Electroplating of Al-Zr alloys in AlCl3-NaCl-KCl molten salts to improve corrosion resistance of Al

Abstract

To improve the corrosion resistance of Al in chloride solutions, electrodeposition of Al-Zr alloys of various compositions was carried out at 448 K by constant potential control in AlCl 3 -NaCl-KCl molten salt containing ZrCl 4 . Cathodic reduction of the Zr ions starts at a potential of 0.4 V vs. Al/Al(III) in the molten salt. The electrodeposition of Al and Zr occurred at potentials more negative than −0.02 V. The concentration of Zr in the electrodeposit increased to 23 at.% at −0.02 V. In the XRD analysis, the electrodeposits formed at −0.05 to −0.15 V had good crystallinity, the electrodeposits containing higher concentrations of Zr formed at −0.02 or −0.04 V show an amorphous or fine crystal structure. The pitting potentials of Al-Zr alloys containing 5-23 at.% Zr in 0.1 M NaCl solution shifted from +0.1 to +0.3 V compared with those of pure Al.

Dissolution Characteristics of Al-Si Alloys in AlCl₃-NaCl-KCl Molten Salt at 423 K

“…However, Fe and Cu may be anodically dissolved depending on the potential change during electrolysis, considering that these impurities formed intermetallic compounds with Al. It has been reported that the Si in Al alloys is anodically dissolved and electrodeposited at the cathode in high-temperature molten salts at 1023 K. 10 Huan et al reported the progressive dissolution of Si for the same AlCl 3 -NaCl-KCl molten salt electrolyte, 21 however, in the present study, LSV measurements and electrorefining results for molten salt at the 423K revealed no anodic dissolution of Si. Fine black particles were found at the bottom of the electrochemical cell after electrorefining, which were found to be crystalline Si from XRD measurements.…”

“…Many studies have reported the electrodeposition of Al alloys using molten salts, [10][11][12] and these studies have been particularly aimed at electrorefining. [13][14][15] However, only a few studies have compared Al-Si alloys of different microstructures.…”

Improvement in corrosion resistance of micro‐arc oxidation coating on PVD Ti‐coated aluminum alloy 7075

“…In order to pursuit their application in seawater environments, surface treatments are always needed to enhance their corrosion‐resistant performance. The coatings, made by thermal spraying, 3 electroplating, 4 chemical vapor deposition (PVD), 5 and PVD 6 etc, were proposed in the past for the protection of the Al form corrosion. Micro‐arc oxidation (MAO), also known as plasma electrolytic oxidation, was developed in recent years for the formation of surface coating on nonferrous metals, such as Al 7 , Ti 8 , Zr 9 , and Mg 10 etc.…”

Design and Fabrication of a Sandwichlike Zn/Cu/Al–Zr Coating for Superior Anticorrosive Protection Performance of ZM5 Mg Alloy

“…To further improve the physical and mechanical properties and the lifetime of Al coating, a minor addition of alloying elements is practically anticipated. − Some relevant literature works show that addition of zirconium (Zr) element to Al coating is a promising way to significantly improve the corrosion resistance and brightness of Al coating. − However, most of them mainly focused on the relation between the alloy composition and electrodeposited parameters, and the corrosion behaviors were preliminarily studied by anodic polarization curves. Notably, electrodeposition of Al–Zr alloys on the Mg substrate in the 1-butyl-3-methylimidazolium chloride (BMIC)–AlCl 3 –ZrCl 4 ionic liquid has not been studied yet.…”