Surface characteristics of porous titanium implants fabricated by environmental electro-discharge sintering of spherical Ti powders in a vacuum atmosphere

A single pulse of 1.5 kJ, from a 300 μF capacitor, was applied to 0.7 g of atomized spherical Ti powders to produce a porous-surfaced implant compact by environmental electro-discharge sintering (EEDS) in a low vacuum atmosphere. A solid core was formed by a discharge in the middle of the compact which is surrounded by a porous layer. Ti, C and O were the main constituents, with a smaller amount of N. The EEDS implant surface was lightly oxidized and was primarily in the form of TiO2. The lightly etched sample showed the surface form of metallic Ti, indicating that the EEDS breaks down the oxide film of the as-received Ti powder during the discharge process. However, a small amount of N in the form of nitride, which was also found in the as-received Ti powder, was not changed in its chemical state by EEDS.