Anticorrosive Behavior Enhancement of Stainless Steel 304 through Tantalum-Based Coatings: Role of Coating Morphology

Stainless steel (SS 304) has good mechanical strength and corrosion resistance properties, but it is not resistive to halides corrosion which limits the use of SS 304 in seawater applications. In this regard, the present work has been focused on the investigation of anticorrosive nature of Ta2O5 (tantalum pentoxide), Ta3N5 (tantalum nitride) and TaON (tantalum oxynitride) films deposited on AISI 304 stainless steel by RF reactive magnetron sputtering technique for anticorrosive applications. The predominant influencing factors especially film composition and surface morphology of the coatings were characterized by XRD, FE-SEM and AFM. The anticorrosive properties of the coatings were investigated through potentiodynamic polarization (Tafel) test and electrochemical impedance spectroscopy in 1M NaCl solution at room temperature. The morphological results showed that the films are uniform with low surface roughness, i.e., less than 10 nm. The contact angle and corrosion study of the films revealed that the tantalum oxynitride film, with nanoscale roughness, has greatly enhanced the corrosion protection of the stainless steel in 1M NaCl solution. The tantalum oxynitride film showed hydrophobic nature and the corrosion current density in the order of 10(-11) A/cm(2), which led to better anticorrosive behavior. The highest polarization resistance (R-p) was observed for tantalum oxynitride film, i.e., 3.14 M omega. Overall, tantalum-based coatings have reduced the corrosion rate and enhanced the inhibition efficiency (more than 50%) in comparison with the bare SS 304 substrate.

Automated summary

The study found that depositing tantalum oxynitride film on stainless steel surface can significantly improve its corrosion resistance in 1M NaCl solution, demonstrating excellent anticorrosive properties.