Corrosion Behavior of MoSi<sub>2</sub> Coated Hastelloy X Utilized in Iodine -Sulfur Cycle for Hydrogen Production Application
Zain Hussain, Zuhair S. Khan, Ali Asghar, Nisar Ahmad, Wajahat Qasim, Altamash Shabbir
Abstract
Molybdenum di silicide (MoSi2) has lower mismatch of coefficient of thermal expansion (CTE) with Hastelloy X as compare to silicon carbide. So, MoSi 2 coatings can be a potential candidate to protect Hastelloy X against high temperature sulfuric acid. Herein, MoSi 2 thin films were deposited via electron beam physical vapor deposition (EBPVD) method. Corrosion behavior of MoSi 2 coated HX and bare HX was analyzed. Corrosion tests of bare Hastelloy X and coated samples was performed at different temperatures (60°C and 120°C) in 98% sulfuric acid using the weight-loss method. The morphology of pre and post corrosion test was also analyzed by using optical microscopy. Bare Hastelloy X showed a slight weight gain at 60°C and a weight loss at 120°C. The MoSi 2 coated Hastelloy X showed slight weight gain at 60°C and a weight loss at 120 °C. The weight gain is the result of oxides formation whereas, weight loss may be attributed to corrosion due to H+ ions. These findings were also accompanied by optical microscopy as corroded and very rough patches were evident for bare HX, whereas, for MoSi 2 coated samples, the coating was still intact.