Corrosion performance of duplex treatments based on plasma nitriding and PAPVD TiAlN coating

Duplex treatments consisting of a plasma nitrided layer followed by a PAPVD hard coating have gained attention in recent years. The aim of this work was to determine the corrosion resistance of AISI H13 steel treated by using this duplex treatment. The samples were pre-nitrided using experimental equipment and, subsequently, TiAlN coating was deposited commercially by a PAPVD process. A series of electrochemical tests such as potentiodynamic polarization and linear polarization were carried out to investigate the corrosion resistance of the surface engineered steel. Surface characterization before and after the corrosion tests was performed by means of the scanning electron microscopy (SEM) technique coupled with the energy dispersive X-ray analysis (EDS). The experimental results indicate that the duplex systems TiAlN coating/nitrided steel protect the substrate against corrosion due to the passivation of the compound layer in the presence of the corrosive solution. Therefore, a better corrosion resistance is obtained as long as the extension of the nitrided layer underneath the hard coating is increased.