Metallic materials are among the most crucial engineering materials widely utilized as biomaterials owing to their significant thermal conductivity, mechanical characteristics, and biocompatibility. Although these metallic biomedical implants, such as stainless steel, gold, silver, dental amalgams, Co-Cr, and Ti alloys, are generally used for bone tissue regeneration and repairing bodily tissue, the need for innovative technologies is required owing to the sensitivity of medical applications and to avoid any potential harmful reactions, thereby improving the implant to bone integration and prohibiting infection lea by corrosion and excessive stress. Taking this into consideration, several research and developments in biomaterial surface modification are geared toward resolving these issues in bone-related medical therapies/implants offering a substantial influence on cell adherence, increasing the longevity of the implant and rejuvenation along with the expansion in cell and molecular biology expertise. The primary objective of this review is to reaffirm the significance of surface modification of biomedical implants by enlightening numerous significant physical surface modifications, including ultrasonic nanocrystal surface modification, thermal spraying, ion implantation, glow discharge plasma, electrophoretic deposition, and physical vapor deposition. Furthermore, we also focused on the characteristics of some commonly used biomedical alloys, such as stainless steel, Co-Cr, and Ti alloys.

Nanotechnology is a discipline of science and engineering that emphasizes developing, modifying, characterizing, and using nanoscale components in a variety of applications. Owing to their multiple advantages, including adhesion strength, surface hardness, long-term and extra-high-temperature corrosion resistance, improvement of interfacial behavior, etc., nanocoatings are efficiently utilized to minimize the influence of a corrosive environment. Additionally, nanocoatings are often applied in thinner and finer concentrations, allowing for greater versatility in instrumentation and reduced operating and maintenance costs. The exemplary physical coverage of the coated substrate is facilitated by the fine dimensions of nanomaterials and the significant density of their grounded boundaries. For instance, fabricated self-healing eco-sustainable corrosion inhibitors including PAC/CuONPs, PAC/Fe₃O₄NPs, and PAC/NiONPs, with uniform distributions and particulate sizes of 23, 10, and 43 nm, correspondingly, were effective in producing PAC/MONPs nanocomposites which exhibited IE% of 93.2, 88.1, 96.1, and 98.6% for carbon steel corrosion in 1M HCl at the optimum concentration of 250 ppm. Therefore, in this review, further steps are taken into the exploration of the significant corrosion-mitigation potential and applications of nanomaterial-based corrosion inhibitors and nano-modified coatings, including self-healing nanocoatings, natural source-based nanocoatings, metal/metallic ion-based nanocoatings, and carbon allotrope-based nanocoatings, to generate defensive film and protection against corrosion for several metals and alloys. These have been illuminated through the in-depth discussion on characterization techniques such as scanning electron microscopy (SEM), electrochemical impedance spectroscopy (EIS), potentiodynamic polarization (PDP), atomic force microscopy (AFM), energy dispersive spectroscopy (EDS), etc. After providing a general summary of the various types of nanomaterials and their protective mechanisms in wide corrosive media, we subsequently present a viewpoint on challenges and future directions.

The corrosion inhibition efficacy of Codiaeum variegatum leaf extract (CVLE) on mild steel in 1 N HCl was assessed utilizing weight-loss (WL), potentiodynamic polarization (PDP), and electrochemical impedance spectroscopy (EIS) methods at different temperatures 298 K, 308 K, 318 K, 328 K and 338 K. The study revealed that CVLE is an environmentally friendly and sustainable corrosion inhibitor, attaining an impressive inhibition efficacy of 91.83 ± 0.04% at 1000 ppm concentration at 298 K. A significant reduction in corrosion rate (C_R) from 21.264 ± 0.02 to 1.735 ± 0.05 mmpy and corrosion current density (i_corr) from 157.63 ± 0.01 to 4.02 ± 0.02 μA cm⁻² was observed with increasing CVLE concentration, highlighting its protective efficacy. The adsorption of CVLE followed the Langmuir adsorption isotherm on the mild steel surface, indicating monolayer adsorption behavior. Potentiodynamic polarization studies classified CVLE as a mixed-type inhibitor, influencing both cathodic and anodic reactions. The mechanism of inhibition occurring on mild steel was discovered using the XPS method. Scanning electron microscopy (SEM) confirmed the creation of a layer of protection by CVLE on the mild steel surface, corroborating its inhibitory action. EIS analysis further demonstrated that the inhibiting efficacy was elevated with higher concentrations of CVLE, consistent with a rise in adsorption equilibrium constant (K_ads), indicating stronger inhibitor–metal interactions. Theoretical studies supported these findings by showing a low energy gap (ΔE), signifying strong adsorption and excellent anti-corrosion potential of CVLE at the molecular level. This inclusive study establishes CVLE as an effective and eco-friendly inhibitor for mild steel corrosion in acidic environments.

1,3,4-Oxadiazole derivative, namely, 3-(5-naphthalen-2-yl-[1,3,4]oxadiazol-2-yl)pyridine (NOP) as a corrosion inhibitor against mild steel in 1M HCl has been evaluated using the weight-loss technique (303-323 K), electrochemical analysis [potentiodynamic polarization (PDP) and electrochemical impedance spectroscopy (EIS)], as well as surface morphology investigations (SEM). Additionally the computational studies such as density functional theory (DFT), the synthesized molecule (NOP) were utilized to better insight into molecular structure and electronic aspects relating to the anti-corrosion activities of the examined inhibitors and to envisage the interaction between designed inhibitors with the mild steel surface. The synthesized molecule (NOP) expressed high inhibition efficiency of 88.62% at an optimal concentration of 500 ppm at 298 K. A mixed-type inhibition mechanism is suggested by potentiodynamic polarization (PDP) analysis. The DFT calculations complement well with the experimental outcomes. This article provides in-depth insights to comprehend the mild steel inhibitor interactions mode and can be very helpful in accentuating the approach to mitigate the metal dissolution occurring in acidic corrosive media.