Abstract
Resistance to stainless steel corrosion in marine-based industries requires more research into materials with an improved surface and enhanced protection by utilizing surface coatings. Herein, a thermally stable aramid–zirconia nanocomposite has been successfully prepared using the sol–gel method to produce a zirconia network-structure bonded to the polymer chain. Using thermal gravimetric analysis (TGA), the residue mass of zirconia retained after the thermal degradation of aramid-zirconia film was determined and found to be 10% by mass. The investigated nanocomposite (using 10% zirconia) was coated on the stainless-steel surface through a facile and effective spin coating method and its protection was examined in saline solution (3.5% NaCl). The aramid–zirconia nanocomposite coating (Ar-Zr10) was found to provide an outstanding corrosion resistance to steel surfaces which led to protecting it against the corrosive marine environment. The electrochemical impedance (EIS) measurements were carried out to evaluate steel resistance against dissolution in chloride solution in the absence and presence of the investigated coatings showed a corrosion protection efficiency of 99.3% using Ar-Zr10 compared to 92.1% using pure aramid. Moreover, the potentiodynamic polarization (PDP) plots showed a pronounced decrease in the corrosion current values which confirmed the formation of a passive layer which mitigated the corrosion reaction and ions diffusion. The water contact angle of stainless-steel coated with pure aramid and the aramid–zirconia was found to be 84.2° and 125°, respectively, confirming the hydrophobic nature of the hybrid coating Ar-Zr10. On the other hand, the results achieved through the electrochemical and surface techniques were used to clarify the protection mechanism. The aramid–zirconia nanocomposite coating showed a remarkable protection performance by controlling the charge transfer at the interface between the steel alloy and the electrolyte which prevented the alloy dissolution.
Highlights
Protection of metals and alloys against corrosion is of great importance in the modern metallic finishing industries due to different economic and environmental considerations
Ramanathan et al, studied the protection of mild steel using a composite of the epoxy resins with the nano-zirconia coating and the results showed good adhesion to the metallic surface with excellent corrosion resistance (Ramanathan and Balasubramanian, 2016)
The protection efficiency of the designated coatings against corrosion was explored via EIS and potentiodynamic polarization (PDP) techniques complemented with scanning electron microscopy (SEM)
Summary
Protection of metals and alloys against corrosion is of great importance in the modern metallic finishing industries due to different economic and environmental considerations. Ramanathan et al, studied the protection of mild steel using a composite of the epoxy resins with the nano-zirconia coating and the results showed good adhesion to the metallic surface with excellent corrosion resistance (Ramanathan and Balasubramanian, 2016). Hybrid coatings based on graphene oxide–zirconia dioxide/epoxy were fabricated and their corrosion protection for steel was investigated and effectively prevented the steel substrate from corrosion attack (Haihui et al, 2016) Due to their pronounced mechanical-strength and efficient thermal-stability, polyimides (PI) and aramids (Ar) are increasingly being used to prepare high-performance nanocomposites (Abadie and Rusanov, 2007; García et al, 2010). The protection efficiency of the designated coatings against corrosion was explored via EIS and PDP techniques complemented with scanning electron microscopy (SEM)
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