Abstract
The aim of this study is to investigate the role of zirconium (Zr) in HVOF coatings in order to formulate a high-temperature oxidation-resistant composition. Ni-20Cr coatings with and without 1% Zr additions were deposited on 347H boiler steel by HVOF spraying and their oxidation behavior was assessed at a temperature of 900 °C under cyclic conditions. Test specimens were also subjected to actual boiler environments to ascertain their erosion-corrosion behavior. Weight change measurements were used to determine high-temperature oxidation kinetics as well as erosion-corrosion resistance. The specimens were examined after each thermal cycle to observe physical changes and spallation in their oxide scales. It was found that the addition of Zr in the Ni-20Cr coating reduced the oxidation rate but had little effect on erosion-corrosion resistance.
