Effect of surface roughness and eutectic segregation on anodising of Al-Si-Cu alloys

Abstract

To study the influence of the surface roughness and eutectic silicon segregation on the anodising of diecast Al-Si-Cu alloys, an AlSi11Cu2(Fe) alloy was high-pressure diecast and hard anodised. The microstructure and surface topography of milled and grit-blasted regions were investigated to analyse their effect on the growth of the anodic layer. The surface mechanical properties of the anodised surfaces were also studied. The results showed how high surface roughness and silicon segregation present in the grit-blasted surface hindered the thickening of the oxide layer. After anodising, the milled surface exhibited better mechanical properties than the grit-blasted one. The wear resistance was enhanced by a thicker anodic layer, while the scratch resistance was positively affected by a lower surface roughness.