Friction stir processed Al - Metal oxide surface composites: Anodization and optical appearance

摘要

Multiple-pass friction stir processing (FSP) was employed to impregnate metal oxide (TiO, YO and CeO) particles into the surface of an Aluminium alloy. The surface composites were then anodized in a sulphuric acid electrolyte. The effect of anodizing parameters on the resulting optical appearance was studied. Microstructural and morphological characterization was performed using transmission electron microscopy (TEM). The surface appearance was analysed using an integrating sphere-spectrometer setup. Increasing the anodizing voltage changed the surface appearance of the composites from dark to greyish white. This is attributed to the localized microstructural and morphological differences around the metal oxide particles incorporated into the anodic alumina matrix. The metal oxide particles in the FSP zone electrochemically shadowed the underlying Al matrix and modified the local morphology of the anodic layer as well as changed the light interaction phenomenon.