Erosion-Corrosion Behavior of HVOF WC-Co Coating in Cl− and SO42− Containing Solutions

With the increasingly severe working condition, machine components need to expose to corrosive media including Cl− and SO42− containing environments. In this work, erosion-corrosion properties of HVOF sprayed conventional WC-12Co coating and CeO2 modified WC-12Co coating were tested in 3.5 wt.% NaCl solution and 1 mol/L H2SO4 solution. Mass loss rate was measured and worn surface were observed to investigate the effects of corrosive media on the erosion-corrosion resistance and mechanism. The results showed that the erosion-corrosion rate was higher at the beginning in 3.5 wt.% NaCl solution than that in 1 mol/L H2SO4 solution. With a longer time exposure, the absorption and osmosis of SO42− into the microcracks reduced the corrosion resistance and load-supporting capacity of the coatings, resulting in the worse erosion-corrosion resistance than that in NaCl solution. Corrosion-accelerated erosion mechanism dominated the erosion-corrosion process.