The study and improvement of the corrosion resistance of materials used in concentrated solar power plants is a permanent field of research. This involves determining their chemical stability when in contact with heat transfer fluids, such as molten nitrate salts. Various studies indicate an improvement in the corrosion resistance of iron-based alloys with the incorporation of elements that show high reactivity and solubility in molten nitrate salts, such as Cr and Mo. This study analyzes the kinetic and thermodynamic aspects of the beginning of the corrosion process of ferritic steels immersed in Solar Salt at 400, 500, and 600 °C. The analysis of the kinetic data using the Arrhenius equation and the Transition State Theory shows that an increase in the Cr/Mo ratio reduces the activation energy, the standard formation enthalpy, and the standard formation entropy. This indicates that its incorporation favors the degradation of steel; however, the results show a reduction in the corrosion rate. This effect is possible due to a synergistic effect by the formation of insoluble Fe-oxide layers that favor the formation of a Cr oxide layer at the Fe-oxide-metal interface, which limits the subsequent oxidation of Fe.

The high-temperature corrosion behavior of A1, T22, and T91 steels was investigated in molten nitrate salts at 400, 500, and 600 °C during 100 h of exposure. The combined influence of temperature and chromium content on corrosion kinetics and oxide-scale stability was evaluated using open-circuit potential (OCP), linear polarization resistance (Rp), electrochemical impedance spectroscopy (EIS), scanning electron microscopy, X-ray diffraction, and cross-sectional elemental mapping. OCP measurements showed a progressive shift toward more negative potential with increasing temperature, indicating enhanced oxidation tendency. Electrochemical measurements revealed a systematic decrease in Rp and impedance magnitude as temperature increased, confirming accelerated corrosion kinetics and reduced interfacial resistance. EIS spectra exhibited two characteristic time constants associated with the outer corrosion products and the inner metal/oxide interface. Significant differences in scale growth were observed depending on alloy composition. At 600 °C, oxide thickness reached approximately 700–800 μm for A1, ~100 μm for T22, and ~10 μm for T91. Chromium-containing steels promoted the formation of a compact Cr-rich inner oxide layer that improved scale adhesion and suppressed the exfoliation phenomena observed in A1 steel. Overall, temperature controls corrosion kinetics, whereas chromium content governs oxide-scale compactness and long-term stability in molten nitrate environments.

The time-dependent electrochemical behavior of a nominal Ni20Cr alloy exposed to molten Solar Salt (60 wt.% NaNO₃–40 wt.% KNO₃) was investigated at 300, 400, and 500 °C for isothermal exposure times of up to 100 h. Open-circuit potential (OCP), linear polarization resistance (LPR), and electrochemical impedance spectroscopy (EIS) were used to monitor the evolution of the alloy/molten-salt interface. OCP measurements revealed time-dependent potential changes during exposure. Because a Pt pseudo-reference electrode was used without independent calibration against a thermodynamic reference or internal redox couple, the OCP data were interpreted primarily in terms of their temporal evolution within each isothermal experiment rather than through direct comparison of absolute potential values between temperatures. LPR measurements showed a strong temperature dependence of the polarization resistance, with a pronounced decrease at 500 °C. The impedance response was consistent with two interfacial contributions, represented using a two-time-constant equivalent circuit and tentatively associated with the surface corrosion-product layer and the underlying alloy/corrosion-product interface. At 500 °C, both resistance contributions were markedly lower than those measured at 300 and 400 °C, consistent with a substantial loss of interfacial barrier effectiveness. The persistence of a surface-related impedance response at 500 °C was therefore not considered evidence of a highly protective layer. Rather, the electrochemical results suggest that a surface-related interfacial contribution remained distinguishable at 500 °C, although its associated resistance was substantially lower than at 300 and 400 °C. These assignments represent electrochemically based interpretations and should not be regarded as unique identification of the underlying microscopic processes. Overall, the results demonstrate that temperature strongly influences the electrochemical behavior of Ni20Cr in molten nitrate salts and that the electrochemical resistance to corrosion-related processes decreases markedly at 500 °C. The 100 h electrochemical exposures investigated here characterize short-term interfacial behavior and do not establish the long-term structural suitability of Ni20Cr for concentrated solar power service.

While aluminum (Al) continues to be a cornerstone for microelectronic interconnect technologies, its chronic tendency toward hillock growth and thermal instability necessitates a transition toward high-performance nanostructured material architectures. This research tackles these reliability bottlenecks by achieving a molecular-level integration of graphene nanoplatelets (GNPs) within Al matrices, a strategy designed to fortify structural resilience. Adopting a green chemistry approach, we synthesized Al-GNP (0.25 vol.%) composite thin films through Pulsed Laser Deposition (PLD) using precursors derived from recycled aluminum. A major obstacle—the formation of the deleterious Al₄C₃ intermetallic phase—was effectively suppressed by ensuring a homogeneous supramolecular dispersion via a specialized dual protocol (ultrasonication and magnetic stirring) during the powder metallurgy stage. Comprehensive physicochemical characterization, utilizing HR-TEM and XRD, verified the structural integrity of the multilayer GNPs (d-spacing = 4.6 Å). Furthermore, surface metrology analysis uncovered a radical shift in growth kinetics: whereas pure Al grew via a “spiky” Volmer-Weber mechanism (Sku = 31.17), the carbon-based inclusion stabilized the film evolution, tempering the kurtosis to Sku = 7.74. Analytical cross-sectional EDS confirmed both stoichiometric fidelity and the achievement of void-free Si/Pt/Al-GNP interfaces. These outcomes prove that a precise nanoscale tailoring of surface morphology via carbonaceous reinforcements significantly bolsters microstructural stamina. Consequently, these PLD-deposited composites emerge as sustainable, cutting-edge candidates for the next generation of microelectronic packaging and interfacial chemistry applications.