Temperature effect on the corrosion and passivation characterization of Ni_(82.3)Cr_7Fe_3Si_(4.5)B_(3.2) alloy in acidic media

摘要

The effects of temperature on corrosion and the electrochemical behavior of Ni_(82.3)Cr_7Fe_3Si_(4.5)B_(3.2) glassy alloy in HC1,H_2SO_4,and H_3PO_4 acids were studied using AC and DC techniques.Impedance data reveal that the susceptibility to localized corrosion increases with increasing temperature.Potentiodynamic polarization curves reveal that the bulk glassy alloy is spontaneously passivated at all the investigated temperature in H_2SO_4 and H_3PO_4 solutions.A localized corrosion effect in HCl solution is clearly observed.The apparent activation energies in the regions of Tafel,active,and passive,as well as the enthalpies and entropies of the dissolution process were determined and discussed.The high apparent activation energy(E_a) value for H_3PO_4 solution in Tafel region is explained by the low aggressivity of PO_4^(3-) ions.