Corrosion resistant Ti-Pd surface alloys produced by high intensity pulsed plasma beams

Surface alloys of Ti-Pd have been produced on titanium foils using high intensity pulsed plasma beams in the pulsed implantation deposition mode, with nitrogen as the plasma gas. Unlike in previous work, the palladium was initially introduced into the titanium foil by ion implantation using a metal vapour vacuum arc (MEVVA) source. The corrosion resistance of the alloys was examined by exposure to 0.1 M H2SO4 solution at 80 °C. This environment has been employed previously to evaluate surface treatments for improving the corrosion resistance of titanium foils used in electron beam technology for removal of pollutants from flue gases. The foils reveal high corrosion resistance relative to untreated titanium. The improved behaviour is associated with the shift of the open-circuit potential into the range of passivity of titanium. During exposure to the test solution, palladium is enriched at the alloy surface, with generation of nanoparticles in association with anatase and possibly amorphous titania. The formation of the nanoparticles in a weakly adherent surface layer results in some loss of the palladium.