The Electrodeposition Of Aluminum On Iron Base Material

The electroplating aluminum coatings have an excellent corrosion resistance and high temperature oxidation resistance, compared to the currently electroplating Zn,Ni, the electroplating aluminum coating has more prominent advantages. The coatings access to a variety of colors, with beautiful appearance by different post-processing procedures such as anodized and electrolytic coloring. We can get the coatings with futher improved corrosion resistance, which also meet the electrical insulation,wear resistance, and other performance requirements.This research content includes two parts:iron-based materials of electroplating aluminum in molten salt system of AICl3-NaCI-KCl and urea-acetamide-NaBr-KBr. Experiments were used to constant current and constant potential electroplating to study the impact of parameters on the coating. Experiment use SEM,EDS,XRD phase analysis to observe electroplating aluminum coating morphology, composition and bonding. Polarization curves used to evaluate the corrosion resistance of aluminum coating.Result shows that certain thickness of aluminum coating can be obtained in the iron base material surface by AICl3-NaCI-KCl molten salt system. Potentiostatic plating grain obtained at the degree of 170 are more tiny and uniform than that at the degree of 150. Under constant current plating in current density 1.5 A/dm2-3.5 A/ dm2,aluminum coating are uniform and compact, with fine grain size, and the adhesive between coating and the matrix is good. Morphology analysis showed that the morphology of the aluminum deposit is mainly affected by grain growth. Current density is too small, fine grain size, but the bond between the coating and substrate is weak. Current density is too large, due to the existence of concentration gradient, grain growth is uneven, easy to form dendrites, which also result in coating and substrate is weak. Coating thickness increases with the extension of electroplating time. Galvanized iron wire and aluminum coating in 3.5% NaCl solution compared dynamic potential polarization curves, the corrosion potential of the former is lower than the latter, and the corrosion current density an order of magnitude higher than the latter.Electroplating aluminum from urea molten salt system research shows that:urea molten salt in the iron-base material electroplated aluminum is feasible. However, the current density is too small to form a good deposit of aluminum. In future research we can take some measures to increase the current density, such as increasing the concentration of Al ions, by adding inducer, appropriately increasing the plating temperature and other methods.