Effects of anodizing parameters on cracking behavior of anodic film on ZL201 aluminium alloy

The effects of oxidation time,sulfuric acid concentration and current density on heat-resistance of anodic film formed on ZL201 aluminium alloy were studied by scanning electron microscopy(SEM) and electrochemical impedance spectroscopy(EIS).The generation of residual stress was also discussed.The results show that there exists a few cracks in sealed anodic oxidation films.When the films are heated,the initial cracks become larger and some new cracks occur.The longer the anodic oxidation is,the more the cracks in the films after heating.The higher density of cracks in anodic films,which are anodized in higher concentration of sulfuric acid solutions,can also be found after heating.On the contrary,with the increase of oxidation current density,the density of cracks in anodic films after heating decreases.