Effect of sodium sulfate-diatomite eutectic mixture functionalized on Inconel 617 and 625 alloys surface a comparative study

Abstract

The global impact on climate change switches to the use of renewable energy. Nowadays, the concentrated solar power (CSP) power plant received more attention in the researcher’s interest. The major problem associated with the CSP plant is the hot corrosion in the container materials exposed under phase change material (PCM). In the present study, Inconel 617 and 625 were used as container materials and Na₂SO₄ (50 Wt.%) +Diatomite (50 Wt.%) as PCM. The PCM based environmental assisted hot corrosion studies were conducted on container materials at 900°C for 40, 80, and 120 h duration. Differential scanning calorimetry (DSC) results confirmed the selected PCM melting temperature. The thermogravimetric analysis (TGA) is performed to determine the mass loss of the PCM. Fourier transform infrared (FT-IR) analysis confirmed the chemical compatibility between Na₂SO₄ and diatomite. After hot corrosion at 120 h for 900°C, the weight change values are 3.1 and 2.6 mg/cm² for Inconel 617 and Inconel 625. In addition, the X-Ray Diffraction (XRD) and Scanning electron microscopy/energy dispersive spectroscopy (SEM/EDS) analysis were carried out to evaluate the hot corrosion behavior. The result indicates that the formation of NiO, Cr₂O₃, and SiO₂ provides better resistance to corrosion in both container materials. Overall, Inconel 625 shows good corrosion resistance compared to Inconel 617 in a PCM environment.