Abstract:Single-layer and multilayer alloy deposits were coated onto a mild steel substrate by a single-bath electroplating process. The developed coating consists of Zn and Fe alloys having different compositions with different layers. The anticorrosion behavior of single-layer and multilayer deposits was evaluated by the potentiodynamic polarization method. The surface morphology of the deposits was studied with a scanning electron microscope. The crystal structure of the deposits was analyzed with the X-ray diffract… Show more
“…This study finding (in which almost crack-free coatings showed better pitting corrosion resistance) is in agreement with previous results of Chien C.W. et al [ 17 ] and Ghaziof S. et al [ 45 ] and others [ [46] , [47] , [48] ], who reported that coating defect like crack is detrimental to the integrity of coatings and should be eliminated as much as possible for an effective application. Fig.…”
“…This study finding (in which almost crack-free coatings showed better pitting corrosion resistance) is in agreement with previous results of Chien C.W. et al [ 17 ] and Ghaziof S. et al [ 45 ] and others [ [46] , [47] , [48] ], who reported that coating defect like crack is detrimental to the integrity of coatings and should be eliminated as much as possible for an effective application. Fig.…”
“…It may be attributed to the increase of Fe content and the cracks in the coating at higher current densities. 47,48 All the corrosion currents of the HEA coatings were lower than that of 304 stainless steels (135.2 μA cm −2 ). On the other hand, the values of polarization resistance (R p ) were obtained by fitting the Tafel curves.…”
High-entropy alloy (HEA) coatings have been widely investigated because they can significantly improve the surface properties of the substrate. Electrodeposition of HEA coatings in an aqueous bath was considered a promising method. In this study, the Fe-Co-Ni-Mo-W HEA coatings were prepared by aqueous electrodeposition. The effects of the current density on the chemical composition and the physical performance of the HEA coatings were investigated. The results showed that the content of Ni, Mo, and W increased, while the content of Fe decreased as the current density increased from 20 to 80 mA/cm2. The coating deposited at 40 mA/cm2 possessed the best mechanical properties. The microhardness and the wear rate were 4.52 Gpa and 2.05×10-5 mm3/N·m, respectively. The electrochemical test showed that the corrosion resistance of HEA coatings increased with the decrease of current density. All the physical properties of the HEA coatings were superior to 304 stainless steel, suggesting a considerable application potential.
“…38 Electrodeposition can be used to generate not only interfacial alloys such as Ni on Au(111) but also alloyed coatings to impart specific properties and change the appearance of an object. One modern aspect of electrodeposition involves the square pulse current sequence procedure 39 to fabricate a number of compositionally modulated multilayered materials, such as ZnFe, 40 ZnCo, 41 and ZnNi, 18,42 on mild steel and others. These alloyed nanocoatings have unique microstructures and electronic properties, eventually leading to superior corrosion resistance.…”
Section: Ni Deposition On Au(111) Without MMImentioning
A nickel film electroplated onto a metal substrate can be used as a catalyst for water splitting and a magnetic material for spin valves. Although the nucleation and growth of Ni on Au(111) have already been examined with in situ scanning tunneling microscopy (STM), the current study provides new insights of the structure of the first layer of Ni on an ordered Au(111) electrode in 0.1 M KSO 4 + 1 mM H 2 SO 4 + 10 mM NiSO 4 (pH 3). Prolonged STM scanning of the Ni monolayer on a Au(111) electrode revealed interfacial mixing to produce a surface alloy, initially assuming segregated Ni domains and later transforming them to a homogeneous Ni/Au phase. The formation of the Ni/Au(111) surface alloy affected the structure of the subsequent bulk Ni deposition. The inclusion of 2-mercapto-1-methylimidazole (MMI) in the deposition bath incurred Ni deposition at a less negative potential and a faster rate, resulting in an overall 5.3 times more Ni deposited on the Au electrode in potentiodynamic experiments. MMI molecules were adsorbed on the Ni deposit to prevent Ni dissolution in the Au(111) electrode. MMI could catalyze the presumed rate-determining step from Ni 2+ to Ni + en route to the metallic Ni. The resultant Ni film with MMI had a 3D texture without a preferred crystal orientation on the Au electrode, as opposed to a layer type growth of Ni on Au(111) without MMI.
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