Improving high temperature corrosion resistance of Cr3C2–25NiCr coating by incorporating nano yttria-stablized zirconia

The hot corrosion behavior of Cr3C2–25NiCr composite coatings reinforced with nano yttria stabilized zirconia (YSZ) was evaluated under actual boiler conditions in a thermal power plant at 850 °C with cyclic thermal loading. The nano YSZ content was varied between 5 and 10 wt%, and the coatings were applied using the high-velocity oxy-fuel (HVOF) method. A comparative analysis of the impact of varying nano YSZ content on hot corrosion performance was conducted through weight change measurements, while corrosion products were characterized using X-ray diffraction, scanning electron microscopy, energy dispersive spectroscopy, and cross-sectional analysis. Results indicated that increasing nano YSZ content improved the corrosion resistance of the coatings at high temperatures in the boiler environment, with lower weight gain and the formation of protective oxide scales. Higher nano YSZ content in the coating matrix led to a decrease in corrosion rates during the hot corrosion tests. The corrosion rates for the 5 wt% and 10 wt% YSZ–Cr3C2–25NiCr coated specimens were 4.82 mpy and 3.45 mpy, respectively, reflecting reductions in corrosion rates of 80.79% and 89.26%. The addition of YSZ significantly decreased the corrosion rate, with further reductions observed as the YSZ content in the Cr3C2–25NiCr coating increased. XRD analysis confirmed the presence of Ni, Cr2O3, Cr3C2 and ZrO2–Y2O3 phases, indicating that YSZ particles remained in the coating matrix after exposure.