Thermal energy storage (TES) materials have been extensivelly used for the storage of the heat from sunlight in concentrated solar power (CSP) plants [1-2]. These TES materials are also known as heat transfer fluids (HTF), allowing the generation of power during the absence of sunlight adding more efficiency and value to CSP plants. Molten salts are commonly used as TES materials due to their low cost, high heat storage capacity, and good thermo-physical properties [3].

The aim of the research is the development of coatings with the ability to increase the maximum service temperature of stainless steels for its implementation in CSP plants. In this work, a substrate of 316L stainless steel manufactured by laser powder bed fusion (L-PBF) has been coated by Ni-based alloy powder. High velocity oxy-fuel (HVOF) technique has been employed for coatings deposition [4].

Different solar salt mixtures have been proposed due to their high heat capacity, low melting point, and low cost. For this porpoise, high-temperature corrosion tests were performed at different temperatures and times in a dry air atmosphere [5].

The coatings obtained by the HVOF technique have been characterized before and after thermal tests by scanning electron microscopy (SEM) to establish the protection ability of the coating. In addition, XRD technique has been used to analyze the oxides and corrosion products formed after the exposure to high temperatures. Metal damage of each substrate-deposit system was quantified by gravimetric measurements and dimensional metrology analysis.

The results obtained in the present research confirmed the viability of HVOF technique to achieve Ni-based coatings with the optimal properties (oxide content, thickness, roughness, adhesion, and micro-hardness) and enough corrosion resistance for their application in the most adverse parts of CSP plants.

References

[1] A, Gomes; Solar Energy, 2019, 177, 408-419.

[2] U, Pelay; Renewable and Sustainable Energy Reviews, 2017, 79, 82-100.

[3] X, Xu; Solar Energy, 2018, 162, 431-441.

[4] N, Abu-warda; Surface & Coatings Technology, 2020, 381, 125133.

[5] N, Abu-warda; Journal of Materials Research and Technology, 2022, 20, 3949-3961.