Temperature-Dependent Morphological Evaluation of in Situ Grown Hard ZrN Coating for Enhanced Mechanical, Wetting and Electrochemical Properties

The temperature-dependent morphological evolution of “in situ” grown zirconium nitride (ZrN) coatings on a low carbon steel plate (LCSP) substrate has been examined using sputtering technique. An optimized gas mixture of Ar+N2 and different substrate temperatures (200, 300 and 400 °C) in sputtering process is accountable for dissimilar hierarchal surface structure (nano-cauliflower, nanopyramids and nanoflakes). The growth mechanism and physical properties of these surface structures were investigated, systematically. The mechanical properties of the as-prepared samples (hardness, elastic modulus, toughness and adhesion) were evaluated using a well-established nano-indentation method. The electrochemical and contact angle experiments were utilized to examine the wetting and corrosion characteristics of the as-prepared samples. The obtained results revealed that the ZrN-based nanoflakes coating shows maximum elastic modulus (335.195 ± 16.75 GPa), hardness (33.173 ± 1.65 GPa), hydrophobicity ( 118.5°) and corrosion resistance in comparison with other samples. Therefore, the ZrN-based nanoflakes coating offers the toughest barrier in the path of corrosive species, resultant higher protection of the low carbon steel plate. A process describing the formation of corrosion initiation and products was also discussed in detail.