材料期刊网

The process of the double layer rare earth metal (REM) conversion coating on aluminum alloy LY12 (2024) was introduced in this paper. The corrosion resistance of REM conversion coating was examined by electrochemical impedance spectroscopy. The results showed that the coating increased the corrosion resistance (R,) of the alloy surface, thus reducing the driving force of corrosion. The morphologies of the coating were studied by scanning electron microscope. The results revealed that the coating consisted of layers of spherical particles with different size, which grew gradually to cover the surface of aluminum alloy. The X-ray diffraction analysis revealed that the film was amorphous. The results of X-ray photoelectron spectroscopy indicated that the film consisted of cerium(III and IV) oxide and cerium(III and IV) hydroxide. (C) 2001 Elsevier Science Ltd. All rights reserved.