Effect of vacuum annealing on the microstructure and tribological properties of Fe-40Al coatings deposited by atmospheric plasma spraying

摘要

The effects of vacuum annealing on the microstructure, phase evolution and tribological behavior of Fe-40Al coatings prepared by atmospheric plasma spraying have been investigated. The deposited specimens were annealed at different temperatures of 500, 650, 900 and 1000℃. Inspections by OM and SEM confirm that the diffusion layers with different thicknesses between the coatings and the substrates form at the annealing temperatures of 900 and 1000℃. Phase analysis by XRD indicated that the vacuum annealing at 650℃ allows the complete transformation of Fe(Al) solid solution into FeAl intermetallics with high long relative order degree. Generation of this transformation increases the coating's hardness. With further raising the annealing temperature, the left shift of diffraction peaks associated with the Al depletion is observed and crystalline size increases slightly. Tribological properties were studied by ball-on-disc friction test. Results showed that the friction coefficients of Fe-40Al coatings unfortunately increase after heat treatment. The wear mechanism is dominated by microfracture.