HIGH-TEMPERATURE OXIDATION BEHAVIOR OF AN N5 NANOCRYSTALLINE COATING DEPOSITED BY ESD ON A NI-BASED SINGLE-CRYSTAL SUPERALLOY

Abstract

An N5 nanocrystalline coating was prepared on a Ni-based single-crystal superalloy by electrospark deposition. The morphologies, chemical composition, and phase constitution of the coating were analyzed by scanning electron microscopy (SEM), energy-dispersive spectrometry (EDS) and X-ray diffraction (XRD), respectively. The high-temperature oxidation resistance of the substrate and coating at 1100℃ was tested in a static isothermal oxidation experiment. The results show that the electrospark deposition coating with columnar crystal structure is composed of nanocrystalline; there is no elemental interdiffusion between the substrate and the coating, which effectively avoids decreasing the mechanical properties of the substrate alloy due to the interdiffusion. Migration and aggregation of a reactive element, Ta, in the nanocrystalline coating substantially improves oxide film adhesion