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.