Chlorine-Induced High-Temperature Corrosion and Erosion Behavior of Sintered Ni–Cr Composites

The microstructural behavior of sintered Ni-based composites was evaluated to understand the performance of the composites in corrosive and abrasive environments. Ni–Cr–Si, Cr₃C₂–Ni–Cr, Ni–Cr–Ti, and Ni–Cr–Mo composites were synthesized using powder metallurgy at 1350 °C for 1 h. Field emission scanning electron microscopy (FE-SEM) equipped with electron diffraction (EDS) was utilized to analyze the microstructural evolution on both the surface and cross section after exposure. Phase identification was conducted using X-ray diffraction (XRD). Mechanical and tribological properties were assessed via surface hardness testing and erosion evaluation, respectively. Corrosion testing was performed under salt vapor conditions at 600 °C for 100 h, while erosion testing was conducted at a 90° impingement angle and 40 kPa erodent pressure. Among the composites, Ni–Cr–Mo demonstrated excellent resistance to corrosion and erosion, with values of 5.90 × 10–5 mm/y and 0.955 mg/g, respectively. It is attributed to dendritic nickel matrix and eutectic micro-Mo₂C, which also enhanced surface hardness to a value of 274 HV. In contrast, chromium carbide phases present in Ni–Cr–Si, Cr₃C₂-Ni–Cr, and Ni–Cr–Ti contributed to localized fracture and cracking. These results highlight Ni–Cr–Mo as a promising candidate for high-performance applications in harsh environments.