Erosion-corrosion of thermal spray coatings

Nine thermal spray coatings on mild steel, including hard tungsten carbide-cobalt and softer, more ductile metals that are supposed to provide wear protection, were eroded-corroded at elevated temperature using 250 μm fluidized bed combustor bed material and quartz particles. It was found that all the coatings had lower material wastage rates than the base metal, 1018 steel. When the coatings were eroded by bed material particles, the ductile metal coatings had the same or lower material wastage rates than the harder tungsten carbide-cobalt. When quartz particles were used as the erodent, the ratio of the target hardness to the hardness of the erodent particles appeared to play a significant role in the erosion-corrosion behavior of the thermal spray coatings. The relationship between coating composition and morphology and the material wastage was determined.