| ZHAO Dan,XU Xu-zhong,XU Bo.Corrosion Behavior of Ni-Zn-P Alloy Coating in Artificial Seawater[J],45(4):169-174 |
| Corrosion Behavior of Ni-Zn-P Alloy Coating in Artificial Seawater |
| Received:December 31, 2015 Revised:April 20, 2016 |
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| DOI：10.16490/j.cnki.issn.1001-3660.2016.04.028 |
| KeyWord:electroless plating Ni-Zn-P alloy coating Ni-P coating corrosion resistance |
| Author | Institution |
| ZHAO Dan |
North China University of Science and Technology, Tangshan , China |
| XU Xu-zhong |
North China University of Science and Technology, Tangshan , China |
| XU Bo |
North China University of Science and Technology, Tangshan , China |
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| Abstract: |
| Objective To improve the service life and corrosion resistance of metal materials in the marine environment. Methods The Ni-P coating and Ni-Zn-P alloy coatings were prepared on Q235 steel by alkaline electroless plating technique. The bath formula was: NiSO4·6H2O 20 ~25 g/ L,C6H5O7Na3·2H2O 50 ~70 g/ L, NH4Cl 25 ~30 g/ L, NaH2PO2·H2O 15 ~25 g/ L. Ni-Zn-P alloy coating was prepared by adding 0. 4 ~0. 8 g/ L of ZnSO4·7H2O into the above formula. The surface morphology of coatings before and after corrosion in artificial simulated seawater was observed by optical microscope and SEM. The surface composition of coatings before and after corrosion was analyzed by EDS. Results The P contents of Ni-P plating and Ni-Zn-P alloy coating were 11. 26 wt% and 9. 97 wt% , respectively. From the P content and coating microstructure, it ccould be determined that the two coatings obtained were continuous dense amorphous coatings. The Ni-Zn-P alloy coating was more uniform and smooth than the Ni-P coating, and the cell boundary was more continuous and denser. After 144 h corrosion in artificial simulated seawater, Ni-P coating showed obvious pitting, while the Ni-Zn-P alloy coating was still intact without damage and localized corrosion. After corrosion, the content of Zn decreased obviously and a small amount of Fe and O appeared in the Ni-Zn-P alloy coating, indicating that Zn was first corroded in the corrosion process of the alloy coating, then the coating was gradually corroded, and finally, the substrate was corroded. The corrosion rate of Ni-Zn-P alloy coating was significantly lower than that of Ni-P coating. Conclusion The Ni-Zn-P alloy coating was more uniform and smooth than the Ni-P coating, and the cell boundary was more continuous and denser. The corrosion rate of Ni-Zn-P alloy coating was significantly lower than that of Ni-P coating. |
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