Wetting and interactions of Ni- and Co-based superalloys with different ceramic materials

In this work, a systematic study of the wetting behavior of two Ni-based and one Co-based superalloys, used, in particular, for the fabrication of turbine blades, is presented with reference to different ceramic substrates: sapphire, polycrystalline alumina, zirconia, and mullite. Wettability tests have been performed by means of the sessile drop method at 1500 A degrees C; the characterization of the interfaces between the molten drop and the substrates has been performed by SEM/EDS analysis in order to check the final characteristics of the solidified interfaces. The results are discussed in terms of chemical interactions in relation to the processing parameters and as a function of the surface and interfacial, morphological and energetic properties of the systems.