Acta Phys. -Chim. Sin. ›› 2000, Vol. 16 ›› Issue (06): 547-552.doi: 10.3866/PKU.WHXB20000614

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Composition,Structure and Properties of Rare Earth Metal Conversion Coating on Al6061/SiCp

Yu Xing-Wen, Cao Chu-Nan, Lin Hai-Chao, Zhou Yu-Hong, Zhou De-Rui, Yin Zhong-Da   

  1. Institute of Corrosion and Protection of Metals,Chinese Academy of Science,State Key Laboratory for Corrosion and Protection,Shenyang 110015|Harbin Institute of Technology,Harbin 150001
  • Received:1999-09-21 Revised:1999-11-29 Published:2000-06-15
  • Contact: Yu Xing-Wen

Abstract:

A double layer Rare Earth Metal (REM) conversion coating process of Al 6061/SiCp metal matrix composites (MMC) was studied. The corrosion resistance of REM conversion coating was examined by electrochemical impedance spectroscopy (EIS).REM conversion coating produced very corrosion resistant surface of Al 6061/SiCp MMC. The X ray diffraction (XRD) analysis revealed that REM conversion coatings exhibited non crystalline structure. The composition of REM conversion coating was studied by X ray photoelectron spectroscopy (XPS).The coatings consisted of cerium oxide and hydrated cerium oxide. Some of Ce3+were oxidized to Ce4+during the formation of the first layer coating in the solution containing Ce3+.During the course of exposing the specimens in open air, some of the residual Ce3+were oxidized to Ce4+.REM conversion coating formed in the solution containing Ce4+consisted entirely of Ce4+compounds.

Key words: Al6061/SiCp metal matrix composites, Rare earth metal conversion coating, Corrosion resistance, Non-crystalline structure