Corrosion, Erosion and Erosion-Corrosion Performance of Plasma Electrolytic Nitrocarburising (PEN/C) on AlSI 4140 Steel

Plasma electrolytic nitro carburizing (PEN/C) has been used on the surface to modify AlSI 4140 steel to a depth of approximately 200 um of compound and diffusive layer. Potentiodynami.c polarizations and electrochemical impedance spectroscopy (EIS) have been made understatic conditions in order to evaluate the corrosion performance ofPEN/C coatings. The erosion and erosion-corrosion performance of the PEN/C coating has also been assessed with a rotating disk electrode at specified rates ofstirring, with and without a given potential to the sample. The erosion and eroaion-corrosion tests were carried out using sub angular sand particles, ranging in size from 135 to 235 Jlm. Scanning electron microscopy (SEM) was used to investigate the coating microstructure and the coating/substrate interlace. The analysis shows that the PEN/C nitrocarburised coatings studied in this investigation had a poreIcrack network. to the steel sub strate, which compromised the corrosion and erosion-corrosion perfurmance.