The influence of anomalous codeposition on few coating alloys properties

Abstract

Due to the presence of tungsten, Fe-W alloys can be applied as anticorrosive coatings. However, the conditions in which they are obtained influence their polarization resistance. This paper investigates how to electrodeposit them in order to increase their anticorrosive properties. The Fe-W alloys were produced by electrodeposition in different experimental conditions. The samples were characterized by X-ray diffraction (XRD) and scanning electronic microscopy (SEM) with energy dispersive X-ray spectroscopy (EDX). The corrosion resistance was evaluated by Tafel extrapolation. This paper reports that alloys that have higher mass composition of tungsten have higher polarization resistance, up to 9924.05 ohm∙cm². Fe-W alloys had 38.85–69.59% tungsten in mass basis, and the alloys with most tungsten were obtained with temperature of 60°C, continuous direct electric current density of 50 mA/cm², 0.01 mol/L iron sulfate concentration, 0.1 mol/L ammonium citrate and 0.1 sodium tungstate concentration. This study obtained alloys with higher tungsten composition, up to 69.59%, in comparison to papers with similar results of faradaic efficiency (10–15%). Using 0.1 mo/L iron sulfate concentration, the decrease of the temperature and the current density increases the tungsten composition, making the FeW alloys more anticorrosive.