Abstract

CORREDOR ACUNA, Jacqueline  and  ECHEVERRIA ECHEVERRIA, Félix. Preparation and evaluation by ciclic oxidation at 700°c of electroless ni-p and ni-p-magnetite coatings. Rev. LatinAm. Metal. Mater. [online]. 2012, vol.32, n.1, pp.107-120. ISSN 0255-6952.

The cyclical oxidation behavior of the electroless Ni-P coating and of the Ni-P-pure magnetite and Ni-P-Aldoped magnetite composite coatings on stainless steel has been studied. During the tests, the bare steel lost mass catastrophically, whilst the samples of coated steel lost mass in a very small amount, showing oxide growth curves that agreed with successive parabolic laws. X-ray diffraction studies of the oxides confirmed that the phases with major concentration were α-Fe₂O₃ on bare steel, NiO on ENP and NiMnxCr_2-xO₄ (with x=0.2 and 1) on composite coatings. The scanning electron microscopy and energy dispersive spectroscopy analyses showed that both, the oxide scale and the coatings evaluated hindered the inward diffusion of oxygen towards the steel substrate.

Keywords : Cyclic oxidation; electroless coatings; magnetite; stainless steel.