ELECTROCHEMICAL PASSIVITY OF TITANIUM IMPLANTED WITH 1 MEV GOLD IONS

Titanium samples implanted with 1 MeV gold ions at doses of 8.8 x 10(1 4) ions/cm(2) to 1.5 x 10(16) ions/cm(2) were allowed to corrode freel y in 20 wt% sulfuric acid solution at 40 degrees C while continuously measuring the open circuit potential (OCP). Inductively Coupled Plasma (ICP), was used to calculate the corrosion rates from the corrosive s olutions. The time required for the OCP to drop to a value characteris tic of pure titanium in this solution (-718 mV(SCE)), was related to t he implant dose. Implantation of gold produced a passivating effect bu t the observed trend towards passivity persisted beyond the depth of i mplanted gold. Rutherford Backscattering (RBS) and Nuclear Resonance S cattering (NRS) spectra revealed the presence of oxygen atoms recoil-i mplanted slightly deeper than the gold. Scanning Tunneling Microscopy (STM) was used to study the differences in surface roughness before an d after ion implantation. (C) 1998 Elsevier Science Ltd. All rights re served.