Corrosion Behaviour of Hypereutectic Al-Si-Cu Alloys Used in Cylinder Liners 2005-01-0539

In this study, the corrosion resistance of four Al-Si hypereutectic alloys has been investigated in a solution of chemical composition typical of the condensed solution from automotive fuel combustion products - here named automotive synthetic condensed solution. The significance of the undertaken study was in the evaluation of materials used for cylinder liners fabrication in relation to the Brazilian motor fuel. Three commercial Al-Si alloys that have been used for cylinder liners and a laboratory made alloy (Osprey Process) were evaluated by electrochemical impedance spectroscopy measurements at increasing times of immersion in this solution. The surfaces of the alloys were evaluated before and after corrosion test by scanning electron microscopy and. Although the corrosion mechanisms present similarities for all the commercial alloys investigated, the results also indicated different corrosion resistances for these alloys, and these were related to their microstructure characteristics. The laboratory prepared alloy showed increased susceptibility to pitting corrosion comparatively to the commercial alloys.