The effect of niobium doping on the corrosion resistance of stainless steel coatings

The corrosion behavior of stainless steel wear-resistant coatings present a key challenge limiting the performance of their products and commercial viability. In this work, the influence of elemental niobium (Nb) on the microstructure and corrosion behavior of stainless steel coatings was surveyed via morphology characterization and electrochemical workstation. The corrosion resistance mechanisms were investigated through first-principle calculations. The experimental results show that the diffusion of elements during the melting pool reaction promotes the precipitation of carbides, and energy dispersive spectroscopy (EDS) line scans indicated pronounced Nb segregation near the grain boundaries. The corrosion resistance of stainless steel coatings was obviously improved by Nb doping, and a highest self-corrosion potential of -0.760 V and a relatively low corrosion current density of 3.481 mu A. cm(-2) was observed. Furthermore, first-principle calculations revealed that Nb segregation raised the activity of iron (Fe) surfaces and enhanced the adsorption of oxygen (O), thereby promoting the formation of oxide films. This work demonstrated a Nb doping to promote the formation of an oxide film on the surface of stainless steel coatings, thereby improving the corrosion behavior of high-Nb stainless steel coatings.