Corrosion and wear behavior of wire-arc sprayed Ni-based coatings

A new Ni-based cored wire was designed to prepare coatings by wire-arc spraying on SA 213-T2 substrate in order to solve the corrosion and wear problems in waste-to-energy (WTE) plants.According to X-ray diffractometry (XRD) and scanning electron microscopy (SEM) analysis,the as-deposited coatings with low content of oxide phases presented uniform and dense layered structure with porosity at around 3%.The wear resistance of the designed coating,about 7 times higher than that of the substrate,was measured by a rubber wheel abrisive testing machine.Thermo-gravimetric technique was used to investigate the high-temperature corrosion behavior of the coatings in molten salt environment (Na₂SO₄-10% NaCl) at 800℃ in a muffle furnace.As a result,the weight gain curve of the coating followed the parabolic law and presented extremely lower corrosion rates,comparing with that of the substrate,due to the formation of Cr₂O₃ and NiCr₂O₄ oxide films on the surface which prevented the diffusion or penetrating of corrosive species.Consequently, the developed coating could provide much better corrosion resistance properties than SA213-T2 substrate.