Nucleation and growth of a passive film on AISI 420 martensitic stainless steel under potentiostatic conditionsFuchs-Godec, Regina (Avtor) Petek, Aljana (Avtor) Doleček, Valter (Avtor) corrosioncorrision resistancemartensitic stainless steelspassive filmspotentiostatic step methodtopochemical reactionsThe kinetics of the early stage s of passive film formation on AISI stainless stell in mixtures of 0.1M ▫$H_2SO_4$▫ and 0.1M ▫$Na_2SO_4$▫, with pH-values of 2.42, 2.85 and 3.33, were studied at different anodic potentials. The potentiostatic step method was used as an electrochemical technique in which the anodic current density was measured as a function of time. For analysis of the measured data, the theory of "topochemical reaction" was applied for the charcterization of the exponent n in that part where the steepest current decay was observed. Through this theory, which includes the Erofeev equation, the number of conversion steps could be obtained, as well as the number of directions in which the nuclei grow. It was found that this theory can be successfully applied to the passivation process of AISI 420 stainles steel.20022015-07-10 19:22:10Znanstveno delo53113sl