A study of the erosion-corrosion behavior of nano-Cr2O3 particles reinforced Ni-based composite alloying layer in aqueous slurry environment

To investigate the role of nano-Cr2O3 particles on the erosion-corrosion behavior of composite alloying layer, a nano-Cr2O3 particles reinforced Ni-based composite alloying layer was fabricated onto AISI 316L stainless steel (SS) via a duplex surface treatment, consisting of Ni/nano-Cr2O3 predeposited by electric brush plating, and subsequent Ni-Cr-Mo-Cu multi-element surface alloying by a double glow process. The microstructure and composition of composite alloying layer were characterized by means of X-ray diffraction (XRD), transmission electron microscope (TEM), scanning electron microscopy (SEM) and energy-dispersive x-ray spectroscopy (EDS). The results indicated that the added nano-Cr2O3 particles were homogeneously distributed in the alloying layer and didn't decompose or react with surrounding metal matrix under alloying temperature (1000 °C) condition. A series of electrochemical techniques, including potentiodynamic polarization, open circuit potential (OCP), current response and electrochemical impedance spectroscopy (EIS), was employed to evaluate the corrosion properties of nano-Cr2O3 particles reinforced composite alloying layer under various hydrodynamic conditions. Erosion-corrosion tests were conducted in 3.5% NaCl solution plus sand particles with varying concentration (50-150 g/L) at different rotation speeds (600-1100 rpm). To estimate the influence of the nature of different nano-particles on the erosion-corrosion property of composite alloying layer, nano-SiO2 particles reinforced Ni-based composite alloying layer, single alloying layer and 316L SS was selected as the reference materials for all the corrosion and erosion-corrosion tests.