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Hot corrosion resistance of Al<inf>2</inf>O<inf>3</inf> coating produced by thermal spray

Abstract:

In this paper the corrosion rates of the aluminum oxide (Al2O3) coatings were determined, obtained through technical produced by thermal spray, using as substrate 316. The coatings were studied by potentiodynamic polarization curves Tafel and Electrochemical Impedance Spectroscopy (EIS), in an exposure time of 150 hours and three temperatures of evaluation 600 ° C, 650 ° C and 700 ° C. Subsequently the samples were cooled to room temperature to avoid the thermal shocks. The methods used X-ray diffraction and electron microscopy applied to define surface showing the attack of the molten salt. It was found increased corrosion rate as the test temperature rises. The values of the polarization resistance are greater than the substrate.