Investigation of Morphology and Corrosion Behavior of Electroless Ni-P Coating on Mg-7Li Alloy with Different Pre-treatments

Document Type : Original Articles

Authors

• Mohammad Ghaderi ¹
• Seyyed Mahmoud Monir Vaghefi ²

¹ Young Researchers and Elite Club, Najafabad Branch, Islamic Azad University, Najafabad, Iran

² Isfahan University of technologhy

10.22067/ma.v0i29.43707

Abstract

In this study, morphology, mechanical and corrosion properties of Ni-P electroless coating was investigated using different pre-treatments on the Mg-Li (MA21) alloy. The results show that adding 125 g/l chromium trioxide and 110 ml/l nitric acid to the pickling solution can increase the uniformity of the intermediate layer and reduce the porosity of the Ni-P electroless coating. The MgF2 and LiF layer uniformity leads to the increase in the number of coating nucleation sites and a fine morphology. The corrosion rate of the MA21 sample, Ni-P electroless coating sample with 125 g/l CrO3 and 110 ml/l HNO3 was 63, 87 and 4 mpy, respectively. The test results of Ni-P electroless coating adhesion with pretreatment number 2 was double that of pretreatment number 1.

Keywords

• Mg-7Li, Electroless Coating
• Ni-P
• Pre-Treatment
• Corrosion Properties
• Coating Adhesion Properties

---

References

1. Hamdy-Makhlouf A.S., "Intelligent Stannate-Based Coatings of Self-Healing Functionality for Magnesium Alloys", Intelligent Coatings for Corrosion Control, A. Butterworth-Heinemann: Boston, pp. 537-55, (2014).

2. Li J., et. al., "Topological origin of subgap conductance in insulating bilayer graphene", Nature Physics, Vol. 7, No. 1, pp. 38-42, (2011).

3. Liu T., et. al., "Microstructure evolution of Mg–14% Li–1% Al alloy during the process of equal channel angular pressing", Materials Science and Engineering A, Vol. 460-461, pp. 499-503, (2007).

4. Trojanova Z., et. al., "Deformation behaviour of Mg–Li alloys at elevated temperatures", Materials Science and Engineering A, Vol. 410-411, pp. 148-151, (2005).

5. Pekguleryuz M., "Alloying behavior of magnesium and alloy design, in Fundamentals of Magnesium Alloy Metallurgy", Woodhead Publishing: New York, pp. 152-196, (2013).

6. Yamauchi N., et. al., "DLC coating on Mg–Li alloy", Surface and Coatings Technology, Vol. 201, No. 9-11, pp. 4913-4918, (2007).

7. Zhao M., et. al., "A chromium-free conversion coating of magnesium alloy by a phosphate–permanganate solution", Surface and Coatings Technology, Vol. 200, No. 18-19, pp. 5407-5412, (2009).

8. Yang L., et. al.," Electroless Ni–P plating with molybdate pretreatment on Mg–8Li alloy", Journal of Alloys and Compounds, Vol. 467, No. 1-2, pp. 562-566, (2009).

9. Li J., et. al., "Studies of the porosity in electroless nickel deposits on magnesium alloy", Applied Surface Science, Vol. 252, No. 8, pp. 2839-2846, (2006).

10. Qin T.-n., et. al., "An in-situ measure method to study deposition mechanism of electroless Ni-P plating on AZ31 magnesium alloy", Transactions of Nonferrous Metals Society of China, Vol. 21, No. 12, pp. 2790-2797, (2011).

11. Zhang Z., et. al., "Studies on influence of zinc immersion and fluoride on nickel electroplating on magnesium alloy AZ91D", Applied Surface Science, Vol. 255, No. 17, pp. 7773-7779, (2009).

12. Luo H.-j., et. al., "Electroless Ni-P plating on Mg-Li alloy by two-step method", Transactions of Nonferrous Metals Society of China, Vol. 21, No. 10, pp. 2225-2230, (2011).

13. Anık M., E. Körpe, "Effect of alloy microstructure on electroless NiP deposition behavior on Alloy AZ91", Surface and Coatings Technology, Vol. 201, No. 8, pp. 4702-4710, (2007).

14. Sun S., et. al., "A novel process for electroless nickel plating on anodized magnesium alloy", Applied Surface Science, Vol. 254, No. 16, pp. 5016-5022, (2008).

15. Zhang H., et. al., "Electroless Ni–P plating on Mg–10Li–1Zn alloy", Journal of Alloys and Compounds, Vol. 474, No. 1-2, pp. 306-310, (2009).

16. Henry J.R., "Electroless (autocatalytic) plating", Metal Finishing, Vol. 97, pp. 424-435, (1999).

17. Yli-Pentti A., "Electroplating and Electroless Plating", Comprehensive Materials Processing, Elsevier: Oxford, pp. 277-306, (2014).

18. Song G.L., "Electroless electrophoresis coatings to improve the corrosion resistance of magnesium (Mg) alloys", Corrosion Prevention of Magnesium Alloys, Woodhead Publishing, pp. 446-468, (2013(.

19. Hofmann U., Weil K.G., "On the oxidation of nickel/phosphorus alloys", Corrosion Science, Vol. 34, No. 3, pp. 423-431, (1993).

20. Liu Z., Gao W., "Electroless nickel plating on AZ91 Mg alloy substrate", Surface and Coatings Technology, Vol. 200, No. 16-17, pp. 5087-5093, (2006).