2000 Volume 49 Issue 9 Pages 553-556
Titanium nitride (TiN) coatings for bearings and seals used in rotating machinery have been developed by the dynamic ion beam mixing (DM) process, in which Ti vapor deposition is combined with simultaneous nitrogen ion beam irradiation. Pinhole defects of TiN coatings on a stainless steel were investigated electrochemically in a 0.5kmol·m-3 H2SO4+0.05kmol·m-3 KSCN solution at 298K. A TiN film with a compositional ratio of N/Ti=0.8 has a single phase TiN structure and the preferred orientation of TiN (111) plane. The critical current density for passivation, icrit, of TiN-coated SUS 304 stainless steel decreased with increasing film thickness. The defect area ratio of TiN coatings was evaluated by comparing the icrit of TiN-coated specimen with that of non-coated specimen, and the ‘true’ defect area ratio was also evaluated by optical microscopy after anodic polarization tests. Such electrochemical methods was proved to be very effective for the quantitative evaluation of pinhole defects in corrosion-resistant coatings.
