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In recent years, the study of renewable energies and its practical application has increased significantly. Solar energy feasibility entails the development of energy storage systems since solar power plants need to be working in unfavorable weather or night periods. The main heat transfer fluid (HTF) used on these plants is a salt mixture of 60% NaNO3/40% NaNO3 which must be kept above 220 °C to prevent freezing. This high operating temperature causes corrosion problems for steels in contact with the HTF, reducing the lifetime of the solar plants. The present research studies the potential of an alumina‐forming austenitic (AFA) stainless steel (OC‐4, Fe‐25Ni‐14Cr‐3.5Al‐2.5Nb wt% base) as a candidate material for solar plant heat exchangers and pipes. Corrosion behavior of OC‐4, relative to 304 stainless steel and T22 steel, was studied by gravimetric analysis and electrochemical impedance spectroscopy (EIS). The AFA OC‐4 exhibited better corrosion resistance in HTF at 390 °C than the currently used 304 austenitic stainless steel.

Performance of HIPIMS deposited CrN/NbN nanostructured coatings exposed to 650°C in pure steam environment. Materials chemistry and physics, 179, 110-119.

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To increase efficiency, modern steam plants are pushing their operational regime from supercritical (600°C/300 bar) to ultra-super-critical (740/760°C/350 bar) stretching existing turbine materials to their limits. The focus is on new generation functional materials and technologies which complement the inherent properties of existing materials. Current work proposes a novel High Power Impulse Magnetron Sputtering (HIPIMS) deposition technology, for the first time, for deposition of a ceramic based CrN/NbN coating with a nanoscale multilayer structure (bi-layer thickness ∆ = 1.9 nm) with superior adhesion (L C2 = 80N) to protect low Chromium P92 steel widely used in steam power plants. Thermodynamic calculations predict the equilibrium phases and aggressive gaseous compounds generated by the interaction of steam with the coating. CrN/NbN coated P92 steel