The effect of heat treatment and surface roughness on the zincate treatment of aluminium alloy 6082

The effect of heat treatment ans surface roughness on the zincate treatment of aluminium alloy 6082 was investigated using scanning electron microscop y, electrochemical measurement and surface profilometry. It has been found that the heat treatment of the alloy has a small effect on the ease of zinc ate plating. The zinc coverage is incomplete at grain boundaries of aged sa mples. Surface roughness has a greater effect: on rougher surfaces, the zin c preferentially grows on peaks rather than in the valleys; the effect is c onsistent with a lower open circuit potential during plating. The roughness effect is explained in terms of the transport of zinc to the surface and l ocal pH changes.