Comparison of oxidation resistance and TGO zone morphology of NiCrAlY plasma sprayed coating and sintered alloy

The basic aim of presented article is related with comparison of internal morphology of atmospheric plasma sprayed NiCrAlY coating and sintered alloy obtained from the same feedstock powder. This part of investigations consisted characterization of phases composition and internal morphology characterization by SEM/EDS method. The second level of this comparing process is characterization of oxidation process in both cases. In order to properly perform these tests the top surfaces of sintered sample was sand blasted to the roughness level adequate to surface condition after plasma spraying process. The oxidation tests were performed at temperature 1000 and 1100°C during the time to 1000h of exposure in air. The specimens after determined intervals were moving out from the furnace and characterized by visual inspection of top surface as well as by SEM/EDS method and XRD analysis to characterization of phases generated during oxidation. The special emphasis was took on the characterization of TGO zone on cross sectioned samples where detailed assessment of oxides zone morphology was made by SEM/EDS method. The oxide thickness was measured as well with dividing of overall oxides zone thickness on the sublayers related with alumina and spinels formation.