Electrodeposited Zn-Ni-sisal Nanocrystals Composite Coatings - Morphology, Structure and Corrosion Resistance

Zn-Ni alloys have been used to decrease the corrosion rate of carbon steel substrates. These are used in applications such as bolt coatings, threaded parts, swift valves for gas pipelines, aircraft landing gear, brake system components and others. Zn-Ni coatings containing nanocrystals of cellulose (CNC) obtained from sisal fiber (Sif), a natural polymer, were manufactured using the electroplating technique. Obtaining the nanocrystals involved bleaching raw sisal fiber and then acid hydrolysis to extract the nanocrystal. The effect of the concentrations of the CNC-Sif (0% v/v, 2%v/v, 3%v/v, and 4%v/v) on the morphology and microstructure of the Zn-Ni coating was analyzed through Scanning Electron Microscopy (SEM), X-ray diffraction, and roughness measurements using confocal microscopy. The effect of the addition of CNC-Sif on the efficiency of galvanostatic deposition was analyzed. The corrosion rate through mass loss and electrochemical tests were also analyzed. The effect of adding CNC-SIF on coating microhardness investigated. This study show that the addition of nanocrystals alters the structure, the morphology, increases current efficiency and the corrosion resistance of the Zn-Ni coating and these effects are more significant with the addition of 2% v/v. The results obtained indicate that the addition of the CNC-Sif in the Zn-Ni coating is promising, because it reduces the energy consumed during the electrodeposition process in addition to increasing corrosion resistance of the Zn-Ni and the microhardness