Corrosion resistance and mechanisms of Nd(NO3)3 and polyvinyl alcohol organic-inorganic hybrid material incorporated MAO coatings on AZ31 Mg alloy

Lei Cai; Xiang Song; Cheng-Bao Liu; Lan-Yue Cui; Shuo-Qi Li; Fen Zhang; M Bobby Kannan; Dong-Chu Chen; Rong-Chang Zeng

doi:10.1016/j.jcis.2022.10.087

Corrosion resistance and mechanisms of Nd(NO₃)₃ and polyvinyl alcohol organic-inorganic hybrid material incorporated MAO coatings on AZ31 Mg alloy

J Colloid Interface Sci. 2023 Jan 15;630(Pt A):833-845. doi: 10.1016/j.jcis.2022.10.087. Epub 2022 Oct 20.

Authors

Lei Cai¹, Xiang Song¹, Cheng-Bao Liu¹, Lan-Yue Cui¹, Shuo-Qi Li¹, Fen Zhang¹, M Bobby Kannan², Dong-Chu Chen³, Rong-Chang Zeng⁴

Affiliations

¹ Corrosion Laboratory for Light Metals, School of Materials Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China.
² School of Engineering, University of Newcastle, Callaghan, New South Wales 2308, Australia.
³ School of Materials Science and Energy Engineering, Foshan University, Foshan 528000, China.
⁴ Corrosion Laboratory for Light Metals, School of Materials Science and Engineering, Shandong University of Science and Technology, Qingdao 266590, China; School of Materials Science and Engineering, Zhengzhou University, Zhengzhou 450002, China; Hubei Key Laboratory of Advanced Technology for Automotive Components, Wuhan University of Technology, Wuhan 430070, China. Electronic address: rczeng@foxmail.com.

PMID: 36279842
DOI: 10.1016/j.jcis.2022.10.087

Abstract

This work reports the design and preparation of novel organic (polyvinyl alcohol, PVA)-inorganic (neodymium nitrate, Nd(NO₃)₃) hybrid coatings on micro-arc oxidation (MAO) coating for magnesium (Mg) alloy corrosion protection. X-ray diffractometer, X-ray photoelectron spectroscopy, fourier transform infrared spectroscopy, field emission scanning electron microscope, Energy Dispersive X-ray spectrometer and surface roughness were applied to characterize the chemical composition and surface morphology of the coatings. The corrosion resistance of the coatings was evaluated by electrochemical and salt spray tests. The results suggested that the formation of PVA-Nd³⁺ and PVA-Mg²⁺ complexes promoted the enrichment of Nd³⁺ on the surface, and thereby improved the sealing quality and compactness of the coating. Interestingly, when the coating was damaged, the Nd³⁺ ions were transformed to their carbonates and covered the active sites, and thus exhibiting self-healing function. Further, the corrosion resistance of PVA-Nd³⁺ modified MAO composite coating on AZ31 Mg alloy was improved.

Keywords: Magnesium alloy; Micro-arc oxidation; Organic-inorganic hybrid; Rare earth elements; Sealing.