Improved tribo-corrosion performance of duplex treatment on H13 steel by plasma nitriding and CrAlN coating

In marine engineering, the harsh service conditions often lead to wear and corrosion in materials simultaneously, necessitating high-performance materials with advanced coating technologies. This study investigates the effect of nitriding pretreatment on corrosion and tribo-corrosion behavior of CrAlN coatings deposited on H13 steel. Two different duplex treatments were employed: a continuous process (arc plasma nitriding and CrAlN coating in one system without vacuum break) and a discontinuous process (separate plasma nitriding followed by CrAlN coating). Results of the study demonstrate that nitriding, particularly the continuous process, significantly improved mechanical properties (strength, toughness, adhesion, etc.) of the CrAlN coatings. In addition, the continuous process resulted in enhanced corrosion resistance of the coatings by mitigating inherent defects in the PVD coatings and promoting the formation of a protective nitride layer. Under tribo-corrosion conditions in 3.5 wt% NaCl solution, the continuously nitrided samples exhibited superior performance attributed to the formation of a compacted wear debris layer and reduced corrosion pits in the wear tracks. These findings highlight the effectiveness of pre-nitriding, especially the continuous process, in improving the surface performance of CrAlN coatings on the H13 steel substrate for marine environment applications.