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 < or = 2 microm) hydrogen remaining after plasma treatment decreased with increasing plasma intensity to below the levels observed in non-acid-etched samples (approximately 1-2%). Thermal desorption spectroscopy was used for desorption studies and investigation of H(2) desorption activation energies. With a surface oxide present, the onset of hydrogen desorption is at ca 400 degrees C, which is the oxide decomposition temperature in vacuum, with an activation energy of ca 2 eV/molecule of H(2). After plasma treatment, that is, without surface oxide present, the onset of desorption was observed at ca 300 degrees C and with an activation energy of ca 0.8 eV/molecule of H(2), indicating a bulk diffusion-limited desorption.
Aronsson
B O
BO
Group for Applied Physics-Biomedical, University of Geneva, CH-1211 Geneva 4, Switzerland. bjorn-owe.aronsson@physics.unige.ch
Hjörvarsson
B
B
Frauchiger
L
L
Taborelli
M
M
Vallotton
P H
PH
Descouts
P
P
D000143:Acids; D001672:Biocompatible Materials; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D006859:Hydrogen / Q000737:chemistry*; D008855:Microscopy, Electron, Scanning; D019736:Prostheses and Implants; D012542:Scattering, Radiation; D013499:Surface Properties; D013816:Thermodynamics; D014025:Titanium / Q000737:chemistry; D014961:X-Ray Diffraction
D000143:Acids; D001672:Biocompatible Materials; D006859:Hydrogen; D014025:Titanium