Knowledge of Research 2014, 1(1), 62-67 Research Article DOI:10.7598/kor2014.106 Naema A. Hikmat * , Ahlam M. Farhan 2 and Rana Afif Majed 3 1 Chemistry Department, College of Science, Baghdad University, Iraq 2 Chemistry Department, College of Science for Woman, Baghdad University, Iraq 3 Materials Engineering Department, University of Technology, Iraq dr.rana_afif@yahoo.com Received 3 November 2014 Revised 13 November 2014 Accepted 10 November 2014 ©ISSAC Publications http://www.knowledgeofresearch.com Thermodynamic and Kinetic Parameters for Corrosion Inhibition of Al-Cu alloy by Sodium Acetate at pH 11 Abstract: Corrosion inhibition properties of Al-Cu alloy in 0.001 M NaOH solution at pH 11 were investigated at four temperatures include 298, 303, 308 and 313 K using potentiostat by adding sodium acetate as inhibitor with three concentrations 0.05, 0.1 and 0.15 M. Corrosion parameters, protection efficiencies, thermodynamic and kinetic functions have been measured to estimate the inhibition efficiency of Al alloy in experimental conditions. The results indicate that 0.05 M of sodium acetate is the best concentration through the data of protection efficiency which supported by the highest value of enthalpy. The values of activation energy became higher indicating the inhibitive action of acetate. The entropy of activation values was negative. Keywords: Al-Cu alloy, Sodium acetate, Corrosion inhibition. Introduction Aluminium alloys are widely employed within the spacecraft industry and they provide the required mechanical and corrosion properties. The choice of Al-alloy depending on its application, the 2xxx series (high copper content) and 7xxx series (high zinc content) are used for structural components due to their high toughness and good fatigue strength. Generally these alloys offer a good corrosion resistance for most environmental exposures. However specific environmental conditions, such as long period storage in humid and salty environments, may trigger corrosion and therefore these alloys require additional protection. An earlier works reported that copper reduces the pitting initiation resistance of aluminium and therefore it was advised to add small quantities of copper (up to 0.15%) to aluminium in order to reduce the pits depths by other increasing pits density 1,2 . On the other hand Galvele and Micheli 3 and Muller and Galvele 4 studied the effect of copper on breakdown potential E b value for aluminium in different concentrations of NaCl solutions and on both (1M NaCl) and saturated AlCl 3 solutions respectively. They found that the presence of copper in solid solution in aluminium shifts E b to more noble values; however this beneficial effect is limited by the solubility of copper in aluminium. The effect of copper to the preferential dissolution of aluminium from the attacked region attribute to Cu – enrichment inside the pits which can reduce the cathodic reaction over potential. The later result was supported by Bicelli et al. 5 who studied the effect of copper on E b value for aluminium in 3.5% NaCl solution. They found that E b value for Al–Cu alloy in the solution treated condition followed by natural ageing was slightly above that for commercially pure aluminium (99.9% Al). Recently, many authors interested corrosion behavior and protection of Al-Cu alloy in different media 6-11 .