Corrosion behaviour on AA2014/15vol. %A1₂0₃P and AA2009/20vol. %SiCw composite after ageing treatment

Abstract

The purpose of this study is to compare the corrosion behaviour between AA2014/15vol. %A1₂0₃P and AA2009/20vol. %SiCw composites after ageing treatment. The former composite was cast composite supplied by Duralcan USA. The later composite was a powder metallurgy composites supplied by Advanced Composite Materials Corporation USA. The corrosion behaviour was investigated by means of immersion test and salt spray test. Before immersion test, the composites were examined for ageing response at 16SoC (0 - 12hours). Microstructure evaluation has been characterized using optical microscope, SEM and EDX. It was observed that the distribution of SiC whiskers in the matrix AA2009 is more homogeneous compared to the distribution of Ah03 particles in the matrix AA2014. The secondary phases such as AhCu and AhCuMg were identified in AA20141l5vol. %A1₂0₃P whereas AhCu was identified in AA2009/20vol. %SiCw composites after ageing. Localized corrosion is more intense in AA2014/15vol. %Ah03p compared with AA2009120vol. %SiCw• The pit shape for composite of AA20141l5vol. %A1₂0₃P is shallow wide pit and differs to composite AA2009/20vol. %SiCw which is shallow deep pit. Salt spray test has been used to assess the corrosion behaviour of the surface of as received composites. The corrosion product has been analysis using XRD after salt spray test. The qualitative diffraction pattern from both composites after 20 hours exposure in salt spray test shows the formation of the corrosion products. It was observed that three corrosion products were identified such as Mg (OHh, A1203, Mn02 in composite AA2014/15vol. %A1₂0₃P and no corrosion product was identified for composite AA2009/20vol. %SiCw.