Corrosion investigation of electrodeposited cobalt-nickel-iron (CoNiFe) fasteners with the different deposition time

Abstract

Abstract Corrosion has been acknowledged as one of the biggest opponents in applications and industries such as in motorized industries, oil and gas industries, manufacturing and chemical plants, electric power generation plants and concrete structuresUsing the electrodeposition process, Cobalt-Nickel-Iron (CoNiFe) nanocrystalline coatings were successfully synthesized onto mild steel fasteners (bolt and washer) with deposition times of 15, 30, and 45 minutes, respectively. The objective of this research is to study the corrosion behaviour of the CoNiFe coated onto the mild steel fasteners. The electrodeposition process was performed by controlling its operating parameters such as temperature, pH, current density, deposition time and electrolyte composition. The temperature used throughout the process was 50 °C in an acidic condition of pH 3. By varying the deposition times, the phase and crystallographic structure, surface morphology, grain size, microhardness, and surface roughness of the CoNiFe coatings were examined. Based on the FESEM micrographs, the grain sizes of the coatings were in the range of 85.34 nm to 95.01 nm. Dendrite and irregular shapes were observed for the microstructure of CoNiFe nanocoating. The CoNiFe nanocrystalline coating prepared with a deposition time of 45 minutes achieved the highest microhardness of 228 HVN. The surface roughness also increases with longer deposition time. It was found that by increasing the deposition time also enhanced the microhardness and magnetic properties of CoNiFe nanocoating. From the salt (fog) spray test, the longer deposition time used had the highest corrosion resistance. Thus, it can be concluded that the optimum deposition time of the electrodeposited CoNiFe coating on the mild steel fasteners was 45 minutes which produces optimum properties.