The preparation and corrosion resistance of Ce and Nd modified anodic films on aluminum

Rare earth element Ce and Nd modified anodic films were prepared on aluminum surface by a relatively simple method: the aluminum samples were first immersed in Ni(NO3)2 solutions containing Ce or Nd salts at 90 °C, then were dried and anodized. The contents of Ce or Nd in the anodic films were from 0.5% to 0.9%, and about 4–5% Ni was also introduced in the films. The modified anodic films were more compact with much smaller pores and increased hardness. In neutral, acidic and basic NaCl solutions, the rare earth modified films showed obviously improved corrosion resistance. The Ce modified films showed better corrosion resistance than Nd modified films. The cracking resistance of the films under heating was also improved.