A comparison of elevated temperature erosion resistance of four new HVCC coatings with other wire sprayed coatings

The elevated temperature erosion resistance of four new high velocity continuous combustion (HVCC) arc-sprayed coatings was determined in a laboratory elevated temperature erosion tester. Test conditions attempted to simulate erosion conditions found at coal-fired boilers. One medium erosive bed ash material retrieved from an operating boiler was used as erodent. Test results were compared with 1018 low carbon steel and five existing wire sprayed coatings. It is found that when eroded by this bed ash, among the four new coatings the coating A (NiW) showed the highest erosion resistance, followed by the coating D (Al2O3–Ni), and the coating C (CrC–NiCr) was the last one. They improved erosion resistance 2–3 times as compared to 1018 steel. Coating A (NiW) had the same level erosion resistance as HVCC Fe27CrC, NiWBC, and NiWC coatings, it was much better than Fe39Cr5C and Armacor M coatings. In this work, the hardness of the coatings was not directly related to their erosion resistance. The morphology of specimens was examined. The erosion mechanism of coatings was also discussed.