In Situ Formation of Extremely High Corrosion Resistant Ni–Ni3Si Nanocomposite Coating Using Spark Plasma Sintering and Subsequent Heat Treatment

In this study, the coating of Ni–Ni 3 Si nanocomposite was produced in-situ on plain carbon steel using spark plasma sintering process of Ni and Si powders followed by heat treatment. Increasing Si content in the powders from 6 to 13 wt% increased the amount of Si in the coatings (from 5.1 to 11.8 wt%). The corrosion behavior of the coated samples in 1 M sulfuric acid solution was investigated by potentiodynamic polarization and electrochemical impedance spectroscopy techniques. In the 13 wt% Si coating, the eutectic structure consisting of the Ni and Ni 3 Si phases was observed to be uniformly distributed. Ni 3 Si nanoparticles with an approximate size of 90 nm were obtained in the coating by heat treatment. The results showed that passive behavior is obtained by heat treatment due to the uniform distribution of Ni 3 Si nanoparticles and also the uniform diffusion of silicon into the nickel phase. The excellent passivation results in the highest corrosion resistance in 13 wt%Si coating after the heat treatment. Graphic Abstract