parameters on electrolytic plasma discharging behaviour and aluminum oxide coating microstructure. Surface and Coatings Technology, 2010. 205(6): p. 1659-1667.
    
    


13. Li, Q., et al., Effects of cathodic voltages on structure and wear resistance of plasma electrolytic oxidation coatings formed on aluminium alloy. Applied Surface Science, 2014. 297: p. 176-181.
    
    


14. Montazeri, M., et al., 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. Applied Surface Science, 2011. 257(16): p. 7268-7275.
    
    


15. Tillous, K., et al., Microstructure and phase composition of microarc oxidation surface layers formed on aluminium and its alloys 2214-T6 and 7050-T74. Surface and Coatings Technology, 2009. 203(19): p. 2969-2973.
    
    


16. Gencer, Y. and A.E. Gulec, The effect of Zn on the microarc oxidation coating behavior of synthetic Al–Zn binary alloys. Journal of alloys and compounds, 2012. 525: p. 159-165.
    
    


17. He, J., et al., Influence of silicon on growth process of plasma electrolytic oxidation coating on Al–Si alloy. Journal of alloys and compounds, 2009. 471(1-2): p. 395-399.
    
    


18. Tarakci, M., Plasma electrolytic oxidation coating of synthetic Al–Mg binary alloys. Materials characterization, 2011. 62(12): p. 1214-1221.
    
    


19. Mehri Ghahfarokhi, N., et al., Plasma electrolytic oxidation (PEO) coating to enhance in vitro corrosion resistance of AZ91 magnesium alloy coated with polydimethylsiloxane (PDMS). Applied Physics A, 2022. 128(2): p. 112.
    
    


20. Li, K., et al., Effects of Si phase refinement on the plasma electrolytic oxidation of eutectic Al-Si alloy. Journal of Alloys and Compounds, 2019. 790: p. 650-656.
    
    


21. Forn, A., et al., Microstructure and tribological properties of anodic oxide layer formed on Al–Si alloy produced by semisolid processing. Surface and Coatings Technology, 2007. 202(4-7): p. 1139-1143.
    
    


22. Warmuzek, M., Aluminum-silicon casting alloys: an atlas of microfractographs. 2004: ASM international.
    
    


23. مشرفی فر, م., et al., بررسی اثر درصد سیلیسیوم زیرلایه بر ریزساختار و ترکیب پوشش‌های اکسیداسیون الکترولیتی پلاسمایی آلیاژهای آلومینیوم-سیلیسیوم. نشریه علوم و مهندسی سطح, 2021. 17(49): p. 1-17.

 

24. Wu, T., C. Blawert, and M.L. Zheludkevich, Influence of secondary phases of AlSi9Cu3 alloy on the plasma electrolytic oxidation coating formation process. Journal of Materials Science & Technology, 2020. 50: p. 75-85.


25. Moshrefifar, M., H. Ebrahimifar, and A. Hakimizad, Systematic Investigation of Silicon Content Effects on the PEO Coatings’ Properties on Al–Si Binary Alloys in Silicate-Based and Tungstate-Containing Electrolytes. Coatings, 2022. 12(10): p. 1438.
    
    


26. Alves, S., et al., Enhanced tribological performance of cylinder liners made of cast aluminum alloy with high silicon content through plasma electrolytic oxidation. Surface and Coatings Technology, 2022. 433: p. 128146.
    
    


27. Wang, P., et al., Ceramic coating formation on high Si containing Al alloy by PEO process. Surface Engineering, 2016. 32(6): p. 428-434.
    
    


28. Stojadinovic, S., et al., Characterization of the plasma electrolytic oxidation of aluminium in sodium tungstate. Corrosion Science, 2010. 52(10): p. 3258-3265.
    
    


29. Matykina, E., et al., Investigation of the growth processes of coatings formed by AC plasma electrolytic oxidation of aluminium. Electrochimica acta, 2009. 54(27): p. 6767-6778.
    
    


30. بروجنی, ر., et al., ارزیابی رفتار تریبولوژیکی پوشش کامپوزیتی اکسیداسیون الکترولیتی پلاسمایی حاوی ذرات اکسید سیلیسیم روی زیرلایه آلیاژ آلومینیوم ۷۰۷۵. فصلنامه علمی-پژوهشی مواد نوین, 2022. 13(49): p. 72-85.
    
    


31. Li, Z., et al., Composite coatings on a Mg–Li alloy prepared by combined plasma electrolytic oxidation and sol–gel techniques. Corrosion science, 2012. 63: p. 358-366.
    
    


32. Duan, H., C. Yan, and F. Wang, Effect of electrolyte additives on performance of plasma electrolytic oxidation films formed on magnesium alloy AZ91D. Electrochimica Acta, 2007. 52(11): p. 3785-3793.
    
    


33. Hussein, R., X. Nie, and D. Northwood, Plasma electrolytic oxidation coatings on Mg-alloys for improved wear and corrosion resistance. Corrosion: Material Performance and Cathodic Protection, 2017. 99: p. 133-134.
    
    


34. Dehnavi, V., et al., Corrosion properties of plasma electrolytic oxidation coatings on an aluminium alloy–The effect of the PEO process stage. Materials Chemistry and Physics, 2015. 161: p. 49-58.