Effect of Cerium Nitrate and Adipic Acid Additives on Anti-Corrosion Resistance and Microstructure of Vanadium Conversion Coating on ۲۰۲۴ Aluminum Alloy

In this research, the effect of inorganic and organic additives of cerium nitrate and adipic acid on anti-corrosion resistance and microstructure of vanadium conversion coating on ۲۰۲۴ aluminum alloy was investigated. First, using the results of electrochemical impedance spectroscopy (EIS) and direct current polarization (DC), optimum value of concentration of both organic and inorganic additives under optimum coating conditions in the absence of additives was determined. Then, in order to properly evaluate the effect of additives, practical process parameters such as immersion time, solution pH and solution temperature were optimized in the presence of additives. Based on the results of direct current polarization and electrochemical impedance spectroscopy, the coated sample with vanadium conversion coating in the presence of ۲ gr/lit of cerium nitrate, solution pH of ۴, immersion time of ۲۵ minutes and at ambient temperature showed the highest anti-corrosion resistance. This anticorrosion performance (corrosion current density of ۰.۰۲۶ µA/cm۲ and impedance at low frequencies of ۸۵,۲۰۰ Ω.cm۲), displayed significant improvement in anti-corrosion resistance of bare substrate (corrosion current density of ۲.۲۸ µA/cm۲ and impedance at low frequencies of ۱۸,۵۱۰ Ω.cm۲) by develpoing vanadium conversion coating in the percense of cerium nitrate. Also, in the presence of adipic acid additive the anti-corrosion resistance of substrate increased. In order to investigate the surface characteristics of the vanadium conversion coating in the presence of additives, water contact angle measurment, scanning electron microscopy and energy dispersive X-ray spectroscopy were used

کلیدواژه ها:

Vanadium conversion coating ، Cerium nitrate ، Adipic acid ، Scanning electron microscopy ، Electrochemical impedance spectroscopy ، ۲۰۲۴ aluminum alloy ، پوشش تبدیلی وانادیوم ، سریم نیترات ، آدپیک اسید ، میکروسکوپ الکترونی روبشی ، طیف سنجی امپدانس الکتروشمیایی ، آلیاژ ۲۰۲۴آلومینیوم