Hydrogen desorption from sand-blasted and acid-etched titanium surfaces after glow-discharge treatment

Hydrogen desorption from argon plasma-treated titanium implants with a high surface roughness was studied. Implants with a high surface roughness have shown an increase in mechanical stability in bone tissue and a different behavior of osteoblasts in vitro. High surface roughness was produced by grit blasting and acid etching, resulting in an increase of the sub-surface hydrogen concentration and the formation of a titanium hydride. After an argon plasma treatment the surface oxide, which always covers titanum surfaces exposed to an oxygen-containing environment, and some of the hydrogen were sputtered away, decreasing the hydrogen concentration in the sub-surface region. Nuclear reaction analysis was used to determine the hydrogen concentration as a function of depth. The total amount of sub-surface (down to a depth of ≤ 2 μm) hydrogen remaining after plasma treatment decreased with increasing plasma intensity to below the levels observed in non-acid-etched samples (∼1–2%). Thermal desorption spectroscopy was used for desorption studies and investigation of H2 desorption activation energies. With a surface oxide present, the onset of hydrogen desorption is at ca 400°C, which is the oxide decomposition temperature in vacuum, with an activation energy of ca 2 eV/molecule of H2. After plasma treatment, that is, without surface oxide present, the onset of desorption was observed at ca 300°C and with an activation energy of ca 0.8 eV/molecule of H2, indicating a bulk diffusion-limited desorption. © 2000 John Wiley & Sons, Inc.