Superior Corrosion Inhibition Activity of CaO Nanoparticles Synthesized from Natural Sources toward Grade 202 Stainless-steel in Chloride-rich Media

Grade 202 Stainless Steel (SS Grade 202), an iron-based alloy with a reasonably high chromium content, is well-regarded for its notable resistance to corrosion in mild environments. Although SS Grade 202 is extensively employed in the industrial sector to develop corrosion-resistant material through further processing, effects of different chemical components present in the surrounding environment on its corrosion behavior in aggressive settings, and potential corrosion inhibitors under such conditions have not been thoroughly investigated. On the other hand, nanoparticles (NPs) inhibit corrosion by adsorption on metal surfaces thereby forming a protective barrier, thus preventing corrosive agents. NPs of CaO obtained from natural materials such as clamshells and limestone by calcination act as highly effective corrosion inhibitors due to their small size and large surface area promoting the passivation of oxide films. The ready availability of clamshells and limestone positions them as sustainable sources to produce CaO NPs, offering a cost-effective and environmentally responsible approach to corrosion protection. Corrosion rates determined with the aid of Tafel plots, depicted by CaO NPs from limestone at 0.05 M strength in the presence of 0.50 M HCl is 3.53×10 ^− 2 mmpy, which is much smaller when compared to CaO NPs synthesized by clamshells (1.24 mmpy).