The corrosion inhibition performance of an imidazolium-based ionic liquid (IL), 1-butyl-3-methylimidazolium thiocyanate (BMIm), was studied on AA 6061 alloy in 1 M HCl solution at 303 K, 333 K, and 363 K by gravimetric tests, potentiodynamic polarization, and electrochemical impedance spectroscopy (EIS) analysis. Scanning electron microscopy with energy dispersive X-ray (SEM-EDX) and X-ray photoelectron spectroscopy (XPS) were used to detect the surface morphologies and chemical composition of the surface films. The results indicate that this IL inhibits AA 6061 corrosion in acid with maximum inhibition efficiencies of 98.2%, 86.6%, and 41.2% obtained at 303 K, 333 K, and 363 K respectively. Inhibition efficiency generally decreased with increasing immersion time; the major exception was at 303 K, whereby the inhibition efficiency was detected to increase with immersion time from 30 to 90 min and then decrease slightly beyond 90 min. The results indicate that BMIm is a mixed-type inhibitor with a predominant effect on cathodic reactions. Surface morphology analyses by SEM revealed less surface damage in the presence of the inhibitor. XPS analysis established the development of a protective film on the AA 6061 surface which was hydrophobic in nature.

Proteins and their concentrations have immense influences on the corrosion of metallic implants. This work systemically investigated the effects of bovine serum albumin (BSA) with time on the corrosion behaviour of austenitic stainless steels (SSs) in phosphate buffer saline (PBS) solution. Potentiodynamic polarization, electrochemical impedance spectroscopy (EIS) and scanning Kelvin probe (SKP) experiments were conducted to study the interactions of BSA and the passive layers and to measure the corrosion parameters. X-ray photoelectron spectroscopy (XPS) and atomic force microscopy (AFM) were used to determine the chemical compositions and surface morphologies. It was observed that the presence of BSA had a significant inhibition effect on the corrosion behaviour of SSs and on improvement of the corrosion resistance with BSA concentrations up to 2.0 g L⁻¹. The SKP results demonstrated that after immersion in PBS solution with BSA, the surface potential difference and the electrochemical non-homogeneity of SS decreased. Surface analysis with XPS and AFM established that corrosion resistance may be related to favorable adsorption of BSA on the steel surface. However, at very high concentrations and with higher immersion times, BSA chelated with the corrosion products, causing disruption of the protective film; thus, it accelerated the corrosion of the alloy. These results allowed the determination of a corrosion mechanism in the presence of protein. It was also established that a low concentration of BSA has significant effects on the corrosion resistance of nitrogen-containing steel with long term exposure.

Magnesium (Mg) alloys with outstanding biocompatibility and mechanical properties are extensively used in medical implantation. However, the rapid degradation and potential cytotoxicity in the physiological environment limit their further clinical applications. In this study, we prepared a calcium phosphate/chitosan (CaP/CTS) coating by chemical conversion and dip-coating methods to increase the corrosion resistance, biocompatibility and antibacterial property of the Mg alloy. The surface morphology, electrochemical and immersion tests signified that the CaP/CTS coating showed a significantly improved corrosion resistance because the chitosan efficiently filled the cracks and reduced the porosity of the CaP coating. In vitro investigation of cell response and contact angle experiments confirmed that the composite coating had excellent cytocompatibility and hydrophilicity. In addition, the composite coating demonstrated a prominent antibacterial ability of 95.9 ± 0.4% against Escherichia coli (E.coli). The strengthened corrosion resistance, biocompatibility and antibacterial property of the CaP/CTS coating deposited Mg alloy make it an up-and-coming prospect in the field of implants.