ELETROCHEMICAL BEHAVIOR AND MICROSTRUCTURAL CHARACTERIZATION OF PLASMA NITRIDED LAYERS ON SINTERED STEELS CONTAINING Mo AND Ni

摘要

This work studies the electrochemical corrosion behavior of sintered and sintered/nitrided steels containing nickel and molybdenum as alloying elements. These steels were sintered in binary form (Fe-5%Mo and Fe-10% Ni) at 1250°C for 2.0h in a hydrogen atmosphere. Plasma-nitritation was performed at 540°C in a gaseous mixture of 75%N_2/25%H_2 for 2.0h. Corrosion tests were carried out in an electrochemical cell of three electrodes, with the sample in study as the working electrode in KNO_3 1.25M. Parameters derived from conventional electrochemical measurements were correlated with post-test examination of the specimen by scanning electron microscopy (SEM) and X-ray Dispersive Energy Analysis (EDAX).