CORROSION STUDIES OF SILICON CARBIDE (SIC) REINFORCED ALUMINIUM 7075 METAL MATRIX COMPOSITES (MMCS) IN ACIDIC AND ALKALINE MEDIA.

The corrosion behavior of Aluminium 7075 reinforced with SiC metal matrix composites was investigated in different concentrations of phosphoric acid medium and potassium hydroxide medium at 25°C. The study was done by electrochemical method using Tafel polarization techniques and electrochemical impedance spectroscopy (EIS) technique. The surface morphology was investigated using scanning electron microscope (SEM). The results showed that the Aluminium 7075 matrix undergoes intense corrosion in sodium hydroxide medium than in phosphoric acid medium. The corrosion rate of SiC reinforced Aluminium 7075 composites increases with an increase in the concentration of acid as well as alkali. The corrosion rate decrease with increase in the percentage of SiC particulate in Aluminium 7075. Desirable reaction mechanism was proposed for the corrosion of Aluminium 7075 in phosphoric acid medium and potassium hydroxide medium. The results obtained by Tafel polarization and electrochemical impedance spectroscopy (EIS) technique were in good agreement with each other. [ABSTRACT FROM AUTHOR]