## 2 Utilization of Various Nano-Modified Coatings for Corrosion Mitigation
### Metal/Metallic Oxide-Incorporated Nanoc Coatings  
Contemporary human civilization has grown significantly as a result of the use of metals. They are necessary for everything from machinery to architecture to technology to consumables. Regrettably, the majority of naturally available and natively inexpensive metals are rarely appropriate for the prevalent industrial purposes in several fields. Owing to unfavorable operating conditions, they gradually lack vitality or crumble. Another of the biggest problems that cause disastrous device breakdown is still metal corrosion. It takes place in commercial facilities including those for electricity, chemical manufacturing, food manufacturing, and building, among others, presenting environmental and public health risks in addition to a heavy financial strain. For the mitigation of metallic corrosion, some studies used nanocoatings centered on metal or metallic oxide [20; 84]. The chemical, physical, and thermal characteristics of a nanocoating are enhanced by the inclusion of metals. The metallic coating is created at the nanoscale, which essentially protects the covered substrate or greatly improves all of the coating's qualities. Several pristine metals including nickel (Ni), phosphorous (P), cobalt (Co), tungsten (W), copper (Cu), zinc (Zn), and iron (Fe), etc., are used in metallic nanocoating. Utilizing a nanosized covering strengthens this improvement since NMs function differentially than micromaterials. For instance, when the thickness of the Zn covering needs to be enhanced to offer the necessary shielding, a finer nanocoating of Zn resolves both the surface integrity and weldability issues. Nevertheless, pristine Zn corrosion resilience is inadequate in extreme oxidizing circumstances and extreme temperatures, thus, it is alloyed with other metals to increase corrosion resistance. It has been demonstrated that Zn-Ni alloy coverings are harder than Zn and Cd individually. Additionally, due to Cd's inadequate adhesive wear resilience, Zn-Ni alloys are a top contender to replace it in aeronautical applications. Figure 13: AFM scans for steel reinforcement substrates subjected to CO\({}_{2}\) for a duration of 180 days: (**a,b**) 2D, 3D scans for regulated and (**c,d**) 2D, 3D scans for inhibited samples including GA-NPs. Reprinted with permission from Ref. [83]. MDPI 2021. In order to manufacture Ni-P-Si\({}_{3}\)N\({}_{4}\) composites using the electroless coating process, [PERSON] et al. [85] included nano Si\({}_{3}\)N\({}_{4}\) (mean diameter -20 nm) and submicron Si\({}_{3}\)N\({}_{4}\) (mean dimension 200 nm) granules when covering a Ni-P alloy in a low-CS surface. Minimal surface flaws including voids and micropores were present in the composite covering comprised of 20 nm Si\({}_{3}\)N\({}_{4}\) NPs, however, following the addition of 200 nm Si\({}_{3}\)N\({}_{4}\) NPs, these flaws were more noticeable. Figure 14 displays the SEM pictures of the coating's interface and cross-section. In contrast to the Ni-P-SN, which seems to exhibit a coarser texture with voids and holes (Figure 14a), the Ni-P covering has a distinctively smoother surface shape (Figure 14b). Furthermore, the Ni-P-nSN coating's uniform texture (Figure 14c) shows no discernible variations from the standard Ni-P covering (Figure 14a). The inherent covering process of the P and Ni atoms in the Ni-P-nSN sample has not been affected by the included nSN particulate, hence the coating surfaces exhibit considerably fewer surface flaws including holes, cavities, and uneven cluster formation. Figure 15 displays the EDS findings of the pristine and eroded substrates denoted by area \"I\" and zone \"II\" in all three samples. Ni-P coating's oxygen level improved from 0.6 wt.% on the uncorroded substrate to 4.8 wt.% (Figure 15a,b). The severe dissolving of Ni, however, was indicated by the Ni content dropping from 90.5 wt.% in the initial substrate to 83.4 wt.% in the damaged area.