Effect of La surface coatings on oxidation behavior of aluminum alloy/SiCp composites

摘要

The oxidation behavior of aluminum-matrix-composites (A3xx.x/SiCp) has been studied after La deposition with conversion and electrolytic treatments. Kinetics data of the corrosion process were obtained from gravimetric tests performed at different temperatures (350, 425 and 500°C). The nature of the corrosion products and the influence of the microstructure on the morphology and growth of the oxidation layer were analyzed by scanning-electron and atomic-force microscopy, X-ray photoelectron spectroscopy and X-ray diffraction. The extent of oxidation degradation in untreated composites was characterized by a phenomenon of oxidation preferentially localized in matrix/SiCp interfaces favoring MgO formation. La coatings favored a homogeneous oxidation of the composite surface favoring MgAl2O4 spinel formation. In addition, this oxide increased the surface hardness of materials. © Springer Science+Business Media, LLC 2007.