“…Regarding the coating’s microstructure, factors like grain size, grain boundary condition, and density significantly impact the corrosion resistance of CrN coatings. Defects within the coating can reduce its inherent corrosion resistance, while various defects can also increase the likelihood of contact between the corrosive medium and the coating substrate, thereby impacting the overall corrosion resistance [ 137 , 138 , 139 ]. Hence, a fine-grained, well-structured, and compact microstructure generally enhances the coating’s corrosion resistance [ 19 , 21 , 139 , 140 , 141 , 142 , 143 , 144 ].…”