Erosion–corrosion of iron and nickel alloys at elevated temperature in a combustion gas environment

This paper reports on the results of a study that compares the erosion–corrosion behavior of a variety of alloys (Fe–2¼Cr–1Mo, 304 SS, 310 SS, Incoloy 800, Haynes 230 and a Fe3Al) in a combustion environment. Advanced coal combustion environments, with higher temperatures, are driving re-examination of traditional and examination of new alloys in these hostile environments. In order to simulate conditions in advanced coal combustion boilers, a special erosion apparatus was used to allow for impingement of particles under a low abrasive flux in a gaseous environment comprised of 20% CO2, 0.05% HCl, 77% N2, 3% O2, and 0.1% SO2. Tests were conducted at room temperature and 700 °C with∼270 μm silica, using an impact velocity of 20 m/s in both air and the simulated combustion gas environment. The erosion–corrosion behavior was characterized by gravimetric measurements and by examination of the degraded surfaces optically and by scanning electron microscopy (SEM). At room temperature most of the alloys had similar loss rates. Not surprisingly, at 700 °C the lower chrome-iron alloy had a very high loss rate. The nickel alloys tended to have higher loss rates than the high chrome austenitic alloys.