HIGH TEMPERATURE OXIDATION BEHAVIOUR OF DETONATION-GUN-SPRAYED Cr_3C_2-NiCr-CeO_2 COATINGS ON INCONEL-718 AT 900°C

摘要

The high temperature oxidation behavior of detonation-gun sprayed Cr_3C_2-NiCr coatings with and without 0.4 wt. % CeO_2 additive on Ni-based superalloy inconel-718 is comparatively discussed in the present study. Oxidation studies were carried out at 900°C for 100 cycles in air under cyclic heating and cooling conditions on bare and coated superalloys. The thermo-gravimetric technique was used to establish kinetics of oxidation. X-ray diffraction, SEM/EDAX and X-ray mapping techniques were used to analyze the oxidation products of bare and coated samples. The results indicate that Cr_3C_2-NiCr-CeO_2 coated specimen showed better oxidation resistance. The overall weight gain and parabolic rate constant of Cr_3C_2-NiCr-CeO_2 coated specimen was found to be lowest in the present study signifying that the addition of CeO_2 in Cr_3C_2-NiCr powder has contributed to the development of adherent and dense oxide scale on the coating at elevated temperature.