Influence of Ni and Cr on the high-temperature wear resistance of FeNiCrAl coatings

Abstract

To reduce the brittleness of Fe-Al intermetallic compound coatings, FeNiCrAl powder wire for high-speed electric arc spraying is developed by integrating Ni and Cr into an Fe-Al intermetallic compound. The corresponding FeNiCrAl coating is prepared via high-speed electric arc spraying technology. A 3Cr13 coating is selected as the material for comparison, and the friction and wear properties of the two coatings are investigated from 200 °C to 800 °C. The friction coefficient variations and friction surface topography patterns of the two coatings are analyzed via X-ray diffractometry (XRD), hardness testing, and scanning electron microscopy (SEM) coupled with energy-dispersive spectroscopy (EDS). The phase compositions of the materials on the wear surfaces are analyzed via X-ray photoelectron energy spectrometry (XPS). The results show that after the friction coefficient of the FeNiCrAl coating reaches its peak value at 400 °C, it declines with increasing temperature, and its wear volume is less than that of the 3Cr13 coating. An XPS-based wear surface composition analysis and SEM wear scar topography results show that the FeNiCrAl coating produces not only Fe, Ni and Cr oxides but also Ni-Al intermetallic compounds during high-temperature friction. After the friction coefficient of the FeNiCrAl coating reaches its peak at 800 °C, more Al2O3 is formed around the Fe3Al, and these compounds aggregate to form a protective film that effectively prevents further intrusion of O ions. A dense oxide layer covers the wear surface, and the formation of hard-phase chemical compounds improves the wear resistance and bearing capability of the coating. Keywords: FeNiCrAl coating, High-speed electric arc spraying, Lamellar structure, Oxide, High-temperature friction