Abstract:Three types of FeMnCrAl/Cr₃C₂ coatings with different Al content were deposited on 20^# steel substrates by the high velocity arc spraying (HVAS) process. Surface microstructures of the coatings were analyzed by optical microscopy (OM) and X-ray diffractometry (XRD). High temperature erosion (HTE) tests were performed in an erosion tester at different impact angles. The surface morphologies of the eroded coatings were observed on a field emission scanning electron microscope(FE-SEM). The laminated structure is found on all the prepared coatings with the porosity and oxide fraction in the coatings decreasing with the Al content from 0 to 15% (mass fraction). Sample FA3 with 15% Al, possessing the lowest porosity and oxide fraction, has the best HTE resistance, which demonstrates that Al addition can improve the HTE resistance of the coatings. The erosion rate of sample FA1 exhibits a maximum value at 90˚ impact angle. The maximum erosion rates of both FA2 and FA3 samples appear in the range of 60˚−90˚ impact angles. Erosion loss of the coatings occurs through brittle breaking, cutting and fatigue spalling.

Key words: high velocity arc spraying (HVAS); coating; erosion mechanism; high temperature erosion(HTE)