Palladium profiles in titanium treated by high-intensity plasma pulses

Palladium-alloyed surface layers in titanium were formed by deposition of palladium followed by treatment with high-intensity nitrogen plasma pulses (pulsed implantation doping, PID), capable of melting the substrate, and compared with those formed by the deposition by pulse erosion (DPE) process, in which erosion of palladium electrodes of the nitrogen plasma gun provided the deposit. As previously reported, the DPE-processed foils have exhibited excellent corrosion resistance to sulphuric acid. RBS and SIMS were used to examine the palladium profiles in order to gain insight into the palladium transport mechanism in molten titanium. A numerical program for solving heat diffusion equation was adapted to simulate palladium diffusion in molten titanium with depth-dependent diffusion duration accounted for. Corrosion tests in 0.1 M H2SO4 solution at 80 °C revealed major improvements in the corrosion resistance of titanium foil following either DPE or PID treatments, as indicated by weight change and open-circuit potential, although the surfaces treated by PID can undergo some detachment of coating material in the acid solution.