Electrochemical evaluation of pinhole defects in TiN films prepared by r.f. reactive sputtering

TiN films were deposited onto stainless steels by r.f. reactive sputtering and they contained more or less pinhole defects. The area ratio of pinhole defects was evaluated potentiodynamically with the ratio of critical passivation current density of TiN-coated and non-coated specimen in a deaerated 0.5 kmol/m3H2SO4 + 0.05 kmol/m3KSCN solution. The result coincided well with the true defect area ratio based on the optical micrographs before and after polarized anodically. Such electrochemical method was concluded to be a reliable evaluation technique for the pinhole defects of corrosion-resistible coating.