ISSN 2070-2051, Protection of Metals and Physical Chemistry of Surfaces, 2009, Vol. 45, No. 3, pp. 342–352. © Pleiades Publishing, Ltd., 2009. 342 1 1. INTRODUCTION There are many studies where acidic solutions were used for the process of producing anodic oxide on alu- minium surface. These studies generally focus on the topics such as the structure of film, the composition of it, the transferring of ions from oxide, as a result of this the growing mechanism of film, the breakdown of film in the solution—producing oxide etc. Many of these researches were performed by using electron micro- scope. In recent years, the processes of determination of the structure of film and the oxidation of ion types and its amount have been performed by spectroscopic methods [1–5]. Near eutectic Al–Si alloys are used extensively as piston materials in modern, small auto- motive engines [5–7]. This class of alloy exhibits com- plex multiphase microstructures, comprising primary (blocky) and eutectic (acicular) Si, Al dendrites and numerous intermetallic particles. Automotive pistons operate under complex mechanical stresses and over a wide temperature range. Through the addition of alloy- ing elements, it is hoped to optimize high temperature fatigue performance without compromising room tem- perature behaviour. The room temperature fatigue behaviour for these classes of alloy has been studied extensively and has identified porosity as a critical fea- ture [7–10]. However improved casting techniques have reduced porosity considerably. Therefore the influence of Si and intermetallic particles on fatigue behaviour have become more critical [11–16]. Paez et al. (1996) exam- 1 The article is published in the original. ined the formation of type barrier anodic films on Al-Cu alloy in their study. At first the formation of type barrier film inside is homogenous and highly produc- tive on the alloy surface of Al ( polished by electrolyti- cal method)—3.5% Cu. Outer parts looking different occur during the anodizing process and the possible structure occurs in anodic film. Zhou et al (1999) inves- tigated anodic oxidation of dual alloys of Al–3% Mg and Al–5% Mg in the electrolyte of ammonium pentab- orat and type barrier anodic film during the of high cur- rent activity. It has been seen that the occurrence of ionic movement of anodic oxide results from both anion and cation migration of amorphous film. Mazhar et al. (2001) state that the corrosion behaviour of Al obtained in spectrums in EIS study is controlled by multi-stepped dissolving. The breakdown of film layer and oxide result from ions of Cl – . The attack of Cl – ions is due to the occurrence of complex–including Cl – in intersurface of film/solution. This makes passive layer thin and leads to pitting corrosion. Al + nCl – AlC + 3é. As the acidity of solution increases, the corrosion current i cor increases, but the polarization resistance decreases. Kowal et al. (1996) researched morphologic variations on the surface of 2024-T3 Al alloy plunged into hydrochloric acidic solution. It was observed that the corrosion of alloy in the mediums including chlo- rine was in acidic type and Al alloy was sensitive to cor- rosion inter grains in hydrochloric acidic medium and have been broken the passiveness of aluminium, there was some dissollutions through the borders of grain. l n n 3 – ( ) – PHYSICOCHEMICAL PROBLEMS OF MATERIALS PROTECTION The Effect of 3-Methyl 1-Pentyn 3-Ol on the Corrosion of Al-Si-Cu Alloys in Acid Solutions by Using SEM, EDX and AAS 1 A. Buyuksagis a , A. A. Aksut b , and D. Ozal a a Afyon Kocatepe University Science and Art Faculty, Afyonkarahisar/TURKEY b Ankara University Science Faculty Chemistry Department Ankara/Turkey *e-mail: absagis@aku.edu.tr, ayselbuyuksagis@hotmail.com Received October 2, 2007 Abstract—In this study, the effect of alloying elements on the corrosion of Al-Si-Cu alloys in H 2 SO 4 and HCl media content 3-methyl–1pentyn–3-ol (3mlp3ol) is investigated by using SEM, EDX, AAS. The effect of active elements and 3-methyl–1-pentyn–3-ol (inhibitor) on the corrosion of alloys is determined using SEM, EDX and AAS results. Experimental results which indicated active alloying elements are Cu, Zn, Mg for Al-Si-Cu alloys in the studied solutions. PACS numbers: 82.45.Kn DOI: 10.1134/S2070205109030113