Investigation on Hot Corrosion Behaviour of Inconel 625 and Incoloy 800H Superalloys with YSZ-Thermal Barrier Coating Under High-Temperature Environment for Bioreactor Applications

Abstract

Thermal energy storage is one of the promising technologies in the modern era for balancing the peak power demand without emitting much emission. Molten-salt technology plays a dominant role among the varieties of thermal energy storage systems. The difficulty in storing the molten-salt technology requires a storage material with high temperature, corrosion, and oxidation resistance properties. The nickel-based superalloys such as Inconel 625 and Incoloy 800H possess the desired properties to be used as a storage material for the molten salts. In this present work, the Incoloy 800H and Inconel 625 superalloy specimens were taken up for investigation. The specimens were coated with yttria-stabilized zirconia as a thermal barrier coating using a plasma spray process. The sodium chloride and potassium chloride molten salts with a weight fraction of 7 : 3 have been taken with both uncoated and YSZ-coated specimens, and specimens were heated up to 1000°C approximately. The specimens were heated for different hours such as 8, 12, and 16 hours, respectively. The increase in heating time also results in the increase in the tensile property of the specimens. The mechanical testing, such as tensile test and hardness test, was performed to comprehend the mechanical properties. Scanning electron microscope images and X-ray diffraction analysis were made to study the microstructural properties and the corrosion resistance property. From the test results, YSZ-coated specimens possess high corrosion resistance and high mechanical strength compared to the uncoated specimens.