Corrosion rates and pore sizes on anodized aluminum 6083 with different voltages using citric acid anodizing process

Abstract

Aluminum alloy such as Al6083 series has a good properties in forming, welding, machining and corrosion resistance. During life cycle of engineering products such as ships, pipes or others which operate on-shore or off-shore, sea water become cause factor of metal corrosion because it induces corrosive environment to metal. In this case then the product need a necessary techniques to prevent corrosion, one of them is by coated it through anodizing processes. In this research, pore sizes and corrosion rate of anodized aluminum 6083 alloy was studied by varying the operating voltage of process of 15V, 20V, and 25V. The other variables were controlled during the research, i.e. electrolyte temperature within ranges of 28 ± 2ºC, electric current of 1 A, distance between the anode and cathode of 20 mm, processing time for 10 minutes and using 15% of citric acid (C₆H₈O₇) as the electrolyte solution. The pore sizes were acquired by taking photos and automatic data display feature to determine pore sizes using the FlexSEM 1000 II apparatus. Data on corrosion rate data were collected using the Autolab PGSTAT204 apparatus. From the results it is known that using citric acid as an electrolyte during the anodizing process obtained an optimal point at a voltage of 20V with the largest pore size of 65.8 nm and a corrosion rate value of 0.00533 mm/year. This shows that increasing the voltage to certain value and using citric acid (C₆H₈0₇) as an electrolyte can improve corrosion resistance due to the formation of aluminum oxide on the surface of the specimen.