Fabrication of niobium coated magnesium alloy for automotive & aerospace applications

Abstract

Magnesium (Mg) and its alloys are being considered as potential materials to enhance fuel efficiency in the aircraft and automotive industries because of the light weight. However, the major limitation of Mg is its high corrosion rate, which needs to be controlled to avoid the failure of the components. Therefore, the present, key challenge lies in controlling Mg degradation rate. The main objective of this thesis was to electrodeposit Niobium (Nb) layer on Mg alloy for corrosion protection. An environmentally friendly solution is demonstrated by forming Nb coating on Mg alloy by the electrodeposition process. The characteristic of Nb electrodeposited layer at room temperature using Nb salt and ionic liquid were discussed in this study. The optimal electrolyte solvent was found to be water as compared to other solvents such as acetone and dimethyl sulphoxide. The morphology of the coating was studied using SEM-EDS and the maximum deposition of 36 weight % Nb in aqueous solution was obtained through electrodeposition at pH 2.5 with ionic liquid 1 butyl-2-3-dimethylimidazolium tetrafluoroborate at room temperature. When considering electrolytes, other than water, such as acetone, the maximum deposition was found to be 22%; whereas in dimethyl sulfoxide, no deposition was found. The environmental effect on deposition rate using glove box in aqueous solution showed no significant difference. Detailed surface characterization using X-Ray diffraction (XRD) and X-Ray photoelectronscopy (XPS) showed Nb peaks that futher confirmed Nb deposition. Electrochemical testing showed an increase in the corrosion resistant property to the Nb coated Mg sample. Salt Spray and Humidity tests showed enhanced corrosion resistant properties and, thus, could be a potential use in automotive and aerospace applications.