Enhancing High Temperature Erosion-Corrosion Resistance of SA213-T91 Steel by HVOF Sprayed Nano-structured Ni-20Cr Coating

摘要

Ni-20Cr nano-crystalline powder was synthesized by the investigators using ball milling technique. The synthesized powder was deposited on T91 boiler steel by high-velocity oxy-fuel (HVOF) spraying process under the set parameters. The uncoated and coated specimens were exposed to superheater zone of a coal fired boiler at 750°C for 15 cycles under cyclic conditions, to ascertain the erosion-corrosion (E-C) behavior. Each cycle comprised of 100 hour of heating in the boiler followed by 1 hour cooling. The kinetics of E-C was established using weight change and thickness loss of the samples. The exposed samples were studied using different characterization techniques, which included SEM/EDS and XRD analysis. The coating was found to be successful to reduce the erosion-corrosion rate of the steel by 85% moreover the investigated nano-structured Ni-20Cr coating has reduced the erosion-corrosion rate of the steel by 58% in comparison to its conventional counterpart.