Materials Transactions Online

Materials Transactions, Vol.47 No.03 (2006) pp.948-951
© 2006 The Japan Institute of Metals

In-Situ Laser Cladding of Al2O3 Reaction Coating on Aluminium Alloy 7075 for Corrosion Resistance Improvement

T. M. Yue, K. J. Huang and H. C. Man

The Advanced Manufacturing Technology Research Centre, Department of Industrial and Systems Engineering, The Hong Kong Polytechnic University, Hung Hom, Hong Kong

The microstructure and corrosion behaviour of the thermite reaction coatings for the systems of Al–CuO–SiO2, Al–Cr2O3–SiO2, and Al–TiO2–SiO2 that produced by laser cladding on aluminium alloy 7075 have been studied. The results of the XRD analysis show that in all the three reaction coatings, α -Al2O3 and γ -Al2O3 phases were present together with various intermetallic phases and the corresponding reduced metal. A comparison of the polarisation curves of the untreated and the various coated specimens shows that except for the Al–CuO–SiO2 system, the corrosion current density of the coated specimens was one order of magnitude lower than that of the untreated specimen, also a higher corrosion potential was obtained. The inferior corrosion resistance of the Al–CuO–SiO2 system is attributed to galvanic corrosion occurred between the reduced metal, the intermetallic compounds and aluminium.

(Received 2005/12/8; Accepted 2006/1/30; Published 2006/3/15)

Keywords: laser cladding, thermite reaction, aluminium alloy, corrosion

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