The creation of a NiCoCrAlY coating on the Ni-base superalloy using the Arc-PVD method And investigation of coating parameters effect on the microstructure, morphology and phase transformation of the coating

NiCoCrAlY coatings are applied through thermal spraying and physical vapor deposition (PVD) methods. The utilization of the PVD technique offers superior properties attributed to reduced porosities and impurities within the coating. In this study, NiCoCrAlY coating was applied on Mar-M-200 nickel-base superalloy using cathodic arc evaporation physical vapor deposition (Arc-PVD). Coatings were produced at bias voltages of -180 and -240 volts, along with arc currents of 80 and 110 amperes. Investigating the effects of negative substrate bias voltage and arc current on the microstructure, defect density, morphology, and phase transformation of the coatings was conducted using an optical microscope (OM) and scanning electron microscope (SEM) equipped with EDS analysis. The experimental findings indicated that increasing the arc current from 80 A to 110 A increased the coating thickness, whereas the thickness decreased at the higher bias voltages. The A110B180 sample exhibited a maximum coating thickness of 13.5 microns. Furthermore, an increase in the arc current resulted in the enlargement and increased number of macroparticles, reaching up to 50 microns. X-ray diffraction analysis of the coatings also demonstrated that the main phases of the coating included γ΄-Ni3Al, γ-Ni, and α-Co, and with increasing arc current from 80 A to 110 A, the intensity of γ΄-Ni3Al and γ-Ni peaks increased. By increasing the bias voltage from -180 V to -240 V, the crystallite sizes were enlarged. Conversely, elevating the arc current from 80 A to 110 A led to a reduction in crystallite size. In the A110B180 and A80B240 specimens, the smallest and largest crystallite sizes were measured at 18 and 24.2 microns, respectively. A comparative analysis of the coated samples revealed that the A110B240 coating exhibited a lower defect density and relatively greater thickness, so it can propose more favorable properties for industrial applications at elevated temperatures such as the hot section blade of the gas turbine.