Aluminum electroplating on steel from a fused bromide electrolyte

Abstract

A quaternary bromide bath (LiBr-KBr-CsBr-AlBr 3 ) was used to electro-coat aluminum on steel substrates. The electrolyte was prepared by the addition of AlBr 3 into the eutectic LiBr-KBr-CsBr melt. A smooth, thick, adherent and shiny aluminum coating could be obtained with 80 wt.% AlBr 3 in the ternary melt. The SEM photographs of the coated surfaces suggest the formation of thick and dense coatings with good aluminum coverage. Both salt immersion and open circuit potential measurement suggested that the coatings did display a good corrosionresistance behavior. Annealing of the coated surfaces, prior to corrosion tests, suggested the robustness of the metallic aluminum coating in preventing the corrosion of the steel surfaces. Studies also indicated that the quaternary bromide plating bath can potentially provide a better aluminum coating on both ferrous and non-ferrous metals, including complex surfaces/geometries.Published by Elsevier B.V.

A Molten Salt Electrochemical Process for the Preparation of Cost-Effective p-Block (Coating) Materials

“…It appears that a relatively elevated temperature may remove some of the limitations that are inherent to low-temperature coating/deposition processes. A recent study from our laboratory, has indeed shown the superior features of the coated components in terms of good adhesion and excellent corrosion-resistance properties in a simulated marine environment [15]. Several published literatures also support such a viewpoint wherein elevated temperatures have been shown to promote formation of smooth, adherent, thick and relatively uniform deposits/coatings [16,17].…”

Electrolytic Aluminizing of Low-Carbon Steel in NaF-KF-AlF₃ Melt

“…Aluminizing treatment is an effective method for producing aluminum-coating layer on steel surface to improve oxidation resistance at high temperatures due to the formation of the thin α-Al 2 O 3 oxide film on the surface of the coating layer [2]. Among aluminizing methods, including physical vapor deposition [3], solid powder route [4], and pack cementation [5 the liquid-phase methods are the most inexpensive and simplest in design : hot deep aluminizing (HDA) in liquid aluminum bath [2, 6 and 7] and electroplating [8].…”

“…Currently molten alkali chlorides with the aluminum-containing additives are the most common media for the electrolytic aluminizing. It was reported that in order to provide a continuous and dense aluminum coating in the AlCl 3 (80)-NaCl(20) mol.% melt (at 175 °С) the current density should be less than 0.016 A•cm -2 or a continuous coating can be obtained in the molten bromides with the AlBr 3 addition at the current density ranged from 0.1 to 0.5 A•cm -2 and elevated temperature 325-350 °C [8]. An advantage of the galvanic coatings obtained at a relatively low temperature (below the Al melting point) is slight interaction between Al-layer and steel substrate and, consequently, an absence of a brittle intermetallic phases layer; and disadvantage is a low rate of the deposition process provided a continuous coating layer.…”