Effect of Electrical Parameters toward Structure and Properties of Anodized Layer in Anodized Aluminum Plates

Many metals are structurally weakened by the oxidation process, but not aluminum. Aluminum can actually be made stronger and more durable through a process called 'anodizing'. The main objective of this project is to study the relationship between the voltages applied (electrical parameter) effect on the structures and properties of anodized aluminum. This project will start with identification of the problem statement and follows with the feasibility study of the topic. After all necessary information has been collected; it comes to part of identifying and selecting all material and chemical solutions to be used. The method that has been used is the electrolysis method using the some specifically combination of circuit system. Certain chemical solutions, tools and equipment needed were identified before start the experiment. The characteristic of the anodized aluminum plates later was analyzed by SEM and FTIR analysis. The acid action is balanced with the oxidation rate to form a coating with microscopic pores of 10-350 nm in diameter. These pores are what allow the electrolyte solution and current to reach the substrate and continue growing the coating to the greater thickness beyond what is produced by autopassivation. Condition such as electrolyte concentration, acidity, solution temperature, and current must be controlled to allow the formation of a consistent oxide layer. Harder, thicker films tend to be produced by more dilute solutions at lower temperatures with higher voltages and currents. Based on the experiments done, it is found that the optimum voltage that needs to be applied on the specimens is 21V and stopping time at 50 – 60 minutes. Exceeding the optimum voltage can cause crack to happen on the surface of anodized aluminum due to the different coefficient of linear thermal expansion between aluminum and aluminum oxide. The FTIR analysis was found to confirm the interaction between the organic dye (carmoisine) chemicals groups with the internal pores surface of the aluminum oxide layer.