Effect of different simulated metal dusting environments on austenitic Alloys 602CA and 800

Abstract

Metal dusting processes and associated filamentous carbon formation were studied on austenitic Alloys 602CA and 800 after exposure to 18.9%CO-79.1%H2-2%H2O and 25%CO-70%H2-5%H2O (vol.%) gas mixtures at 650°C. The alloys were studied by visual examination, optical microscopy, scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX), Raman spectroscopy and X-ray diffraction (XRD). Alloy 602CA was more resistant to metal dusting than Alloy 800. SEM imaging of the surfaces showed that Alloy 800 suffered metal attack at 168 h, whereas Alloy 602CA suffered minor attack only after 336 h. Coke deposits increased on Alloy 800 with increased exposure, and there was little coke deposited on Alloys 602CA from after 336 h. Raman spectroscopy confirmed graphite by the characteristic D- and G-peaks.