CORROSION BEHAVIOR OF STAINLESS STEELS IN MOLTEN SALTS USED FOR CONCENTRATED SOLAR POWER
Keywords:
High temperature corrosion, Molten salts, StainlessAbstract
The current demand for energy to produce electricity from non-sustainable fuels such as oil and natural gas, is becoming a huge problem for the country, as they are likely to become depleted in the near future. However, solar energy is a major renewable energy source and concentrated solar power (CSP) technology is the most suitable candidate for storing energy due to its low cost and relatively high efficiency. The thermal energy received from CSP is transferred via a heat transfer fluid (HTF), one of which is molten nitrate salts. However, the major degradation of materials are concerned with high temperature corrosion in the hot molten salts. The purpose of this study is to study the corrosion behavior of ferritic AISI430 and austenitic AISI304 stainless steels samples immersed in conventional (60 wt% sodium nitrate (NaNO3)/40 wt% potassium nitrate (KNO3)) and modified (57 wt% sodium nitrate (NaNO3)/38 wt%potassium nitrate (KNO3)/5 wt% sodium chloride (NaCl)) molten nitrate salt mixtures at 600C for 2 h to simulate the working conditions in a CSP plant. Corrosion products of materials were primarily Fe and Fe oxide. Corrosion testing determined with a potentiostat analyzer, electrochemical characterizations were then investigated. It was found that there was the effect of NaCl on the corrosion rate, showing higher corrosion rate. According to the surface morphology and electrochemical results, the mechanism of hot corrosion of stainless steels was further discussed in this research.
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