Investigation on the high-temperature oxidation behavior and mechanism of laser-cladded Inconel625 coating at various temperatures

Abstract

This study examines the high-temperature oxidation behavior of laser-clad Inconel 625 coatings under different temperature and time conditions. The coating's microstructure, compositional elements, and oxidation products have been characterized through various analytical methods, including Scanning Electron Microscopy (SEM), Energy Dispersive Spectroscopy (EDS), X-Ray Diffraction (XRD), and Laser Confocal Microscopy. The experimental results showed that as the temperature increased in the isothermal oxidation process, the mass of the coatings increased, and the mass gain followed a parabolic relationship with oxidation time. The rate constant exhibited an exponential relationship with temperature. Both oxidation time and temperature had significant effects on the composition and formation of the oxide layer. At lower temperatures, the oxidation process is slow, with an oxidation weight gain of approximately 0.00053 mg/cm2. However, above 600 °C, the oxidation films began to form rapidly, increasing by 0.0169 mg/cm2. Moreover, as the temperature rose, different types of oxides formed at various temperature regimes. At 800 °C, the oxidation film had a thickness of approximately 3.75 μm and a weight gain of 1.19921 mg/cm2. At this point, oxides such as Cr2O3, Nb2O5, NiO, and spinel NiCr2O4 appeared. When the temperature reached 1000 °C, the oxidation film expanded to approximately 63.88 μm in thickness, with a weight gain of 3.5326 mg/cm2. The oxidation products at this temperature were Cr3O4 and spinels NiCr2O4, CrNbO4, NiNb2O6. These findings contribute valuable insights for understanding the dynamic behavior and assessing the service life of laser-clad nickel-based alloy coatings subjected to high-temperature oxidation corrosion.