Erosion–corrosion of preoxidised Incoloy 800H in fluidised bed environments: effects of temperature, velocity, and exposure time

The effects of preoxidation as a potential protective measure for alloys exposed to erosion-corrosion have been evaluated for Incoloy 800H in laboratory simulated fluidised bed conditions. The performance of the specimens after exposure to such environments was estimated from weight change data, electron microscopy, and X-ray diffraction patterns. The results showed that, in 'corrosion dominated' conditions, i.e. at relatively high temperatures and low velocities, preoxidation was successful in reducing the erosion-corrosion of the underlying alloy. However, when the velocity was increased and the temperature decreased, preoxidation afforded only some short term protection to the alloy. In these more 'erosion-corrosion dominated' regimes, preoxidation delayed the incubation period for erosion-corrosion of the alloy, but, once the scale was removed, the erosion-corrosion rates were similar to those of the non-preoxidised alloys. Comparisons are made between the results of the present and other erosion-corrosion studies, to explain the distinctive pattern of alloy wastage in these environments.