Chromite vs. magnetite as an erodent for coatings to be applied in steam turbines

Erosion of steam turbine components by magnetite, generated in the boiler and superheater tubes, can become an issue that affects the aerodynamics of the steam turbine and hence its efficiency. The use of coatings to protect the turbines from impact damage is gaining ground, which has prompted laboratory scale testing to help down select coatings for in-situ testing. This paper examines the pros and cons of using magnetite and chromite as erodents at room temperature. Although there was very little difference between the erosion rates of the uncoated NiCr alloy when eroded with the two different erodents, the coatings exhibited a large difference in erosion rates.